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Sample records for acid etched microtexture

  1. Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture.

    PubMed

    Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E; Soballe, Kjeld

    2008-11-01

    Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3-44.6%)] compared to the control [18.4% (15.6-20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface. PMID:18186059

  2. Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture

    PubMed Central

    Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E.; Soballe, Kjeld

    2013-01-01

    Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3–44.6%)] compared to the control [18.4% (15.6–20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface. PMID:18186059

  3. Nanotexturing process on microtextured surfaces of silicon solar cells by SF6/O2 reactive ion etching.

    PubMed

    Ji, Hyungyong; Choi, Jaeho; Lim, Gyoungho; Parida, Bhaskar; Kim, Keunjoo; Jo, Jung Hee; Kim, Hong Seub

    2013-12-01

    We investigated a nanotexturing process on the microtextured surface of single crystalline silicon solar cell by the reactive ion etching process in SF6/O2 mixed gas ambient. P-type Si wafer samples were prepared using a chemical wet etching process to address saw damage removal and achieve microtexturing. The microtextured wafers were further processed for nanotexturing by exposure to reactive ions within a circular tray of wafer carrier containing many small holes for uniform etching. As the dry etching times were increased to 2, 4 and finally to 8 min, surface structures were observed in a transition from nanoholes to nanorods, and a variation in wafer color from dark blue to black. The surface nanostructures showed a lowered photoreflectance and enhanced quantum efficiency within the visible light region with wavelengths of less than 679 nm. The nanohole structure etched for 2 min showed enhanced conversion efficiency when compared to the bare sample; however, the nanorod structure etched for 8 min exhibited the decreased efficiency with a reduced short circuit current, indicating that the surface nanostructural damage with the enlarged nanoperimetric surface area is sensitive to surface passivation from the surface recombination process.

  4. Human Mesenchymal Stem Cell Morphology and Migration on Microtextured Titanium

    PubMed Central

    Banik, Brittany L.; Riley, Thomas R.; Platt, Christina J.; Brown, Justin L.

    2016-01-01

    The implant used in spinal fusion procedures is an essential component to achieving successful arthrodesis. At the cellular level, the implant impacts healing and fusion through a series of steps: first, mesenchymal stem cells (MSCs) need to adhere and proliferate to cover the implant; second, the MSCs must differentiate into osteoblasts; third, the osteoid matrix produced by the osteoblasts needs to generate new bone tissue, thoroughly integrating the implant with the vertebrate above and below. Previous research has demonstrated that microtextured titanium is advantageous over smooth titanium and PEEK implants for both promoting osteogenic differentiation and integrating with host bone tissue; however, no investigation to date has examined the early morphology and migration of MSCs on these surfaces. This study details cell spreading and morphology changes over 24 h, rate and directionality of migration 6–18 h post-seeding, differentiation markers at 10 days, and the long-term morphology of MSCs at 7 days, on microtextured, acid-etched titanium (endoskeleton), smooth titanium, and smooth PEEK surfaces. The results demonstrate that in all metrics, the two titanium surfaces outperformed the PEEK surface. Furthermore, the rough acid-etched titanium surface presented the most favorable overall results, demonstrating the random migration needed to efficiently cover a surface in addition to morphologies consistent with osteoblasts and preosteoblasts. PMID:27243001

  5. Orthodontic bonding to acid- or laser-etched prebleached enamel

    PubMed Central

    Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

    2013-01-01

    Objective Bonding forces of brackets to enamel surfaces may be affected by the procedures used for bleaching and enamel etching. The aim of this study was to investigate the bonding strength of orthodontic brackets to laser-etched surfaces of bleached teeth. Methods In a nonbleached control group, acid etching (group A) or Er:YAG laser application (group B) was performed prior to bracket bonding (n = 13 in each group). Similar surface treatments were performed at 1 day (groups C and D; n = 13 in each subgroup) or at 3 weeks (groups E and F; n = 13 in each subgroup) after 38% hydrogen peroxide bleaching in another set of teeth. The specimens were debonded after thermocycling. Results Laser etching of bleached teeth resulted in clinically unacceptable low bonding strength. In the case of acid-etched teeth, waiting for 3 weeks before attachment of brackets to the bleached surfaces resulted in similar, but not identical, bond strength values as those obtained with nonbleached surfaces. However, in the laser-etched groups, the bonding strength after 3 weeks was the same as that for the nonbleached group. Conclusions When teeth bleached with 38% hydrogen peroxide are meant to be bonded immediately, acid etching is preferable. PMID:23814709

  6. In Vitro Evaluation of Microleakage Around Orthodontic Brackets Using Laser Etching and Acid Etching Methods

    PubMed Central

    Toodehzaeim, Mohammad Hossein; Yassaei, Sogra; Karandish, Maryam; Farzaneh, Sedigeh

    2014-01-01

    Objective: path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques. Materials and Method: The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1), laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2), and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3). After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test. Results: For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups. Conclusion: According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding. PMID:25628661

  7. Dental zirconia can be etched by hydrofluoric acid.

    PubMed

    Sriamporn, Tool; Thamrongananskul, Niyom; Busabok, Chumphol; Poolthong, Sushit; Uo, Motohiro; Tagami, Junji

    2014-01-01

    The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25°C for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80°C for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25°C for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface.

  8. Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

    PubMed Central

    Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

    2014-01-01

    Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG) laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under ×10 magnification and adhesive remnant index (ARI) score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa) was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa) (P = 0.41). There was no significant difference in the ARI scores between two groups (P = 0.08). However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching. PMID:25097641

  9. Bonding to enamel/dentin etched with phosphoric and hydrofluoric acids.

    PubMed

    Barghi, Nassar; Covington, Kendra; Fischer, Dan E; Herbold, Edward T

    2004-10-01

    Repairing porcelain intraorally allows clinicians to provide their patients with a conservative means of treating fractured or debonded restorations. This requires, however, the etching of both porcelain and tooth structure with etching solutions. It is thus relevant to understand the effect that different etching procedures have on shear bond strengths of composite resins to both dentin and enamel structures. Based on the results of this investigation, the authors recommend isolation of tooth structures and the etching of porcelain with hydrofluoric acid.

  10. Bond strengths of all-ceramics: acid vs laser etching.

    PubMed

    Gökçe, B; Ozpinar, B; Dündar, M; Cömlekoglu, E; Sen, B H; Güngör, M A

    2007-01-01

    Various applications of dental lasers on dental materials have been proposed for surface modifications. This study evaluated whether laser etching could be an alternative to hydrofluoric acid (HF) etching. One hundred and ten lithia-based all-ceramic specimens (Empress 2) (R: 4 mm, h: 4 mm) were prepared and divided into five groups (n = 22/group). The untreated specimens served as the control, while one of the experimental groups was treated with 9.5% HF for 30 seconds. Three remaining test groups were treated with different laser (Er:YAG laser wavelength:2940 nm, OpusDent) power settings: 300 mJ, 600 mJ and 900 mJ. Ten specimens in each group were luted to the other 10 specimens by a dual-curing cement (Variolink II), and shear-bond strength (SBS) tests were performed (Autograph, crosshead speed: 0.5 mm/minute). The results were statistically analyzed (Kruskal Wallis and Mann Whitney-U, alpha = .05). Mean SBS (MPa) were 31.9 +/- 4.0, 41.4 +/- 4.3, 42.8 +/- 6.2, 29.2 +/- 4.5 and 27.4 +/- 3.8 for the control and HF, 300, 600 and 900 mJ groups, respectively. SEM evaluations revealed different surface morphologies depending on the laser parameters. The differences between HF acid and 300 mJ, when compared with the control, 600 and 900 mJ groups, were significant (p < .05). The 300 mJ laser group exhibited the highest shear-bond strength values, indicating that laser etching could also be used for surface treatments.

  11. Effect of acid etching time and technique on bond strength of an etch-and-rinse adhesive.

    PubMed

    Faria-e-Silva, André L; Silva, João L; Almeida, Thauanna G; Veloso, Francielle B; Ribeiro, Sandra M; Andrade, Tiago D; Vilas-Boas, Bruna V; Martins, Marisa C; Menezes, Murilo S

    2011-01-01

    The aim of this study was to evaluate the effect of acid etching time and technique on bond strength of a two-step etch-and-rinse adhesive system to dentin and enamel. Thirty human third molars were mesio-distally sectioned, parallel to the long axis of each tooth, in two halves. Buccal/lingual surfaces were abraded to obtain both flat exposed enamel and dentine. The etchant was applied with and without the use of dispensing tips provided by manufacturer. When the tip was not used, the etchant was agitated (active) over the substrate or left undisturbed (passive). The etchings were done for 15 or 30s. After rinsing the acid, the adhesive XP Bond (Dentsply Caulk, Milford, DE, USA) was applied and light-cured. Resin composite cylinders were built up on dentin and enamel substrates. A shear load was applied to the samples at a crosshead speed of 0.5 mm/min until failure. Data were statistically analyzed by three-way ANOVA and Tukey test (alpha = 0.05). There was no difference between the etching techniques in bonding to enamel. Application with the tip or active without the tip promoted higher bond strength to dentin than passive application. Extending the etching time reduced the bond strength to dentin and did not alter the values for enamel. The passive application without tips produced the lowest bond strength when the etchant was applied for 15s. All techniques demonstrated similar values for application during 30s. The acid etching time and technique significantly influence the bond strength of etch-and-rinse adhesive to dentin. PMID:22010410

  12. [Recovery of fluoride orally on the acid-etched tooth surface].

    PubMed

    Tanaka, M; Kobayashi, K; Okumura, F; Ono, H; Kadoma, Y; Imai, Y

    1989-01-01

    There are many reports concerning the recovery phenomenon of acid-etched enamel surfaces of teeth. Many studies of surface hardness, acid resistant properties, radiolucency, and surface morphology suggest that orally the acid-etched enamel reverts to a state nearly similar to that of the intact enamel before the acid etching. This study was conducted in order to verify the existence of the recovery phenomenon of fluoride on acid-etched enamel, because the surface layer of a high fluoride concentration is removed from the surface enamel by the acid etching. The deciduous upper central incisors of both sides were etched with phosphoric acid. The fluoride content of one incisor was measured immediately after the etching and that of the opposite incisor was also measured in vivo after 4 weeks, during which period no special fluoride was used. The fluoride content of the tooth surface in the mouth after 4 weeks significantly increased by about 50 ppm, when compared to that immediately after the acid etching. No significant relationship was found between the fluoride increase and the fluoride concentration of the patients' saliva and drinking water which were the probable supply sources of fluoride for the teeth. No relationship was found between the fluoride increase and the number of second deciduous molars with defects or fillings, which was counted as a measure of the patient's susceptibility to caries.

  13. A Comparison of Shear Bond Strengths of Metal and Ceramic Brackets using Conventional Acid Etching Technique and Er:YAG Laser Etching

    PubMed Central

    Yassaei, Sogra; Fekrazad, Reza; Shahraki, Neda; Goldani Moghadam, Mahdjoube

    2014-01-01

    Background and aims. The aim of this study was to compare shear bond strength (SBS) of metal and ceramic brackets bonded to enamel using acid versus Er:YAG laser etching. Materials and methods. Eighty premolars were divided into 4 groups: AM (acid etching/ metal brackets), AC (acid etching/ ceramic brackets), LM (laser etching/ metal brackets) and LC (laser etching/ ceramic brackets). Enamel condition-ing was done using acid in AC and AM and Er:YAG laser in LC and LM. Brackets were debonded with a Dartec machine and the SBSs were determined. Adhesive remnant index was evaluated under a stereomicroscope. Two additional teeth were conditioned with acid and laser for scanning electron microscopy examination. Comparisons of SBS value were done by ANOVA test. Results. statistical analyses showed that SBSs of acid groups were significantly higher than that of laser groups, but dif-ferences between SBS values of AC/ AM and LC/LM were not significant. SEM examination revealed different etching pattern. Conclusion. Low power Er:YAG laser etching offers clinically acceptable SBS which besides its other superiorities to acid etching can be an appropriate alternative for bonding of ceramic brackets. PMID:25024836

  14. An in vitro comparison of acid etched vs. nonacid etched dentin bonding agents/composite interfaces over primary dentin.

    PubMed

    Donly, K J; Keprta, M; Stratmann, R G

    1991-01-01

    The purpose of this study was to evaluate acid etchant penetration on dentin bonding agents and its effect on the composite resin bond strength. Forty primary molars were mounted, then the buccal and lingual surfaces were prepared into dentin. The teeth were divided into four groups of 10, and four dentin bonding agents were placed on the buccal and lingual surfaces of exposed dentin, as recommended by the manufacturers. One surface of each tooth was etched randomly for 60 sec with 35% phosphoric acid. A standardized tube of composite resin was placed on each dentin surface and polymerized for 60 sec. The tubes were sheared off with an Instron Testing Machine. The specimens then were sectioned to be examined by a scanning electron microscope (SEM). Results demonstrated shear strengths (kg/cm2) of etched (e) and unetched (u) bonding agents to be: Scotchbond (3M Dental Products, St. Paul, MN) (e) 116.7 +/- 37.7, (u) 116.7 +/- 63.0; Scotchbond 2 (3M Dental Products, St. Paul, MN) (e) 112.0 +/- 40.6, (u) 127.0 +/- 38.7; Gluma (Bayer Dental, Leverkusen, Federal Republic of Germany) (e) 80.1 +/- 21.7, (u) 107.0 +/- 16.6; Bondlite (Kerr Manufacturing Co., Romulus, MI) (e) 53.4 +/- 34.7, (u) 79.1 +/- 26.3. The analysis of variance (ANOVA) demonstrated a statistical significance in variance at the P less than 0.001 level. Scheffe's Test indicated no statistically significant differences between the bond strengths of etched vs. nonetched dentin bonding agents and composite resin. SEM evaluation indicated that the acid etchant penetrated none of the dentin bonding agents. PMID:1886824

  15. Morphological categorization of acid-base resistant zones with self-etching primer adhesive systems.

    PubMed

    Inoue, Go; Nikaido, Toru; Sadr, Alireza; Tagami, Junji

    2012-01-01

    This study investigated the influence of the composition of self-etching primer adhesive systems on the morphology of acid-base resistant zones (ABRZs). One-step self-etching primer systems (Clearfil Tri-S Bond, G-Bond, and One-Up Bond F Plus) and two-step self-etching primer systems (Clearfil SE Bond, Clearfil Protect Bond, UniFil Bond, and Mac Bond II) were used in this study. Each adhesive was applied on prepared dentin disk surfaces, and a resin composite was placed between two dentin disks. All resin-bonded specimens were subjected to acid-base challenge. Observation under a scanning electron microscope (SEM) revealed the creation of an ABRZ adjacent to the hybrid layer for all the self-etch primer adhesive systems, even when non-fluoride releasing adhesives were used. The presence of fluoride in two-step self-etching adhesive significantly increased the thickness of ABRZ created. Results suggested that an ABRZ was created with the use of self-etching primer adhesive systems, but its morphology differed between one-and two-step self-etching primer adhesive systems and was influenced by fluoride release activity.

  16. Early odontoblastic layer response to cavity preparation and acid etching in rats.

    PubMed

    Nemeth, Lidija; Erman, Andreja; Stiblar-Martincic, Draga

    2006-01-01

    The aim of this study was to establish the early odontoblastic layer response and quantitatively to estimate the number of odontoblasts after cavity preparation with and without acid etching. Half of 56 cavities prepared on rats' first upper molars were acid etched. Qualitative and morphometric analyses were made on histological and ultrathin sections 5 min, 6 h, 24 h and 72 h post-operatively. Under the etched cavity, a greater disarrangement of odontoblasts was found, modifications in nuclear shape and condensed chromatin 5 min. post-operatively. An additional reduction of odontoblast number was detected and an increase of aspirated cell number 5 min, 6 h and 24 h post-operatively, pronounced hyperaemia 6, 24 and 72 hours post-operatively and increased odontoblast number 72 hours post-operatively, compared to unetched cavities. In conclusion, injury to the odontoblastic layer was greater, but numerical renewal of the odontoblastic layer began earlier in etched cavities compared to unetched cavities. PMID:17044256

  17. Ion beam microtexturing and enhanced surface diffusion

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1982-01-01

    Ion beam interactions with solid surfaces are discussed with particular emphasis on microtexturing induced by the deliberate deposition of controllable amounts of an impurity material onto a solid surface while simultaneously sputtering the surface with an ion beam. Experimental study of the optical properties of microtextured surfaces is described. Measurements of both absorptance as a function of wavelength and emissivity are presented. A computer code is described that models the sputtering and ion reflection processes involved in microtexture formation.

  18. Spatial statistical characterization and simulation of microtexture

    NASA Astrophysics Data System (ADS)

    Sparkman, Daniel Murray

    Microtexture has been found to affect the macro-scale behavior of materials in many ways. For example, in titanium alloys, microtexture regions are preferential sites of fatigue crack formation. Also, yield strength and fatigue life have been shown to be affected by the microtexture. Despite the consensus on the importance of the presence of microtextured regions in polycrystals, no standard methods exist to statistically characterize these regions. The only published method for simulation of microtexture does not take into account the spatial nature of the regions. In this work, it is proposed that microtexture may be characterized with spatial statistics. Methods were also developed for simulation of microtexture. Characterization of microtexture regions allows for quantitative comparison of different materials and different thermal-mechanical processing routes. Simulation of microtexture regions allows for prediction of bulk material properties from micro-scale models. Combining the characterization and simulation methods proposed in this work will allow for optimization of material processing for improved material properties and performance.

  19. Comparative Evaluation of the Etching Pattern of Er,Cr:YSGG & Acid Etching on Extracted Human Teeth-An ESEM Analysis

    PubMed Central

    Mazumdar, Dibyendu; Ranjan, Shashi; Krishna, Naveen Kumar; Kole, Ravindra; Singh, Priyankar; Lakiang, Deirimika; Jayam, Chiranjeevi

    2016-01-01

    Introduction Etching of enamel and dentin surfaces increases the surface area of the substrate for better bonding of the tooth colored restorative materials. Acid etching is the most commonly used method. Recently, hard tissue lasers have been used for this purpose. Aim The aim of the present study was to evaluate and compare the etching pattern of Er,Cr:YSGG and conventional etching on extracted human enamel and dentin specimens. Materials and Methods Total 40 extracted non-diseased teeth were selected, 20 anterior and 20 posterior teeth each for enamel and dentin specimens respectively. The sectioned samples were polished by 400 grit Silicon Carbide (SiC) paper to a thickness of 1.0 ± 0.5 mm. The enamel and dentin specimens were grouped as: GrE1 & GrD1 as control specimens, GrE2 & GrD2 were acid etched and GrE3 & GrD3 were lased. Acid etching was done using Conditioner 36 (37 % phosphoric acid) according to manufacturer instructions. Laser etching was done using Er,Cr:YSGG (Erbium, Chromium : Ytrium Scandium Gallium Garnet) at power settings of 3W, air 70% and water 20%. After surface treatment with assigned agents the specimens were analyzed under ESEM (Environmental Scanning Electron Microscope) at X1000 and X5000 magnification. Results Chi Square and Student “t” statistical analysis was used to compare smear layer removal and etching patterns between GrE2-GrE3. GrD2 and GrD3 were compared for smear layer removal and diameter of dentinal tubule opening using the same statistical analysis. Chi-square test for removal of smear layer in any of the treated surfaces i.e., GrE2-E3 and GrD2-D3 did not differ significantly (p>0.05). While GrE2 showed predominantly type I etching pattern (Chi-square=2.78, 0.05

    0.10) and GrE3 showed type III etching (Chi-square=4.50, p<0.05). The tubule diameters were measured using GSA (Gesellschaft fur Softwareentwicklung und Analytik, Germany) image analyzer and the ‘t’ value of student ‘t’ test was 18.10 which was a

  20. Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

    PubMed

    Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

    2012-01-01

    Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

  1. The removal torque of titanium screw inserted in rabbit tibia treated by dual acid etching.

    PubMed

    Cho, Sung-Am; Park, Kyung-Tae

    2003-09-01

    Chemical acid etching alone of the titanium implant surface have the potential to greatly enhance osseointegration without adding particulate matter (e.g. TPS or hydroxyapatite) or embedding surface contaminants (e.g. grit particles). The aims of the present study were to evaluate any differences between the machined and dual acid etching implants with the removal torque as well as topographic analysis. A total of 40 custom-made, screw-shaped, commercially pure titanium implants with length of 5 mm and an outer diameter of 3.75 mm were divided into 4 groups, 10 screws in each, and chemical modification of the titanium implant surfaces were achieved using HF and HCl/H(2)SO(4) dual acid etching. The first exposure was to hydrofluoric acid and the second was to a combination of hydrochloric acid and sulfuric acid. The tibia metaphysics was exposed by incisions through the skin, fascia, and periosteum. One implant of each group was inserted in every rabbit, 2 in each proximal tibia metaphysics. Every rabbit received 3 implants with acid etched surfaces and 1 implant with a machined surface. Twelve weeks post-surgically, 7 rabbits were sacrificed, Subsequently, the leg was stabilized and the implant was removed under reverse torque rotation with a digital torque gauge (Mark-10 Corporation, USA) (Fig. 1). Twelve weeks after implant placement, the removal torque mean values were the dual acid etched implants (24%HF+HCl/H(2)SO(4), group C) required a higher average force (34.7 Ncm), than the machined surface implants (group A) (p=0.045) (Mann-Whiteney test). Scanning electron micrographs of acid etching of the titanium surface created an even distribution of very small (1-2 microm) peaks and valleys, while machining of the titanium surface created typical microscopically grooved surface characteristics. Nonetheless, there was no difference in surface topography between each acid etched implant groups. Therefore, chemically acid etching implant surfaces have higher

  2. Immunohistochemical and ultrastructural evaluation of the effects of phosphoric acid etching on dentin proteoglycans.

    PubMed

    Oyarzún, A; Rathkamp, H; Dreyer, E

    2000-12-01

    It has been reported that phosphoric acid (PA) produces structural and molecular alterations in dentin collagen fibrils; however, no relevant information exists on the influence of etching with PA on dentin non-collagenous macromolecules. The present study investigated, by immunohistochemistry and ultrastructural histochemistry, the behavior of dentin proteoglycans (PG) after etching human dentin samples with 35% PA gel (thickened with colloidal silica) or with a 35% PA liquid for 15, 30 and 120 s. Immunolabeling with a mouse monoclonal anti-chondroitin sulfate antibody demonstrated that glycosaminoglycans (GAG) were preserved within dentinal tubules opened to the surface after etching with PA gel. In addition, the cationic tracer polyethyleneimine, used for the ultramicroscopic localization of PG anionic sites, revealed that treatment of dentin samples with PA gel preserved the polyanionic peritubular PG in the etched area. On the other hand, etching with the PA liquid produced loss of peritubular GAG and PG anionic sites in the etched dentin surface. The results obtained indicated that similar concentrations of PA in gel or liquid formulations differently affect the organization of dentin PG. The clinical significance of these in vitro findings and the structural and molecular interactions of dentin PG with adhesive systems are still unknown.

  3. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations.

    PubMed

    Bona, Alvaro Della; Pinzetta, Caroline; Rosa, Vinícius

    2007-06-01

    The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24 degrees C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  4. In vivo Acid Etching Effect on Bacteria within Caries-Affected Dentin

    PubMed Central

    Gu, F.; Bresciani, E.; Barata, T.J.; Fagundes, T.C.; Navarro, M.F.; Dickens, S.H.; Fenno, J.C.; Peters, M.C.

    2010-01-01

    Acid etching procedures may disrupt residual bacteria and contribute to the success of incomplete caries removal followed by adhesive restoration. This study evaluated the in vivo effect of acid etching on cariogenic bacterial activity within affected dentin after minimally invasive treatment of caries lesions. Twenty-eight carious permanent teeth received standardized selective caries removal and random acid etch treatment (E) or not (NE) prior to adhesive restoration. Baseline and 3-month dentin biopsies were collected. The number of bacteria and activity of total bacterial cells and Streptococcus mutans were determined by quantitative PCR and RT-PCR. No statistically significant differences were observed in total bacterial number and activity between E and NE treatments (p > 0.3008). For NE, however, the residual S. mutans bacterial cells were reduced (p = 0.0027), while the activity per cell was significantly increased (p = 0.0010) after reentry at 3 months after restoration. This effect was not observed in group E. Although no significant differences were found between groups, this study suggests that acid etching of affected dentin prior to adhesive restoration may directly or indirectly have an inhibitive effect on the activity of residual cariogenic bacteria. Further research is required to investigate this potential effect. PMID:20861631

  5. Acid Etching and Plasma Sterilization Fail to Improve Osseointegration of Grit Blasted Titanium Implants

    PubMed Central

    Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation. The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time. Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner. PMID:22962567

  6. Metal etching composition

    NASA Technical Reports Server (NTRS)

    Otousa, Joseph E. (Inventor); Thomas, Clark S. (Inventor); Foster, Robert E. (Inventor)

    1991-01-01

    The present invention is directed to a chemical etching composition for etching metals or metallic alloys. The composition includes a solution of hydrochloric acid, phosphoric acid, ethylene glycol, and an oxidizing agent. The etching composition is particularly useful for etching metal surfaces in preparation for subsequent fluorescent penetrant inspection.

  7. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    PubMed Central

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-01-01

    Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. Results: The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS. PMID:27559352

  8. Phosphoric acid-etching promotes bond strength and formation of acid-base resistant zone on enamel.

    PubMed

    Li, N; Nikaido, T; Alireza, S; Takagaki, T; Chen, J-H; Tagami, J

    2013-01-01

    This study examined the effect of phosphoric acid (PA) etching on the bond strength and acid-base resistant zone (ABRZ) formation of a two-step self-etching adhesive (SEA) system to enamel. An etch-and-rinse adhesive (EAR) system Single Bond (SB) and a two-step SEA system Clearfil SE Bond (SE) were used. Human teeth were randomly divided into four groups according to different adhesive treatments: 1) SB; 2) SE; 3) 35% PA etching→SE primer→SE adhesive (PA/SEp+a); (4) 35% PA etching→SE adhesive (PA/SEa). Microshear bond strength to enamel was measured and then statistically analyzed using one-way analysis of variance and the Tukey honestly significant difference test. The failure mode was recorded and analyzed by χ( 2 ) test. The etching pattern of the enamel surface was observed with scanning electron microscope (SEM). The bonded interface was exposed to a demineralizing solution (pH=4.5) for 4.5 hours and then 5% sodium hypochlorite with ultrasonication for 30 minutes. After argon-ion etching, the interfacial ultrastructure was observed using SEM. The microshear bond strength to enamel of the SE group was significantly lower (p<0.05) than that of the three PA-etched groups, although the latter three were not significantly different from one another. The ABRZ was detected in all the groups. In morphological observation, the ABRZ in the three PA-etched groups were obviously thicker compared with the SE group with an irregular wave-shaped edge.

  9. Martian surface microtexture from orbital observations

    NASA Astrophysics Data System (ADS)

    Fernando, J.; Schmidt, F.; Douté, S.

    2015-10-01

    The information about the surface microtexture is useful to constrain the geological processes (e.g., transportation, deposition, weathering). In this study, the grain microtexture is derived from the orbital CRISM/MRO multi-angular observations allowing to characterize the surface scattering behavior. The Hapke radiative transfer model is inverted to derive the photometric parameters which have physical meanings (e.g., grain size, roughness, shape, internal structure). Eight sites having various geological contexts are selected. The results show a high diversity of grain microtexture. This result put forward that Mars have experimented various geological processes. The link between information about the grain microtexture and the geological processes will be presented at the conference.

  10. Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel

    PubMed Central

    Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

    2010-01-01

    Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel. PMID:20922162

  11. Hydrofluoric acid etched stainless steel wire for solid-phase microextraction.

    PubMed

    Xu, Hua-Ling; Li, Yan; Jiang, Dong-Qing; Yan, Xiu-Ping

    2009-06-15

    Stainless steel wire has been widely used as the substrate of solid-phase microextraction (SPME) fibers to overcome the shortcomings of conventional silica fibers such as fragility, by many researchers. However, in previous reports various sorbent coatings are always required in conjunction with the stainless steel wire for SPME. In this work, we report the bare stainless steel wire for SPME without the need for any additional coatings taking advantage of its high mechanical and thermal stability. To evaluate the performance of stainless steel wire for SPME, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, chlorobenzene, n-propylbenzene, aniline, phenol, n-hexane, n-octane, n-decane, n-undecane, n-dodecane, chloroform, trichloroethylene, n-octanol, and butanol were tested as analytes. Although the stainless steel wire had almost no extraction capability toward the tested analytes before etching, it did exhibit high affinity to the tested PAHs after etching with hydrofluoric acid. The etched stainless steel wire gave a much bigger enhancement factor (2541-3981) for the PAHs than the other analytes studied (< or = 515). Etching with hydrofluoric acid produced a porous and flower-like structure with Fe(2)O(3), FeF(3), Cr(2)O(3), and CrF(2) on the surface of the stainless steel wire, giving high affinity to the PAHs due to cation-pi interaction. On the basis of the high selectivity of the etched stainless steel wire for PAHs, a new SPME method was developed for gas chromatography with flame ionization detection to determine PAHs with the detection limits of 0.24-0.63 microg L(-1). The precision for six replicate extractions using one SPME fiber ranged from 2.9% to 5.3%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.3-8.8%. One etched stainless steel wire can stand over 250 cycles of SPME without significant loss of extraction efficiency. The developed etched stainless steel wire is very stable, highly selective, and

  12. Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive

    PubMed Central

    Khan, Saba; Verma, Sanjeev K.; Maheshwari, Sandhya

    2015-01-01

    Aims: A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent. Material and Methods: A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac™ N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test. Results: ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9–7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group. Conclusion: Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity

  13. Scanning Acoustic Microscopy Investigation of Frequency-Dependent Reflectance of Acid-Etched Human Dentin Using Homotopic Measurements

    PubMed Central

    Marangos, Orestes; Misra, Anil; Spencer, Paulette; Katz, J. Lawrence

    2013-01-01

    Composite restorations in modern restorative dentistry rely on the bond formed in the adhesive-infiltrated acid-etched dentin. The physical characteristics of etched dentin are, therefore, of paramount interest. However, characterization of the acid-etched zone in its natural state is fraught with problems stemming from a variety of sources including its narrow size, the presence of water, heterogeneity, and spatial scale dependency. We have developed a novel homotopic (same location) measurement methodology utilizing scanning acoustic microscopy (SAM). Homotopic measurements with SAM overcome the problems encountered by other characterization/ imaging methods. These measurements provide us with acoustic reflectance at the same location of both the pre- and post-etched dentin in its natural state. We have applied this methodology for in vitro measurements on dentin samples. Fourier spectra from acid-etched dentin showed amplitude reduction and shifts of the central frequency that were location dependent. Through calibration, the acoustic reflectance of acid-etched dentin was found to have complex and non-monotonic frequency dependence. These data suggest that acid-etching of dentin results in a near-surface graded layer of varying thickness and property gradations. The measurement methodology described in this paper can be applied to systematically characterize mechanical properties of heterogeneous soft layers and interfaces in biological materials. PMID:21429849

  14. Comparison of shear bond strength of composite resin to enamel surface with laser etching versus acid etching: An in vitro evaluation

    PubMed Central

    Hoshing, Upendra A; Patil, Suvarna; Medha, Ashish; Bandekar, Siddhesh Dattatray

    2014-01-01

    Introduction: The aim of the study is in vitro evaluation of the shear bond strength of composite resin bonded to enamel which is pretreated using acid etchant and Er,Cr:Ysgg. Materials and Methods: 40 extracted human teeth were divided in two groups of 20 each (Groups A and B). In Group A, prepared surface of enamel was etched using 37% phosphoric acid (Scotchbond, 3M). In Group B, enamel was surface treated by a an Er, Cr: YSGG laser system (Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA) operating at a wavelength of 2,780 nm and having a pulse duration of 140-200 microsecond with a repetition rate of 20 Hz and 40 Hz. Bonding agent ((Scotchbond Multipurpose, 3M) was applied over the test areas on 20 samples of Groups A and B each, and light cured. Composite resin (Ceram X duo Nanoceramic restorative, Densply) was applied onto the test areas as a 3 × 3 mm diameter bid, and light cured. The samples were tested for shear bond strength. Results: Mean shear bond strength for acid-etched enamel (26.41 ± 0.66MPa, range 25.155 to 27.150 MPa) was significantly higher (P < 0.01) than for laser-etched enamel (16.23 ± 0.71MPa, range 15.233 to 17.334 MPa). Conclusions: For enamel surface, mean shear bond strength of bonded composite obtained after laser etching were significantly lower than those obtained after acid etching. PMID:25125842

  15. Laser micromachined and acid-etched Fabry-Perot cavities in silica fibres

    NASA Astrophysics Data System (ADS)

    Machavaram, V. R.; Tuck, C. J.; Teagle, M. C.; Badcock, R. A.; Fernando, G. F.

    2006-01-01

    This paper reports on two techniques for creating Fabry-Perot cavities in conventional single- and multi-mode optical fibres. The authors have reported previously on the design and fabrication of extrinsic fibre Fabry-Perot interferometric multi-functional sensors. Here, the authors report on two novel techniques for creating intrinsic fibre optic sensors based on the Fabry-Perot etalon. The first technique involved the use of hydrofluoric acid to preferentially etch the core of the optical fibre. This technique is simple to carry out and provides a cost-effective means for manufacturing intrinsic fibre Fabry-Perot sensors. In the second technique, a 157 nm excimer laser along with a custom-designed beam delivery system was used to ablate (micro-machine) near-paralleled walled cavities through the diameter of the optical fibre (outer diameter of 125 μm). The paper details the experimental methodology and the associated instrumentation for the two techniques. The acid etched and laser ablated cavities were characterised using a 3-D surface profiler, optical and scanning electron microscopy. The feasibility of using these cavities as intrinsic fibre Fabry-Perot strain sensors is demonstrated. This was achieved by surface-mounting the acid etched cavities on to composite tensile test specimens. The output from the optical fibre devices was compared with surface-mounted electrical resistance strain gauges.

  16. Effect of acid etching time and technique on interfacial characteristics of the adhesive-dentin bond using differential staining.

    PubMed

    Wang, Yong; Spencer, Paulette

    2004-06-01

    Dentin bonding using the total-etch method has been claimed to be technique-sensitive. The aim of this study is to examine the effect of acid-etch variations on the dentin demineralization and interfacial structure of the adhesive-dentin bond using a differential staining technique. Single Bond adhesive with 35% phosphoric acid gel was used. The occlusal one-third of the crown was removed from 60 extracted, unerupted human third molars. Smear layers were created by abrading the dentin with 600 grit SiC under water for 30 s. The prepared teeth were randomly assigned to four groups according to etching time (Group 1, 10 s; Group 2, 15 s; Group 3, 30 s; Group 4, 60 s). In each group, the etching gel was: (i) applied and spread to the dentin surface and left to stand undisturbed; (ii) applied and gently agitated during etching; (iii) applied without using dispensing tips for the syringe and left for the same period as above. After rinsing, the etched dentin was then treated with the adhesive per manufacturers' instructions. 3-5 micro m thin sections of the adhesive/dentin (a/d) interface were cut with a microtome and stained with Goldner's trichrome. Stained, thin sections from each prepared tooth were imaged with light microscopy. The depth and extent of dentin demineralization, and the a/d interdiffusion zone were clearly visible by this differential staining microtechnique. The thickness of the interdiffusion zone increased as a function of etching time. However, the etchant gel application methods have a significant influence on dentin demineralization. Although agitating acid gel facilitates the penetration and etching into dentin, it should not be recommended, especially for longer etching time. These results indicated that the etching technique has a large effect on the profile of both dentin demineralization and interfacial structure.

  17. Investigation of Acid-Etched CO2 Laser Ablated Enamel Surfaces Using Polarization Sensitive Optical Coherence Tomography

    PubMed Central

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10–15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 5–10 seconds. PMID:23539418

  18. Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10-15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 5-10 seconds.

  19. Micro/nanofabrication of poly(L-lactic acid) using focused ion beam direct etching

    NASA Astrophysics Data System (ADS)

    Oyama, Tomoko Gowa; Hinata, Toru; Nagasawa, Naotsugu; Oshima, Akihiro; Washio, Masakazu; Tagawa, Seiichi; Taguchi, Mitsumasa

    2013-10-01

    Micro/nanofabrication of biocompatible and biodegradable poly(L-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  20. Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

    PubMed Central

    Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

    2016-01-01

    ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

  1. Nitric-phosphoric acid etching effects on the surface chemical composition of CdTe thin film.

    NASA Astrophysics Data System (ADS)

    Irfan, Irfan; Ding, Huanjun; Xia, Wei; Lin, Hao; Tang, Ching W.; Gao, Yongli

    2009-03-01

    Nitric-phosphoric (NP) acid etching has been regarded as one of the most successful methods for the formation of low resistance back contact with the metal electrode in CdTe based solar cells. We report back surface chemical composition for eight different durations of NP etching of CdTe polycrystalline thin film. We studied the surfaces with x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IEPS) and atomic force microscopy (AFM). Etching dependence on the back surface composition and electronic structure was observed. Valence and conduction band shifts relative to the Fermi level of the system with different etching duration were analyzed. The sample was left in open ambient condition for three weeks and XPS data were obtained again in order to study the difference in surface chemical composition with the pristine CdTe film. Unetched and highly etched part of the sample were sputtered and the depth profile analyzed.

  2. Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study

    PubMed Central

    Mirzakouchaki, Behnam; Sharghi, Reza; Shirazi, Samaneh; Moghimi, Mahsan; Shahrbaf, Shirin

    2016-01-01

    Background Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. Results The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems. Conclusions The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. Key words:Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch. PMID:26855704

  3. Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic.

    PubMed

    Zogheib, Lucas Villaça; Bona, Alvaro Della; Kimpara, Estevão Tomomitsu; McCabe, John F

    2011-01-01

    The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

  4. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics.

    PubMed

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A; Divakar, Darshan Devang; Matinlinna, Jukka P; Vallittu, Pekka K

    2016-05-27

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces' microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  5. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

    PubMed Central

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A.; Divakar, Darshan Devang; Matinlinna, Jukka P.; Vallittu, Pekka K.

    2016-01-01

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability. PMID:27240353

  6. Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin

    PubMed Central

    Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

    2013-01-01

    Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05). Results. Mean shear bond strength for acid etching (20.1±1.8 MPa) and acid+laser (15.6±3.5 MPa) groups were significantly higher than those for laser+acid (15.6±3.5 MPa), laser etching (14.1±3.4 MPa) and control (8.1±2.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching. PMID:23875083

  7. Facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity on aluminum alloy surface by simple acid etching and polymer coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Sun, Linyu; Luo, Yuting; Wu, Ruomei; Jiang, Haiyun; Chen, Yi; Zeng, Guangsheng; Liu, Yuejun

    2013-09-01

    The transition from the hydrophilic surface to the superhydrophilic and superhydrophobic surface on aluminum alloy via hydrochloric acid etching and polymer coating was investigated by contact angle (CA) measurements and scanning electron microscope (SEM). The effects of etching and polymer coating on the surface were discussed. The results showed that a superhydrophilic surface was facilely obtained after acid etching for 20 min and a superhydrophobic surface was readily fabricated by polypropylene (PP) coating after acid etching. When the etching time was 30 min, the CA was up to 157̊. By contrast, two other polymers of polystyrene (PS) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after acid etching. The results showed that the CA was up to 159̊ by coating PP-g-MAH, while the CA was only 141̊ by coating PS. By modifying the surface with the silane coupling agent before PP coating, the durability and solvent resistance performance of the superhydrophobic surface was further improved. The micro-nano concave-convex structures of the superhydrophilic surface and the superhydrophobic surface were further confirmed by scanning electron microscope (SEM). Combined with the natural hydrophilicity of aluminum alloy, the rough micro-nano structures of the surface led to the superhydrophilicity of the aluminum alloy surface, while the rough surface structures led to the superhydrophobicity of the aluminum alloy surface by combination with the material of PP with the low surface free energy.

  8. Color Stability of Enamel following Different Acid Etching and Color Exposure Times

    PubMed Central

    Jahanbin, Arezoo; Basafa, Mohammad; Moazzami, Mostafa; Basafa, Behnoush; Eslami, Neda

    2014-01-01

    Background and aims. The aim of this study was to evaluate the effect of different etching times on enamel color stability after immediate versus delayed exposure to colored artificial saliva (CAS). Materials and methods. Human first premolars were divided into five groups of twenty. A colorimeter was used according to the CIE system on the mid-buccal and mid-lingual surfaces to evaluate initial tooth color. Samples in group A remained unetched. In groups B to E, buccal and lingual surfaces were initially etched with phosphoric acid for 15 and 60 seconds, respectively. Then, the samples in groups A and C were immersed in colored artificial saliva (cola+saliva). In group B, the teeth were immersed in simple artificial saliva (AS). Samples in groups D and E were immersed in AS for 24 and 72 hours, respectively before being immersed in colored AS. The teeth were immersed for one month in each solution before color measurement. During the test period, the teeth were retrieved from the staining solution and stored in AS for five minutes. This was repeated 60 times. Color changes of buccal and lingual surfaces were calculated. Kruskal-Wallis and Wilcoxon tests were used for statistical analysis (α ≤0.05). Results. There were no significant differences between the groups in term of ΔE of buccal (P = 0.148) and lingual surfaces (P = 0.73). Conclusion. Extended time of etching did not result in significant enamel color change. Immediate and delayed exposure of etched enamel to staining solutions did not result in clinically detectable tooth color changes. PMID:25093048

  9. Effect of storage and acid etching on the tensile bond strength of composite resins to glass ionomer cement.

    PubMed

    Mesquita, M F; Domitti, S S; Consani, S; de Goes, M F

    1999-01-01

    This in vitro study evaluates the effect of storage time and acid etching on the tensile bond strength of glass ionomer cement to composite resins. The bonded assemblies were stored at 100% relative humidity and 37 degrees C for 1 hour, 1 day, 1 week, 1 month and 3 months. The test specimen was loaded at tension to failure on an Otto Wolpert-Werke testing instrument with a crosshead speed of 6 mm/min. The results showed a significant statistical difference for etched Vidrion F when compared to etched Ketac Bond at all storage periods. The unetched samples were statistically similar at 3 months, with the highest values for Vidrion F.

  10. In situ chemical functionalization of gallium nitride with phosphonic acid derivatives during etching.

    PubMed

    Wilkins, Stewart J; Greenough, Michelle; Arellano, Consuelo; Paskova, Tania; Ivanisevic, Albena

    2014-03-01

    In situ functionalization of polar (c plane) and nonpolar (a plane) gallium nitride (GaN) was performed by adding (3-bromopropyl) phosphonic acid or propyl phosphonic acid to a phosphoric acid etch. The target was to modulate the emission properties and oxide formation of GaN, which was explored through surface characterization with atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), inductively coupled plasma-mass spectrometry, and water contact angle. The use of (3-bromopropyl) phosphonic acid and propyl phosphonic acid in phosphoric acid demonstrated lower amounts of gallium oxide formation and greater hydrophobicity for both sample sets, while also improving PL emission of polar GaN samples. In addition to crystal orientation, growth-related factors such as defect density in bulk GaN versus thin GaN films residing on sapphire substrates were investigated as well as their responses to in situ functionalization. Thin nonpolar GaN layers were the most sensitive to etching treatments due in part to higher defect densities (stacking faults and threading dislocations), which accounts for large surface depressions. High-quality GaN (both free-standing bulk polar and bulk nonpolar) demonstrated increased sensitivity to oxide formation. Room-temperature PL stands out as an excellent technique to identify nonradiative recombination as observed in the spectra of heteroepitaxially grown GaN samples. The chemical methods applied to tune optical and physical properties of GaN provide a quantitative framework for future novel chemical and biochemical sensor development.

  11. Comparative Study of the Effect of Acid Etching on Enamel Surface Roughness between Pumiced and Non-pumiced Teeth

    PubMed Central

    Abreu, Lucas Guimarães; Paiva, Saul Martins; Pretti, Henrique; Lages, Elizabeth Maria Bastos; Júnior, João Batista Novães; Ferreira, Ricardo Alberto Neto

    2015-01-01

    Background: The objective was to perform a comparative analysis of the effect of acid etching on enamel roughness between pumiced and non-pumiced teeth. Materials and Methods: The sample was composed of 32 dental surfaces divided into two groups: Group 1-16 surfaces having received pumice prophylaxis; and Group 2-16 surfaces not having received pumice prophylaxis. The teeth were kept in saline until the first record of surface roughness prior to etching. For each surface, a roughness graph was obtained through trials using a surface roughness tester. This procedure was repeated two more times at different locations for a total of three readings which, later, were converted in a mean value. The teeth were then acid etched with a 37% phosphoric acid for 60 s, rinsed with water, air dried, and tested with the roughness tester again using the same protocol described for baseline. The Quantikov image analysis program was used to measure the length of the graphs. The average value of the lengths was recorded for each surface before and after etching. The increase in roughness caused by acid etching was calculated and compared between groups. Results: The mean increase in roughness caused by the etching was 301 µm (11.37%) in Group 1 and 214 µm (8.33%) in Group 2. No statistically significant difference was found between samples with and without pumice prophylaxis (P = 0.283). Conclusion: The present study showed that the effect of acid etching on enamel roughness was not significantly affected by prior pumice prophylaxis. PMID:26435607

  12. In vitro remineralization of acid-etched human enamel with Ca 3SiO 5

    NASA Astrophysics Data System (ADS)

    Dong, Zhihong; Chang, Jiang; Deng, Yan; Joiner, Andrew

    2010-02-01

    Bioactive and inductive silicate-based bioceramics play an important role in hard tissue prosthetics such as bone and teeth. In the present study, a model was established to study the acid-etched enamel remineralization with tricalcium silicate (Ca 3SiO 5, C 3S) paste in vitro. After soaking in simulated oral fluid (SOF), Ca-P precipitation layer was formed on the enamel surface, with the prolonged soaking time, apatite layer turned into density and uniformity and thickness increasingly from 250 to 350 nm for 1 day to 1.7-1.9 μm for 7 days. Structure of apatite crystals was similar to that of hydroxyapatite (HAp). At the same time, surface smoothness of the remineralized layer is favorable for the oral hygiene. These results suggested that C 3S treated the acid-etched enamel can induce apatite formation, indicating the biomimic mineralization ability, and C 3S could be used as an agent of inductive biomineralization for the enamel prosthesis and protection.

  13. Cell Adhesion and in Vivo Osseointegration of Sandblasted/Acid Etched/Anodized Dental Implants

    PubMed Central

    Kim, Mu-Hyon; Park, Kyeongsoon; Choi, Kyung-Hee; Kim, Soo-Hong; Kim, Se Eun; Jeong, Chang-Mo; Huh, Jung-Bo

    2015-01-01

    The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20% ± 10.89%) was much greater than those of machined (33.58% ± 8.63%), SLA (58.47% ± 12.89), or ANO Ti (59.62% ± 18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant. PMID:25955650

  14. Stretchability of Silver Films on Thin Acid-Etched Rough Polydimethylsiloxane Substrates Fabricated by Electrospray Deposition

    NASA Astrophysics Data System (ADS)

    Mehdi, S. M.; Cho, K. H.; Kang, C. N.; Choi, K. H.

    2015-07-01

    This paper investigates the fabrication of Ag films through the electrospray deposition (ESD) technique on sub-millimeter-thick acid-etched rough polydimethylsiloxane (PDMS) substrates having both low and high modulus of elasticity. The main focus of the study is on the stretchable behavior of ESD-deposited Ag nanoparticles-based thin films on these substrates when subjected to axial strains. Experimental results suggest that the as-fabricated films on thin acid-etched rough low modulus PDMS has an average stretchability of 5.6% with an average increase in the resistance that is 23 times that of the initial resistance at electrical failure (complete rupture of the films). Comparatively, the stretchability of Ag films on the high modulus PDMS was found to be 3 times higher with 4.65 times increase in the resistance at electrical failure. Also, a high positive value of the piezoresistive coefficient for these films suggests that the resistivity changes during stretching, and thus deviation from the simplified models is inevitable. Based on these results, new models are presented that quantify the changes in resistance with strain.

  15. Microtextured Silicon Surfaces for Detectors, Sensors & Photovoltaics

    SciTech Connect

    Carey, JE; Mazur, E

    2005-05-19

    With support from this award we studied a novel silicon microtexturing process and its application in silicon-based infrared photodetectors. By irradiating the surface of a silicon wafer with intense femtosecond laser pulses in the presence of certain gases or liquids, the originally shiny, flat surface is transformed into a dark array of microstructures. The resulting microtextured surface has near-unity absorption from near-ultraviolet to infrared wavelengths well below the band gap. The high, broad absorption of microtextured silicon could enable the production of silicon-based photodiodes for use as inexpensive, room-temperature multi-spectral photodetectors. Such detectors would find use in numerous applications including environmental sensors, solar energy, and infrared imaging. The goals of this study were to learn about microtextured surfaces and then develop and test prototype silicon detectors for the visible and infrared. We were extremely successful in achieving our goals. During the first two years of this award, we learned a great deal about how microtextured surfaces form and what leads to their remarkable optical properties. We used this knowledge to build prototype detectors with high sensitivity in both the visible and in the near-infrared. We obtained room-temperature responsivities as high as 100 A/W at 1064 nm, two orders of magnitude higher than standard silicon photodiodes. For wavelengths below the band gap, we obtained responsivities as high as 50 mA/W at 1330 nm and 35 mA/W at 1550 nm, close to the responsivity of InGaAs photodiodes and five orders of magnitude higher than silicon devices in this wavelength region.

  16. Influence of Organic Acids from the Oral Biofilm on the Bond Strength of Self-Etch Adhesives to Dentin.

    PubMed

    Amaral, Cristiane Mariote; Correa, Danielly de Sá; Miragaya, Luciana Meirelles; Silva, Eduardo Moreira da

    2015-10-01

    The aim of this study was to evaluate the microtensile bond strength of self-etch adhesive systems to dentin after storage in acids from oral biofilm. Three adhesive systems were used in the study: a two-step self-etch adhesive for use with a silorane-based resin composite (Filtek P90 adhesive system - P90), a two-step self-etch adhesive (Clearfil SE Bond - CSE) and a one-step self-etch adhesive (Adper Easy One - AEO). The bond strength of these products was evaluated by bonding resin composite (Filtek Z350 for CSE and AEO; and Filtek P90 for P90) to 90 bovine dentin tooth fragments, according to the manufacturer's instructions. After 24 h of water storage at 37 °C, the specimens were sectioned into beams (1 mm2) divided and stored in distilled water, lactic acid and propionic acid, for 7 and 30 days. After storage, the specimens were tested for microtensile bond strength. Data were analyzed by three-way ANOVA and Tukey´s test (α=0.05). CSE presented the highest microtensile bond strength after storage in distilled water for 7 and 30 days. The microtensile bond strength of all adhesive systems was lower after storage in lactic acid and propionic acid than after water storage. Significant difference was not found between storage times. PMID:26647935

  17. Shear bond strength of resin cement to an acid etched and a laser irradiated ceramic surface

    PubMed Central

    Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

    2013-01-01

    PURPOSE To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic. MATERIALS AND METHODS Fifty-five ceramic blocks (5 mm × 5 mm × 2 mm) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at 37℃ for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05). RESULTS Adhesion was significantly stronger in Group 2 (3.88 ± 1.94 MPa) and Group 3 (3.65 ± 1.87 MPa) than in Control group (1.95 ± 1.06 MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 (3.59 ± 1.19 MPa) and Control group. Shear bond strength was highest in Group 1 (8.42 ± 1.86 MPa; P<.01). CONCLUSION Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique. PMID:23755333

  18. Resin–dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding

    PubMed Central

    Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H.; Tay, Franklin R.; Watson, Timothy F.; Osorio, Raquel

    2013-01-01

    Objective To compare resin–dentin bond strengths and the micropermeability of hydrophobic vs. hydrophilic resins bonded to acid-etched or EDTA-treated dentin, using the ethanol wet-bonding technique. Methods Flat dentin surfaces from extracted human third molars were conditioned before bonding with: 37% H3PO4 (15 s) or 0.1 M EDTA (60 s). Five experimental resin blends of different hydrophilicities and one commercial adhesive (SBMP: Scotchbond Multi-Purpose) were applied to ethanol wet-dentin (1 min) and light-cured (20 s). The solvated resins were used as primers (50% ethanol/50% comonomers) and their respective neat resins were used as the adhesive. The resin-bonded teeth were stored in distilled water (24 h) and sectioned in beams for microtensile bond strength testing. Modes of failure were examined by stereoscopic light microscopy and SEM. Confocal tandem scanning microscopy (TSM) interfacial characterization and micropermeability were also performed after filling the pulp chamber with 1 wt% aqueous rhodamine-B. Results The most hydrophobic resin 1 gave the lowest bond strength values to acid-etched dentin and all beams failed prematurely when the resin was applied to EDTA-treated dentin. Resins 2 and 3 gave intermediate bond strengths to both conditioned substrates. Resin 4, an acidic hydrophilic resin, gave the highest bond strengths to both EDTA-treated and acid-etched dentin. Resin 5 was the only hydrophilic resin showing poor resin infiltration when applied on acid-etched dentin. Significance The ethanol wet-bonding technique may improve the infiltration of most of the adhesives used in this study into dentin, especially when applied to EDTA-treated dentin. The chemical composition of the resin blends was a determining factor influencing the ability of adhesives to bond to EDTA-treated or 37% H3PO4 acid-etched dentin, when using the ethanol wet-bonding technique in a clinically relevant time period. PMID:20074787

  19. Comparative Evaluation of Tensile – Bond Strength of An Orthodontic Adhesive with and without Fluoride Application, After Acid Etching -An Invitro Study

    PubMed Central

    Yugandhar, G; Ramana, I Venkata; Srinivas, K; Yadav, S. Sarjeev Singh

    2015-01-01

    Background Fixed appliances hinder the effective control of plaque accumulation and white spot lesions may develop under the ill fitting bands or adjacent to the stainless steel brackets during orthodontic treatment particularly the etching process. Aims and Objectives Comparative study of tensile bond strength of an orthodontic adhesive with and without fluoride application after acid etching to know the effect of fluoride on bond strength. Materials and Methods This study is carried out on 90 non carious human premolar teeth, and divided in 6 groups with each group of 15 specimens. In those Groups I and IV were control group acid etch treatment, Group II and V is 1.23% APF gel (acid etch plus APF gel treatment,) and group III and VI is 8% SnF2 (acid etch plus SnF2 treatment). Samples of Group I, II and III bond strength were tested after 24 h and groups IV, V and VI after one month on microtechtensometer machine. The scanning electron microscope (SEM) investigation was carried out for the 2 specimens for the control group after acid etch and 4 specimens after acid etch with fluoride application for fluoride groups. Results Control and SnF2 treated groups was found to be nearly similar to the control group whereas APF treated group showed less focal holes than the other 2 groups. Conclusion Fluoride application after acid etching without having an adverse effect on bond strength but we can prevent the white spot lesions and caries. PMID:26023648

  20. Mechanically robust superamphiphobic aluminum surface with nanopore-embedded microtexture.

    PubMed

    Barthwal, Sumit; Kim, Young Su; Lim, Si-Hyung

    2013-09-24

    A simple fabrication technique was developed for preparing a mechanically robust superamphiphobic surface on an aluminum (Al) plate. Dual geometric architectures with micro- and nanoscale structures were formed on the surface of the Al plate by a combination of simple chemical etching and anodization. This proposed methodology involves (1) fabrication of irregular microscale plateaus on the surface of the Al plate, (2) formation of nanopores, and (3) fluorination. Wettability measurements indicated that the fabricated Al surface became super-repellent toward a broad range of liquids with surface tension in the range 27.5-72 mN/m. By varying the anodization time, we measured and compared the effects of morphological change on the wettability. The adhesion property and mechanical durability of the fabricated superamphiphobic Al surface were evaluated by the Scotch tape and hardness tests, respectively. The results showed that the fabricated Al surface retained mechanical robustness because the down-directed surface made by nanopores on the microtextured surface was durable enough even after high force was applied. Almost no damage of the film was observed, and the surface still exhibited superamphiphobicity after the tests. The fabricated superamphiphobic surface also remained stable after long-term storage. The simple and time-saving fabrication technique can be extended to any large-area three-dimensional surface, making it potentially suitable for large-scale industrial fabrications of mechanically robust superamphiphobic surfaces.

  1. HVPE homoepitaxial growth of high quality bulk GaN using acid wet etching method and its mechanism analysis

    NASA Astrophysics Data System (ADS)

    Liu, Nanliu; Cheng, Yutian; Wu, Jiejun; Li, Xingbin; Yu, Tongjun; Xiong, Huan; Li, Wenhui; Chen, Jiao; Zhang, Guoyi

    2016-11-01

    In this paper, crack-free 2-inch bulk GaN wafer with the thickness up to 3 mm was obtained by HVPE homoepitaxy. A new method of acid wet etching was used to pre-treat GaN substrate before re-growth. The formation of the mesh-like subsurface crack and interface layer were found to be suppressed between the re-growth layer and as-grown GaN substrate. EDS and time varied contact angle measurement proved that chemical etching would decrease the oxygen related surface adsorption and increase atoms diffusion length during HVPE homoepitaxial growth. Moreover, Morphology, Low temperature photoluminescence measurements indicated a reduction in stress of wet etching treated as-grown GaN substrate due to etching effect on its N face. High quality bulk GaN with the dislocation density of 1×106 cm-2 was achieved by using wet etching and HVPE multiple re-growth. It would offer a simple method to obtain bulk GaN with thicker layer and high quality.

  2. Clinical Use of Laser-Microtextured Abutments: A Case Series.

    PubMed

    Shapoff, Cary A; Babushkin, Jeffrey A; Wohl, David J

    2016-01-01

    This article discusses the clinical use of laser-microtextured abutments on dental implant restorations. Four cases are presented, each using one of the four commercially available laser-microtextured abutment styles. Numerous preclinical and clinical studies have shown the positive effects of laser microtexturing on the implant platform in limiting crestal bone loss and benefiting soft tissue stability. Other histologic studies of laser microtexturing on the implant abutment have demonstrated the ability of this specific feature to block epithelial downgrowth and provide a functional connective tissue attachment to the abutment surface. Other abutment designs, styles, and materials have only demonstrated a soft tissue seal with epithelial adhesion and a circular ring of connective tissue fibers around the abutment without direct contact. This article presents clinical and radiographic case examples from a private practice perspective on the longterm successful use of microtextured abutments with respect to crestal bone levels, exceptional soft tissue health, and stability with minimal sulcular depth. PMID:27560683

  3. Inactivation of Matrix-bound MMPs by Cross-linking Agents in Acid Etched Dentin

    PubMed Central

    Scheffel, Débora Lopes Salles; Hebling, Josimeri; Scheffel, Régis Henke; Agee, Kelly A.; Turco, Gianluca; de Souza Costa, Carlos Alberto; Pashley, David H.

    2014-01-01

    Objectives Published TEM analysis of in vivo resin-dentin bonds shows that in 44 months almost 70% of collagen fibrils from the hybrid layer disappear. Matrix metalloproteinases (MMPs) play an important role in that process and are thought to be the main factor responsible for the solubitization of dentin collagen. Therefore, this study aimed to evaluate the inactivation of matrix-bound MMPs by carbodiimide (EDC) or proanthocyanidin (PA) both cross-linking agents, or the MMP-inhibitor, chlorhexidine (CHX), on acid-etched dentin using a simplified MMP assay method. Methods Dentin beams (1×1×6mm) were obtained from mid-coronal dentin of sound third molars and randomly divided into 6 groups (G) according to the dentin treatment: G1: Deionized water (control), G2: 0.1M EDC, G3: 0.5M EDC, G4: 0.5M EDC+35% HEMA, G5: 5% Proanthocyanidin (PA) and G6: 2% CHX. The beams were etched for 15s with 37% phosphoric acid, rinsed and then immersed for 60s in one of the treatment solutions. The total MMP activity of dentin was analyzed for 1 h by colorimetric assay (Sensolyte). Data were submitted to Wilcoxon non-parametric test and Mann-Whitney tests (p>0.05). Results All experimental cross-linking solutions significantly reduced MMP activity compared to control, except 0.1M EDC (53.6% ±16.1). No difference was observed between cross-linking agents and 2% CHX 0.5M EDC + 35% HEMA (92.3% ±8.0) was similar to 0.5M EDC (89.1% ±6.4), 5% PA (100.8% ±10.9) and 2% CHX (83.4% ±10.9). Conclusion Dentin treatment with cross-linking agents is effective to significantly reduce MMP activity. Mixing 0.5M EDC and 35% HEMA did not influence EDC inhibitor potential. PMID:23786610

  4. Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

    PubMed Central

    MENA-SERRANO, Alexandra Patricia; GARCIA, Eugenio Jose; PEREZ, Miguel Muñoz; MARTINS, Gislaine Cristine; GRANDE, Rosa Helena Miranda; LOGUERCIO, Alessandro Dourado; REIS, Alessandra

    2013-01-01

    Objectives: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. Material and Methods: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm2) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). Results: The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. Conclusions: The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested. PMID:23739856

  5. Characterization and adsorption properties of diatomaceous earth modified by hydrofluoric acid etching.

    PubMed

    Tsai, Wen-Tien; Lai, Chi-Wei; Hsien, Kuo-Jong

    2006-05-15

    This work was a study of the chemical modification of diatomaceous earth (DE) using hydrofluoric acid (HF) solution. Under the experimental conditions investigated, it was found that HF under controlled conditions significantly etched inward into the interior of the existing pore structure in the clay mineral due to its high content of silica, leaving a framework possessing a larger BET surface area (ca. 10 m2 g(-1)) in comparison with that (ca. 4 m2 g(-1)) of its precursor (i.e., DE). Further, the results indicated that the HF concentration is a more determining factor in creating more open pores than other process parameters (temperature, holding time, and solid/liquid ratio). This observation was also in close agreement with the examinations by the silicon analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption kinetics and the adsorption isotherm of methylene blue onto the resulting clay adsorbent can be well described by a pseudo-second-order reaction model and the Freundlich model, respectively.

  6. Bone contact around acid-etched implants: a histological and histomorphometrical evaluation of two human-retrieved implants.

    PubMed

    Degidi, Marco; Petrone, Giovanna; Iezzi, Giovanna; Piattelli, Adriano

    2003-01-01

    The surface characteristics of dental implants play an important role in their clinical success. One of the most important surface characteristics of implants is their surface topography or roughness. Many techniques for preparing dental implant surfaces are in clinical use: turning, plasma spraying, coating, abrasive blasting, acid etching, and electropolishing. The Osseotite surface is prepared by a process of thermal dual etching with hydrochloric and sulfuric acid, which results in a clean, highly detailed surface texture devoid of entrapped foreign material and impurities. This seems to enhance fibrin attachment to the implant surface during the clotting process. The authors retrieved 2 Osseotite implants after 6 months to repair damage to the inferior alveolar nerve. Histologically, both implants appeared to be surrounded by newly formed bone. No gaps or fibrous tissues were present at the interface. The mean bone-implant contact percentage was 61.3% (+/- 3.8%). PMID:12614080

  7. Facet dependent binding and etching: ultra-sensitive colorimetric visualization of blood uric acid by unmodified silver nanoprisms.

    PubMed

    Tan, Kanghui; Yang, Guang; Chen, Huide; Shen, Pengfei; Huang, Yucheng; Xia, Yunsheng

    2014-09-15

    By combination of experiments and density functional theory calculations, we present a simple but effective "facet dependent binding and etching" strategy for non-enzymatic and non-aggregated colorimetric sensing of blood uric acid (UA), using unmodified Ag nanoprisms as the signal readout. In the absence of UA, the triangular Ag nanoprisms are etched alongside (110) facets by H2O2 and form round nanodiscs, and a more than 160 nm surface plasmon resonance (SPR) blue shift is observed. Because of special affinity between UA and side facets of the Ag nanoprisms, pre-added UA can well protect the Ag nanoprisms from etching. Such protection effect can be used for well quantifying UA in the range of 10-3000 nM, based on the inverse proportion of the SPR blue shift with the added analyte. Due to very thin plate morphology (5 nm) and facet dependent binding/etching effects of the Ag nanoprisms, the sensing system has ultrahigh sensitivity. The detection limit is only 10nM, which is about 2 to 4 orders of magnitude lower than that of previous colorimetric sensing systems. In addition to accurate quantitation, the proposed strategy can conveniently discriminate the patient of hyperuricemia from normal person by naked eyes. So, the present simple, low-cost and visualized UA chemosensor has great potential in the applications for point-of-care diagnostics.

  8. Comparison of bond strength and surface morphology of dental enamel for acid and Nd-YAG laser etching

    NASA Astrophysics Data System (ADS)

    Parmeswearan, Diagaradjane; Ganesan, Singaravelu; Ratna, P.; Koteeswaran, D.

    1999-05-01

    Recently, laser pretreatment of dental enamel has emerged as a new technique in the field of orthodontics. However, the changes in the morphology of the enamel surface is very much dependent on the wavelength of laser, emission mode of the laser, energy density, exposure time and the nature of the substance absorbing the energy. Based on these, we made a comparative in vitro study on laser etching with acid etching with reference to their bond strength. Studies were conducted on 90 freshly extracted, non carious, human maxillary or mandibular anteriors and premolars. Out of 90, 60 were randomly selected for laser irradiation. The other 30 were used for conventional acid pretreatment. The group of 60 were subjected to Nd-YAG laser exposure (1060 nm, 10 Hz) at differetn fluences. The remaining 30 were acid pretreated with 30% orthophosphoric acid. Suitable Begg's brackets were selected and bound to the pretreated surface and the bond strength were tested using Instron testing machine. The bond strength achieved through acid pretreatment is found to be appreciably greater than the laser pretreated tooth. Though the bond strength achieved through the acid pretreated tooth is found to be significantly greater than the laser pretreated specimens, the laser pretreatement is found to be successful enough to produce a clinically acceptable bond strength of > 0.60 Kb/mm. Examination of the laser pre-treated tooth under SEM showed globule formation which may produce the mechanical interface required for the retention of the resin material.

  9. Fabrication of Highly-Oleophobic and Superhydrophobic Surfaces on Microtextured al Substrates

    NASA Astrophysics Data System (ADS)

    Liu, Changsong; Zhou, Jigen; Zheng, Dongmei; Wan, Yong; Li, Zhiwen

    2011-06-01

    Theoretical calculations suggest that creating highly-oleophobic surfaces would require a surface energy lower than that of any known materials. In the present work, we demonstrate microtextured Al substrate surfaces with veins-like micro/nanostructures displaying apparent contact angles (CA) greater than 120°, even with nitromethane (surface tension γ1 = 37 mN/m). The Al substrate was microtextured by a chemical solution mixed by zinc nitrate hexahydrate, hexamethyltetramine and a little of hydrofluoric acid. A fluoroalkylsilane (FAS) agent was used to tune the surface wettability. The Al substrates were microtextured by veins-like micro/nanostructures and generating a solid-liquid-vapor composite interface. Combination with FAS modification, the Al surfaces resulted in an oleophobicity with CA for nitromethane was 126.3° (152.7° for diethylene glycol, γ1 = 45.2 mN/m). In addition, the Al surfaces demonstrated a low rolling-off angle with < 6° even for diethylene glycol. However, nitromethane droplet favored to pin on the sample surface even the sample stage is tilted to 90°. It is noted that this highly-oleophobic behavior is induced mainly by topography, which form a composite surface of air and solid with oil drop sitting partially on air. The results are expected to promote the study on self-cleaning applications, especially in the condition with oil contaminations.

  10. Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

    SciTech Connect

    Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Hinata, Toru; Washio, Masakazu; Oshima, Akihiro; Tagawa, Seiichi

    2013-10-14

    Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  11. Effect of Fluoride on the Morphology of Calcium Phosphate Crystals Grown on Acid-Etched Human Enamel

    PubMed Central

    Fan, Y.; Sun, Z.; Moradian-Oldak, J.

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2–10 μm wide) were formed. With 1–10 mg/l fluoride, arrays of denser needle-like nanocrystals (20–30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro. PMID:19321991

  12. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s. PMID:27315775

  13. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s.

  14. Method of making a coating of a microtextured surface

    DOEpatents

    Affinito, John D [Tucson, AZ; Graff, Gordon L [West Richland, WA; Martin, Peter M [Kennewick, WA; Gross, Mark E [Pasco, WA; Burrows, Paul E [Kennewick, WA; Sapochak, Linda S [Henderson, NV

    2004-11-02

    A method for conformally coating a microtextured surface. The method includes flash evaporating a polymer precursor forming an evaporate, passing the evaporate to a glow discharge electrode creating a glow discharge polymer precursor plasma from the evaporate, cryocondensing the glow discharge polymer precursor plasma on the microtextured surface and crosslinking the glow discharge polymer precursor plasma thereon, wherein the crosslinking resulting from radicals created in the glow discharge polymer precursor plasma.

  15. Influence of acid-etching and ceramic primers on the repair of a glass ceramic.

    PubMed

    Queiroz, J R C; Souza, Rodrigo O A; Nogueira Junior, L; Ozcan, M; Bottino, M A

    2012-01-01

    The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The μTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P < 0.05); no difference was observed between the composites (P > 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength. PMID:22414522

  16. Influence of acid-etching and ceramic primers on the repair of a glass ceramic.

    PubMed

    Queiroz, J R C; Souza, Rodrigo O A; Nogueira Junior, L; Ozcan, M; Bottino, M A

    2012-01-01

    The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The μTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P < 0.05); no difference was observed between the composites (P > 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength.

  17. Early endosseous integration enhanced by dual acid etching of titanium: a torque removal study in the rabbit.

    PubMed

    Klokkevold, P R; Johnson, P; Dadgostari, S; Caputo, A; Davies, J E; Nishimura, R D

    2001-08-01

    Textured implant surfaces are thought to enhance endosseous integration. Torque removal forces have been used as a biomechanical measure of anchorage, or endosseous integration, in which the greater forces required to remove implants may be interpreted as an increase in the strength of bony integration. The purpose of this study was to compare the torque resistance to removal of screw-shaped titanium implants having a dual acid-etched surface (Osseotite) with implants having either a machined surface, or a titanium plasma spray surface that exhibited a significantly more complex surface topography. Three custom screw-shaped implant types - machined, dual acid-etched (DAE), and titanium plasma sprayed (TPS) - were used in this study. Each implant surface was characterized by scanning electron microscopy and optical profilometry. One DAE implant was placed into each distal femur of eighteen adult New Zealand White rabbits along with one of the other implant types. Thus, each rabbit received two DAE implants and one each of the machined, or TPS, implants. All implants measured 3.25 mm in diameter x 4.00 mm in length without holes, grooves or slots to resist rotation. Eighteen rabbits were used for reverse torque measurements. Groups of six rabbits were sacrificed following one, two and three month healing periods. Implants were removed by reverse torque rotation with a digital torque-measuring device. Three implants with the machined surface preparation failed to achieve endosseous integration. All other implants were anchored by bone. Mean torque values for machined, DAE and TPS implants at one, two and three months were 6.00+/-0.64 N-cm, 9.07+/-0.67 N-cm and 6.73+/-0.95 N-cm; 21.86+/-1.37 N-cm, 27.63+/-3.41 N-cm and 27.40+/-3.89 N-cm; and 27.48+/-1.61 N-cm, 44.28+/-4.53 N-cm and 59.23+/-3.88 N-cm, respectively. Clearly, at the earliest time point the stability of DAE implants was comparable to that of TPS implants, while that of the machined implants was an order of

  18. Bond strength of composite to dentin: effect of acid etching and laser irradiation through an uncured self-etch adhesive system

    NASA Astrophysics Data System (ADS)

    Castro, F. L. A.; Carvalho, J. G.; Andrade, M. F.; Saad, J. R. C.; Hebling, J.; Lizarelli, R. F. Z.

    2014-08-01

    This study evaluated the effect on micro-tensile bond strength (µ-TBS) of laser irradiation of etched/unetched dentin through an uncured self-etching adhesive. Dentinal surfaces were treated with Clearfil SE Bond Adhesive (CSE) either according to the manufacturer’s instructions (CSE) or without applying the primer (CSE/NP). The dentin was irradiated through the uncured adhesive, using an Nd:YAG laser at 0.75 or 1 W power settings. The adhesive was cured, composite crowns were built up, and the teeth were sectioned into beams (0.49 mm2) to be stressed under tension. Data were analyzed using one-way ANOVA and Tukey statistics (α = 5%). Dentin of the fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM). The results showed that non-etched irradiated surfaces presented higher µ-TBS than etched and irradiated surfaces (p < 0.05). Laser irradiation alone did not lead to differences in µ-TBS (p > 0.05). SEM showed solidification globules on the surfaces of the specimens. The interfaces were similar on irradiated and non-irradiated surfaces. Laser irradiation of dentin through the uncured adhesive did not lead to higher µ-TBS when compared to the suggested manufacturer’s technique. However, this treatment brought benefits when performed on unetched dentin, since bond strengths were higher when compared to etched dentin.

  19. A comparative study of shear bond strength of orthodontic bracket after acid-etched and Er:YAG treatment on enamel surface

    NASA Astrophysics Data System (ADS)

    Leão, Juliana C.; Mota, Cláudia C. B. O.; Cassimiro-silva, Patricia F.; Gomes, Anderson S. L.

    2016-02-01

    This study aimed to evaluate the shear bond strength (SBS) of teeth prepared for orthodontic bracket bonding with 37% phosphoric acid and Er:YAG laser. Forty bovine incisors were divided into two groups. In Group I, the teeth were conditioned with 37% phosphoric acid and brackets were bonded with Transbond XT; in Group II, the teeth were irradiated with Er:YAG and bonding with Transbond XT. After SBS test, the adhesive remnant index was determined. Adhesion to dental hard tissues after Er:YAG laser etching was inferior to that obtained after acid etching but exceeded what is believed to be clinically sufficient strength, and therefore can be used in patients.

  20. Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant.

    PubMed

    Monje, Alberto; González-García, Raúl; Fernández-Calderón, María Coronada; Hierro-Oliva, Margarita; González-Martín, María Luisa; Del Amo, Fernando Suarez-Lopez; Galindo-Moreno, Pablo; Wang, Hom-Lay; Monje, Florencio

    2016-02-01

    The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined. PMID:25642739

  1. Characterization and biocompatibility of a titanium dental implant with a laser irradiated and dual-acid etched surface.

    PubMed

    Hsu, Shan-Hui; Liu, Bai-Shuan; Lin, Wen-Hung; Chiang, Heng-Chieh; Huang, Shih-Ching; Cheng, Shih-Shyong

    2007-01-01

    The biological properties of commercial pure titanium (cp-Ti) dental implants can be improved by surface treatment. In this study, the cp-Ti surfaces were prepared to enable machined surfaces (TM) to be compared to the machined, sandblasted, laser irradiated and dual-acid etched surfaces (TA). The surface elements and roughness were characterized. The biocompatibility was evaluated by cell and organ culture in vitro. The removal torque was measured in rabbit implantation. Surface characterization revealed that TA surface was more oxidized than TM surface. The TA surface had micrometric, beehive-like coarse concaves. The average roughness (2.28 mum) was larger than that typical of acid-etched surfaces. Extracts of both materials were not cytotoxic to bone cells. The morphology of cells attached on the TA surface was superior to that on the TM surface. TA promoted cell migration and repaired damaged bones more effectively in organ culture. The formation of bone-like nodules on TA disk exceeded that on TM disk. Rabbit tibia implantation also proved that TA implant had greater removal torque value. These results suggested that TA had good osteoconductivity and was a potential material for dental implantation. PMID:17264387

  2. Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant.

    PubMed

    Monje, Alberto; González-García, Raúl; Fernández-Calderón, María Coronada; Hierro-Oliva, Margarita; González-Martín, María Luisa; Del Amo, Fernando Suarez-Lopez; Galindo-Moreno, Pablo; Wang, Hom-Lay; Monje, Florencio

    2016-02-01

    The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined.

  3. Effect of hydrofluoric acid etching on shear bond strength of an indirect resin composite to an adhesive cement.

    PubMed

    Hori, Sayaka; Minami, Hiroyuki; Minesaki, Yoshito; Matsumura, Hideo; Tanaka, Takuo

    2008-07-01

    This study evaluated the effect of 1% hydrofluoric acid (HF) treatment on the bonding of an adhesive cement (Panavia F 2.0) to an indirect resin composite (Estenia C&B). Pairs of composite disks (10 and 8 mm in diameter by 3 mm thickness) were prepared. Adhesive surfaces were pretreated with either airborne particle abrasion or HF etching before being soaked for 30 seconds, five minutes or 10 minutes, with or without application of silane coupling agent. Adhesive specimens were fabricated by cementing a pair of treated disks. Shear bond strength was determined before and after 50,000 times of thermocycling (4 and 60 degrees C). All data were statistically analyzed using two-way ANOVA and Bonferroni's test (a=0.05). Bond strength achieved with five minutes of HF etching (18.3+/-1.1 MPa) was significantly higher (P=0.0025) than that obtained with airborne particle abrasion followed by application of silane coupling agent (14.3+/-1.8 MPa) after thermocycling.

  4. UV-induced graft polymerization of acrylic acid in the sub-micronchannels of oxidized PET track-etched membrane

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Taltenov, Abzal A.

    2015-12-01

    In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate) (PET TeMs) oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H2O2/UV) system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP) photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid) (PAA) chains inside the membrane sub-micronchannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA) were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV-vis, ATR-FTIR, XPS spectroscopies and by SEM.

  5. Evaluation of Bone Healing on Sandblasted and Acid Etched Implants Coated with Nanocrystalline Hydroxyapatite: An In Vivo Study in Rabbit Femur

    PubMed Central

    Melin Svanborg, Lory; Meirelles, Luiz; Franke Stenport, Victoria; Currie, Fredrik; Andersson, Martin

    2014-01-01

    This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA) were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone. PMID:24723952

  6. Bone contact around osseointegrated implants: histologic analysis of a dual-acid-etched surface implant in a diabetic patient.

    PubMed

    Bugea, Calogero; Luongo, Roberto; Di Iorio, Donato; Cocchetto, Roberto; Celletti, Renato

    2008-04-01

    The clinical applicability and predictability of osseointegrated implants in healthy patients have been studied extensively. Although successful treatment of patients with medical conditions including diabetes, arthritis, and cardiovascular disease has been described, insufficient information is available to determine the effects of diabetes on the process of osseointegration. An implant placed and intended to support an overdenture in a 65-year-old diabetic woman was prosthetically unfavorable and was retrieved after 2 months. It was then analyzed histologically. No symptoms of implant failure were detected, and histomorphometric evaluation showed the bone-to-implant contact percentage to be 80%. Osseointegration can be obtained when implants with a dual-acid-etched surface are placed in properly selected diabetic patients. PMID:18546810

  7. Changes in the surface of bone and acid-etched and sandblasted implants following implantation and removal

    PubMed Central

    Eroglu, Cennet Neslihan; Ertugrul, Abdullah Seckin; Eskitascioglu, Murat; Eskitascioglu, Gurcan

    2016-01-01

    Objective: The aim of this study was to determine whether there are any changes in the surface of bone or implant structures following the removal of a screwed dental implant. Materials and Methods: For this, six individual samples of acid-etched and sandblasted implants from three different manufacturers’ implant systems were used. They were screwed in a D1 bovine bone, and they were removed after primary stabilization. The bone and implant surfaces are evaluated with scanning electron microscope. Results: Through examination of the surfaces of the bone prior to implantation and of the used and unused implant surfaces, it was found that inhomogeneity in the implant surface can cause microcracking in the bone. Conclusions: This is attributed to the stress induced during the implantation of self-tapping implants and suggests that a tap drill may be required in some instances to protect the implant surface. PMID:27011744

  8. Dynamics of Spreading on Micro-Textured Surfaces

    NASA Astrophysics Data System (ADS)

    Mohammad Karim, Alireza; Rothstein, Jonathan; Kavehpour, Pirouz

    2015-11-01

    Ultrahydrophobic surfaces, due to their large water-repellency characteristic, have a vast variety of applications in technology and nature, such as de-icing of airplane wings, efficiency increase of power plants, and efficiency of pesticides on plants, etc. The significance of ultrahydrophobic surfaces requires enhancing the knowledge on the spreading dynamics on such surfaces. The best way to produce an ultrahydrophobic surface is by patterning of smooth hydrophobic surfaces with micron sized posts. In this research, the micro-textured surfaces have been fabricated by patterning several different sizes of micro-textured posts on Teflon plates. The experimental study has been performed using forced spreading with Tensiometer to obtain the dependencw of dynamic contact angle to the contact line velocity to describe the spreading dynamics of Newtonian liquids on the micro-textured surfaces. The effect of the geometrical descriptions of the micro-posts along with the physical properties of liquids on the spreading dynamics on micro-textured Teflon plates have been also studied.

  9. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

    DOEpatents

    Hankins, Matthew G.

    2009-10-06

    Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

  10. Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

    PubMed Central

    STEINHAUSER, Henrique Caballero; TURSSI, Cecília Pedroso; FRANÇA, Fabiana Mantovani Gomes; do AMARAL, Flávia Lucisano Botelho; BASTING, Roberta Tarkany

    2014-01-01

    Objective The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8): C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results One-way ANOVA test showed no significant difference between treatments (p=0.3197) and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed. PMID:24676577

  11. In vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste.

    PubMed

    Praxedes-Neto, Otávio José; Borges, Boniek Castillo Dutra; Florêncio-Filho, Cícero; Farias, Arthur Costa Rodrigues; Drennan, John; De Lima, Kenio Costa

    2012-07-01

    This study aimed to evaluate the in vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste. One hundred and twenty teeth from 30 volunteers were selected. The teeth were assigned to four treatments: no treatment (negative control); 37% phosphoric acid-etching (PAE) (positive control); PAE + resin-modified glass ionomer cement (RMGIC); and, PAE + composite resin. Patients brushed teeth with fluoridated (n = 15) or non-fluoridated (n = 15) toothpastes, so that etched enamel was protected with screens and it was not in contact with the brush bristles. Remineralization was evaluated by means of laser fluorescence (LF), environmental scanning electronic microscopy, and energy dispersive spectrometry after extraction. The LF means were compared by means of Wilcoxon and Mann Whitney tests. Environmental scanning electron microscopy scores were compared among the groups using a Kruskal Wallis test, whereas the Ca/P ratio was evaluated by means of an Analysis of Variance with subparcels (treatments) and Tukey's post-hoc test. There were no statistically significant differences between the tooth pastes and between the orthodontic adhesives evaluated. Most teeth presented only partial enamel remineralization. Therefore, the fluoride released by the RMGIC was not enough to cause increased crystal regrowth in the acid-etched enamel. The use of fluoridated toothpaste did not provide positive additional effect.

  12. Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conventional Acid-Etching

    PubMed Central

    Hosseini, M.H.; Namvar, F.; Chalipa, J.; Saber, K.; Chiniforush, N.; Sarmadi, S.; Mirhashemi, A.H.

    2012-01-01

    Introduction: The purpose of this study was to compare shear bond strength (SBS) of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching. Materials and Methods: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI) scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types. Results: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively. Conclusion: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning. PMID:22924098

  13. Metal-like conductivity exhibited by triboelectrically deposited polyaniline (emeraldine base) particles on microtextured SiC surfaces

    NASA Astrophysics Data System (ADS)

    Bayer, I. S.; Caramia, V.; Biswas, A.; Cingolani, R.; Athanassiou, A.

    2012-05-01

    We demonstrate a simple and rapid way to deposit layers of polyaniline (emeraldine base) particles on flexible microtextured silicon carbide surfaces by contact charging them using a smooth dielectric rubber. Wetting of the layers by trifluoroacetic acid creates conductive, continuous polymeric films after drying. Pre-functionalization of the textured surfaces with anionic surfactants prevents particle coagulation during contact charging and decreases sheet resistance to metal-like levels (˜60 Ω/□). Conductivity of the films can be tuned by controlling the rate of acid evaporation. Conductive films are highly stable under ambient conditions and show no hysteresis when biased with zero delay-time.

  14. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    NASA Astrophysics Data System (ADS)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  15. Effect of sodium sulfite, carboxylic monomer, and phosphoric acid etching on bonding of tri-n-butylborane initiated resin to human enamel.

    PubMed

    Nogawa, Hiroshi; Koizumi, Hiroyasu; Akazawa, Nobutaka; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

    2015-03-01

    The purpose of the present study is evaluation of bonding durability of tri-n-butylborane (TBB) initiated resin without 4-methacryloyloxyethyl trimellitate anhydride (4-META) joined to human enamel. Ground human enamel was bonded with TBB resin under six surface conditions: 1) as ground, 2) primed with Teeth Primer, 3) sodium sulfite solution, 4) 4-META solution, 5) acetone-water, and 6) phosphoric acid etching. Pre- and post-thermocycling bond strengths and change in strength after thermocycling were compared. Etching enamel with 35-45% phosphoric acid enhanced bonding durability between enamel and TBB-initiated resin. Priming with Teeth Primer or 4-META solution improved bond strength between enamel and TBB-initiated resin. Sodium sulfite had little effect on enamel bonding in the present bonding systems. PMID:25807904

  16. Fabrication, characterization, and biological assessment of multilayer DNA coatings on sandblasted-dual acid etched titanium surface.

    PubMed

    Liu, Li; Song, Li-Na; Yang, Guo-Li; Zhao, Shi-Fang; He, Fu-Ming

    2011-06-01

    As local gene therapy has received attention, immobilizing functional gene onto irregular oral implant surface has become an advanced challenge. Electrostatic layer-by-layer (LBL) assembly technique could achieve this goal and allow local and efficient administration of genes to the target cells. In this study, multilayers of cationic lipid/plasmid DNA (pEGFP-C1) complex (LDc) and anionic hyaluronic acid were assembled onto sandblasted-dual acid etched titanium disks by the LBL technique. Surface characteristics of the coatings were performed by x-ray photospectroscopy (XPS), contact angle measurements, and scanning electron microscopy (SEM). The cell biological characteristics of the coatings were evaluated by in vitro experiments. SEM results demonstrated that the porous titanium surface was gradually flattened with the increase of the multilayer. The XPS survey indicated that the N element was found from the coating. The coating degradation and pEGFP-C1 releasing kinetics showed that the more assembled layer numbers were, the larger the amount of DNA released in the first 30 h. MC3T3-E1 cells were cultured directly on the DNA-loaded surface. Higher enhanced green fluorescent protein (EGFP) expression efficiency was achieved by increasing the number of layers when cells were cultured after 24 or 72 h. The MC3T3-E1 cell viability on the surface of multilayer DNA coatings was significantly higher than that on control porous titanium surface. It was concluded that the approach established by the LBL technique had great potential in immobilizing gene coatings onto the porous titanium surface and subsequently influenced the function of the cultured cell. PMID:21448994

  17. Petrologic and experimental evidence for the etching of garnets by organic acids in the upper Jurassic Morrision Formation, northwestern New Mexico.

    USGS Publications Warehouse

    Hansley, P.L.

    1987-01-01

    Etching of garnets and partial to complete dissolution of other aluminosilicate minerals were caused by high concentrations of organic acids generated during the maturation of epigenetic organic matter (predominantly type-III kerogen) in the Morrison Formation. The presence of authigenic phases that form near 100oC indicates that temperatures were high enough during diagenesis to cause the thermal degradation of kerogen.-from Author

  18. No Positive Effect of Acid Etching or Plasma Cleaning on Osseointegration of Titanium Implants in a Canine Femoral Condyle Press-Fit Model

    PubMed Central

    Saksø, H; Jakobsen, T; Saksø, M; Baas, J; Jakobsen, SS; Soballe, K

    2013-01-01

    Purpose: Implant surface treatments that improve early osseointegration may prove useful in long-term survival of uncemented implants. We investigated Acid Etching and Plasma Cleaning on titanium implants. Methods: In a randomized, paired animal study, four porous coated Ti implants were inserted into the femurs of each of ten dogs. PC (Porous Coating; control)PC+PSHA (Plasma Sprayed Hydroxyapatite; positive control)PC+ET (Acid Etch)PC+ET+PLCN (Plasma Cleaning) After four weeks mechanical fixation was evaluated by push-out test and osseointegration by histomorphometry. Results: The PSHA-coated implants were better osseointegrated than the three other groups on outer surface implant porosity (p<0.05) while there was no statistical difference in deep surface implant porosity when compared with nontreated implant. Within the deep surface implant porosity, there was more newly formed bone in the control group compared to the ET and ET+PCLN groups (p<0.05). In all compared groups, there was no statistical difference in any biomechanical parameter. Conclusions: In terms of osseointegration on outer surface implant porosity PC+PSHA was superior to the other three groups. Neither the acid etching nor the plasma cleaning offered any advantage in terms of implant osseointegration. There was no statistical difference in any of the biomechanical parameters among all groups in the press-fit model at 4 weeks of evaluation time. PMID:23341850

  19. Modulated regeneration of acid-etched human tooth enamel by a functionalized dendrimer that is an analog of amelogenin.

    PubMed

    Chen, Mei; Yang, Jiaojiao; Li, Jiyao; Liang, Kunneng; He, Libang; Lin, Zaifu; Chen, Xingyu; Ren, Xiaokang; Li, Jianshu

    2014-10-01

    In the bioinspired repair process of tooth enamel, it is important to simultaneously mimic the organic-matrix-induced biomineralization and increase the binding strength at the remineralization interface. In this work, a fourth-generation polyamidoamine dendrimer (PAMAM) is modified by dimethyl phosphate to obtain phosphate-terminated dendrimer (PAMAM-PO3H2) since it has a similar dimensional scale and peripheral functionalities to that of amelogenin, which plays important role in the natural development process of enamel. Its phosphate group has stronger affinity for calcium ion than carboxyl group and can simultaneously provide strong hydroxyapatite (HA)-binding capability. The MTT assay demonstrates the low cytotoxicity of PAMAM-PO3H2. Adsorption tests indicate that PAMAM-PO3H2 can be tightly adsorbed on the human tooth enamel. Scanning electron microscopy and X-ray diffraction are used to analyze the remineralization process. After being incubated in artificial saliva for 3weeks, there is a newly generated HA layer of 11.23μm thickness on the acid-etched tooth enamel treated by PAMAM-PO3H2, while the thickness for the carboxyl-terminated one (PAMAM-COOH) is only 6.02μm. PAMAM-PO3H2 can regulate the remineralization process to form ordered new crystals oriented along the Z-axis and produce an enamel prism-like structure that is similar to that of natural tooth enamel. The animal experiment also demonstrates that PAMAM-PO3H2 can induce significant HA regeneration in the oral cavity of rats. Thus PAMAM-PO3H2 shows great potential as a biomimetic restorative material for human tooth enamel.

  20. Effect of modifications of dual acid-etched implant surfaces on periimplant bone formation. Part II: calcium phosphate coatings.

    PubMed

    Schliephake, H; Aref, A; Scharnweber, D; Rösler, S; Sewing, A

    2009-01-01

    The aim of the present study was to test the hypothesis that calcium phosphate coatings of dual acid-etched surfaces (DAEs) can improve periimplant bone regeneration. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Five types of surface states were evaluated in each animal: (i) implants with a machined surface (MS) (Control 1); (ii) implants with a DAE (Control 2); (iii) implants with a DAE coated with collagen I (Control 3); (iv) implants with a DAE with mineralized collagen I; and (v) implants with a DAE with a hydroxylapatite (HA) coating. Periimplant bone regeneration was assessed by histomorphometry after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the volume density of the newly formed periimplant bone (BVD). After 1 month, mean BIC of experimental implants did not differ significantly from implants with DAE and collagen-coated surfaces, but was significantly higher than the MS implants. BVD was enhanced significantly only in implants with mineralized collagen coating compared with DAE and collagen-coated controls. After 3 months, the mean values of BIC had increased significantly in the group of implants with HA and mineralized collagen coating but were not significantly different from implants with DAE and collagen-coated surfaces. The same held true for the mean BVD values. In conclusion, the present study could not verify the hypothesis that calcium phosphate coatings of DAEs in the present form enhanced periimplant bone formation compared with the DAE surface alone. PMID:19126106

  1. Surface Properties and Osteoblastic Cytocompatibility of Two Blasted and Acid-Etched Titanium Implant Systems with Distinct Microtopography

    PubMed Central

    Mesquita, Pedro; Gomes, Pedro de Sousa; Sampaio, Paula; Juodzbalys, Gintaras; Afonso, Américo

    2012-01-01

    ABSTRACT Objectives The aim of this study is to compare two commercially available screw-type sandblasted and acid-etched (SLA) Ti implant systems from Eckermann Laboratorium S.L., with similar geometry and distinct microtopography, regarding surface properties and osteoblastic cytocompatibility. Material and Methods Implant I (referred as a conventional SLA system) and Implant II (a system patented as Eckcyte®) were characterized for macro and microtopograpphy, surface roughness and chemical composition. For the cytocompatibility studies, human bone marrow osteoblastic cells were seeded over the implants' surface, and the cell response was assessed for cell adhesion and proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. Results Implant I presented a rough surface with irregularly shaped and sized cavities among flatter-appearing areas, whereas Implant II exhibited a homogeneous rough microporous surface. Compared to Implant I, Implant II presented higher Ra values (0.8 [SD 0.008] μm and 1.21 [SD 0.15] μm, respectively, P < 0.05) and also increased values of Rz, Rt and Rsm, a more negative value of Rsk, and similar RKu values. XPS showed the expected presence of Ti, O, C and N; Al, Si, F, P and Ca were detected in low concentrations. Implant II exhibited significantly lower Al levels. Both implants supported the adhesion, proliferation and differentiation of osteoblastic cells. Implant II showed a thicker fibrilar cell layer and an earlier onset and more abundant matrix mineralization. Conclusions The homogeneous rough and microporous surface of Implant II is most probably a main contributor for its improved cell response. PMID:24422006

  2. Evaluation of an endosseous titanium implant with a sandblasted and acid-etched surface in the canine mandible: radiographic results.

    PubMed

    Cochran, D L; Nummikoski, P V; Higginbottom, F L; Hermann, J S; Makins, S R; Buser, D

    1996-09-01

    Previous studies have demonstrated in short-term experiments that sandblasted and acid-etched (SLA) titanium implant had a greater bone-to-implant contact than a titanium plasma-sprayed (TPS) implant in non-oral bone. In the present study, an SLA implant was compared radiographically to a TPS implant under unloaded and loaded conditions in the canine mandible for up to 15 months. 69 implants were placed in 6 foxhounds. Standardized radiographs were taken at baseline, preload, 3, 6, 9, and 12 months of loading. Loaded implants were restored with gold crowns similar to the natural dentition. Radiographic assessment of the bone response to the implants was carried out by measuring the distance between the implant shoulder and the most coronal bone-to-implant contact (DIB) and by evaluated of bone density changes using computer-assisted densitometric image analysis (CADIA). 5 different areas-of-interest (AOI) were defined coronally and apically along the implant. DIB measurements revealed that SLA implants had significantly less bone height loss (0.52 mm) than TPS implants (0.69 mm) at the preload evaluation (p = 0.0142) as well as at 3 months of loading (0.73 mm/1.06 mm; p = 0.0337). This difference was maintained between the implant types during the 1-year follow-up period. The same trend was also evident for CADIA measurements with SLA implants showing higher crestal bone density values when comparing preload to baseline data (p = 0.0890) and 3 months to baseline data (p = 0.0912). No measurable bone density changes were apparent in the apical areas of either implant. These results suggest that SLA implants are superior to TPS implants as measured radiographically in oral bone under unloaded and loaded conditions.

  3. Uniform nano-ripples on the sidewall of silicon carbide micro-hole fabricated by femtosecond laser irradiation and acid etching

    SciTech Connect

    Khuat, Vanthanh; Chen, Tao; Gao, Bo; Si, Jinhai Ma, Yuncan; Hou, Xun

    2014-06-16

    Uniform nano-ripples were observed on the sidewall of micro-holes in silicon carbide fabricated by 800-nm femtosecond laser and chemical selective etching. The morphology of the ripple was analyzed using scanning electronic microscopy. The formation mechanism of the micro-holes was attributed to the chemical reaction of the laser affected zone with mixed solution of hydrofluoric acid and nitric acid. The formation of nano-ripples on the sidewall of the holes could be attributed to the standing wave generated in z direction due to the interference between the incident wave and the reflected wave.

  4. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    PubMed

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  5. Micro-PIXE and micro-RBS characterization of micropores in porous silicon prepared using microwave-assisted hydrofluoric acid etching.

    PubMed

    Ahmad, Muthanna; Grime, Geoffrey W

    2013-04-01

    Porous silicon (PS) has been prepared using a microwave-assisted hydrofluoric acid (HF) etching method from a silicon wafer pre-implanted with 5 MeV Cu ions. The use of microbeam proton-induced X-ray emission (micro-PIXE) and microbeam Rutherford backscattering techniques reveals for the first time the capability of these techniques for studying the formation of micropores. The porous structures observed from micro-PIXE imaging results are compared to scanning electron microscope images. It was observed that the implanted copper accumulates in the same location as the pores and that at high implanted dose the pores form large-scale patterns of lines and concentric circles. This is the first work demonstrating the use of microwave-assisted HF etching in the formation of PS.

  6. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    PubMed

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C. PMID:27295338

  7. Quasi-liquid states observed on ion beam microtextured surfaces

    NASA Technical Reports Server (NTRS)

    Rossnagel, S. M.; Robinson, R. S.

    1982-01-01

    Liquid-like properties have been observed on surface structures developed by means of ion beam microtexturing. The structures include cones, pyramids, or wavelike formations. The observed liquid-like effects are drips and ripples on the sides of cones, droplet formation, the apparent flow and coalescence of closely packed structures, wetting angle and other surface tension effects, and the bending of cones by additional heating. The bulk temperatures are in the range of 50-600 C. These effects are seen to some extent on Cu, Al, Au, Pb, and Ni substrates.

  8. EBSD analysis of the microtexture of Ba-hexaferrite samples

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Chen, Y.; Harris, V. G.

    2010-01-01

    The microtexture of differently prepared Ba-hexaferrite samples is investigated by means of electron backscatter diffraction (EBSD). Kikuchi patterns are obtained with a high image quality, enabling a spatial resolution of the EBSD maps of about 20 nm. The spatially highly resolved EBSD mappings provide additional information (individual grain orientation, misorientation angles, grain size distribution) as compared to the standard analysis techniques, which can contribute to an optimization of the growth process. Furthermore, as the crystallographic orientation of each grain is known, an exact analysis of the grain aspect ratio becomes possible which provides further insight to the microstructural dependence of the magnetic properties of ferrites.

  9. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

    NASA Astrophysics Data System (ADS)

    Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

    2016-03-01

    In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

  10. Optical investigation of the intergrowth structure and accessibility of Brønsted acid sites in etched SSZ-13 zeolite crystals by confocal fluorescence microscopy.

    PubMed

    Sommer, Linn; Svelle, Stian; Lillerud, Karl Petter; Stöcker, Michael; Weckhuysen, Bert M; Olsbye, Unni

    2010-11-01

    Template decomposition followed by confocal fluorescence microscopy reveals a tetragonal-pyramidal intergrowth of subunits in micrometer-sized nearly cubic SSZ-13 zeolite crystals. In order to accentuate intergrowth boundaries and defect-rich areas within the individual large zeolite crystals, a treatment with an etching NaOH solution is applied. The defective areas are visualized by monitoring the spatial distribution of fluorescent tracer molecules within the individual SSZ-13 crystals by confocal fluorescence microscopy. These fluorescent tracer molecules are formed at the inner and outer crystal surfaces by utilizing the catalytic activity of the zeolite in the oligomerization reaction of styrene derivatives. This approach reveals various types of etching patterns that are an indication for the defectiveness of the studied crystals. We can show that specially one type of crystals, denoted as core-shell type, is highly accessible to the styrene molecules after etching. Despite the large crystal dimensions, the whole core-shell type SSZ-13 crystal is utilized for catalytic reaction. Furthermore, the confocal fluorescence microscopy measurements indicate a nonuniform distribution of the catalytically important Brønsted acid sites underlining the importance of space-resolved measurements. PMID:20496927

  11. Effects of Dextrose and Lipopolysaccharide on the Corrosion Behavior of a Ti-6Al-4V Alloy with a Smooth Surface or Treated with Double-Acid-Etching

    PubMed Central

    Faverani, Leonardo P.; Assunção, Wirley G.; de Carvalho, Paulo Sérgio P.; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T.; Barao, Valentim A.

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2 = 0.726, p<0.0001 for the smooth surface; R2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no

  12. Effects of dextrose and lipopolysaccharide on the corrosion behavior of a Ti-6Al-4V alloy with a smooth surface or treated with double-acid-etching.

    PubMed

    Faverani, Leonardo P; Assunção, Wirley G; de Carvalho, Paulo Sérgio P; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T; Barao, Valentim A

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2 = 0.726, p<0.0001 for the smooth surface; R2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no

  13. Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin: microcomputed tomography and scanning electron microscopy analysis.

    PubMed

    Al-Fouzan, Khalid; Al-Garawi, Ziad; Al-Hezaimi, Khalid; Javed, Fawad; Al-Shalan, Thakib; Rotstein, Ilan

    2012-12-01

    The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm(3), (0.053±0.002) mm(3), (0.003 6±0.001) mm(3) and (0.005 9±0.002) mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA. PMID:23306857

  14. 24% Indigenously Prepared Ethylene Diamine Tetra Acetic Acid Compared to Self-Etching Adhesives and their Effect on Shear Bond Strength of Composites in Primary Teeth: An In-vitro Study

    PubMed Central

    Nagar, Priya; Tandil, Yogesh L.; T.P., Chandru; Gupta, Anamika; Kalaria, Devendra; Kumar, Prafful

    2015-01-01

    Background: Over the years, it has been known that 34% phosphoric acid is the benchmark in etchants with the best shear bond strength shown with composites in primary teeth. However, with latest technological advancements and innovations, in order to reduce the number of steps and less damage to the tooth structure, non-rinse conditioner (NRC) & Single-Etch and various other etchants have been tried and tested. These etchants have been found to have shear bond strength comparable to phosphoric acid. In this study, indigenously prepared 24% ethylenediaminetetraacetic acid (EDTA) has been compared with established etchants, as to prove if their shear bond strength was closely related. As it is a well-known fact that EDTA could be less damaging to the enamel during etching and hence can be an alternative for etching of primary teeth. Materials and Methods: For the study 60 caries-free primary molars were used, they were sectioned in the middle, after making area for bonding; the marked area was then etched using different etchants for 30 s. Each of the teeth was then rinsed and bonded with composite resin and thermocycling was done. Shear bond strength testing was done on the composite using Universal Testing Machine. Results: Results of the study showed that phosphoric acid showed the highest bond strength, closely followed by Single Etch (Adper Prompt) and NRC, then by EDTA. Conclusions: About 24% EDTA can be another comparable replacement for phosphoric acid if used with a Single Etch Primer, like Prime and Bond NT on primary teeth. 34% phosphoric acid has the highest bond strength values with composite resin. Single etch followed by NRC has the second and third highest bond strength values, which are comparable to phosphoric acid. PMID:26464540

  15. Early bone response to sandblasted, dual acid-etched and H2O2/HCl treated titanium implants: an experimental study in the rabbit.

    PubMed

    He, F M; Yang, G L; Li, Y N; Wang, X X; Zhao, S F

    2009-06-01

    The aim of this study was to evaluate the influence of a roughened H(2)O(2)/HCl heat-treated titanium surface on peri-implant bone formation at an early stage in vivo. 24 Ti(6)Al(4)V alloy implants were used; half were treated by sandblasted and dual acid-etched treatments (control group), while the others were treated by sandblasted, dual acid-etched and H(2)O(2)/HCl heat treatments (test group). The morphology and roughness were analyzed by field emission SEM and atomic force microscopy. The implants were inserted into the femora of 12 adult white rabbits. After 2 and 4 weeks, femora block specimens were prepared for histological and histomorphometric analysis. SEM micrographs showed that multilevel and different sized pits were formed on both surfaces. New bone formation was observed on both implant surfaces. Test implants demonstrated a greater mean percentage of bone-implant contact as compared with controls at 2 (46.84 vs. 41.81, p=0.000) and 4 weeks (49.43 vs. 44.87, p=0.006) of healing. It is concluded that the H(2)O(2)/HCl heat-treated rough titanium surface promoted enhanced bone apposition during the early stages of new bone formation around the implant. PMID:19406618

  16. Ethylene Diamine Tetraacetic Acid Etched Quantum Dots as a "Turn-On" Fluorescence Probe for Detection of Trace Zinc in Food.

    PubMed

    Liu, Wei; Wei, Fangdi; Xu, Guanhong; Wu, Yanzi; Hu, Chunting; Song, Quan; Yang, Jing; Hu, Qin

    2016-06-01

    In the present paper, a simple and rapid "turn-on" fluorescence sensor for Zn2+ based on ethylene diamine tetraacetic acid (EDTA) etched CdTe quantum dots (QDs) was developed. First, the initial bright fluorescence of mercaptopropionic acid (MPA) capped CdTe QDs was effectively quenched by EDTA, and then the presence of Zn2+ could "turn on" the weak fluorescence of QDs quenched by EDTA due to the formation of ZnS passivation shell. The increase of fluorescence intensity of EDTA etched QDs was found to be linear with the concentration of Zn2+ added. Under the optimum conditions, the calibration curve of this method showed good linearity in the concentration range of 9.1-1 09.1 μM of Zn2+ with the correlation coefficient R2 = 0.998. The limit of detection (3σ/K) was 2 μM. The developed QDs-based sensor was successfully applied to detect trace zinc in zinc fortified table salts and energy drinks with satisfactory results. PMID:27427745

  17. Etching study of poled lithium tantalate crystal using wet etching technique with ultrasonic assistance

    NASA Astrophysics Data System (ADS)

    Gao, Z. D.; Wang, Q. J.; Zhang, Y.; Zhu, S. N.

    2008-02-01

    Utilizing the difference in etching rates of the positive and negative domains in an acid solution, domain pattern can be fabricated on the polarity surface of a congruent lithium tantalate crystal. Our results show that the ultrasonic agitation can improve the etching rate. An enhanced factor up to six was realized under a 50 W of ultrasonic power in a mixture with volumetric ratio of HF to H 2SO 4 at 1:2. The dependences of etching morphology on etching time and etching etchant for congruent lithium tantalate crystal were studied. The technique is applicable to fabricating three-dimensional microstructures on the surface of ferroelectric crystals.

  18. Dry etching of metallization

    NASA Technical Reports Server (NTRS)

    Bollinger, D.

    1983-01-01

    The production dry etch processes are reviewed from the perspective of microelectronic fabrication applications. The major dry etch processes used in the fabrication of microelectronic devices can be divided into two categories - plasma processes in which samples are directly exposed to an electrical discharge, and ion beam processes in which samples are etched by a beam of ions extracted from a discharge. The plasma etch processes can be distinguished by the degree to which ion bombardment contributes to the etch process. This, in turn is related to capability for anisotropic etching. Reactive Ion Etching (RIE) and Ion Beam Etching are of most interest for etching of thin film metals. RIE is generally considered the best process for large volume, anisotropic aluminum etching.

  19. Process for etching mixed metal oxides

    DOEpatents

    Ashby, C.I.H.; Ginley, D.S.

    1994-10-18

    An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

  20. Process for etching mixed metal oxides

    DOEpatents

    Ashby, Carol I. H.; Ginley, David S.

    1994-01-01

    An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

  1. Etching of Crystalline ZnO Surfaces upon Phosphonic Acid Adsorption: Guidelines for the Realization of Well-Engineered Functional Self-Assembled Monolayers.

    PubMed

    Ostapenko, Alexandra; Klöffel, Tobias; Eußner, Jens; Harms, Klaus; Dehnen, Stefanie; Meyer, Bernd; Witte, Gregor

    2016-06-01

    Functionalization of metal oxides by means of covalently bound self-assembled monolayers (SAMs) offers a tailoring of surface electronic properties such as their work function and, in combination with its large charge carrier mobility, renders ZnO a promising conductive oxide for use as transparent electrode material in optoelectronic devices. In this study, we show that the formation of phosphonic acid-anchored SAMs on ZnO competes with an unwanted chemical side reaction, leading to the formation of surface precipitates and severe surface damage at prolonged immersion times of several days. Combining atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal desorption spectroscopy (TDS), the stability and structure of the aggregates formed upon immersion of ZnO single crystal surfaces of different orientations [(0001̅), (0001), and (101̅0)] in phenylphosphonic acid (PPA) solution were studied. By intentionally increasing the immersion time to more than 1 week, large crystalline precipitates are formed, which are identified as zinc phosphonate. Moreover, the energetics and the reaction pathway of this transformation have been evaluated using density functional theory (DFT), showing that zinc phosphonate is thermodynamically more favorable than phosphonic acid SAMs on ZnO. Precipitation is also found for phosphonic acids with fluorinated aromatic backbones, while less precipitation occurs upon formation of SAMs with phenylphosphinic anchoring units. By contrast, no precipitates are formed when PPA monolayer films are prepared by sublimation under vacuum conditions, yielding smooth surfaces without noticeable etching. PMID:27159837

  2. Copper-assisted, anti-reflection etching of silicon surfaces

    SciTech Connect

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  3. Tobacco etch virus infectivity in Capsicum spp. is determined by a maximum of three amino acids in the viral virulence determinant VPg.

    PubMed

    Perez, Kari; Yeam, Inhwa; Kang, Byoung-Cheorl; Ripoll, Daniel R; Kim, Jinhee; Murphy, John F; Jahn, Molly M

    2012-12-01

    Potyvirus resistance in Capsicum spp. has been attributed to amino acid substitutions at the pvr1 locus that cause conformational shifts in eukaryotic translation initiation factor eIF4E. The viral genome-linked protein (VPg) sequence was isolated and compared from three Tobacco etch virus (TEV) strains, highly aphid-transmissible (HAT), Mex21, and N, which differentially infect Capsicum genotypes encoding Pvr1(+), pvr1, and pvr1(2). Viral chimeras were synthesized using the TEV-HAT genome, replacing HAT VPg with Mex21 or N VPg. TEV HAT did not infect pepper plants homozygous for either the pvr1 or pvr1(2) allele. However, the novel chimeric TEV strains, TEVHAT(Mex21-VPg) and TEV-HAT(N-VPg), infected pvr1 and pvr1(2) pepper plants, respectively, demonstrating that VPg is the virulence determinant in this pathosystem. Three dimensional structural models predicted interaction between VPg and the susceptible eIF4E genotype in every case, while resistant genotypes were never predicted to interact. To determine whether there is a correlation between physical interaction of VPg with eIF4E and infectivity, the effects of amino acid variation within VPg were assessed. Interaction between pvr1(2) eIF4E and N VPg was detected in planta, implying that the six amino acid differences in N VPg relative to HAT VPg are responsible for restoring the physical interaction and infectivity.

  4. Evaluation of dentin bonding performance and acid-base resistance of the interface of two-step self-etching adhesive systems.

    PubMed

    IIda, Yasuhiro; Nikaido, Toru; Kitayama, Shuzo; Takagaki, Tomohiro; Inoue, Go; Ikeda, Masaomi; Foxton, Richard M; Tagami, Junji

    2009-07-01

    The purpose of this study was to evaluate dentin bond strengths and to observe the adhesive-dentin interface after acid-base challenge using fluoride-free and fluoride-releasing self-etching adhesive systems; Clearfil SE Bond (SE), FL-Bond (FL) and FL-Bond II(FL II). Fifteen dentin surfaces from human molars were ground and bonded with one of three adhesive systems. The microtensile bond strength (muTBS) test was performed at a crosshead speed of 1 mm/min. The interface of the bonded specimens after acid-base challenge were also examined by a SEM. The muTBS of SE were significantly higher than those of FL and FL II (p<0.05), however, there were no significant differences between FL and FL II (p>0.05). An acid-base resistant zone (ABRZ) was observed in all the groups, however, formation of the ABRZ was material dependent. Fluoride-release from the adhesive is a key factor to create thick ABRZ.

  5. Spinner For Etching Of Semiconductor Wafers

    NASA Technical Reports Server (NTRS)

    Lombardi, Frank

    1989-01-01

    Simple, inexpensive apparatus coats semiconductor wafers uniformly with hydrofluoric acid for etching. Apparatus made in part from small commercial electric-fan motor. Features bowl that collects acid. Silicon wafer placed on platform and centered on axis; motor switched on. As wafer spins, drops of hydrofluoric acid applied from syringe. Centrifugal force spreads acid across wafer in fairly uniform sheet.

  6. Kinetics and microtextures formation during serpentinization: role of grain scale processes and transport

    NASA Astrophysics Data System (ADS)

    malvoisin, B.; Brunet, F.; Carlut, J. H.

    2013-12-01

    Serpentinization of mantle rocks plays a key role on the physical properties of the lithosphere at mid-ocean ridges and in subduction zones. This reaction is controlled by processes occurring at scales ranging from the grain to the lithosphere but the relative importance of these processes on the kinetics and microtextures formation has not been investigated. First, hydrothermal experiments on powders of San Carlos olivine at 500 bars in the 250 - 350 °C range were monitored with a magnetic method to study the kinetics and processes of the reaction at the grain scale. For an initial grain size (IGS) > 5 μm, lizardite, brucite, magnetite and hydrogen formed at a rate one to two orders of magnitude slower than the kinetics used to model serpentinization-related processes. Moreover, the serpentinization rate decreased linearly with the square of the IGS and reaction progress vs. time curves displayed a sigmoid form. The kinetics were controlled by the dissolution of olivine increasing with its reactive surface area which was generated with two cooperating processes (etch pits and grain fracturing) during the first stages of the reaction. Then, hydrothermal experiments were conducted on sintered San Carlos olivine to investigate the role of transport on the reaction. On sintered with a grain size of 1 to 5 μm, low reaction progresses of ~ 3 % in 10 months were obtained and the rate of serpentinization was one order of magnitude slower than on powders and one order of magnitude faster than on a single grain of the size of the sintered. Kinetics were controlled by a coupling between the reaction rate at the grain scale and the rate of fluid pathways formation at grain boundaries. Lizardite precipitated where olivine dissolved whereas magnetite and brucite segregated at the surface of the sintered. These results are in agreement with the observation of magnetite formation and segregation in fractures in naturally serpentinized peridotites and could explain the sparse

  7. Effect of cavity preparation method on microtensile bond strength of a self-etching primer vs phosphoric acid etchant to enamel.

    PubMed

    de Souza-Zaroni, Wanessa Christine; Delfino, Carina Sinclér; Ciccone-Nogueira, Juliane Cristina; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

    2007-10-01

    This study evaluated the effect of cavity preparation using air abrasion or carbide bur on bond strength to enamel treated with a self-etching primer (Tyrian SPE) or a phosphoric acid etchant. Twenty-four molars were divided into three groups: high-speed; standard handpiece (ST air abrasion) or supersonic handpiece (SP air abrasion) of the same air-abrasive system. The enamel surfaces were treated with one of the two etchants and the same adhesive agent One Step Plus, and then composite buildups were done with Filtek Z250. After 24 h at 37 degrees C, beams (0.8 mm2) were obtained and subjected to tensile stress in a universal testing machine (0.5 mm/min). The data were submitted to analysis of variance and Tukey's test (P < 0.05). For the conditioning agents, it was observed that the specimens conditioned with phosphoric acid presented superior results than the specimens that used Tyrian SPE. For the preparation techniques, it was verified that the SP air abrasion groups showed the highest bond strengths and carbide-bur groups presented the lowest bond strengths when the specimens were conditioned with Tyrian SPE. It can be concluded that the influence of the cavity preparation method was dependent on the conditioning system used, only when using carbide-bur preparation technique.

  8. Alkaline etch system qualification

    SciTech Connect

    Goldammer, S.E.; Pemberton, S.E.; Tucker, D.R.

    1997-04-01

    Based on the data from this qualification activity, the Atotech etch system, even with minimum characterization, was capable of etching production printed circuit products as good as those from the Chemcut system. Further characterization of the Atotech system will improve its etching capability. In addition to the improved etch quality expected from further characterization, the Atotech etch system has additional features that help reduce waste and provide for better consistency in the etching process. The programmable logic controller and computer will allow operators to operate the system manually or from pre-established recipes. The evidence and capabilities of the Atotech system made it as good as or better than the Chemcut system for etching WR products. The Printed Wiring Board Engineering Department recommended that the Atotech system be released for production. In December 1995, the Atotech system was formerly qualified for production.

  9. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu2+/bicinchoninic acid pair with improved sensitivity

    NASA Astrophysics Data System (ADS)

    Liu, Wenqi; Hou, Shuai; Yan, Jiao; Zhang, Hui; Ji, Yinglu; Wu, Xiaochun

    2015-12-01

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml-1) and a wide working range (0.5 to 1000 μg ml-1) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications.Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical

  10. Microtextural analysis of quartz grains of tsunami and non-tsunami deposits - A case study from Tirúa (Chile)

    NASA Astrophysics Data System (ADS)

    Bellanova, Piero; Bahlburg, Heinrich; Nentwig, Vanessa; Spiske, Michaela

    2016-08-01

    In order to estimate the tsunami hazard it is essential to reliably identify and differentiate tsunami deposits from other high-energy events like storms. Recently, the microtextural analysis of quartz grain surfaces was introduced as a method to differentiate between tsunami and other deposits. Using tsunami deposits sampled from a bank profile of the Tirúa river (central Chile), an area that was significantly affected by the 2010 and 1960 Chile tsunamis, we tested the microtextural analysis method for its capability to identify tsunami deposits. A total of 815 quartz grain surfaces of two tsunami layers, two non-tsunami marsh sediment samples, and three reference samples from nearby beach, dune and river were analyzed using scanning electron microscopy (SEM). We grouped the detected microtexture features into five microtextural families: angularity, fresh surfaces, percussion marks, adhering particles and dissolution features. Both the tsunami deposits and reference samples reveal high numbers of fresh surfaces and percussion marks. Thus, there are no statistically significant differences between tsunami, beach, dune and river deposits in characteristics and abundances in all microtextural families. Our study indicates that the microtextural analysis of quartz grains may not be a suitable method to identify tsunami deposits in Tirúa (Chile), due to local factors such as high numbers of inherited microtextures and the possible effects of the high amount of heavy minerals.

  11. Effects of rhBMP-2 on Sandblasted and Acid Etched Titanium Implant Surfaces on Bone Regeneration and Osseointegration: Spilt-Mouth Designed Pilot Study.

    PubMed

    Kim, Nam-Ho; Lee, So-Hyoun; Ryu, Jae-Jun; Choi, Kyung-Hee; Huh, Jung-Bo

    2015-01-01

    This study was conducted to evaluate effects of rhBMP-2 applied at different concentrations to sandblasted and acid etched (SLA) implants on osseointegration and bone regeneration in a bone defect of beagle dogs as pilot study using split-mouth design. Methods. For experimental groups, SLA implants were coated with different concentrations of rhBMP-2 (0.1, 0.5, and 1 mg/mL). After assessment of surface characteristics and rhBMP-2 releasing profile, the experimental groups and untreated control groups (n = 6 in each group, two animals in each group) were placed in split-mouth designed animal models with buccal open defect. At 8 weeks after implant placement, implant stability quotients (ISQ) values were recorded and vertical bone height (VBH, mm), bone-to-implant contact ratio (BIC, %), and bone volume (BV, %) in the upper 3 mm defect areas were measured. Results. The ISQ values were highest in the 1.0 group. Mean values of VBH (mm), BIC (%), and BV (%) were greater in the 0.5 mg/mL and 1.0 mg/mL groups than those in 0.1 and control groups in buccal defect areas. Conclusion. In the open defect area surrounding the SLA implant, coating with 0.5 and 1.0 mg/mL concentrations of rhBMP-2 was more effective, compared with untreated group, in promoting bone regeneration and osseointegration. PMID:26504807

  12. Physico/chemical characterization and in vivo evaluation of nanothickness bioceramic depositions on alumina-blasted/acid-etched Ti-6Al-4V implant surfaces.

    PubMed

    Coelho, Paulo G; Lemons, Jack E

    2009-08-01

    The objective of this study was to physico/chemically characterize and evaluate the in vivo performance of two nanothickness ion beam assisted depositions (IBAD) of bioceramic coatings on implants in a beagle model. Alumina-blasted/acid-etched (AB/AE) Ti-6Al-4V implants were subjected to two different IBAD depositions (IBAD I and IBAD II), which were physico/chemically characterized by SEM, EDS, XPS, XPS + ion-beam milling (depth profiling), XRD, AFM, and ToF-SIMS. A beagle dog tibia model was utilized for histomorphometric and biomechanical (torque) comparison between AB/AE, IBAD I, IBAD II, and plasma-sprayed hydroxyapatite (PSHA) coated implants that remained in vivo for 3 and 5 weeks. The coatings were characterized as amorphous Ca-P with high Ca/P stoichiometries with thicknesses of an order of magnitude difference (IBAD I = 30-50 nm and IBAD II = 300-500 nm). The histomorphometric and biomechanical testing results showed that the 300-500 nm thickness deposition (IBAD II) and PSHA positively modulated bone healing at early implantation times. PMID:18508352

  13. Comparative Study of the Early Loading of Resorbable Blasting Media and Sandblasting with Large-grit and Acid-etching Surface Implants: A Retrospective Cohort Study

    PubMed Central

    Kim, Sung-Beom; Kim, Young-Kyun; Kim, Su-Gwan; Oh, Ji-Su; Kim, Byung-Hoon

    2014-01-01

    Purpose: This study compares the prognosis (the survival rate and marginal bone loss) of resorbable blasting media (RBM) surface implants and sandblasting with large-grit and acid-etching (SLA) surface implants in the early loading. Methods: This study targeted 123 patients treated by implants installation from January 2008 to March 2010. The loading was initiated in the maxilla within three to four months and in the mandible within one to two months. The types of restoration were single crown and fixed partial prosthesis. Those functioned over one year. The implants were classified by the surface of implants as Group 1: RBM surface (GS III; OSSTEM, Busan, Korea) and, Group 2: SLA surface (Superline; Dentium, Seoul, Korea). The groups were categorized by maxilla and mandible and compared by survival rate, marginal bone loss through clinical records evaluation, and radiographic measurements. Results: The marginal bone loss in the maxilla was 0.14±0.34 mm (Group 1) and 0.30±0.37 mm (Group 2), a statistically significant difference (P <0.05). In the mandible those were 0.28±0.54 mm (Group 1) and 0.20±0.33 mm (Group 2), not significant (P >0.05). There was no significant difference of marginal bone loss between maxilla and mandible by groups. During observation there was no implant failure, a survival rate of 100%. Conclusion: Both surfaces showed an excellent survival rate, and the marginal bone loss was not substantial. PMID:27489842

  14. Early bone response to machined, sandblasting acid etching (SLA) and novel surface-functionalization (SLAffinity) titanium implants: characterization, biomechanical analysis and histological evaluation in pigs.

    PubMed

    Chiang, Hsi-Jen; Hsu, Heng-Jui; Peng, Pei-Wen; Wu, Ching-Zong; Ou, Keng-Liang; Cheng, Han-Yi; Walinski, Christopher J; Sugiatno, Erwan

    2016-02-01

    The purpose of the present study was to examine early tissue response and osseointegration in the animal model. The surface morphologies of SLAffinity were characterized using scanning electron microscopy and atomic force microscopy. The microstructures were examined by X-ray diffraction, and hardness was measured by nanoindentation. Moreover, the safety and toxicity properties were evaluated using computer-aided programs and cell cytotoxicity assays. In the animal model, implants were installed in the mandibular canine-premolar area of 12 miniature pigs. Each pig received three implants: machine, sandblasted, large grit, acid-etched, and SLAffinity-treated implants. The results showed that surface treatment did affect bone-to-implant contact (BIC) significantly. At 3 weeks, the SLAffinity-treated implants were found to present significantly higher BIC values than the untreated implants. The SLAffinity treatments enhanced osseointegration significantly, especially at early stages of bone tissue healing. As described above, the results of the present study demonstrate that the SLAffinity treatment is a reliable surface modification method.

  15. Effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of sand-blasted, large grit, acid-etched implants

    PubMed Central

    Lee, Ji-Hun; Kwon, Young-Hyuk; Herr, Yeek; Shin, Seung-Il

    2011-01-01

    Purpose The present study was performed to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on sand-blasted, large grit, acid-etched (SLA) implant surface microstructure according to varying energy levels and application times of the laser. Methods The implant surface was irradiated by the Er:YAG laser under combined conditions of 100, 140, or 180 mJ/pulse and an application time of 1 minute, 1.5 minutes, or 2 minutes. Scanning electron microscopy (SEM) was used to examine the surface roughness of the specimens. Results All experimental conditions of Er:YAG laser irradiation, except the power setting of 100 mJ/pulse for 1 minute and 1.5 minutes, led to an alteration in the implant surface. SEM evaluation showed a decrease in the surface roughness of the implants. However, the difference was not statistically significant. Alterations of implant surfaces included meltdown and flattening. More extensive alterations were present with increasing laser energy and application time. Conclusions To ensure no damage to their surfaces, it is recommended that SLA implants be irradiated with an Er:YAG laser below 100 mJ/pulse and 1.5 minutes for detoxifying the implant surfaces. PMID:21811689

  16. Adult stem cells properties in terms of commitment, aging and biological safety of grit-blasted and Acid-etched ti dental implants surfaces.

    PubMed

    Gardin, Chiara; Ferroni, Letizia; Bressan, Eriberto; Calvo-Guirado, José L; Degidi, Marco; Piattelli, Adriano; Zavan, Barbara

    2014-01-01

    Titanium (Ti) is one of the most widely used biomaterials for manufacturing dental implants. The implant surface properties strongly influence osseointegration. The aim of the present study was to in vitro investigate the characteristics of Ti dental implants in terms of mutagenicity, hemocompatibility, biocompatibility, osteoinductivity and biological safety. The Ames test was used to test the mutagenicity of the Ti dental implants, and the hemolysis assay for evaluating their hemocompatibility. Human adipose - derived stem cells (ADSCs) were then seeded onto these implants in order to evaluate their cytotoxicity. Gene expression analyzing with real-time PCR was carried out to investigate the osteoinductivity of the biomaterials. Finally, the genetic stability of the cells cultured onto dental implants was determined by karyotyping. Our results demonstrated that Ti dental implants are not mutagenic, do not cause hemolysis, and are biocompatible. The MTT assay revealed that ADSCs, seeded on Ti dental implants, proliferate up to 30 days in culture. Moreover, ADSCs loaded on Ti dental implants show a substantial expression of some osteoblast specific markers, such as COL1A1, OPN, ALPL, and RUNX2, as well as chromosomal stability after 30 days of culture in a medium without osteogenic factors. In conclusion, the grit-blasted and acid-etched treatment seems to favor the adhesion and proliferation of ADSCs and improve the osteoinductivity of Ti dental implant surfaces.

  17. Effects of rhBMP-2 on Sandblasted and Acid Etched Titanium Implant Surfaces on Bone Regeneration and Osseointegration: Spilt-Mouth Designed Pilot Study

    PubMed Central

    Kim, Nam-Ho; Lee, So-Hyoun; Ryu, Jae-Jun; Choi, Kyung-Hee; Huh, Jung-Bo

    2015-01-01

    This study was conducted to evaluate effects of rhBMP-2 applied at different concentrations to sandblasted and acid etched (SLA) implants on osseointegration and bone regeneration in a bone defect of beagle dogs as pilot study using split-mouth design. Methods. For experimental groups, SLA implants were coated with different concentrations of rhBMP-2 (0.1, 0.5, and 1 mg/mL). After assessment of surface characteristics and rhBMP-2 releasing profile, the experimental groups and untreated control groups (n = 6 in each group, two animals in each group) were placed in split-mouth designed animal models with buccal open defect. At 8 weeks after implant placement, implant stability quotients (ISQ) values were recorded and vertical bone height (VBH, mm), bone-to-implant contact ratio (BIC, %), and bone volume (BV, %) in the upper 3 mm defect areas were measured. Results. The ISQ values were highest in the 1.0 group. Mean values of VBH (mm), BIC (%), and BV (%) were greater in the 0.5 mg/mL and 1.0 mg/mL groups than those in 0.1 and control groups in buccal defect areas. Conclusion. In the open defect area surrounding the SLA implant, coating with 0.5 and 1.0 mg/mL concentrations of rhBMP-2 was more effective, compared with untreated group, in promoting bone regeneration and osseointegration. PMID:26504807

  18. Adult Stem Cells Properties in Terms of Commitment, Aging and Biological Safety of Grit-Blasted and Acid-Etched Ti Dental Implants Surfaces

    PubMed Central

    Gardin, Chiara; Ferroni, Letizia; Bressan, Eriberto; Calvo - Guirado, José L.; Degidi, Marco; Piattelli, Adriano; Zavan, Barbara

    2014-01-01

    Titanium (Ti) is one of the most widely used biomaterials for manufacturing dental implants. The implant surface properties strongly influence osseointegration. The aim of the present study was to in vitro investigate the characteristics of Ti dental implants in terms of mutagenicity, hemocompatibility, biocompatibility, osteoinductivity and biological safety. The Ames test was used to test the mutagenicity of the Ti dental implants, and the hemolysis assay for evaluating their hemocompatibility. Human adipose - derived stem cells (ADSCs) were then seeded onto these implants in order to evaluate their cytotoxicity. Gene expression analyzing with real-time PCR was carried out to investigate the osteoinductivity of the biomaterials. Finally, the genetic stability of the cells cultured onto dental implants was determined by karyotyping. Our results demonstrated that Ti dental implants are not mutagenic, do not cause hemolysis, and are biocompatible. The MTT assay revealed that ADSCs, seeded on Ti dental implants, proliferate up to 30 days in culture. Moreover, ADSCs loaded on Ti dental implants show a substantial expression of some osteoblast specific markers, such as COL1A1, OPN, ALPL, and RUNX2, as well as chromosomal stability after 30 days of culture in a medium without osteogenic factors. In conclusion, the grit-blasted and acid-etched treatment seems to favor the adhesion and proliferation of ADSCs and improve the osteoinductivity of Ti dental implant surfaces. PMID:25635249

  19. A patterned microtexture to reduce friction and increase longevity of prosthetic hip joints

    PubMed Central

    Chyr, Anthony; Qiu, Mingfeng; Speltz, Jared; Jacobsen, Ronald L.; Sanders, Anthony P.; Raeymaekers, Bart

    2014-01-01

    More than 285,000 total hip replacement surgeries are performed in the US each year. Most prosthetic hip joints consist of a cobalt-chromium (CoCr) femoral head that articulates with a polyethylene acetabular component, lubricated with synovial fluid. The statistical survivorship of these metal-on-polyethylene prosthetic hip joints declines significantly after 10 to 15 years of use, primarily as a result of polyethylene wear and wear debris incited disease. The current engineering paradigm to increase the longevity of prosthetic hip joints is to improve the mechanical properties of the polyethylene component, and to manufacture ultra-smooth articulating surfaces. In contrast, we show that adding a patterned microtexture to the ultra-smooth CoCr femoral head reduces friction when articulating with the polyethylene acetabular liner. The microtexture increases the load-carrying capacity and the thickness of the joint lubricant film, which reduces contact between the articulating surfaces. As a result, friction and wear is reduced. We have used a lubrication model to design the geometry of the patterned microtexture, and experimentally demonstrate reduced friction for the microtextured compared to conventional smooth surrogate prosthetic hip joints. PMID:25013240

  20. A patterned microtexture to reduce friction and increase longevity of prosthetic hip joints.

    PubMed

    Chyr, Anthony; Qiu, Mingfeng; Speltz, Jared; Jacobsen, Ronald L; Sanders, Anthony P; Raeymaekers, Bart

    2014-07-15

    More than 285,000 total hip replacement surgeries are performed in the US each year. Most prosthetic hip joints consist of a cobalt-chromium (CoCr) femoral head that articulates with a polyethylene acetabular component, lubricated with synovial fluid. The statistical survivorship of these metal-on-polyethylene prosthetic hip joints declines significantly after 10 to 15 years of use, primarily as a result of polyethylene wear and wear debris incited disease. The current engineering paradigm to increase the longevity of prosthetic hip joints is to improve the mechanical properties of the polyethylene component, and to manufacture ultra-smooth articulating surfaces. In contrast, we show that adding a patterned microtexture to the ultra-smooth CoCr femoral head reduces friction when articulating with the polyethylene acetabular liner. The microtexture increases the load-carrying capacity and the thickness of the joint lubricant film, which reduces contact between the articulating surfaces. As a result, friction and wear is reduced. We have used a lubrication model to design the geometry of the patterned microtexture, and experimentally demonstrate reduced friction for the microtextured compared to conventional smooth surrogate prosthetic hip joints.

  1. Effect of surface micro-texture on bubble dynamics and boiling critical heat flux

    NASA Astrophysics Data System (ADS)

    Dhillon, Navdeep; Buongiorno, Jacopo; Varanasi, Kripa

    2014-11-01

    We present results of an experimental study on the effect of surface texture on the dynamics of bubble growth and departure in pool boiling of water and correlate them to the measured values of critical heat flux (CHF) on these surfaces. Although it is well known that surface roughness or micro-texture has a significant impact on macroscale boiling parameters such as boiling heat transfer coefficient (HTC) and CHF, the physics underlying these processes is not well understood. Using high speed optical and infrared (IR) imaging, we explored the mechanism of single bubble growth and departure on micro-textured surfaces fabricated using photolithography techniques. Interestingly, we observed that the introduction of the micro-texture not only completely changed bubble dynamics and boiling surface thermal characteristics but there was a clear correlation between the micro-texture parameters and the salient bubble characteristics such as the departure diameter and frequency. To explain these results, we propose a physical model based on micro-texture-induced surface microflows supplementing the conventional bubble growth and departure theory based on buoyancy and capillary pinning forces, and verify it using CHF measurements. Funding for this project is provided by Chevron Corp.

  2. In vivo assessment of bone ingrowth potential of three-dimensional e-beam produced implant surfaces and the effect of additional treatment by acid etching and hydroxyapatite coating.

    PubMed

    Biemond, J Elizabeth; Hannink, Gerjon; Jurrius, Annemarijn M G; Verdonschot, Nico; Buma, Pieter

    2012-03-01

    The bone ingrowth potential of three-dimensional E-beam-produced implant surfaces was examined by histology and compared to a porous plasma-sprayed control. The effects of acid etching and a hydroxyapatite (HA) coating were also evaluated by histology. Specimens were implanted in the distal femur of 10 goats. Histological analysis of bone ingrowth was performed 6 weeks after implantation. The E-beam-produced surfaces showed significantly better bone ingrowth compared to the plasma-sprayed control. Additional treatment of the E-beam surface structures with a HA coating, further improved bone ingrowth potential of these structures significantly. Acid etching of the E-beam structures did not influence bone ingrowth significantly. In conclusion, the HA-coated, E-beam-produced structures are promising potential implant surfaces.

  3. Comparison of alkaline phosphatase activity of MC3T3-E1 cells cultured on different Ti surfaces: modified sandblasted with large grit and acid-etched (MSLA), laser-treated, and laser and acid-treated Ti surfaces

    PubMed Central

    Li, Lin-Jie; Kim, So-Nam

    2016-01-01

    PURPOSE In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P<.05). Furthermore, ALP expression levels of MSLA and LAT surfaces were significantly higher than expression levels of LT surface-adherent cells at 7, 14, and 21 days, respectively (P<.05). However, ALP expression levels between MSLA and LAT surface were equal at 7, 14, and 21 days (P>.05). CONCLUSION This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies. PMID:27350860

  4. Er:YAG laser radiation etching of enamel

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav

    1996-12-01

    This study compares the effects of acid treatment and Er:YAG laser radiation on the enamel. The permanent human molars were used. Oval cavities in the buccal surface were prepared and the edges of cavities were irradiated by Er:YAG radiation. The energy of laser was 105 mJ and repetition rate 1 Hz. The radiation was focused by CaF2 lens and the sample was placed in the focus. Ten samples were etched by 35 percent phosphoric acid during 60 s. Than cavities were filled with composite resin following manufacturers directions. By laser etching the structure enamel in section was rougher. The optimal connection between the enamel and composite resin was achieved in 75 percent by acid etching and in 79.2 percent by Er:YAG laser etching. Er:YAG laser etching could be alternative method for etching of enamel.

  5. Metal etching with reactive gas cluster ion beams using pickup cell

    SciTech Connect

    Toyoda, Noriaki; Yamada, Isao

    2012-11-06

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O{sub 2} neutral clusters pick up acetic acid and formed mixed cluster beam. By using O{sub 2}-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  6. Metal etching with reactive gas cluster ion beams using pickup cell

    NASA Astrophysics Data System (ADS)

    Toyoda, Noriaki; Yamada, Isao

    2012-11-01

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O2 neutral clusters pick up acetic acid and formed mixed cluster beam. By using O2-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  7. Sputtered gold mask for deep chemical etching of silicon

    NASA Technical Reports Server (NTRS)

    Pisciotta, B. P.; Gross, C.; Olive, R. S.

    1975-01-01

    Sputtered mask resists chemical attack from acid and has adherence to withstand prolonged submergence in etch solution without lifting from silicon surface. Even under prolonged etch conditions with significant undercutting, gold mask maintained excellent adhesion to silicon surface and imperviousness to acid.

  8. The isotopic composition of zinc, palladium, silver, cadmium, tin, and tellurium in acid-etched residues of the Allende meteorite

    SciTech Connect

    Loss, R.D.; Rosman, K.J.R.; De Laeter, J.R. )

    1990-12-01

    The isotopic and elemental abundances of Zn, Pd, Ag, Cd, Sn, and Te have been measured in three acid-resistant residues extracted from the Allende meteorite. High-efficiency, low-contamination ion-exchange procedures were developed to separate and purify the nanogram amounts of these elements present. Elemental-abundance determinations performed by Mass Spectrometric Isotope Dilution agree with previously published work for similarly derived residues. No isotope anomalies similar to those found for Xe (Xe-HL) in these samples were detected for any of these elements, which is consistent with the residues not being derived directly from the Xe-HL carriers. The lack of major Te-isotope anomalies does not support earlier reports of {sup 126}Te and {sup 130}Te excesses which were measured by neutron activation in similar samples. Small excesses were detected in the minor isotopes of Sn and Te, but these may be due to measurement problems associated with the small ion currents obtained for these samples. Two of the residue solutions contain Cd with up to several percent excesses for {sup 106}Cd and {sup 108}Cd. Interpretations of these results are limited by the unknown nature of the carrier minerals in the residues but may indicate the presence of a p-process component in Allende residues.

  9. Nanoparticle-based etching of silicon surfaces

    DOEpatents

    Branz, Howard; Duda, Anna; Ginley, David S.; Yost, Vernon; Meier, Daniel; Ward, James S.

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  10. Microtextural Study of Feldspar in Petrologic Type 3 LL Ordinary Chondrites: A Record of Parent Body Metasomatism

    NASA Astrophysics Data System (ADS)

    Lewis, J. A.; Jones, R. H.

    2014-09-01

    We have carried out a detailed study of LL3 ordinary chondrites, focusing on the chemical and microtextural development of feldspar, to help understand the low-temperature evolution of the LL parent body(ies).

  11. Five-year retrospective radiographic follow-up study of dental implants with sandblasting with large grit, and acid etching-treated surfaces

    PubMed Central

    2015-01-01

    Objectives The purpose of this study is to evaluate five-year radiographic follow-up results of the Korean sandblasting with large grit, and acid etching (SLA)-treated implant system. Materials and Methods The subjects of the study are 54 patients who have been followed-up to date, of the patients who underwent implant surgery from May 1, 2009 to April 30, 2011. In all, 176 implant placements were performed. Radiographs were taken before the first surgery, immediately after the first and second surgeries, immediately and six months after the final prosthesis installation, and every year after that. Bone loss was evaluated by the method suggested by Romanos and Nentwig. Results A total of 176 implant placements were performed-122 in men and 54 in women. These patients have been followed-up for an average of 4.9 years. In terms of prosthetic appliances, there were 156 bridges and 20 single prostheses. Nine implants installed in the maxillary molar area, three in the mandibular molar area and two in the maxillary premolar area were included in group M, with bone loss less than 2 mm at the crestal aspect of the implant. Of these, eight implants were single prostheses. In all, six implants failed-four in the mandible and two in the maxilla. All of these failures occurred in single-implant cases. The implant survival rate was 98.1% on the maxilla and 94.3% on the mandible, with an overall survival of 96.6%. Conclusion Within the limitations of this study, implants with the SLA surface have a very superior survival rate in relatively poor bone environments such as the maxilla. PMID:26734558

  12. Chemical etching of deformation sub-structures in quartz

    NASA Astrophysics Data System (ADS)

    Wegner, M. W.; Christie, J. M.

    1983-02-01

    Chemical etching of dislocations has been studied in natural and synthetic quartz single crystals, in deformed synthetic quartz and in naturally and experimentally deformed quartzites. The ability of different etchants to produce polished or preferentially etched surfaces on quartz is described. Dislocation etching was achieved on all crystal planes examined by using a saturated solution of ammonium bifluoride as the etchant. Appropriate etching times were determined for etching quartzites for grain size, subgrain boundaries, deformation lamellae, dislocations and twins. Growth and polished surfaces of synthetic single crystal quartz were similarly etched and dislocation etch pits, characteristic of various orientations were found. The use of ammonium bifluoride proved to be expecially advantageous for the basal plane, producing a polished surface with etch pits, suitable for dislocation etch pit counting. “Double” etch pits have been found on Dauphiné twin boundaries on the basal plane and the first order prism, using this etchant. Slip lines and deformation bands were suitably etched on deformed synthetic crystal surfaces for identification of the slip planes. Other acidic etchants have been explored and their application to the study of deformation structures in quartz crystals is discussed.

  13. Feasibility of hydrofluoric acid etched sand particles for enrichment and determination of polychlorinated biphenyls at trace levels in environmental water samples.

    PubMed

    Xing, Han-Zhu; Chen, Xiang-Feng; Wang, Xia; Wang, Ming-Lin; Zhao, Ru-Song

    2014-06-01

    This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography-tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L(-1)), wide linear range (10 to 1,000 ng L(-1)), and high repeatability (1.9 to 8.2%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples.

  14. Teasing apart the contributions of hard dietary items on 3D dental microtextures in primates.

    PubMed

    Calandra, Ivan; Schulz, Ellen; Pinnow, Mona; Krohn, Susanne; Kaiser, Thomas M

    2012-07-01

    3D dental microtexture analysis is a powerful tool for reconstructing the diets of extinct primates. This method is based on the comparison of fossils with extant species of known diet. The diets of primates are highly diversified and include fruits, seeds, grass, tree leaves, bark, roots, tubers, and animal resources. Fruits remain the main component in the diets of most primates. We tested whether the proportion of fruit consumed is correlated with dental microtexture. Two methods of microtexture analysis, the scale-sensitive fractal analysis (SSFA) and the Dental Areal Surface Texture Analysis (DASTA; after ISO/FDIS 25178-2), were applied to specimens of eight primate species (Alouatta seniculus, Gorilla gorilla, Lophocebus albigena, Macaca fascicularis, Pan troglodytes, Papio cynocephalus, Pongo abelii, Theropithecus gelada). These species largely differ in the mean annual proportion of fruit (from 0 to 90%) in their diet, as well as in their consumption of other hard items (seeds, bark, and insect cuticles) and of abrasive plants. We find the complexity and heterogeneity of textures (SSFA) to correlate with the proportion of fruits consumed. Textural fill volume (SSFA) indicates the proportion of both fruits and other hard items processed. Furthermore, anisotropy (SSFA) relates to the consumption of abrasive plants like grass and other monocots. ISO parameters valley height, root mean square height, material volume, density of peaks, and closed hill and dale areas (DASTA) describe the functional interaction between food items and enamel facets during mastication. The shallow, plastic deformation of enamel surfaces induced by small hard particles, such as phytoliths or dust, results in flat microtexture relief, whereas the brittle, deep fracture caused by large hard items such as hard seeds creates larger relief.

  15. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  16. Morphological Changes of Human Dentin after Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) and Carbon Dioxide (CO2) Laser Irradiation and Acid-etch Technique: An Scanning Electron Microscopic (SEM) Evaluation

    PubMed Central

    Shahabi, Sima; Chiniforush, Nasim; Juybanpoor, Nasrin

    2013-01-01

    Introduction: The aim of this study was to investigate the morphological changes of human dentin after Erbium-Doped Yttrium Aluminum Garnet (Er:YAG), Carbon Dioxide(CO2) laser-irradiation and acid-etching by means of scanning electron microscopic (SEM) Methods: 9 extracted human third molars were used in this study. The teeth were divided in three groups: first group, CO2 laser with power of 1.5 w and frequency of 80 Hz; second group, Er:YAG laser with output power of 1.5 W frequency of 10 Hz, very short pulse with water and air spray was applied; and third group, samples were prepared by acid-etching 37% for 15 sec and rinsed with air-water spray for 20 sec. Then, the samples were prepared for SEM examination. Results: Melting and cracks can be observed in CO2 laser but in Er:YAG laser cleanedablated surfaces and exposed dentinal tubules, without smear layer was seen. Conclusion: It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods. But CO2 laser has some thermal side effects which make this device unsuitable for this purpose. PMID:25606306

  17. Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising.

    PubMed

    Dong, Yangchun; Svoboda, Petr; Vrbka, Martin; Kostal, David; Urban, Filip; Cizek, Jan; Roupcova, Pavla; Dong, Hanshan; Krupka, Ivan; Hartl, Martin

    2015-03-01

    An advanced surface engineering process combining micro-texture with a plasma carburising process was produced on CoCrMo femoral head, and their tribological properties were evaluated by the cutting-edge pendulum hip joint simulator coupled with thin film colorimetric interferometry. FESEM and GDOES showed that precipitation-free C S-phase with a uniform case depth of 10μm was formed across the micro-textures after duplex treatment. Hip simulator tests showed that the friction coefficient was reduced by 20% for micro-metre sized texture, and the long-term tribological property of microtexture was enhanced by the C-supersaturated crystalline microstructure formed on the surface of duplex treated CoCrMo, thereby enhancing biotribological durability significantly. In-situ colorimetric interferometry confirmed that the maximum film thickness around texture area was 530nm, indicating that the additional lubricant during sliding motion might provide exceptional bearing life. PMID:26594781

  18. Chemical downstream etching of tungsten

    SciTech Connect

    Blain, M.G.; Jarecki, R.L.; Simonson, R.J.

    1998-07-01

    The downstream etching of tungsten and tungsten oxide has been investigated. Etching of chemical vapor deposited tungsten and e-beam deposited tungsten oxide samples was performed using atomic fluorine generated by a microwave discharge of argon and NF{sub 3}. Etching was found to be highly activated with activation energies approximated to be 6.0{plus_minus}0.5thinspkcal/mol and 5.4{plus_minus}0.4thinspkcal/mol for W and WO{sub 3}, respectively. In the case of F etching of tungsten, the addition of undischarged nitric oxide (NO) directly into the reaction chamber results in the competing effects of catalytic etch rate enhancement and the formation of a nearly stoichiometric WO{sub 3} passivating tungsten oxide film, which ultimately stops the etching process. For F etching of tungsten oxide, the introduction of downstream NO reduces the etch rate. {copyright} {ital 1998 American Vacuum Society.}

  19. Multiple-mask chemical etching

    NASA Technical Reports Server (NTRS)

    Cannon, D. L.

    1969-01-01

    Multiple masking techniques use lateral etching to reduce the total area of the high etch-rate oxide exposed to the chemical etchant. One method uses a short-term etch to remove the top layer from the silicon oxide surface, another acts before the top layer is grown.

  20. Etching fission tracks in zircons

    USGS Publications Warehouse

    Naeser, C.W.

    1969-01-01

    A new technique has been developed whereby fission tracks can be etched in zircon with a solution of sodium hydroxide at 220??C. Etching time varied between 15 minutes and 5 hours. Colored zircon required less etching time than the colorless varieties.

  1. Microstructural and microtextural characterization of oxide scale on steel using electron backscatter diffraction.

    PubMed

    Birosca, S; Dingley, D; Higginson, R L

    2004-03-01

    High-temperature oxidation of steel has been extensively studied. The microstructure of iron oxides is, however, not well understood because of the difficulty in imaging it using conventional methods, such as optical or electron microscopy. A knowledge of the oxide microstructure and texture is critical in understanding how the oxide film behaves during high-temperature deformation of steels and more importantly how it can be removed following processing. Recently, electron back-scatter diffraction (EBSD) has proved to be a powerful technique for distinguishing the different phases in scales. This technique gives valuable information both on the microstructure and on the orientation relationships between the steel and the scale layers. In the current study EBSD has been used to investigate the microstructure and microtexture of iron oxide layers grown on interstitial free steel at different times and temperatures. Heat treatments have been carried out under normal oxidation conditions in order to relate the results to real steel manufacturing in industry. The composition, morphologies, microstructure and microtexture of selected conditions have been studied using EBSD. PMID:15009690

  2. Microstructural and microtextural characterization of oxide scale on steel using electron backscatter diffraction.

    PubMed

    Birosca, S; Dingley, D; Higginson, R L

    2004-03-01

    High-temperature oxidation of steel has been extensively studied. The microstructure of iron oxides is, however, not well understood because of the difficulty in imaging it using conventional methods, such as optical or electron microscopy. A knowledge of the oxide microstructure and texture is critical in understanding how the oxide film behaves during high-temperature deformation of steels and more importantly how it can be removed following processing. Recently, electron back-scatter diffraction (EBSD) has proved to be a powerful technique for distinguishing the different phases in scales. This technique gives valuable information both on the microstructure and on the orientation relationships between the steel and the scale layers. In the current study EBSD has been used to investigate the microstructure and microtexture of iron oxide layers grown on interstitial free steel at different times and temperatures. Heat treatments have been carried out under normal oxidation conditions in order to relate the results to real steel manufacturing in industry. The composition, morphologies, microstructure and microtexture of selected conditions have been studied using EBSD.

  3. Orthodox etching of HVPE-grown GaN

    SciTech Connect

    Weyher, J.L.; Lazar, S.; Macht, L.; Liliental-Weber, Z.; Molnar,R.J.; Muller, S.; Nowak, G.; Grzegory, I.

    2006-08-10

    Orthodox etching of HVPE-grown GaN in molten eutectic of KOH + NaOH (E etch) and in hot sulfuric and phosphoric acids (HH etch) is discussed in detail. Three size grades of pits are formed by the preferential E etching at the outcrops of threading dislocations on the Ga-polar surface of GaN. Using transmission electron microscopy (TEM) as the calibration tool it is shown that the largest pits are formed on screw, intermediate on mixed and the smallest on edge dislocations. This sequence of size does not follow the sequence of the Burgers values (and thus the magnitude of the elastic energy) of corresponding dislocations. This discrepancy is explained taking into account the effect of decoration of dislocations, the degree of which is expected to be different depending on the lattice deformation around the dislocations, i.e. on the edge component of the Burgers vector. It is argued that the large scatter of optimal etching temperatures required for revealing all three types of dislocations in HVPE-grown samples from different sources also depends upon the energetic status of dislocations. The role of kinetics for reliability of etching in both etches is discussed and the way of optimization of the etching parameters is shown.

  4. Etching patterns of Co-Cr alloys for bonded cast restorations.

    PubMed

    Ekstrand, K; Ruyter, I E

    1987-09-01

    Resin-bonded bridges may replace missing teeth and act as splints in periodontal treatment. The objective of this study was to investigate the etch pattern after electrolytic etching of selected Co-Cr alloys in hydrochloric acid and to assess the changes in alloy composition after different etching times. The alloys investigated were Vitallium, Wironit, Wironium, Nobilium Hard, and Niranium NN. Alloy specimens were electrolytically etched in a hydrochloric acid solution for 1, 2, 5, and 10 min. The etched specimens were examined in a light microscope and a scanning electron microscope (SEM). Different etching patterns were revealed in the various alloys. Microprobe analyses after the etching of Vitallium showed generally that Co was released and that Cr content increased at the surface. PMID:3305640

  5. Influence of preliminary etching on the stability of bonds created by one-step self-etch bonding systems.

    PubMed

    Taschner, Michael; Nato, Fernando; Mazzoni, Annalisa; Frankenberger, Roland; Falconi, Mirella; Petschelt, Anselm; Breschi, Lorenzo

    2012-06-01

    We evaluated the effects of preliminary etching of dentine on the stability of the bond created by one-step self-etch adhesives under different storage conditions. Adper Easy Bond (3M ESPE) and iBond Self-Etch (iBond SE; Heraeus Kulzer) were applied with an etch-and-rinse (i.e. after preliminary phosphoric acid etching for 15 s) or a self-etch approach. Resin-dentine bonded specimens were sectioned perpendicularly to the adhesive interface according to the 'non-trimming technique'. Beams were stored in artificial saliva for 24 h, 6 months, or 1 yr at 37°C, or in 10% NaOCl for 5 h at room temperature, and then stressed until failure; the microtensile bond strengths were calculated. Interfacial nanoleakage of additional teeth was evaluated using light microscopy or transmission electron microscopy. Adper Easy Bond showed higher bond strength than iBond SE, regardless of the dentine treatment. Similar microtensile bond strength results were obtained for teeth subjected to artificial ageing in 10% NaOCl for 5 h at room temperature and for teeth stored in artificial saliva for 6 months at 37°C. The additional etching step increased the microtensile bond strength for Adper Easy Bond and iBond SE. This study supports the use of one-step adhesives on etched dentine because of the increased bond strength compared with their application onto smear-layer-covered dentine, regardless of storage conditions. PMID:22607341

  6. Bond strength between resin composite and etched and non-etched glass ionomer.

    PubMed

    Zanata, R L; Navarro, M F; Ishikiriama, A; da Silva e Souza Júnior, M H; Delazari, R C

    1997-01-01

    The authors evaluated, in vitro, the effects of etching glass ionomer cements prior to the application of a bonding agent and a resin composite on the bond strength of the glass ionomer/resin composite interface. Six glass ionomer cements were tested using the same bonding agent/resin composite system (Scotchbond Multipurpose/Z 100). For each material, 16 specimens were prepared and divided into two groups. Eight of the specimens were not etched while eight were etched with 37% phosphoric acid for 15 seconds. All the materials were used according to the manufacturers' instructions. Glass ionomer cylinders were prepared and were mounted in an assembly apparatus and the bonding agent/resin composite transferred to a demarcated area on the cement surface. The specimens were stored for 24 hours in distilled water at 37 degrees C and thermocycled. After thermocycling, the specimens were placed in a testing machine and a shear load applied with a knife-edged rod at the glass ionomer/resin composite interface. The shear bond strength was calculated and expressed in MPa. Data were analyzed by ANOVA and the Tukey-Kramer test. There were no significant differences among the shear bond strengths of the resin composite to etched and non-etched glass ionomer cements.

  7. Selective Etching of Semiconductor Glassivation

    NASA Technical Reports Server (NTRS)

    Casper, N.

    1982-01-01

    Selective etching technique removes portions of glassivation on a semi-conductor die for failure analysis or repairs. A periodontal needle attached to a plastic syringe is moved by a microprobe. Syringe is filled with a glass etch. A drop of hexane and vacuum pump oil is placed on microcircuit die and hexane is allowed to evaporate leaving a thin film of oil. Microprobe brings needle into contact with area of die to be etched.

  8. Etching of enamel for direct bonding with a thulium fiber laser

    NASA Astrophysics Data System (ADS)

    Kabaş Sarp, Ayşe S.; Gülsoy, Murat

    2011-03-01

    Background: Laser etching of enamel for direct bonding can decrease the risk of surface enamel loss and demineralization which are the adverse effects of acid etching technique. However, in excess of +5.5°C can cause irreversible pulpal responses. In this study, a 1940- nm Thulium Fiber Laser in CW mode was used for laser etching. Aim: Determination of the suitable Laser parameters of enamel surface etching for direct bonding of ceramic brackets and keeping that intrapulpal temperature changes below the threshold value. Material and Method: Polycrystalline ceramic orthodontic brackets were bonded on bovine teeth by using 2 different kinds of etching techniques: Acid and Laser Etching. In addition to these 3 etched groups, there was also a group which was bonded without etching. Brackets were debonded with a material testing machine. Breaking time and the load at the breaking point were measured. Intrapulpal temperature changes were recorded by a K-type Thermocouple. For all laser groups, intrapulpal temperature rise was below the threshold value of 5.5°C. Results and Conclusion: Acid-etched group ( 11.73 MPa) significantly required more debonding force than 3- second- irradiated ( 5.03 MPa) and non-etched groups ( 3.4 MPa) but the results of acid etched group and 4- second- irradiated group (7.5 MPa) showed no significant difference. Moreover, 4- second irradiated group was over the minimum acceptable value for clinical use. Also, 3- second lasing caused a significant reduction in time according to acid-etch group. As a result, 1940- nm laser irradiation is a promising method for laser etching.

  9. Shock-thermal history of Kavarpura IVA iron: Evidences from microtextures and nickel profiling

    NASA Astrophysics Data System (ADS)

    Ray, Dwijesh; Ghosh, S.; Murty, S. V. S.

    2015-11-01

    We classify Kavarpura iron (fell in August, 2006, in Rajasthan, India), an inclusion-free member of high-Ni IVA group. Widmanstätten pattern and finger-cellular plessites textures characteristic of IVA group are present in Kavarpura. Symmetric and asymmetric textural zoning within the cloudy taenite and plessite refer to long term martensitisation process with mean metallographic cooling rate of 200 °C/Ma. Imprints of variable shock pressure domains (Neumann bands and shock hatched ε kamacite) suggest alteration by up to 600 kb shock pressure. Degeneration of cellular plessites, bending of finger plessites and plastic flowage of taenites bear textural evidences corresponding to post-shock annealing which is further confirmed by Ni profiles across the cloudy taenites and plessites under high shock pressure domains. Based on microtextural evidences and Ni profiling, we suggest Kavarpura had cooled at steady state and subsequently suffered multiple impacts.

  10. Microtexture and Nanoindentation Study of Delamination Cracking in Al-Cu-Li-X Alloys

    NASA Technical Reports Server (NTRS)

    Crooks, R.; Domack, M. S.; Wagner, J. A.

    2005-01-01

    Commercial Al-Li alloys have strength and weight advantages over non-Li aluminum alloys. The fracture behavior of these alloys is unusual and has limited their use. The fracture mode, described as delamination, is intergranular, along the broad grain boundaries parallel to the rolling plane of the plate. Microtexture analyses have shown that delaminations occur along boundaries with greater than 30 misorientation. However, it was observed that relatively few of the high angle boundaries exhibited this behavior. Some grains of the retained deformation texture show high internal misorientation, which is a measure of stored strain energy. Delamination tends to occur between these grains and adjacent, recrystallized grains. Nanoindentation studies indicate a higher hardness for the high internal misorientation grains. These results suggest that the delamination could be reduced by processing the alloys to minimize grain-to-grain property disparities.

  11. Formation of nanostructured silicon surfaces by stain etching

    PubMed Central

    2014-01-01

    In this work, we report the fabrication of ordered silicon structures by chemical etching of silicon in vanadium oxide (V2O5)/hydrofluoric acid (HF) solution. The effects of the different etching parameters including the solution concentration, temperature, and the presence of metal catalyst film deposition (Pd) on the morphologies and reflective properties of the etched Si surfaces were studied. Scanning electron microscopy (SEM) was carried out to explore the morphologies of the etched surfaces with and without the presence of catalyst. In this case, the attack on the surfaces with a palladium deposit begins by creating uniform circular pores on silicon in which we distinguish the formation of pyramidal structures of silicon. Fourier transform infrared spectroscopy (FTIR) demonstrates that the surfaces are H-terminated. A UV-Vis-NIR spectrophotometer was used to study the reflectance of the structures obtained. A reflectance of 2.21% from the etched Si surfaces in the wavelength range of 400 to 1,000 nm was obtained after 120 min of etching while it is of 4.33% from the Pd/Si surfaces etched for 15 min. PMID:25435830

  12. Scanning electron microscopy evaluation of the effect of etching agents on human enamel surface.

    PubMed

    Zanet, Caio G; Arana-Chavez, Victor E; Fava, Marcelo

    2006-01-01

    Acid etching promotes microporosities on enamel surface, which provide a better bonding surface to adhesive materials. The purpose of this study was to comparatively analyze the microstructure of enamel surface after etching with 37% phosphoric acid or with two self-etching primers, Non-rinse conditioner (NRC) and Clearfil SE Bond (CSEB) using scanning electron microscopy. Thirty sound premolars were divided into 3 groups with ten teeth each: Group 1: the buccal surface was etched with 37% phosphoric acid for 15 seconds; Group 2: the buccal surface was etched with NRC for 20 seconds; Group 3: the buccal surface was etched with CSEB for 20 seconds. Teeth from Group 1 were rinsed with water; teeth from all groups were air-dried for 15 seconds. After that, all specimens were processed for scanning electron microscopy and analyzed in a Jeol 6100 SEM. The results showed deeper etching when the enamel surface was etched with 37% phosphoric acid, followed by NRC and CSEB. It is concluded that 37% phosphoric acid is still the best agent for a most effective enamel etching. PMID:16683674

  13. Enhancement of surface wettability via the modification of microtextured titanium implant surfaces with polyelectrolytes.

    PubMed

    Park, Jung Hwa; Schwartz, Zvi; Olivares-Navarrete, Rene; Boyan, Barbara D; Tannenbaum, Rina

    2011-05-17

    Micrometer- and submicrometer-scale surface roughness enhances osteoblast differentiation on titanium (Ti) substrates and increases bone-to-implant contact in vivo. However, the low surface wettability induced by surface roughness can retard initial interactions with the physiological environment. We examined chemical modifications of Ti surfaces [pretreated (PT), R(a) ≤ 0.3 μm; sand blasted/acid etched (SLA), R(a) ≥ 3.0 μm] in order to modify surface hydrophilicity. We designed coating layers of polyelectrolytes that did not alter the surface microstructure but increased surface ionic character, including chitosan (CHI), poly(L-glutamic acid) (PGA), and poly(L-lysine) (PLL). Ti disks were cleaned and sterilized. Surface chemical composition, roughness, wettability, and morphology of surfaces before and after polyelectrolyte coating were examined by X-ray photoelectron spectroscopy (XPS), contact mode profilometry, contact angle measurement, and scanning electron microscopy (SEM). High-resolution XPS spectra data validated the formation of polyelectrolyte layers on top of the Ti surface. The surface coverage of the polyelectrolyte adsorbed on Ti surfaces was evaluated with the pertinent SEM images and XPS peak intensity as a function of polyelectrolyte adsorption time on the Ti surface. PLL was coated in a uniform thin layer on the PT surface. CHI and PGA were coated evenly on PT, albeit in an incomplete monolayer. CHI, PGA, and PLL were coated on the SLA surface with complete coverage. The selected polyelectrolytes enhanced surface wettability without modifying surface roughness. These chemically modified surfaces on implant devices can contribute to the enhancement of osteoblast differentiation.

  14. Optimization of silver-assisted nano-pillar etching process in silicon

    NASA Astrophysics Data System (ADS)

    Azhari, Ayu Wazira; Sopian, Kamaruzzaman; Desa, Mohd Khairunaz Mat; Zaidi, Saleem H.

    2015-12-01

    In this study, a respond surface methodology (RSM) model is developed using three-level Box-Behnken experimental design (BBD) technique. This model is developed to investigate the influence of metal-assisted chemical etching (MACE) process variables on the nanopillars profiles created in single crystalline silicon (Si) substrate. Design-Expert® software (version 7.1) is employed in formulating the RSM model based on five critical process variables: (A) concentration of silver (Ag), (B) concentration of hydrofluoric acid (HF), (C) concentration of hydrogen peroxide (H2O2), (D) deposition time, and (E) etching time. This model is supported by data from 46 experimental configurations. Etched profiles as a function of lateral etching rate, vertical etching rate, height, size and separation between the Si trenches and etching uniformity are characterized using field emission scanning electron microscope (FE-SEM). A quadratic regression model is developed to correlate critical process variables and is validated using the analysis of variance (ANOVA) methodology. The model exhibits near-linear dependence of lateral and vertical etching rates on both the H2O2 concentration and etching time. The predicted model is in good agreement with the experimental data where R2 is equal to 0.80 and 0.67 for the etching rate and lateral etching respectively. The optimized result shows minimum lateral etching with the average pore size of about 69 nm while the maximum etching rate is estimated at around 360 nm/min. The model demonstrates that the etching process uniformity is not influenced by either the etchant concentration or the etching time. This lack of uniformity could be attributed to the surface condition of the wafer. Optimization of the process parameters show adequate accuracy of the model with acceptable percentage errors of 6%, 59%, 1.8%, 38% and 61% for determination of the height, separation, size, the pore size and the etching rate respectively.

  15. Microtensile bond strength of a resin-based fissure sealant to Er,Cr:YSGG laser-etched primary enamel.

    PubMed

    Sungurtekin-Ekci, Elif; Oztas, Nurhan

    2016-05-01

    The aim of this study was to evaluate the effect of Er,Cr:YSGG laser pre-treatment alone, or associated with acid-etching, on the microtensile bond strength of a resin-based fissure sealant to primary enamel. Twenty-five human primary molars were randomly divided into five groups including (1) 35 % acid etching, (2) 2.5-W laser etching, (3) 3.5-W laser etching, (4) 2.5-W laser etching + acid etching, and (5) 3.5-W laser etching + acid etching. Er,Cr:YSGG laser was used at a wavelength of 2.780 nm and pulse duration of 140-200 μs with a repetition rate of 20 Hz. Following surface pre-treatment, the fissure sealant (ClinPro™, 3M Dental Products) was applied. Each tooth was sectioned and subjected to microtensile testing. Kruskal-Wallis test was used for statistical analysis. The level of significance was set at p < 0.05. The microtensile bond strength values of group 1 were significantly higher than those of group 2, while no statistically significant difference was detected between groups 1, 3, 4, and 5. It was concluded that 3.5-W laser etching produced results comparable to conventional acid etching technique, whereas 2.5-W laser etching was not able to yield adequate bonding performance.

  16. Improvement of photocatalytic activity of brookite titanium dioxide nanorods by surface modification using chemical etching

    NASA Astrophysics Data System (ADS)

    Zhang, Linjie; Menendez-Flores, Victor M.; Murakami, Naoya; Ohno, Teruhisa

    2012-05-01

    Surface morphology of brookite titanium dioxide (TiO2) nanorods was modified by chemical etching with aqueous hydrogen (H2O2)-ammonia (NH3) or sulfuric acid (H2SO4) solution. The brookite nanorods after chemical etching were characterized by TEM, SAED, FE-SEM, XRD and specific surface area measurements. Brookite nanorods after chemical etching with H2O2-NH3 solution exposed new crystal faces in the tips, and nanorods with sharper tips were observed. On the other hand, etching with H2SO4 at 200 °C induced morphological changes in the tip faces and broadened the angle between tip faces as a result of dissolution along the [0 0 1] direction, though brookite nanorods were only slightly etched after etching with H2SO4 at room temperature. Photocatalytic activity of brookite nanorods was tested by toluene decomposition in gas phase under ultraviolet irradiation. Brookite nanorods etched with H2O2-NH3 solution showed higher photocatalytic activity than that of brookite nanorods before etching. In the case of H2SO4 etching at 200 °C, brookite nanorods after etching exhibited lower photocatalytic activity. One reason for this may be that the formation of newly exposed crystal faces by H2O2-NH3 etching improved separation of redox sites due to their strong oxidation ability.

  17. Wetting state on hydrophilic and hydrophobic micro-textured surfaces: Thermodynamic analysis and X-ray visualization

    SciTech Connect

    Yu, Dong In; Kwak, Ho Jae; Doh, Seung Woo; Park, Hyun Sun Kiyofumi, Moriyama; Kang, Hie Chan; Ahn, Ho Seon; Kim, Moo Hwan

    2015-04-27

    In this study, the wetting state on hydrophobic and hydrophilic micro-textured surfaces was investigated. High spatial resolution synchrotron X-ray radiography was used to overcome the limitations in visualization in previous research and clearly visualize the wetting state for each droplet under quantified surface conditions. Based on thermodynamic characteristics, a theoretical model for wetting state depending on the chemical composition (intrinsic contact angle) and geometrical morphology (roughness ratio) of the surfaces was developed.

  18. Response of bone marrow derived connective tissue progenitor cell morphology and proliferation on geometrically modulated microtextured substrates

    PubMed Central

    Kim, Eun Jung; Fleischman, Aaron J.; Muschler, George F.; Roy, Shuvo

    2013-01-01

    Varying geometry and layout of microposts on a cell culture substrate provides an effective technique for applying mechanical stimuli to living cells. In the current study, the optimal geometry and arrangement of microposts on the polydimethylsiloxane (PDMS) surfaces to enhance cell growth behavior were investigated. Human bone marrow derived connective tissue progenitor cells were cultured on PDMS substrates comprising unpatterned smooth surfaces and cylindrical post microtextures that were 10 µm in diameter, 4 heights (5, 10, 20 and 40 µm) and 3 pitches (10, 20, and 40 µm). With the same 10 µm diameter, post heights ranging from 5 to 40 µm resulted in a more than 535000 fold range of rigidity from 0.011 nNµm−1 (40 µm height) up to 5888 nNµm−1(5 µm height). Even though shorter microposts result in higher effective stiffness, decreasing post heights below the optimal value, 5 µm height micropost in this study decreased cell growth behavior. The maximum number of cells was observed on the post microtextures with 20 µm height and 10 µm inter-space, which exhibited a 675% increase relative to the smooth surfaces. The cells on all heights of post microtextures with 10 µm and 20 µm inter-spaces exhibited highly contoured morphology. Elucidating the cellular response to various external geometry cues enables us to better predict and control cellular behavior. In addition, knowledge of cell response to surface stimuli could lead to the incorporation of specific size post microtextures into surfaces of implants to achieve surface-textured scaffold materials for tissue engineering applications. PMID:23378044

  19. Rate controlled metal assisted chemical etching to fabricate vertical and uniform Si nanowires

    NASA Astrophysics Data System (ADS)

    Song, Ari; Yun, Seokhun; Lokhande, Vaibhav; Ji, Taeksoo

    2016-03-01

    Mac(metal assisted chemical) etching is a simple, low-cost and anisotropic etching method to make Si NWs (silicon nanowires). In this method, smaller surface area is damaged compared to dry etching process, either. Mac etching uses a combination of an oxide removal acid (e.g. HF), an oxidant (e.g. H2O2) with a noble metal (e.g. Au, Ag, Pt, etc.) as the catalyst. Typically, the Si beneath the noble metal is etched faster than the Si without noble metal coverage by electron transfer mechanism at the noble metal /solution and the noble metal/Si interface. While Mac etching to build Si NWs, unwanted etching occurs in the bulk silicon layer resulting from excess hole diffusion caused by the increase in hole concentration at the nearby metal layers. In this study, we explored the ratio of oxidant to oxide removal acid in the Mac etching solution that is most effective in etching the Si underneath the noble metal layer suppressing the unwanted etching. At the optimized ratio, Si NWs were fabricated at a faster rate with good uniformity.

  20. Does the Laser-Microtextured Short Implant Collar Design Reduce Marginal Bone Loss in Comparison with a Machined Collar?

    PubMed Central

    Sirali, Ali; Gultekin, Pinar; Yalcin, Serdar; Mijiritsky, Eitan

    2016-01-01

    Purpose. To compare marginal bone loss between subgingivally placed short-collar implants with machined collars and those with machined and laser-microtextured collars. Materials and Methods. The investigators used a retrospective study design and included patients who needed missing posterior teeth replaced with implants. Short-collar implants with identical geometries were divided into two groups: an M group, machined collar; and an L group, machined and laser-microtextured collar. Implants were evaluated according to marginal bone loss, implant success, and probing depth (PD) at 3 years of follow-up. Results. Sixty-two patients received 103 implants (56 in the M group and 47 in the L group). The cumulative survival rate was 100%. All implants showed clinically acceptable marginal bone loss, although bone resorption was lower in the L group (0.49 mm) than in the M group (1.38 mm) at 3 years (p < 0.01). A significantly shallower PD was found for the implants in the L group during follow-up (p < 0.01). Conclusions. Our results suggest predictable outcomes with regard to bone loss for both groups; however, bone resorption was less in the L group than in the M group before and after loading. The laser-microtextured collar implant may provide a shallower PD than the machined collar implant. PMID:27660765

  1. Does the Laser-Microtextured Short Implant Collar Design Reduce Marginal Bone Loss in Comparison with a Machined Collar?

    PubMed Central

    Sirali, Ali; Gultekin, Pinar; Yalcin, Serdar; Mijiritsky, Eitan

    2016-01-01

    Purpose. To compare marginal bone loss between subgingivally placed short-collar implants with machined collars and those with machined and laser-microtextured collars. Materials and Methods. The investigators used a retrospective study design and included patients who needed missing posterior teeth replaced with implants. Short-collar implants with identical geometries were divided into two groups: an M group, machined collar; and an L group, machined and laser-microtextured collar. Implants were evaluated according to marginal bone loss, implant success, and probing depth (PD) at 3 years of follow-up. Results. Sixty-two patients received 103 implants (56 in the M group and 47 in the L group). The cumulative survival rate was 100%. All implants showed clinically acceptable marginal bone loss, although bone resorption was lower in the L group (0.49 mm) than in the M group (1.38 mm) at 3 years (p < 0.01). A significantly shallower PD was found for the implants in the L group during follow-up (p < 0.01). Conclusions. Our results suggest predictable outcomes with regard to bone loss for both groups; however, bone resorption was less in the L group than in the M group before and after loading. The laser-microtextured collar implant may provide a shallower PD than the machined collar implant.

  2. Submicron patterned metal hole etching

    DOEpatents

    McCarthy, Anthony M.; Contolini, Robert J.; Liberman, Vladimir; Morse, Jeffrey

    2000-01-01

    A wet chemical process for etching submicron patterned holes in thin metal layers using electrochemical etching with the aid of a wetting agent. In this process, the processed wafer to be etched is immersed in a wetting agent, such as methanol, for a few seconds prior to inserting the processed wafer into an electrochemical etching setup, with the wafer maintained horizontal during transfer to maintain a film of methanol covering the patterned areas. The electrochemical etching setup includes a tube which seals the edges of the wafer preventing loss of the methanol. An electrolyte composed of 4:1 water: sulfuric is poured into the tube and the electrolyte replaces the wetting agent in the patterned holes. A working electrode is attached to a metal layer of the wafer, with reference and counter electrodes inserted in the electrolyte with all electrodes connected to a potentiostat. A single pulse on the counter electrode, such as a 100 ms pulse at +10.2 volts, is used to excite the electrochemical circuit and perform the etch. The process produces uniform etching of the patterned holes in the metal layers, such as chromium and molybdenum of the wafer without adversely effecting the patterned mask.

  3. ZERODUR: bending strength data for etched surfaces

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Leys, Antoine; Carré, Antoine; Kerz, Franca; Westerhoff, Thomas

    2014-07-01

    In a continuous effort since 2007 a considerable amount of new data and information has been gathered on the bending strength of the extremely low thermal expansion glass ceramic ZERODUR®. By fitting a three parameter Weibull distribution to the data it could be shown that for homogenously ground surfaces minimum breakage stresses exist lying much higher than the previously applied design limits. In order to achieve even higher allowable stress values diamond grain ground surfaces have been acid etched, a procedure widely accepted as strength increasing measure. If surfaces are etched taking off layers with thickness which are comparable to the maximum micro crack depth of the preceding grinding process they also show statistical distributions compatible with a three parameter Weibull distribution. SCHOTT has performed additional measurement series with etch solutions with variable composition testing the applicability of this distribution and the possibility to achieve further increase of the minimum breakage stress. For long term loading applications strength change with time and environmental media are important. The parameter needed for prediction calculations which is combining these influences is the stress corrosion constant. Results from the past differ significantly from each other. On the basis of new investigations better information will be provided for choosing the best value for the given application conditions.

  4. Improvement in etching rate for epilayer lift-off with surfactant

    NASA Astrophysics Data System (ADS)

    Wu, Fan-Lei; Horng, Ray-Hua; Lu, Jian-Heng; Chen, Chun-Li; Kao, Yu-Cheng

    2013-03-01

    In this study, the GaAs epilayer is quickly separated from GaAs substrate by epitaxial lift-off (ELO) process with mixture etchant solution. The HF solution mixes with surfactant as mixture etchant solution to etch AlAs sacrificial layer for the selective wet etching of AlAs sacrificial layer. Addiction surfactants etchant significantly enhance the etching rate in the hydrofluoric acid etching solution. It is because surfactant provides hydrophilicity to change the contact angle with enhances the fluid properties of the mixture etchant between GaAs epilayer and GaAs substrate. Arsine gas was released from the etchant solution because the critical reaction product in semiconductor etching is dissolved arsine gas. Arsine gas forms a bubble, which easily displaces the etchant solution, before the AlAs layer was undercut. The results showed that acetone and hydrofluoric acid ratio of about 1:1 for the fastest etching rate of 13.2 μm / min. The etching rate increases about 4 times compared with pure hydrofluoric acid, moreover can shorten the separation time about 70% of GaAs epilayer with GaAs substrate. The results indicate that etching ratio and stability are improved by mixture etchant solution. It is not only saving the epilayer and the etching solution exposure time, but also reducing the damage to the epilayer structure.

  5. Bond strength with various etching times on young permanent teeth

    SciTech Connect

    Wang, W.N.; Lu, T.C. )

    1991-07-01

    Tensile bond strengths of an orthodontic resin cement were compared for 15-, 30-, 60-, 90-, or 120-second etching times, with a 37% phosphoric acid solution on the enamel surfaces of young permanent teeth. Fifty extracted premolars from 9- to 16-year-old children were used for testing. An orthodontic composite resin was used to bond the bracket directly onto the buccal surface of the enamel. The tensile bond strengths were tested with an Instron machine. Bond failure interfaces between bracket bases and teeth surfaces were examined with a scanning electron microscope and calculated with mapping of energy-dispersive x-ray spectrometry. The results of tensile bond strength for 15-, 30-, 60-, or 90-second etching times were not statistically different. For the 120-second etching time, the decrease was significant. Of the bond failures, 43%-49% occurred between bracket and resin interface, 12% to 24% within the resin itself, 32%-40% between resin and tooth interface, and 0% to 4% contained enamel fragments. There was no statistical difference in percentage of bond failure interface distribution between bracket base and resin, resin and enamel, or the enamel detachment. Cohesive failure within the resin itself at the 120-second etching time was less than at other etching times, with a statistical significance. To achieve good retention, to decrease enamel loss, and to reduce moisture contamination in the clinic, as well as to save chairside time, a 15-second etching time is suggested for teenage orthodontic patients.

  6. Controlled in situ etch-back

    NASA Technical Reports Server (NTRS)

    Mattauch, R. J.; Seabaugh, A. C. (Inventor)

    1981-01-01

    A controlled in situ etch-back technique is disclosed in which an etch melt and a growth melt are first saturated by a source-seed crystal and thereafter etch-back of a substrate takes place by the slightly undersaturated etch melt, followed by LPE growth of a layer by the growth melt, which is slightly supersaturated.

  7. Etching and Growth of GaAs

    NASA Technical Reports Server (NTRS)

    Seabaugh, A. C.; Mattauch, R., J.

    1983-01-01

    In-place process for etching and growth of gallium arsenide calls for presaturation of etch and growth melts by arsenic source crystal. Procedure allows precise control of thickness of etch and newly grown layer on substrate. Etching and deposition setup is expected to simplify processing and improve characteristics of gallium arsenide lasers, high-frequency amplifiers, and advanced integrated circuits.

  8. Decontamination of metals using chemical etching

    DOEpatents

    Lerch, Ronald E.; Partridge, Jerry A.

    1980-01-01

    The invention relates to chemical etching process for reclaiming contaminated equipment wherein a reduction-oxidation system is included in a solution of nitric acid to contact the metal to be decontaminated and effect reduction of the reduction-oxidation system, and includes disposing a pair of electrodes in the reduced solution to permit passage of an electrical current between said electrodes and effect oxidation of the reduction-oxidation system to thereby regenerate the solution and provide decontaminated equipment that is essentially radioactive contamination-free.

  9. Femtosecond laser etching of dental enamel for bracket bonding.

    PubMed

    Kabas, Ayse Sena; Ersoy, Tansu; Gülsoy, Murat; Akturk, Selcuk

    2013-09-01

    The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.

  10. Microtextured metals for stray-light suppression in the Clementine startracker

    NASA Technical Reports Server (NTRS)

    Johnson, E. A.

    1993-01-01

    Anodized blacks for suppressing stray light in optical systems can now be replaced by microscopically textured metal surfaces. An application of these black surfaces to the Clementine star-tracker navigational system, which will be launched in early 1994 to examine the Moon, en route to intercept an asteroid, is detailed. Rugged black surfaces with Lambertian BRDF less than 10(exp -2) srad(sup -1) are critical for suppressing stray light in the star-tracker optical train. Previously available materials spall under launch vibrations to contaminate mirrors and lenses. Microtextured aluminum is nearly as dark, but much less fragile. It is made by differential ion beam sputtering, which generates light-trapping pores and cones slightly smaller than the wavelength to be absorbed. This leaves a sturdy but light-absorbing surface that can survive challenging conditions without generating debris or contaminants. Both seeded ion beams and plasma immersion (from ECR plasmas) extraction can produce these microscopic textures without fragile interfaces. Process parameters control feature size, spacing, and optical effects (THR, BRDF). Both broad and narrow absorption bands can be engineered with tuning for specific wavelengths and applications. Examples are presented characterized by FTIR in reflection librators (0.95 normal emissivity), heat rejection, and enhanced nucleate boiling.

  11. Numerical modelling of microdroplet self-propelled jumping on micro-textured surface

    NASA Astrophysics Data System (ADS)

    Attarzadeh, S. M. Reza; Dolatabadi, Ali; Chun Kim, Kyung

    2015-11-01

    Understanding various stages of single and multiple droplet impact on a super-hydrophobic surface is of interest for many industrial applications such as aerospace industry. In this study, the phenomenon of coalescence induced droplets self-propelled jumping on a micro-textured super-hydrophobic surface is numerically simulated using Volume of Fluid (VOF) method. This model mimics the scenario of coalescing cloud-sized particles over the surface structure of an aircraft. The VOF coupled with a dynamic contact angle model is used to simulate the coalescence of two equal size droplets, that are initially placed very closed to each other with their interface overlapping with each other's which triggers the incipience of their coalescence. The textured surface is modeled as a series of equally spaced squared pillars, with 111° as the intrinsic contact angle all over the solid contact area. It is shown that the radial velocity of coalescing liquid bridge is reverted to upward direction due to the counter action of the surface to the basal area of droplet in contact. The presence of air beneath the droplet inside micro grooves which aimed at repelling water droplet is also captured in this model. The simulated results are found in good agreement with experimental observations. The authors gratefully acknowledge the financial support from Natural Sciences and Engineering Research Council of Canada (NSERC), Consortium de Recherche et d'innovation en Aerospatiale au Quebec (CRIAQ), Bombardier Aerospace, Pratt Whitney Canada.

  12. Wetting behaviour of laser synthetic surface microtextures on Ti-6Al-4V for bioapplication.

    PubMed

    Dahotre, Narendra B; Paital, Sameer R; Samant, Anoop N; Daniel, Claus

    2010-04-28

    Wettability at the surface of an implant material plays a key role in its success as it modulates the protein adsorption and thereby influences cell attachment and tissue integration at the interface. Hence, surface engineering of implantable materials to enhance wettability to physiological fluid under in vivo conditions is an area of active research. In light of this, in the present work, laser-based optical interference and direct melting techniques were used to develop synthetic microtextures on Ti-6Al-4V alloys, and their effects on wettability were studied systematically. Improved wettability to simulated body fluid and distilled water was observed for Ca-P coatings obtained by direct melting technique. This superior wettability was attributed to both the appropriate surface chemistry and the three-dimensional surface features obtained using this technique. To assert a better control on surface texture and wettability, a three-dimensional thermal model based on COMSOL's multiphysics was employed to predict the features obtained by laser melting technique. The effect of physical texture and wetting on biocompatibility of laser-processed Ca-P coatings was evaluated in the preliminary efforts on culturing of mouse MC3T3-E1 osteoblast cells.

  13. Metal nanoparticle-enhanced photocurrent in GaAs photovoltaic structures with microtextured interfaces.

    PubMed

    Dmitruk, Nicolas L; Borkovskaya, Olga Yu; Mamontova, Iryna B; Mamykin, Sergii V; Malynych, Sergii Z; Romanyuk, Volodymyr R

    2015-01-01

    The photocurrent enhancement effect caused by Au and Ag nanoparticles for GaAs-based photovoltaic structures of surface barrier or p-n junction type with microtextured interfaces has been investigated in dependence on the conditions of nanoparticles deposition and, respectively, on the shape and local dielectric environment of obtained nanoparticle arrays. Three nanoparticle deposition methods have been checked: 1) photoinduced chemical deposition of Au from aqueous AuCl3 solution forming nanowires on the ridges of quasigrating-type surface microrelief, 2) deposition of Ag nanoparticles from colloidal suspension on the GaAs substrate covered with poly(vinylpyridine), and 3) drop and dry deposition of Au/SiO2 core-shell nanoparticles from aqueous colloid solution. The comprehensive investigation of optical reflectance, photoelectric, and electrical characteristics of the fabricated barrier structures has shown the highest photovoltaic parameters for surface microrelief of quasigrating-type and electroless Au nanoparticle deposition. The analysis of characteristics obtained allowed us also to define the mechanisms of the total photocurrent enhancement. PMID:25852368

  14. Dry Ice Etches Terrain

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Every year seasonal carbon dioxide ice, known to us as 'dry ice,' covers the poles of Mars. In the south polar region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.

    The channels take on many forms. In the subimage shown here (figure 1) the gas from the dry ice has etched wide shallow channels. This region is relatively flat, which may be the reason these channels have a different morphology than the 'spiders' seen in more hummocky terrain.

    Observation Geometry Image PSP_003364_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Apr-2007. The complete image is centered at -85.4 degrees latitude, 104.0 degrees East longitude. The range to the target site was 251.5 km (157.2 miles). At this distance the image scale is 25.2 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:57 PM and the scene is illuminated from the west with a solar incidence angle of 75 degrees, thus the sun was about 15 degrees above the horizon. At a solar longitude of 219.6 degrees, the season on Mars is Northern Autumn.

  15. Which self-etch bonding systems are suitable for which clinical indications?

    PubMed

    Haller, Bernd

    2013-10-01

    Self-etch bonding systems are promoted as a time-saving and user-friendly alternative to etch-and-rinse bonding systems. Self-etch adhesives are characterized by a relatively mild etching effect, resulting in a relatively low incidence of postoperative hypersensitivity. On the other hand, their mild etching effect causes a reduction in bond strength to enamel compared to that achieved with phosphoric acid etching. All-in-one adhesives still suffer from less-than-optimal initial bond strengths and from inadequate durability of the bond. Future developments need to focus on the elimination of water deposits along the adhesive interface of all-in-one adhesives. While self-etch adhesives may yield acceptable results when applied in combination with light-cured composite resin, their acidic monomers inhibit the polymerization of auto-cured and dual-cured composite resins. Unfortunately, most "self-cure" or "dual-cure" activators do not overcome this problem. This incompatibility has to be taken into consideration when using self-etch adhesives for adhesive cementation and for core build-up restorations. When assessing self-etch bonding systems, it should be noted that they do not represent a homogenous category of materials but rather comprise a great variety of different types of products, each with specific strengths and weaknesses. PMID:23971056

  16. Bonding with self-etching primers--pumice or pre-etch? An in vitro study.

    PubMed

    Fitzgerald, Ian; Bradley, Gerard T; Bosio, Jose A; Hefti, Arthur F; Berzins, David W

    2012-04-01

    The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (± 1 SD) for groups 1-4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs.

  17. Wet Chemical Etching Survey of III-Nitrides

    SciTech Connect

    Abernathy, C.R.; Cho, H.; Hays, D.C.; MacKenzie, J.D.; Pearton, S.J.; Ren, F.; Shul, R.J.; Vartuli, C.B.; Zolper, J.C.

    1999-02-04

    Wet chemical etching of GaN, InN, AlN, InAlN and InGaN was investigated in various acid and base solutions at temperatures up to 75 C. Only KOH-based solutions were found to etch AlN and InAlN. No etchants were found for the other nitrides, emphasizing their extreme lack of chemical reactivity. The native oxide on most of the nitrides could be removed in potassium tetraborate at 75 C, or HCl/H{sub 2}O at 25 C.

  18. Martian surface microtexture from orbital CRISM multi-angular observations: A new perspective for the characterization of the geological processes

    NASA Astrophysics Data System (ADS)

    Fernando, J.; Schmidt, F.; Douté, S.

    2016-09-01

    The surface of Mars has a high morphological and mineralogical diversity due to the intricacy of external, internal processes, and exchanges with the atmosphere, the hydrosphere and the cryosphere. In particular, liquid water played an important role in surface evolution. However, the origin, duration and intensity of those wet events have been highly debated, especially in the clay-bearing geological units. Similarly, questions still remain about magma crystallization and volatile quantity of the dominant basaltic crust. In this work, six sites having hydrated minerals, salts and basaltic signatures (i.e., Mawrth Vallis, Holden crater, Eberswalde crater, Capri mensa, Eridania basin, Terra Sirenum) are investigated in order to better characterize the geological processes responsible for their formation and evolution (e.g., fluvial, lacustrine, in situ weathering, evaporitic, volcanic and aeolian processes). For that purpose, we use orbital multi-angular measurements from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on-board the Mars Reconnaissance Orbiter spacecraft to analyze the manner in which light is scattered by the surface materials (photometry) in the near-infrared range (at 750 nm). The surface bidirectional reflectance depends on the composition but also on the surface microtexture such as the grain size distribution, morphology, internal structure and surface roughness, tracers of the geological processes. The Hapke semi-analytical model of radiative transfer in granular medium is used to model the surface bidirectional reflectance estimated at 750 nm from the orbital measurements after an atmospheric correction. The model depends on different radiative properties (e.g., single scattering albedo, grain phase function and regolith roughness) related to the surface composition and microtexture. In particular previous laboratory works showed that the particle phase function parameters, which describe the characteristics of the

  19. A three dimensional scaffold with precise micro-architecture and surface micro-textures

    PubMed Central

    Mata, Alvaro; Kim, Eun Jung; Boehm, Cynthia A.; Fleischman, Aaron J.; Muschler, George F.; Roy, Shuvo

    2013-01-01

    A three-dimensional (3D) structure comprising precisely defined microarchitecture and surface micro-textures, designed to present specific physical cues to cells and tissues, may provide an efficient scaffold in a variety of tissue engineering and regenerative medicine applications. We report a fabrication technique based on microfabrication and soft lithography that permits for the development of 3D scaffolds with both precisely engineered architecture and tailored surface topography. The scaffold fabrication technique consists of three key steps starting with microfabrication of a mold using an epoxy-based photoresist (SU-8), followed by dual-sided molding of a single layer of polydimethylsiloxane (PDMS) using a mechanical jig for precise motion control; and finally, alignment, stacking, and adhesion of multiple PDMS layers to achieve a 3D structure. This technique was used to produce 3D Texture and 3D Smooth PDMS scaffolds, where the surface topography comprised 10 μm-diameter/height posts and smooth surfaces, respectively. The potential utility of the 3D microfabricated scaffolds, and the role of surface topography, were subsequently investigated in vitro with a combined heterogeneous population of adult human stem cells and their resultant progenitor cells, collectively termed connective tissue progenitors (CTPs), under conditions promoting the osteoblastic phenotype. Examination of bone-marrow derived CTPs cultured on the 3D Texture scaffold for 9 days revealed cell growth in three dimensions and increased cell numbers compared to those on the 3D Smooth scaffold. Furthermore, expression of alkaline phosphatase mRNA was higher on the 3D Texture scaffold, while osteocalcin mRNA expression was comparable for both types of scaffolds. PMID:19524292

  20. Cryptic microtextures and geological histories of K-rich alkali feldspars revealed by charge contrast imaging

    NASA Astrophysics Data System (ADS)

    Flude, Stephanie; Lee, Martin R.; Sherlock, Sarah C.; Kelley, Simon P.

    2012-06-01

    Charge contrast imaging in the scanning electron microscope can provide new insights into the scale and composition of alkali feldspar microtextures, and such information helps considerably with the interpretation of their geological histories and results of argon isotope thermochronological analyses. The effectiveness of this technique has been illustrated using potassium-rich alkali feldspars from the Dartmoor granite (UK). These feldspars contain strain-controlled lamellar crypto- and microperthites that are cross-cut by strain-free deuteric microperthites. The constituent albite- and orthoclase-rich phases of both microperthite generations can be readily distinguished by atomic number contrast imaging. The charge contrast results additionally show that sub-micrometre-sized albite `platelets' are commonplace between coarser exsolution lamellae and occur together to make cryptoperthites. Furthermore, charge contrast imaging reveals that the orthoclase-rich feldspar is an intergrowth of two phases, one that is featureless with uniform contrast and another that occurs as cross-cutting veins and grains with the {110} adularia habit. Transmission electron microscopy shows that the featureless feldspar is tweed orthoclase, whereas the veins and euhedral grains are composed of irregular microcline that has formed from orthoclase by `unzipping' during deuteric or hydrothermal alteration. The charge contrast imaging results are especially important in demonstrating that deuteric perthites are far more abundant in alkali feldspars than would be concluded from investigations using conventional microscopy techniques. The unexpected presence of such a high volume of replacement products has significant implications for understanding the origins and geological histories of crustal rocks and the use of alkali feldspars in geo- and thermochronology. Whilst the precise properties of feldspars that generate contrast remain unclear, the similarity between charge contrast images

  1. Plasma Etching Improves Solar Cells

    NASA Technical Reports Server (NTRS)

    Bunyan, S. M.

    1982-01-01

    Etching front surfaces of screen-printed silicon photovoltaic cells with sulfur hexafluoride plasma found to increase cell performance while maintaining integrity of screen-printed silver contacts. Replacement of evaporated-metal contacts with screen-printed metal contacts proposed as one way to reduce cost of solar cells for terrestrial applications.

  2. Chemical etching of nitinol stents.

    PubMed

    Katona, Bálint; Bognár, Eszter; Berta, Balázs; Nagy, Péter; Hirschberg, Kristóf

    2013-01-01

    At present the main cause of death originates from cardiovascular diseases. Primarily the most frequent cause is vessel closing thus resulting in tissue damage. The stent can help to avoid this. It expands the narrowed vessel section and allows free blood flow. The good surface quality of stents is important. It also must have adequate mechanical characteristics or else it can be damaged which can easily lead to the fracture of the implant. Thus, we have to consider the importance of the surface treatment of these implants. In our experiments the appropriate design was cut from a 1.041 mm inner diameter and 0.100 mm wall thickness nitinol tube by using Nd:YAG laser device. Then, the stent was subjected to chemical etching. By doing so, the burr created during the laser cutting process can be removed and the surface quality refined. In our research, we changed the time of chemical etching and monitored the effects of this parameter. The differently etched stents were subjected to microscopic analysis, mass measurement and in vivo environment tests. The etching times that gave suitable surface and mechanical features were identified.

  3. EBSD Study on Grain Boundary and Microtexture Evolutions During Friction Stir Processing of A413 Cast Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mostaan, Hossein; Safari, Mehdi; Szpunar, Jerzy A.

    2016-07-01

    The as-cast Al alloys contain heterogeneous distributions of non-deforming particles due to non-equilibrium solidification effects. Therefore, these alloys have poor tribological and mechanical behaviors. It is well known that using friction stir processing (FSP), very fine microstructure is created in the as-cast Al alloys, while their wear resistance can be improved. In this research work, FSP is used to locally refine a surface layer of the coarse as-cast microstructure of cast A413 Al alloy. The main objective of this study is to investigate the effect of FSP on microstructure and microtexture evolutions in A413 cast Al alloy. The grain boundary character distribution, grain structure, and microtexture evolutions in as-cast and friction stir processed A413 Al alloy are analyzed by electron back scatter diffraction technique. It is found that with the FSP, the fraction of low ∑boundary such as ∑3, 7, and 9 are increased. The obtained results show that there are no deformation texture components in the structure of friction stir processed samples. However, some of the main recrystallization texture components such as BR and cubeND are formed during FSP which indicate the occurrence of dynamic recrystallization phenomenon due to the severe plastic deformation induced by the rotation of tool.

  4. Apparatus for edge etching of semiconductor wafers

    NASA Technical Reports Server (NTRS)

    Casajus, A.

    1986-01-01

    A device for use in the production of semiconductors, characterized by etching in a rapidly rotating etching bath is described. The fast rotation causes the surface of the etching bath to assume the form of a paraboloid of revolution, so that the semiconductor wafer adjusted at a given height above the resting bath surface is only attacked by etchant at the edges.

  5. Nanoscrews: Asymmetrical Etching of Silver Nanowires.

    PubMed

    Tan, Rachel Lee Siew; Chong, Wen Han; Feng, Yuhua; Song, Xiaohui; Tham, Chu Long; Wei, Jun; Lin, Ming; Chen, Hongyu

    2016-08-31

    World's smallest screws with helical threads are synthesized via mild etching of Ag nanowires. With detailed characterization, we show that this nanostructure arises not from the transformation of the initial lattice, but the result of a unique etching mode. Three-dimensional printed models are used to illustrate the evolution of etch pits, from which a possible mechanism is postulated. PMID:27513181

  6. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K. (Inventor); Giapis, Konstantinos P. (Inventor)

    1999-01-01

    An at-least dual chamber apparatus and method in which high flux beams of fast moving neutral reactive species are created, collimated and used to etch semiconductor or metal materials from the surface of a workpiece. Beams including halogen atoms are preferably used to achieve anisotropic etching with good selectivity at satisfactory etch rates. Surface damage and undercutting are minimized.

  7. Integrating hematite (U-Th)/He dating, microtextural analysis, and thermomechanical modeling to date seismic slip

    NASA Astrophysics Data System (ADS)

    McDermott, R.; Ault, A. K.; Evans, J. P.; Reiners, P. W.; Shuster, D. L.

    2015-12-01

    Linking petrologic and geochronologic evidence for seismicity in the rock record is challenging, yet critical for understanding slip mechanics in natural faults, structural histories, and modern seismic hazards. We couple hematite (U-Th)/He (HeHe) dating with microtextural analysis and thermomechanical modeling to decipher this record from locally iridescent, hematite-coated fault surfaces in the seismogenic Wasatch fault zone (WFZ), Utah. Prior study of one fault surface linked textural evidence for elevated temperatures with a pattern of HeHe dates to hypothesize that this surface preserves evidence of multiple seismic slip events. New scanning electron microscopy (SEM) and HeHe data from a larger sample suite test this hypothesis. The SEM images reveal the presence of <500 nm polygonal hematite crystals at some iridescent regions, suggesting co- to post-seismic hematite annealing and recrystallization at temperatures >800 °C. Fault surface samples yield 3.8 ± 0.03 to 1.5 ± 0.1 Ma dates, with younger dates in iridescent regions. These results are younger than 88.5 ± 15.0 Ma and 10.8 ± 0.8 Ma dates from veins associated with initial hematite mineralization as well as new apatite (U-Th)/He dates of 4.0 ± 0.6 Ma-5.4±1.1 Ma that constrain the footwall thermal history. Reproducible but statistically different HeHe dates from samples on the same fault surface are consistent with prior observations. Collectively, these observations suggest that hematite He dates record rapid cooling from localized shear heating at asperities to temperatures hot enough to reset the hematite He system. Models incorporate rate-dependent friction and half-space cooling to constrain shear zone temperature evolution. Results reveal temperatures >800 °C are sufficient to reset hematite up to 200 μm from the fault surface and HeHe dates may represent patches of rate-strengthening friction during seismic slip. Ongoing work utilizes SEM to target aliquots with textural evidence for

  8. Heavy Minerals in Palaeotsunami Deposits: Assemblages, Spatial Distribution and Microtextural Imprints

    NASA Astrophysics Data System (ADS)

    Costa, P. J.; Andrade, C.; Cascalho, J.; Dawson, A. G.; Freitas, M. C.; Dawson, S.; Mahaney, W. C.

    2013-12-01

    more likely source areas. In addition, preliminary results of SEM analysis of microtextural features imprinted in the surface of heavy minerals indicate an increase in the number of mechanical marks in the surface of palaeotsunami grains when compared with potential source materials (beach, dune, inshore and offshore samples). This work further reveals the potential to use heavy minerals as a complementary sedimentological tool in the study of palaeotsunami deposits.

  9. Note: Dissolved hydrogen detection in power transformer oil based on chemically etched fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Ma, Guo-ming; Song, Hong-tu; Zhou, Hong-yang; Li, Cheng-rong; Luo, Ying-ting; Wang, Hong-bin

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG.

  10. Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals.

    PubMed

    Avci, Civan; Ariñez-Soriano, Javier; Carné-Sánchez, Arnau; Guillerm, Vincent; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2015-11-23

    Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

  11. Note: Dissolved hydrogen detection in power transformer oil based on chemically etched fiber Bragg grating.

    PubMed

    Jiang, Jun; Ma, Guo-ming; Song, Hong-tu; Zhou, Hong-yang; Li, Cheng-rong; Luo, Ying-ting; Wang, Hong-bin

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG.

  12. Cryogenic electron beam induced chemical etching.

    PubMed

    Martin, Aiden A; Toth, Milos

    2014-11-12

    Cryogenic cooling is used to enable efficient, gas-mediated electron beam induced etching (EBIE) in cases where the etch rate is negligible at room and elevated substrate temperatures. The process is demonstrated using nitrogen trifluoride (NF3) as the etch precursor, and Si, SiO2, SiC, and Si3N4 as the materials volatilized by an electron beam. Cryogenic cooling broadens the range of precursors that can be used for EBIE, and enables high-resolution, deterministic etching of materials that are volatilized spontaneously by conventional etch precursors as demonstrated here by NF3 and XeF2 EBIE of silicon. PMID:25333843

  13. Enamel resistance to demineralization following Er:YAG laser etching for bonding orthodontic brackets

    PubMed Central

    Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

    2012-01-01

    Background: Several studies have shown that laser-etching of enamel for bonding orthodontic brackets could be an appropriate alternative for acid conditioning, since a potential advantage of laser could or might be caries prevention. This study compared enamel resistance to demineralization following etching with acid phosphoric or Er:YAG laser for bonding orthodontic brackets. Materials and Methods: Fifty sound human premolars were divided into two equal groups. In the first group, enamel was etched with 37% phosphoric acid for 15 seconds. In the second group, Er:YAG laser (wavelength, 2 940 nm; 300 mJ/pulse, 10 pulses per second, 10 seconds) was used for tooth conditioning. The teeth were subjected to 4-day PH-cycling process to induce caries-like lesions. The teeth were then sectioned and the surface area of the lesion was calculated in each microphotographs and expressed in pixel. The total surface of each specimen was 196 608 pixels. Results: Mean lesion areas were 7 171 and 7532 pixels for Laser-etched and Acid-etched groups, respectively. The two sample t-test showed that there was no significant difference in lesion area between the two groups (P = 0.914). Conclusion: Although Er:YAG laser seems promising for etching enamel before bonding orthodontic brackets, it does not reduce enamel demineralization when exposed to acid challenge. PMID:23162591

  14. Ion-beam-assisted etching of diamond

    NASA Technical Reports Server (NTRS)

    Efremow, N. N.; Geis, M. W.; Flanders, D. C.; Lincoln, G. A.; Economou, N. P.

    1985-01-01

    The high thermal conductivity, low RF loss, and inertness of diamond make it useful in traveling wave tubes operating in excess of 500 GHz. Such use requires the controlled etching of type IIA diamond to produce grating like structures tens of micrometers deep. Previous work on reactive ion etching with O2 gave etching rates on the order of 20 nm/min and poor etch selectivity between the masking material (Ni or Cr) and the diamond. An alternative approach which uses a Xe(+) beam and a reactive gas flux of NO2 in an ion-beam-assisted etching system is reported. An etching rate of 200 nm/min was obtained with an etching rate ratio of 20 between the diamond and an aluminum mask.

  15. Time-temperature evolution of microtextures and contained fluids in a plutonic alkali feldspar during heating

    NASA Astrophysics Data System (ADS)

    Parsons, Ian; Fitz Gerald, John D.; Lee, James K. W.; Ivanic, Tim; Golla-Schindler, Ute

    2010-08-01

    Microtextural changes brought about by heating alkali feldspar crystals from the Shap granite, northern England, at atmospheric pressure, have been studied using transmission and scanning electron microscopy. A typical unheated phenocryst from Shap is composed of about 70 vol% of tweed orthoclase with strain-controlled coherent or semicoherent micro- and crypto-perthitic albite lamellae, with maximum lamellar thicknesses <1 μm. Semicoherent lamellae are encircled by nanotunnel loops in two orientations and cut by pull-apart cracks. The average bulk composition of this microtexture is Ab27.6Or71.8An0.6. The remaining 30 vol% is deuterically coarsened, microporous patch and vein perthite composed of incoherent subgrains of oligoclase, albite and irregular microcline. The largest subgrains are ~3 μm in diameter. Heating times in the laboratory were 12 to 6,792 h and T from 300°C into the melting interval at 1,100°C. Most samples were annealed at constant T but two were heated to simulate an 40Ar/39Ar step-heating schedule. Homogenisation of strain-controlled lamellae by Na↔K inter-diffusion was rapid, so that in all run products at >700°C, and after >48 h at 700°C, all such regions were essentially compositionally homogeneous, as indicated by X-ray analyses at fine scale in the transmission electron microscope. Changes in lamellar thickness with time at different T point to an activation energy of ~350 kJmol-1. A lamella which homogenised after 6,800 h at 600°C, therefore, would have required only 0.6 s to do so in the melting interval at 1,100°C. Subgrains in patch perthite homogenised more slowly than coherent lamellae and chemical gradients in patches persisted for >5,000 h at 700°C. Homogenisation T is in agreement with experimentally determined solvi for coherent ordered intergrowths, when a 50-100°C increase in T for An1 is applied. Homogenisation of lamellae appears to proceed in an unexpected manner: two smooth interfaces, microstructurally sharp

  16. Fabrication of ultra-high aspect ratio silicon nanopores by electrochemical etching

    SciTech Connect

    Schmidt, Torsten; Zhang, Miao; Linnros, Jan; Yu, Shun

    2014-09-22

    We report on the formation of ultra-high aspect ratio nanopores in silicon bulk material using photo-assisted electrochemical etching. Here, n-type silicon is used as anode in contact with hydrofluoric acid. Based on the local dissolution of surface atoms in pre-defined etching pits, pore growth and pore diameter are, respectively, driven and controlled by the supply of minority charge carriers generated by backside illumination. Thus, arrays with sub-100 nm wide pores were fabricated. Similar to macropore etching, it was found that the pore diameter is proportional to the etching current, i.e., smaller etching currents result in smaller pore diameters. To find the limits under which nanopores with controllable diameter still can be obtained, etching was performed at very low current densities (several μA cm{sup −2}). By local etching, straight nanopores with aspect ratios above 1000 (∼19 μm deep and ∼15 nm pore tip diameter) were achieved. However, inherent to the formation of such narrow pores is a radius of curvature of a few nanometers at the pore tip, which favors electrical breakdown resulting in rough pore wall morphologies. Lowering the applied bias is adequate to reduce spiking pores but in most cases also causes etch stop. Our findings on bulk silicon provide a realistic chance towards sub-10 nm pore arrays on silicon membranes, which are of great interest for molecular filtering and possibly DNA sequencing.

  17. Plasmoids for etching and deposition

    NASA Astrophysics Data System (ADS)

    Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter

    2014-11-01

    In this manuscript we show fascinating properties of plasmoids, which are known to be self-sustained plasma entities, and can exist without being in contact with any power supply. Plasmoids are produced in a filamentary discharge in a Ar/CH4 mixture with a high production rate of about 105 s-1. It is observed that plasmoids etch the solid amorphous hydrocarbon film with high efficiency. Energy density of the plasmoid, which is estimated on the basis of glowing area of plasmoids in the photographic image and sublimation enthalpy of the etched hydrocarbon film, amounts to about 90 J m-3. This value is much lower than the energy density of observed ball lightning (natural plasmoid). A very surprising property is an attraction between plasmoids, and the formation of plasmoid-groups. Because of this attractive force, carbon material, which is collected in plasmoids by etching of the hydrocarbon film or by propagation through a methane/argon gas mixture, is compressed into crystals.

  18. Metal Oleate Induced Etching and Growth of Semiconductor Nanocrystals, Nanorods, and Their Heterostructures.

    PubMed

    Oh, Nuri; Shim, Moonsub

    2016-08-24

    Unexpected etching of nanocrystals, nanorods, and their heterostructures by one of the most commonly used metal precursors, metal oleates, is reported. Zn oleate is shown to etch CdS nanorods anisotropically, where the length decreases without a significant change in the diameter. Sodium oleate enhances the etch rate, whereas oleic acid alone does not cause etching, indicating the importance of the countercation on the rate of oleate induced etching. Subsequent addition of Se precursors to the partially etched nanorods in Zn oleate solution can lead to epitaxial growth of CdSe particles rather than the expected ZnSe growth, despite an excess amount of Zn precursors being present. The composition of this epitaxial growth can be varied from CdSe to ZnSe, depending on the amount of excess oleic acid or the reaction temperature. Similar tuning of composition can be observed when starting with collinear CdSe/CdS/CdSe rod/rod/rod heterostructures and spherical CdS (or CdSe/CdS core/shell) nanocrystals. Conversion of collinear rod/rod/rod structures to barbells and interesting rod growth from nearly spherical particles among other structures can also result due to the initial etching effect of metal oleates. These observations have important implications on our understanding of nanocrystal heterostructure synthesis and open up new routes to varying the composition and morphology of these materials. PMID:27485673

  19. In-Plasma Photo-Assisted Etching

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2015-09-01

    A methodology to precisely control the ion energy distribution (IED) on a substrate allowed the study of silicon etching as a function of ion energy at near-threshold energies. Surprisingly, a substantial etching rate was observed, independent of ion energy, when the ion energy was below the ion-assisted etching threshold (~ 16 eV for etching silicon with chlorine plasma). Careful experiments led to the conclusion that this ``sub-threshold'' etching was due to photons, predominately at wavelengths <1700 Å. Among the plasmas investigated, photo-assisted etching (PAE) was lowest in Br2/Ar gas mixtures and highest in HBr/Cl2/Ar. Above threshold etching rates scaled with the square root of ion energy. PAE rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. In-plasma PAE may be be a complicating factor for processes that require low ion energies, such as atomic layer etching. On the other hand PAE could produce sub-10 nm high aspect ratio (6:1) features by highly selective plasma etching to transfer nascent nanopatterns in silicon. Work supported by DOE Plasma Science Center and NSF.

  20. Effect of enamel etching time on roughness and bond strength.

    PubMed

    Barkmeier, Wayne W; Erickson, Robert L; Kimmes, Nicole S; Latta, Mark A; Wilwerding, Terry M

    2009-01-01

    The current study examined the effect of different enamel conditioning times on surface roughness and bond strength using an etch-and-rinse system and four self-etch adhesives. Surface roughness (Ra) and composite to enamel shear bond strengths (SBS) were determined following the treatment of flat ground human enamel (4000 grit) with five adhesive systems: (1) Adper Single Bond Plus (SBP), (2) Adper Prompt L-Pop (PLP), (3) Clearfil SE Bond (CSE), (4) Clearfil S3 Bond (CS3) and (5) Xeno IV (X4), using recommended treatment times and an extended treatment time of 60 seconds (n = 10/group). Control groups were also included for Ra (4000 grit surface) and SBS (no enamel treatment and Adper Scotchbond Multi-Purpose Adhesive). For surface roughness measurements, the phosphoric acid conditioner of the SBP etch-and-rinse system was rinsed from the surface with an air-water spray, and the other four self-etch adhesive agents were removed with alternating rinses of water and acetone. A Proscan 2000 non-contact profilometer was used to determine Ra values. Composite (Z100) to enamel bond strengths (24 hours) were determined using Ultradent fixtures and they were debonded with a crosshead speed of 1 mm/minute. The data were analyzed with ANOVA and Fisher's LSD post-hoc test. The etch-and- rinse system (SBP) produced the highest Ra (microm) and SBS (MPa) using both the recommended treatment time (0.352 +/- 0.028 microm and 40.5 +/- 6.1 MPa) and the extended treatment time (0.733 +/- 0.122 microm and 44.2 +/- 8.2 MPa). The Ra and SBS of the etch-and-rinse system were significantly greater (p < 0.05) than all the self-etch systems and controls. Increasing the treatment time with phosphoric acid (SBP) and PLP produced greater surface roughness (p < 0.05) but did not result in significantly higher bond strengths (p > 0.05). PMID:19363978

  1. Proterozoic polymetamorphism in the Quanji Block, northwestern China: Evidence from microtextures, garnet compositions and monazite CHIME ages

    NASA Astrophysics Data System (ADS)

    Wang, Qinyan; Pan, Yuanming; Chen, Nengsong; Li, Xiaoyan; Chen, Haihong

    2009-05-01

    The Quanji Block, situated close to the triple junction of three major Precambrian terranes in China (i.e., the North China Craton, the Yangtze Block and the Tarim Block), is composed of Precambrian metamorphic crystalline basement and an unmetamorphosed Mesozoic-Paleozoic sedimentary cover; it has been interpreted as a remnant continental fragment. Microtextural relationships, garnet trace element compositions, and monazite CHIME ages in paragneisses, schists and granitic leucosomes show two episodes of regional metamorphism in the Quanji Block basement. The first regional metamorphism and accompaning anatexis took place at ˜1.93 Ga; the second regional metamorphism occurred between ˜1.75 and ˜1.71 Ga. Mineral compositions of the first metamorphism, including those of monazite, were significantly disturbed by the second event. These two regional metamorphic episodes were most likely linked to assembly and breakup of the supercontinent Columbia, respectively.

  2. Fabrication of IR-transparent microfluidic devices by anisotropic etching of channels in CaF2.

    PubMed

    Lehmkuhl, Brynson; Noblitt, Scott D; Krummel, Amber T; Henry, Charles S

    2015-11-21

    A simple fabrication method for generating infrared (IR) transparent microfluidic devices using etched CaF2 is demonstrated. To etch microfluidic channels, a poly(dimethylsiloxane) (PDMS) microfluidic device was reversibly sealed on a CaF2 plate and acid was pumped through the channel network to perform anisotropic etching of the underlying CaF2 surface. To complete the CaF2 microfluidic device, another CaF2 plate was sealed over the etched channel using a 700 nm thick layer of PDMS adhesive. The impact of different acids and their concentrations on etching was studied, with HNO3 giving the best results in terms of channel roughness and etch rates. Etch rate was determined at etching times ranging from 4-48 hours and showed a linear correlation with etching time. The IR transparency of the CaF2 device was established using a Fourier Transform IR microscope and showed that the device could be used in the mid-IR region. Finally, utility of the device was demonstrated by following the reaction of N-methylacetamide and D2O, which results in an amide peak shift to 1625 cm(-1) from 1650 cm(-1), using an FTIR microscope. PMID:26450455

  3. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application.

    PubMed

    Reshak, A H; Shahimin, M M; Shaari, S; Johan, N

    2013-11-01

    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells. PMID:24139943

  4. Method for etching thin films of niboium and niobium-containing compounds for preparing superconductive circuits

    DOEpatents

    Kampwirth, R.T.; Schuller, I.K.; Falco, C.M.

    1979-11-23

    An improved method of preparing thin film superconducting electrical circuits of niobium or niobium compounds is provided in which a thin film of the niobium or niobium compound is applied to a nonconductive substrate and covered with a layer of photosensitive material. The sensitive material is in turn covered with a circuit pattern exposed and developed to form a mask of the circuit in photoresistive material on the surface of the film. The unmasked excess niobium film is removed by contacting the substrate with an aqueous etching solution of nitric acid, sulfuric acid, and hydrogen fluoride, which will rapidly etch the niobium compound without undercutting the photoresist. A modification of the etching solution will permit thin films to be lifted from the substrate without further etching.

  5. Method for etching thin films of niobium and niobium-containing compounds for preparing superconductive circuits

    DOEpatents

    Kampwirth, Robert T.; Schuller, Ivan K.; Falco, Charles M.

    1981-01-01

    An improved method of preparing thin film superconducting electrical circuits of niobium or niobium compounds in which a thin film of the niobium or niobium compound is applied to a nonconductive substrate, and covered with a layer of photosensitive material. The sensitive material is in turn covered with a circuit pattern exposed and developed to form a mask of the circuit in photoresistive material on the surface of the film. The unmasked excess niobium film is removed by contacting the substrate with an aqueous etching solution of nitric acid, sulfuric acid and hydrogen fluoride, which will rapidly etch the niobium compound without undercutting the photoresist. A modification of the etching solution will permit thin films to be lifted from the substrate without further etching.

  6. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application.

    PubMed

    Reshak, A H; Shahimin, M M; Shaari, S; Johan, N

    2013-11-01

    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.

  7. Evaluation of over-etching technique in the endodontically treated tooth restoration

    PubMed Central

    Migliau, Guido; Piccoli, Luca; Besharat, Laith Konstantinos; Di Carlo, Stefano; Pompa, Giorgio

    2015-01-01

    Summary The main purpose of a post-endodontic restoration with posts is to guarantee the retention of the restorative material. The aim of the study was to examine, through the push-out test, how bond strength between the post and the dentin varied with etching time with 37% orthophosphoric acid, before cementation of a glass fiber post. Moreover, it has been examined if over-etching (application time of the acid: 2 minutes) was an effective technique to improve the adhesion to the endodontic substrate, after highlighting the problems of adhesion concerning its anatomical characteristics and the changes after the endodontic treatment. Highest bond strength values were found by etching the substrate for 30 sec., while over-etching didn’t improve bond strength to the endodontic substrate. PMID:26161247

  8. Etching method for photoresists or polymers

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R. (Inventor); Wydeven, Theodore J., Jr. (Inventor)

    1991-01-01

    A method for etching or removing polymers, photoresists, and organic contaminants from a substrate is disclosed. The method includes creating a more reactive gas species by producing a plasma discharge in a reactive gas such as oxygen and contacting the resulting gas species with a sacrificial solid organic material such as polyethylene or polyvinyl fluoride, reproducing a highly reactive gas species, which in turn etches the starting polymer, organic contaminant, or photoresist. The sample to be etched is located away from the plasma glow discharge region so as to avoid damaging the substrate by exposure to high energy particles and electric fields encountered in that region. Greatly increased etching rates are obtained. This method is highly effective for etching polymers such as polyimides and photoresists that are otherwise difficult or slow to etch downstream from an electric discharge in a reactive gas.

  9. Laser-driven fusion etching process

    DOEpatents

    Ashby, C.I.H.; Brannon, P.J.; Gerardo, J.B.

    1987-08-25

    The surfaces of solids are etched by a radiation-driven chemical reaction. The process involves exposing a substrate coated with a layer of a reactant material on its surface to radiation, e.g., a laser, to induce localized melting of the substrate which results in the occurrence of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic substrates, e.g., LiNbO/sub 3/, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  10. Laser-driven fusion etching process

    DOEpatents

    Ashby, Carol I. H.; Brannon, Paul J.; Gerardo, James B.

    1989-01-01

    The surfaces of solid ionic substrates are etched by a radiation-driven chemical reaction. The process involves exposing an ionic substrate coated with a layer of a reactant material on its surface to radiation, e.g. a laser, to induce localized melting of the substrate which results in the occurrance of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic salt substrates, e.g., a solid inorganic salt such as LiNbO.sub.3, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  11. Etching of glass microchips with supercritical water.

    PubMed

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-01

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  12. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

    A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

  13. Evaluation of shear bond strength of orthodontic brackets bonded with Er-YAG laser etching

    PubMed Central

    Raji, S. Hamid; Birang, Reza; Majdzade, Fateme; Ghorbanipour, Reza

    2012-01-01

    Background: Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. Materials and Methods: In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey's test and Kruskal Wallis were used to analyze the data. Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001). Conclusions: laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding. PMID:23087733

  14. Selective etching of silicon carbide films

    DOEpatents

    Gao, Di; Howe, Roger T.; Maboudian, Roya

    2006-12-19

    A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

  15. Controlled ion implant damage profile for etching

    DOEpatents

    Arnold, Jr., George W.; Ashby, Carol I. H.; Brannon, Paul J.

    1990-01-01

    A process for etching a material such as LiNbO.sub.3 by implanting ions having a plurality of different kinetic energies in an area to be etched, and then contacting the ion implanted area with an etchant. The various energies of the ions are selected to produce implant damage substantially uniformly throughout the entire depth of the zone to be etched, thus tailoring the vertical profile of the damaged zone.

  16. Dry etching technologies for reflective multilayer

    NASA Astrophysics Data System (ADS)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Kase, Yoshihisa; Yoshimori, Tomoaki; Muto, Makoto; Nonaka, Mikio; Iwami, Munenori

    2012-11-01

    We have developed a highly integrated methodology for patterning Extreme Ultraviolet (EUV) mask, which has been highlighted for the lithography technique at the 14nm half-pitch generation and beyond. The EUV mask is characterized as a reflective-type mask which is completely different compared with conventional transparent-type of photo mask. And it requires not only patterning of absorber layer without damaging the underlying multi reflective layers (40 Si/Mo layers) but also etching multi reflective layers. In this case, the dry etch process has generally faced technical challenges such as the difficulties in CD control, etch damage to quartz substrate and low selectivity to the mask resist. Shibaura Mechatronics ARESTM mask etch system and its optimized etch process has already achieved the maximal etch performance at patterning two-layered absorber. And in this study, our process technologies of multi reflective layers will be evaluated by means of optimal combination of process gases and our optimized plasma produced by certain source power and bias power. When our ARES™ is used for multilayer etching, the user can choose to etch the absorber layer at the same time or etch only the multilayer.

  17. Method for dry etching of transition metals

    DOEpatents

    Ashby, C.I.H.; Baca, A.G.; Esherick, P.; Parmeter, J.E.; Rieger, D.J.; Shul, R.J.

    1998-09-29

    A method for dry etching of transition metals is disclosed. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorus-containing {pi}-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/{pi}-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the {pi}-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the {pi}-acceptor ligand for forming the volatile transition metal/{pi}-acceptor ligand complex.

  18. Method for dry etching of transition metals

    DOEpatents

    Ashby, Carol I. H.; Baca, Albert G.; Esherick, Peter; Parmeter, John E.; Rieger, Dennis J.; Shul, Randy J.

    1998-01-01

    A method for dry etching of transition metals. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorous-containing .pi.-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/.pi.-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the .pi.-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the .pi.-acceptor ligand for forming the volatile transition metal/.pi.-acceptor ligand complex.

  19. AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

    NASA Astrophysics Data System (ADS)

    Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

    2001-10-01

    The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

  20. Etch challenges for DSA implementation in CMOS via patterning

    NASA Astrophysics Data System (ADS)

    Pimenta Barros, P.; Barnola, S.; Gharbi, A.; Argoud, M.; Servin, I.; Tiron, R.; Chevalier, X.; Navarro, C.; Nicolet, C.; Lapeyre, C.; Monget, C.; Martinez, E.

    2014-03-01

    This paper reports on the etch challenges to overcome for the implementation of PS-b-PMMA block copolymer's Directed Self-Assembly (DSA) in CMOS via patterning level. Our process is based on a graphoepitaxy approach, employing an industrial PS-b-PMMA block copolymer (BCP) from Arkema with a cylindrical morphology. The process consists in the following steps: a) DSA of block copolymers inside guiding patterns, b) PMMA removal, c) brush layer opening and finally d) PS pattern transfer into typical MEOL or BEOL stacks. All results presented here have been performed on the DSA Leti's 300mm pilot line. The first etch challenge to overcome for BCP transfer involves in removing all PMMA selectively to PS block. In our process baseline, an acetic acid treatment is carried out to develop PMMA domains. However, this wet development has shown some limitations in terms of resists compatibility and will not be appropriated for lamellar BCPs. That is why we also investigate the possibility to remove PMMA by only dry etching. In this work the potential of a dry PMMA removal by using CO based chemistries is shown and compared to wet development. The advantages and limitations of each approach are reported. The second crucial step is the etching of brush layer (PS-r-PMMA) through a PS mask. We have optimized this step in order to preserve the PS patterns in terms of CD, holes features and film thickness. Several integrations flow with complex stacks are explored for contact shrinking by DSA. A study of CD uniformity has been addressed to evaluate the capabilities of DSA approach after graphoepitaxy and after etching.

  1. One-year clinical evaluation of the bonding effectiveness of a one-step, self-etch adhesive in noncarious cervical lesion therapy.

    PubMed

    Faye, Babacar; Sarr, Mouhamed; Bane, Khaly; Aidara, Adjaratou Wakha; Niang, Seydina Ousmane; Kane, Abdoul Wakhabe

    2015-01-01

    This study evaluated the one-year clinical performance of a one-step, self-etch adhesive (Optibond All-in-One, Kerr, CA, USA) combined with a composite (Herculite XRV Ultra, Kerr Hawe, CA, USA) to restore NCCLs with or without prior acid etching. Restorations performed by the same practitioner were evaluated at baseline and after 3, 6, and 12 months using modified USPHS criteria. At 6 months, the recall rate was 100%. The retention rate was 84.2% for restorations with prior acid etching, but statistically significant differences were observed between baseline and 6 months. Without acid etching, the retention rate was 77%, and no statistically significant difference was noted between 3 and 6 months. Marginal integrity (93.7% with and 87.7% without acid etching) and discoloration (95.3% with and 92.9% without acid etching) were scored as Alpha or Bravo, with better results after acid etching. After one year, the recall rate was 58.06%. Loss of pulp vitality, postoperative sensitivity, or secondary caries were not observed. After one year retention rate was of 90.6% and 76.9% with and without acid conditioning. Optibond All-in-One performs at a satisfactory clinical performance level for restoration of NCCLs after 12 months especially after acid etching. PMID:25810720

  2. One-Year Clinical Evaluation of the Bonding Effectiveness of a One-Step, Self-Etch Adhesive in Noncarious Cervical Lesion Therapy

    PubMed Central

    Faye, Babacar; Sarr, Mouhamed; Bane, Khaly; Aidara, Adjaratou Wakha; Niang, Seydina Ousmane; Kane, Abdoul Wakhabe

    2015-01-01

    This study evaluated the one-year clinical performance of a one-step, self-etch adhesive (Optibond All-in-One, Kerr, CA, USA) combined with a composite (Herculite XRV Ultra, Kerr Hawe, CA, USA) to restore NCCLs with or without prior acid etching. Restorations performed by the same practitioner were evaluated at baseline and after 3, 6, and 12 months using modified USPHS criteria. At 6 months, the recall rate was 100%. The retention rate was 84.2% for restorations with prior acid etching, but statistically significant differences were observed between baseline and 6 months. Without acid etching, the retention rate was 77%, and no statistically significant difference was noted between 3 and 6 months. Marginal integrity (93.7% with and 87.7% without acid etching) and discoloration (95.3% with and 92.9% without acid etching) were scored as Alpha or Bravo, with better results after acid etching. After one year, the recall rate was 58.06%. Loss of pulp vitality, postoperative sensitivity, or secondary caries were not observed. After one year retention rate was of 90.6% and 76.9% with and without acid conditioning. Optibond All-in-One performs at a satisfactory clinical performance level for restoration of NCCLs after 12 months especially after acid etching. PMID:25810720

  3. Ultradeep fused silica glass etching with an HF-resistant photosensitive resist for optical imaging applications

    NASA Astrophysics Data System (ADS)

    Nagarah, John M.; Wagenaar, Daniel A.

    2012-03-01

    Microfluidic and optical sensing platforms are commonly fabricated in glass and fused silica (quartz) because of their optical transparency and chemical inertness. Hydrofluoric acid (HF) solutions are the etching media of choice for deep etching into silicon dioxide substrates, but processing schemes become complicated and expensive for etching times greater than 1 h due to the aggressiveness of HF migration through most masking materials. We present here etching into fused silica more than 600 µm deep while keeping the substrate free of pits and maintaining a polished etched surface suitable for biological imaging. We utilize an HF-resistant photosensitive resist (HFPR) which is not attacked in 49% HF solution. Etching characteristics are compared for substrates masked with the HFPR alone and the HFPR patterned on top of Cr/Au and polysilicon masks. We used this etching process to fabricate suspended fused silica membranes, 8-16 µm thick, and show that imaging through the membranes does not negatively affect image quality of fluorescence microscopy of biological tissue. Finally, we realize small through-pore arrays in the suspended membranes. Such devices will have applications in planar electrophysiology platforms, especially where optical imaging is required.

  4. Etching with electron beam generated plasmas

    SciTech Connect

    Leonhardt, D.; Walton, S.G.; Muratore, C.; Fernsler, R.F.; Meger, R.A.

    2004-11-01

    A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen-argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was seen as gas composition went from pure oxygen to 70% argon, implying the resist removal mechanism in this system required the additional energy supplied by the ions. With silicon substrates at room temperature, mixtures of argon and sulfur hexafluoride etched approximately seven times faster (1375 nm/min) than mixtures of oxygen and sulfur hexafluoride ({approx}200 nm/min) with 200 eV ions, the difference is attributed to the passivation of the silicon by involatile silicon oxyfluoride (SiO{sub x}F{sub y}) compounds. At low incident ion energies, the Ar-SF{sub 6} mixtures showed a strong chemical (lateral) etch component before an ion-assisted regime, which started at {approx}75 eV. Etch rates were independent of the 0.5%-50% duty factors studied in this work.

  5. Simulation of Etching Profiles Using Level Sets

    NASA Technical Reports Server (NTRS)

    Hwang, Helen; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Using plasma discharges to etch trenches and via holes in substrates is an important process in semiconductor manufacturing. Ion enhanced etching involves both neutral fluxes, which are isotropic, and ion fluxes, which are anisotropic. The angular distributions for the ions determines the degree of vertical etch, while the amount of the neutral fluxes determines the etch rate. We have developed a 2D profile evolution simulation which uses level set methods to model the plasma-substrate interface. Using level sets instead of traditional string models avoids the use of complicated delooping algorithms. The simulation calculates the etch rate based on the fluxes and distribution functions of both ions and neutrals. We will present etching profiles of Si substrates in low pressure (10s mTorr) Ar/Cl2 discharges for a variety of incident ion angular distributions. Both ion and neutral re-emission fluxes are included in the calculation of the etch rate, and their contributions to the total etch profile will be demonstrated. In addition, we will show RIE lag effects as a function of different trench aspect ratios. (For sample profiles, please see http://www.ipt.arc.nasa.gov/hwangfig1.html)

  6. Note: electrochemical etching of sharp iridium tips.

    PubMed

    Lalanne, Jean-Benoît; Paul, William; Oliver, David; Grütter, Peter H

    2011-11-01

    We describe an etching procedure for the production of sharp iridium tips with apex radii of 15-70 nm, as determined by scanning electron microscopy, field ion microscopy, and field emission measurements. A coarse electrochemical etch followed by zone electropolishing is performed in a relatively harmless calcium chloride solution with high success rate.

  7. Analysis methods for meso- and macroporous silicon etching baths

    NASA Astrophysics Data System (ADS)

    Nehmann, Julia B.; Kajari-Schröder, Sarah; Bahnemann, Detlef W.

    2012-07-01

    Analysis methods for electrochemical etching baths consisting of various concentrations of hydrofluoric acid (HF) and an additional organic surface wetting agent are presented. These electrolytes are used for the formation of meso- and macroporous silicon. Monitoring the etching bath composition requires at least one method each for the determination of the HF concentration and the organic content of the bath. However, it is a precondition that the analysis equipment withstands the aggressive HF. Titration and a fluoride ion-selective electrode are used for the determination of the HF and a cuvette test method for the analysis of the organic content, respectively. The most suitable analysis method is identified depending on the components in the electrolyte with the focus on capability of resistance against the aggressive HF.

  8. Optical fiber nanoprobe preparation for near-field optical microscopy by chemical etching under surface tension and capillary action.

    PubMed

    Mondal, Samir K; Mitra, Anupam; Singh, Nahar; Sarkar, S N; Kapur, Pawan

    2009-10-26

    We propose a technique of chemical etching for fabrication of near perfect optical fiber nanoprobe (NNP). It uses photosensitive single mode optical fiber to etch in hydro fluoric (HF) acid solution. The difference in etching rate for cladding and photosensitive core in HF acid solution creates capillary ring along core-cladding boundary under a given condition. The capillary ring is filled with acid solution due to surface tension and capillary action. Finally it creates near perfect symmetric tip at the apex of the fiber as the height of the acid level in capillary ring decreases while width of the ring increases with continuous etching. Typical tip features are short taper length (approximately 4 microm), large cone angle (approximately 38 degrees ), and small probe tip dimension (<100 nm). A finite difference time domain (FDTD) analysis is also presented to compare near field optics of the NNP with conventional nanoprobe (CNP). The probe may be ideal for near field optical imaging and sensor applications.

  9. Surface engineering on CeO2 nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation

    NASA Astrophysics Data System (ADS)

    Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

    2015-07-01

    Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications. Electronic supplementary information (ESI) available: Diameter distributions of as-prepared and etched samples, optical images, specific catalytic data of CO oxidation and comparison of CO oxidation. See DOI: 10.1039/c5nr01846c

  10. Graphene nanoribbons: Relevance of etching process

    SciTech Connect

    Simonet, P. Bischoff, D.; Moser, A.; Ihn, T.; Ensslin, K.

    2015-05-14

    Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely, O{sub 2} plasma ashing and O{sub 2 }+ Ar reactive ion etching (RIE). O{sub 2} plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused by more or larger localized states at the edges of the ashed device compared to the RIE defined device.

  11. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

    Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

    2015-09-01

    Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

  12. Aspect ratio dependent etching lag reduction in deep silicon etch processes

    SciTech Connect

    Lai, S.L.; Johnson, D.; Westerman, R.

    2006-07-15

    Microelectromechanical system (MEMS) device fabrication often involves three dimensional structures with high aspect ratios. Moreover, MEMS designs require structures with different dimensions and aspect ratios to coexist on a single microchip. There is a well-documented aspect ratio dependent etching (ARDE) effect in deep silicon etching processes. For features with different dimensions etched simultaneously, the ARDE effect causes bigger features to be etched at faster rates. In practice, ARDE effect has many undesired complications to MEMS device fabrication. This article presents a physical model to describe the time division multiplex (TDM) plasma etch processes and thereafter the experimental results on ARDE lag reduction. The model breaks individual plasma etch cycles in the TDM plasma etch processes into polymer deposition, polymer removal, and spontaneous silicon etching stages. With the insights gained from the model and control over the passivation and etch steps, it has been demonstrated that ARDE lag can be controlled effectively. Experiments have shown that a normal ARDE lag can be changed to an inverse ARDE lag. Under optimized conditions, the ARDE lag is reduced to below 2%-3% for trenches with widths ranging from 2.5 to 100 {mu}m, while maintaining good etch profile in trenches with different dimensions. Such results are achieved at etch rates exceeding 2 {mu}m/min.

  13. Correlation between surface chemistry and ion energy dependence of the etch yield in multicomponent oxides etching

    SciTech Connect

    Berube, P.-M.; Poirier, J.-S.; Margot, J.; Stafford, L.; Ndione, P. F.; Chaker, M.; Morandotti, R.

    2009-09-15

    The influence of surface chemistry in plasma etching of multicomponent oxides was investigated through measurements of the ion energy dependence of the etch yield. Using pulsed-laser-deposited Ca{sub x}Ba{sub (1-x)}Nb{sub 2}O{sub 6} (CBN) and SrTiO{sub 3} thin films as examples, it was found that the etching energy threshold shifts toward values larger or smaller than the sputtering threshold depending on whether or not ion-assisted chemical etching is the dominant etching pathway and whether surface chemistry is enhancing or inhibiting desorption of the film atoms. In the case of CBN films etched in an inductively coupled Cl{sub 2} plasma, it is found that the chlorine uptake is inhibiting the etching reaction, with the desorption of nonvolatile NbCl{sub 2} and BaCl{sub 2} compounds being the rate-limiting step.

  14. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    SciTech Connect

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  15. Strongly reduced Si surface recombination by charge injection during etching in diluted HF/HNO3.

    PubMed

    Greil, Stefanie M; Schöpke, Andreas; Rappich, Jörg

    2012-08-27

    Herein, we investigate the behaviour of the surface recombination of light-induced charge carriers during the etching of Si in alkaline (KOH) and acidic etching solutions of HF/HNO(3)/CH(3)COOH (HNA) or HF/HNO(3)/H(3)PO(4) (HNP) at different concentration ratios of HF and HNO(3) by means of photoluminescence (PL) measurements. The surface recombination velocity is strongly reduced during the first stages of etching in HF/HNO(3)-containing solutions pointing to a interface well passivated by the etching process, where a positive surface charge is induced by hole injection from NO-related surface species into the Si near-surface region (back surface field effect). This injected charge leads to a change in band bending by about 150 mV that repulses the light-induced charge carriers from the surface and therefore enhances the photoluminescence intensity, since non-radiative surface recombination is reduced.

  16. Optimal conditions for the preparation of superhydrophobic surfaces on al substrates using a simple etching approach

    NASA Astrophysics Data System (ADS)

    Ruan, Min; Li, Wen; Wang, Baoshan; Luo, Qiang; Ma, Fumin; Yu, Zhanlong

    2012-07-01

    Many methods have been proposed to develop the fabrication techniques for superhydrophobic surfaces. However, such techniques are still at their infant stage and suffer many shortcomings. In this paper, the superhydrophobic surfaces on an Al substrate were prepared by a simple etching method. Effects of etching time, modifiers, and modification concentration and time were investigated, and optimal conditions for the best superhydrophobicity were studied. It was demonstrated that for etching the aluminum plate in Beck's dislocation, if the etching time was 15 s, modifier was Lauric acid-ethanol solution, and modification concentration and time was 5% and 1.5 h, respectively, the surface exhibited a water contact angle as high as 167.5° and a contact angle hysteresis as low as 2.3°.

  17. Plasma etching in a multipolar discharge

    NASA Astrophysics Data System (ADS)

    Wicker, T. E.; Mantei, T. D.

    1985-03-01

    Etching of silicon and SiO2 has been investigated in a dc plasma discharge confined by a multipolar surface magnetic field layer. The reactive plasma is produced by primary ionizing electrons drawn from heated tungsten filaments and confined by permanent magnets. Electrical probe measurements show that a uniform high-density plasma (1010-1011 cm-3) is sustained in SF6-O2 at very low pressure (0.2-2.0×10-3 Torr). Substrates are biased independently of plasma production by a low-frequency alternating voltage (0-400 V) applied to the substrate through a blocking capacitor. Anisotropic profiles are etched into Si in SF6-20% O2 with etch rates in excess of 1 μm/min at 2×10-3 Torr. The etch rate increases with increasing primary electron current (up to 3 A) and energy (up to 60 eV), gas pressure (up to 2.0×10-3 Torr), substrate bias voltage, and the addition of up to 20% O2. For higher ionizing electron energies (>60 eV) and higher gas pressure (>2.0×10-3 Torr), etching is partially blocked by residue formation. The etch anisotropy depends mainly on substrate bias, increasing for higher values of bias voltage. The Si:SiO2 etch selectivity is typically 10-20, becoming large with decreasing substrate bias and plasma ion density.

  18. Fe-catalyzed etching of graphene layers

    NASA Astrophysics Data System (ADS)

    Cheng, Guangjun; Calizo, Irene; Hight Walker, Angela; PML, NIST Team

    We investigate the Fe-catalyzed etching of graphene layers in forming gas. Fe thin films are deposited by sputtering onto mechanically exfoliated graphene, few-layer graphene (FLG), and graphite flakes on a Si/SiO2 substrate. When the sample is rapidly annealed in forming gas, particles are produced due to the dewetting of the Fe thin film and those particles catalyze the etching of graphene layers. Monolayer graphene and FLG regions are severely damaged and that the particles catalytically etch channels in graphite. No etching is observed on graphite for the Fe thin film annealed in nitrogen. The critical role of hydrogen indicates that this graphite etching process is catalyzed by Fe particles through the carbon hydrogenation reaction. By comparing with the etched monolayer and FLG observed for the Fe film annealed in nitrogen, our Raman spectroscopy measurements identify that, in forming gas, the catalytic etching of monolayer and FLG is through carbon hydrogenation. During this process, Fe particles are catalytically active in the dissociation of hydrogen into hydrogen atoms and in the production of hydrogenated amorphous carbon through hydrogen spillover.

  19. Etch Characteristics of GaN using Inductively Coupled Cl{sub 2} Plasma Etching

    SciTech Connect

    Rosli, Siti Azlina; Aziz, A. Abdul

    2008-05-20

    In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl{sub 2}/Ar plasmas were investigated. It has shown that the results of a study of inductively coupled plasma (ICP) etching of gallium nitride by using Cl{sub 2}/Ar is possible to meet the requirement (anisotropy, high etch rate and high selectivity), simultaneously. We have investigated the etching rate dependency on the percentage of Argon in the gas mixture, the total pressure and DC voltage. We found that using a gas mixture with 20 sccm of Ar, the optimum etch rate of GaN was achieved. The etch rate were found to increase with voltage, attaining a maximum rate 2500 A/min at -557 V. The addition of an inert gas, Ar is found to barely affect the etch rate. Surface morphology of the etched samples was verified by scanning electron microscopy and atomic force microscopy. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer.

  20. Dynamics of ion-assisted etching

    NASA Astrophysics Data System (ADS)

    Sebel, Petrus Gerardus Maria

    In this thesis a study is presented on the fundamentals of ion-assisted etching of silicon. The research was performed in the Atomic Physics and Quantum Electronics Group (AQT/B) of the Physics Department at the Eindhoven University of Technology. Etching is a key technique in the production process of integrated circuits. Industrial etching is usually done in a plasma reactor. However, to unravel the detailed mechanisms determining the etch process, a different approach was chosen. In this scheme, well defined beams of XeF2 and Ar + ions are directed towards the Si sample in an ultra-high vacuum (UHV) setup. In this way the relevant ingredients of a plasma (neutrals and ions) are simulated. The etching reaction is monitored by a quadruple mass spectrometer (QMS) which detects the desorption of non-reacted XeF2 and the main reaction products SiF4 and SiF2. We conclude that we have obtained a detailed microscopic picture of the etching of silicon by beams of neutrals and ions. However, there is still a gap between beam etching and plasma etching. To bridge this gap an ellipsometer has been added to our setup, because it is a common non-invasive diagnostic tool used in a plasma reactor. In addition, also a sample exchange mechanism was installed to facilitate the frequent exchange of samples. The first ellipsometric results of spontaneous etching show the construction of a reaction layer followed by surface roughening. The XeF2 dose needed to build the reaction layer as derived from the ellipsometric results is in good agreement with results from the mass spectrometer. Additional experiments have to be performed to obtain a full understanding of the roughening of the surface, but a first link between microscopic and macroscopic features has been established. (Abstract shortened by UMI.)

  1. Dry etching method for compound semiconductors

    DOEpatents

    Shul, Randy J.; Constantine, Christopher

    1997-01-01

    A dry etching method. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators.

  2. Dry etching method for compound semiconductors

    DOEpatents

    Shul, R.J.; Constantine, C.

    1997-04-29

    A dry etching method is disclosed. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators. 1 fig.

  3. Method of sputter etching a surface

    DOEpatents

    Henager, Jr., Charles H.

    1984-01-01

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion.

  4. Method of sputter etching a surface

    DOEpatents

    Henager, C.H. Jr.

    1984-02-14

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion. 4 figs.

  5. Microleakage and penetration depth of three types of materials in fissure sealant: self-etching primer vs etching: an in vitro study.

    PubMed

    Gillet, D; Nancy, J; Dupuis, V; Dorignac, G

    2002-01-01

    Clinical preventive procedures must be done after a risk assessment. One of the risk factors is the occlusal morphology of the posterior teeth. These caries-free fissures must be sealed. This first in vitro experimentation of the study evaluated the microleakage and the penetration depth of three types of materials by Vivadent: Helioseal F, Tetric, Tetric Flow. The teeth were etched with phosphoric acid and bonded using a one bottle bonding in order to determine the best material for the sealing of the fissure. The depth of penetration of fuschine dye as well as that of the tested material was measured with a grid. The results, compared to the depth of the fissures, are expressed in percentage of penetration. The results were as follows: penetration of fuschine dye: 0% for the 2 composites, 100% for Helioseal F; penetration of the materials: 96.90% for Helioseal F, 70.82 for Tetric and 86.10 for Tetric Flow (significant difference, Wilcoxon test = 0.0105). In this first in vitro study, Tetric Flow shows no microleakage and is more efficient when compared to Helioseal F and Tetric in obturating deep fissures of non carious bicuspids. The second experiment of the study evaluated the microleakage and the penetration depth of Tetric Flow when it is bonded by two different methods: Group 1: total etch (phosphoric acid) and Scotch-bond 1 (3M), and Group 2: self-etching primer with Prompt (Espe). There was no significant difference (p > 0.03) between classical bonding vs self-etching primer. The self-etching primer Prompt is very efficient vs phosphoric acid in obturating the fissures of non carious bicuspids with Tetric Flow. It is concluded that for prevention by sealing, using a flowable ceromer (Tetric Flow) with the self-etching (Prompt), is a really good technique.

  6. Surface engineering on CeO₂ nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation.

    PubMed

    Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

    2015-07-21

    Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce(3+) fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.

  7. Estimation of martensite feature size in a low-carbon alloy steel by microtexture analysis of boundaries.

    PubMed

    Karthikeyan, T; Dash, Manmath Kumar; Saroja, S; Vijayalakshmi, M

    2015-01-01

    A methodology for classifying the hierarchy of martensite boundaries from the EBSD microtexture data of low-carbon steel is presented. Quaternion algebra has been used to calculate the ideal misorientation between product α variants for Kurdjumov-Sachs (KS) and its nearby orientation relationships, and arrive at the misorientation angle-axis set corresponding to packet (12 types), block (3 types) and sub-block boundaries. Analysis of proximity of experimental misorientation between data points from the theoretical misorientation set is found to be useful for identifying the different types of martensite boundaries. The optimal OR in the alloy system and the critical deviation threshold for identification of martensite boundaries could both be ascertained by invoking the 'Enhancement Factor' concept. The prior-γ grain boundaries, packet, block and sub-block boundaries could be identified reasonably well, and their average intercept lengths in a typical tempered martensite microstructure of 9Cr-1Mo-0.1C steel was estimated as 31 μm, 14 μm, 9 μm and 4 μm respectively.

  8. Estimation of martensite feature size in a low-carbon alloy steel by microtexture analysis of boundaries.

    PubMed

    Karthikeyan, T; Dash, Manmath Kumar; Saroja, S; Vijayalakshmi, M

    2015-01-01

    A methodology for classifying the hierarchy of martensite boundaries from the EBSD microtexture data of low-carbon steel is presented. Quaternion algebra has been used to calculate the ideal misorientation between product α variants for Kurdjumov-Sachs (KS) and its nearby orientation relationships, and arrive at the misorientation angle-axis set corresponding to packet (12 types), block (3 types) and sub-block boundaries. Analysis of proximity of experimental misorientation between data points from the theoretical misorientation set is found to be useful for identifying the different types of martensite boundaries. The optimal OR in the alloy system and the critical deviation threshold for identification of martensite boundaries could both be ascertained by invoking the 'Enhancement Factor' concept. The prior-γ grain boundaries, packet, block and sub-block boundaries could be identified reasonably well, and their average intercept lengths in a typical tempered martensite microstructure of 9Cr-1Mo-0.1C steel was estimated as 31 μm, 14 μm, 9 μm and 4 μm respectively. PMID:25464145

  9. Selective emitter using a screen printed etch barrier in crystalline silicon solar cell.

    PubMed

    Song, Kyuwan; Kim, Bonggi; Lee, Hoongjoo; Lee, Youn-Jung; Park, Cheolmin; Balaji, Nagarajan; Ju, Minkyu; Choi, Jaewoo; Yi, Junsin

    2012-07-23

    The low level doping of a selective emitter by etch back is an easy and low cost process to obtain a better blue response from a solar cell. This work suggests that the contact resistance of the selective emitter can be controlled by wet etching with the commercial acid barrier paste that is commonly applied in screen printing. Wet etching conditions such as acid barrier curing time, etchant concentration, and etching time have been optimized for the process, which is controllable as well as fast. The acid barrier formed by screen printing was etched with HF and HNO3 (1:200) solution for 15 s, resulting in high sheet contact resistance of 90 Ω/sq. Doping concentrations of the electrode contact portion were 2 × 1021 cm-3 in the low sheet resistance (Rs) region and 7 × 1019 cm-3 in the high Rs region. Solar cells of 12.5 × 12.5 cm2 in dimensions with a wet etch back selective emitter Jsc of 37 mAcm-2, open circuit voltage (Voc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on Voc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with Jsc of 36.90 mAcm-2, Voc of 625.7 mV, and efficiency of 17.60%.

  10. Selective emitter using a screen printed etch barrier in crystalline silicon solar cell

    PubMed Central

    2012-01-01

    The low level doping of a selective emitter by etch back is an easy and low cost process to obtain a better blue response from a solar cell. This work suggests that the contact resistance of the selective emitter can be controlled by wet etching with the commercial acid barrier paste that is commonly applied in screen printing. Wet etching conditions such as acid barrier curing time, etchant concentration, and etching time have been optimized for the process, which is controllable as well as fast. The acid barrier formed by screen printing was etched with HF and HNO3 (1:200) solution for 15 s, resulting in high sheet contact resistance of 90 Ω/sq. Doping concentrations of the electrode contact portion were 2 × 1021 cm−3 in the low sheet resistance (Rs) region and 7 × 1019 cm−3 in the high Rs region. Solar cells of 12.5 × 12.5 cm2 in dimensions with a wet etch back selective emitter Jsc of 37 mAcm−2, open circuit voltage (Voc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on Voc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with Jsc of 36.90 mAcm−2, Voc of 625.7 mV, and efficiency of 17.60%. PMID:22823978

  11. Synergistic etch rates during low-energetic plasma etching of hydrogenated amorphous carbon

    SciTech Connect

    Hansen, T. A. R.; Weber, J. W.; Colsters, P. G. J.; Mestrom, D. M. H. G.; Sanden, M. C. M. van de; Engeln, R.

    2012-07-01

    The etch mechanisms of hydrogenated amorphous carbon thin films in low-energetic (<2 eV) high flux plasmas are investigated with spectroscopic ellipsometry. The results indicate a synergistic effect for the etch rate between argon ions and atomic hydrogen, even at these extremely low kinetic energies. Ion-assisted chemical sputtering is the primary etch mechanism in both Ar/H{sub 2} and pure H{sub 2} plasmas, although a contribution of swift chemical sputtering to the total etch rate is not excluded. Furthermore, ions determine to a large extent the surface morphology during plasma etching. A high influx of ions enhances the etch rate and limits the surface roughness, whereas a low ion flux promotes graphitization and leads to a large surface roughness (up to 60 nm).

  12. Carrier-lifetime-controlled selective etching process for semiconductors using photochemical etching

    DOEpatents

    Ashby, Carol I. H.; Myers, David R.

    1992-01-01

    The minority carrier lifetime is significantly much shorter in semiconductor materials with very high impurity concentrations than it is in semiconductor materials with lower impurity concentration levels. This phenomenon of reduced minority carrier lifetime in semiconductor materials having high impurity concentration is utilized to advantage for permitting highly selective semiconductor material etching to be achieved using a carrier-driven photochemical etching reaction. Various means may be employed for increasing the local impurity concentration level in specific near-surface regions of a semiconductor prior to subjecting the semiconductor material to a carrier-driven photochemical etching reaction. The regions having the localized increased impurity concentration form a self-aligned mask inhibiting photochemical etching at such localized regions while the adjacent regions not having increased impurity concentrations are selectively photochemically etched. Liquid- or gas-phase etching may be performed.

  13. Black Germanium fabricated by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    A reactive ion etching technique for the preparation of statistical "Black Germanium" antireflection surfaces, relying on self-organization in a Cl2 etch chemistry, is presented. The morphology of the fabricated Black Germanium surfaces is the result of a random lateral distribution of pyramidal etch pits with heights around (1450 ± 150) nm and sidewall angles between 80° and 85°. The pyramids' base edges are oriented along the <110> crystal directions of Germanium, indicating a crystal anisotropy of the etching process. In the Vis-NIR, the tapered Black Germanium surface structure suppresses interface reflection to <2.5 % for normal incidence and still to <6 % at an angle of incidence of 70°. The presented Black Germanium might find applications as low-cost AR structure in optoelectronics and IR optics.

  14. Epoxy bond and stop etch fabrication method

    DOEpatents

    Simmons, Jerry A.; Weckwerth, Mark V.; Baca, Wes E.

    2000-01-01

    A class of epoxy bond and stop etch (EBASE) microelectronic fabrication techniques is disclosed. The essence of such techniques is to grow circuit components on top of a stop etch layer grown on a first substrate. The first substrate and a host substrate are then bonded together so that the circuit components are attached to the host substrate by the bonding agent. The first substrate is then removed, e.g., by a chemical or physical etching process to which the stop etch layer is resistant. EBASE fabrication methods allow access to regions of a device structure which are usually blocked by the presence of a substrate, and are of particular utility in the fabrication of ultrafast electronic and optoelectronic devices and circuits.

  15. Symphony and cacophony in ion track etching: how to control etching results

    NASA Astrophysics Data System (ADS)

    Fink, D.; Kiv, A.; Cruz, S. A.; Muñoz H., G.; Vacík, J.

    2012-07-01

    In general, etching of two identical ion-irradiated polymer foils in the same vessel with the same etchant for the same times does not lead to identical track shapes in both foils. In contrast, the track shapes, the etching speeds, and consequently also the etchant consumption of the two foils diverge increasingly with increasing etching times, unless this is prevented by forceful external equilibration of the system. This tendency toward divergence of a system of multiple ion tracks originates from its lack of self-synchronization during etching. A theory has been developed for this case that also shows general applicability to other diverging effects in human life.

  16. Method for anisotropic etching in the manufacture of semiconductor devices

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor); Cross, Jon B. (Inventor)

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by hyperthermal atomic oxygen beams (translational energies of 0.2 to 20 eV, preferably 1 to 10 eV). Etching with hyperthermal oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask protected areas.

  17. Method for anisotropic etching in the manufacture of semiconductor devices

    DOEpatents

    Koontz, Steven L.; Cross, Jon B.

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by atomic oxygen beams (translational energies of 0.2-20 eV, preferably 1-10 eV). Etching with hyperthermal (kinetic energy>1 eV) oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask-protected areas.

  18. Metal assisted anodic etching of silicon.

    PubMed

    Lai, Chang Quan; Zheng, Wen; Choi, W K; Thompson, Carl V

    2015-07-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P(+)-type and N(+)-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P(+)-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N(+)-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si. PMID:26059556

  19. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  20. Plasma etching: Yesterday, today, and tomorrow

    SciTech Connect

    Donnelly, Vincent M.; Kornblit, Avinoam

    2013-09-15

    The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

  1. Investigations of Wafer Scale Etching with Xenon Difluoride

    NASA Astrophysics Data System (ADS)

    Chen, K. N.; Hoivik, N.; Lin, C. Y.; Young, A.; Ieong, M.; Shahidi, G.

    2006-03-01

    A good and uniform bulk silicon wafer etching method can be applied to the wafer thinning process in MEMS and 3D applications. In this study, the use of a Xenon Difluoride (XeF2) gas-phase etching system, operating at room temperature, has been investigated for bulk silicon wafer thinning. We investigated the Si-wafer surface morphology and profile following each XeF2 etching process cycle. Theoretical results are used to compare with the experimental results as well. A clean wafer surface by proper surface treatments is significant to achieve a uniform surface profile and morphology for XeF2 etching. A proper design of etching cycle with nitrogen ambient during etching is necessary to achieve the fastest and uniform silicon etching rate. The silicon etching rate is reported as a function of etching pressure, nitrogen pressure, and etching duration.

  2. Investigation of Nitride Morphology After Self-Aligned Contact Etch

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Keil, J.; Helmer, B. A.; Chien, T.; Gopaladasu, P.; Kim, J.; Shon, J.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Self-Aligned Contact (SAC) etch has emerged as a key enabling technology for the fabrication of very large-scale memory devices. However, this is also a very challenging technology to implement from an etch viewpoint. The issues that arise range from poor oxide etch selectivity to nitride to problems with post etch nitride surface morphology. Unfortunately, the mechanisms that drive nitride loss and surface behavior remain poorly understood. Using a simple langmuir site balance model, SAC nitride etch simulations have been performed and compared to actual etched results. This approach permits the study of various etch mechanisms that may play a role in determining nitride loss and surface morphology. Particle trajectories and fluxes are computed using Monte-Carlo techniques and initial data obtained from double Langmuir probe measurements. Etched surface advancement is implemented using a shock tracking algorithm. Sticking coefficients and etch yields are adjusted to obtain the best agreement between actual etched results and simulated profiles.

  3. Surface/interface morphology and bond strength to glass ceramic etched for different periods.

    PubMed

    Naves, Lucas Z; Soares, Carlos J; Moraes, Rafael R; Gonçalves, Luciano S; Sinhoreti, Mário Alexandre C; Correr-Sobrinho, Lourenço

    2010-01-01

    This study evaluated the influence of etching periods on the surface/interface morphology and bond strength to glass ceramic with or without application of an unfilled resin after silane. Ceramic discs were divided into 12 groups, defined by etching time with 10% hydrofluoric acid: G1/G7--etching for 10 seconds, G2/G8--20 seconds; G3/G9--40 seconds; G4/G10--60 seconds; G5/G11--120 seconds and G6/G12--60 + 60 seconds. All the groups were silanated after etching and G7 - G12 received a layer of unfilled resin after silane. Microshear testing using resin cement was performed, with 12 resin cylinders tested per group. The data was submitted to two-way ANOVA and the Student-Newman-Keuls' test (p<0.05). Evaluation of the etching pattern and bonding interfaces was conducted by SEM. The bond strength means (MPa) were: 19.4 +/- 3.5, 22.3 +/- 5.1, 22.2 +/- 3.2, 17.8 +/- 2.1, 15.3 +/- 3.0 and 14.3 +/- 1.8 for G1-G6 and 17.4 +/- 4.8, 21.3 +/- 2.1, 21.1 +/- 2.3, 24.7 +/- 5.8, 20.4 +/- 2.2 and 18.5 +/- 4.6 for G7-G12. Poor etching was detected after 10 seconds of conditioning; whereas deep channels were extensively observed on surfaces etched for 120 and 60 + 60 seconds. Unfilled voids underlying the ceramic-cement interface were detected when only silane was applied. Full completion of the irregularities on G11 was detected using unfilled resin. When only silane was applied, the 60-second group and those etched for longer periods showed lower bond strengths. When both silane and unfilled resin were applied, all etching periods generally showed similar values. In conclusion, the etching period influenced the surface/interface topography and bond strength to ceramic. The application of unfilled resin was able to infiltrate all unfilled voids beneath the ceramic-cement interface, except on re-etched surfaces.

  4. Assessment of Microshear Bond Strength: Self-Etching Sealant versus Conventional Sealant

    PubMed Central

    Biria, Mina; Ghasemi, Amir; Torabzadeh, Hassan; Shisheeian, Arash; Baghban, Alireza Akbarzadeh

    2014-01-01

    Objective Recently, self-etching fissure sealants have been introduced to reduce technical sensitivity; however, their efficacy should be assessed. The aim of this study was to assess of the microshear bond strength of self-etching and conventional fissure sealants. Materials and Methods: Thirty non-carious third molars were randomly divided into three groups (N=10). Microcylinders of Concise fissure sealant were bonded to prepared buccal and lingual surfaces using the two following procedures. In the first group, phosphoric acid was used to prepare the substrate; whereas in group two, Concise was used in combination with Prompt L-Pop. In group 3, a self-etching fissure sealant (Enamel Loc) was utilized per se. After 24 hours, the samples were subjected to 500 rounds of thermocycling and shear bond testing using a microtensile tester machine with a crosshead speed of 0.5mm/min. Data were analyzed using one-way repeated measure ANOVA and Bonferroni Post HOC tests (SPSS version 16). Results: The mean and standard deviation of microshear bond strength of the groups were as follows: Group 1: Concise+ etching (14.59 ± 1.19 MPa), Group 2: Concise+Prompt L-Pop (12.86 ± 1.98 MPa), and Group 3: Enamel Loc (5.59 ± 0.72 MPa). One-way ANOVA revealed that all the differences were significant and the conventional sealant exhibited the highest mean bond strength. Conclusion: Conventional sealant using phosphoric acid etch application prior to fissure sealant application demonstrated more bond strength in comparison with that of self-etch bonding and self-etch sealant. PMID:24910688

  5. Peculiarities of latent track etching in SiO2/Si structures irradiated with Ar, Kr and Xe ions

    NASA Astrophysics Data System (ADS)

    Al'zhanova, A.; Dauletbekova, A.; Komarov, F.; Vlasukova, L.; Yuvchenko, V.; Akilbekov, A.; Zdorovets, M.

    2016-05-01

    The process of latent track etching in SiO2/Si structures irradiated with 40Ar (38 MeV), 84Kr (59 MeV) and 132Xe (133 and 200 MeV) ions has been investigated. The experimental results of SiO2 etching in a hydrofluoric acid solution have been compared with the results of computer simulation based on the thermal spike model. It has been confirmed that the formation of a molten region along the swift ion trajectory with minimum radius of 3 nm can serve as a theoretical criterion for the reproducible latent track etching tracks in SiO2.

  6. Chemically Etched Open Tubular and Monolithic Emitters for Nanoelectrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Page, Jason S.; Luo, Quanzhou; Moore, Ronald J.; Orton, Daniel J.; Tang, Keqi; Smith, Richard D.

    2006-11-15

    We have developed a new procedure for fabricating fused silica emitters for electrospray ionization-mass spectrometry (ESI-MS) in which the end of a bare fused silica capillary is immersed into aqueous hydrofluoric acid, and water is pumped through the capillary to prevent etching of the interior. Surface tension causes the etchant to climb the capillary exterior, and the etch rate in the resulting meniscus decreases as a function of distance from the bulk solution. Etching continues until the silica touching the hydrofluoric acid reservoir is completely removed, essentially stopping the etch process. The resulting emitters have no internal taper, making them much less prone to clogging compared to e.g. pulled emitters. The high aspect ratios and extremely thin walls at the orifice facilitate very low flow rate operation; stable ESI-MS signals were obtained for model analytes from 5-μm-diameter emitters at a flow rate of 5 nL/min with a high degree of inter-emitter reproducibility. In extensive evaluation, the etched emitters were found to enable approximately four times as many LC-MS analyses of proteomic samples before failing compared with conventional pulled emitters. The fabrication procedure was also employed to taper the ends of polymer monolith-containing silica capillaries for use as ESI emitters. In contrast to previous work, the monolithic material protrudes beyond the fused silica capillaries, improving the monolith-assisted electrospray process.

  7. Micro fiber-optic Fabry-Perot interferometer fabricated by chemical etching of Er-doped fiber

    NASA Astrophysics Data System (ADS)

    Gong, Yuan; Rao, Yun-Jiang; Guo, Yu; Wu, Yu; Ran, Zeng-Ling

    2009-10-01

    Micro extrinsic fiber-optic Fabry-Perot interferometers (MEFPI) are fabricated by chemically etching Er-doped fiber and then splicing the etched fiber to a single-mode fiber, for the first time to our knowledge. By using the mixture of Hydrochloric (HCl) acid and Hydrofluoric (HF) acid as etching solution, a cavity length of up to ~27 μm and a maximum fringe contrast of ~24dB are obtained. Experimental results show that the MEFPI is insensitive to temperature change but highly sensitive to strain, with temperature and strain sensitivities of ~0.65 pm/°C and 3.15 pm/ μɛ, respectively. Such type of MEFPI sensors based on the etched Er-doped fiber is compact, cost-effective and especially suitable for mass production, offering great potential for a wide range of applications.

  8. Etching rate control of mask material for XeF2 etching using UV exposure

    NASA Astrophysics Data System (ADS)

    Sugano, Koji; Tabata, Osamu

    2001-09-01

    A new technique to control etching rates of mask materials during XeF2 etching was proposed. By exposing Si sample with SiO2 and Si3N4 as mask materials to UV light of 3 W/cm2 during XeF2 etching, the etching rates of SiO2 and Si3N4 were dramatically increased from 2.52 angstrom/pulse to 42.0 angstrom/pulse and from 27.3 angstrom/pulse to 403 angstrom/pulse, respectively. This new technique allows us to remove the mask material selectively and change the mask pattern by UV light exposure during in- situ etching process without additional photolithography step and opens a new silicon micromachining process for 3- dimensional fabrication. The multi-step Si structure was successfully realized by this technique.

  9. Plasma characteristics and etch uniformity in CF4 magnetron etching using an annular permanent magnet

    NASA Astrophysics Data System (ADS)

    Kinoshita, Haruhisa; Ishida, Toshimasa; Ohno, Seigo

    1987-11-01

    Etch characteristics of SiO2 and Si obtained by magnetron etching using an annular permanent magnet were analyzed. From these analyses, etch characteristics were found to be classified into three regimes. Remarkable enhancements in SiO2 etch rate, 25-40 times, were observed at constant Vrf by applying magnetic field of 150 G. Ion densities over the cathode were found to be distributed linearly along the E×B drift direction. Such an ion density distribution will be formed by the repeated process (ionization→ion bombardment→electron emission and drift→ionization). Etch distribution can be averaged and flattened to a uniformity of below ±2% by the magnetic field being rotated in 90° steps.

  10. Polymer etching in the oxygen afterglow - Increased etch rates with increased reactor loading

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1989-01-01

    Reactor loading has an effect on the etch rate (rate of decrease of film thickness) of films of polyvinylfluoride (Tedlar) and polyethylene exposed in the afterglow of an RF discharge in oxygen. The etch rate is found to increase with the total surface area of the polymer exposed in the reactor. The etch rates of polypyromellitimide (Kapton H) and polystyrene under these conditions are very low. However, the etch rate of these polymers is greatly enhanced by adding either Tedlar or polyethylene to the reactor. A kinetic model is proposed based on the premise that the oxygen atoms produced by the RF discharge react with Tedlar or polyethylene to produce a much more reactive species, which dominates the etching of the polymers studied.

  11. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    SciTech Connect

    Nakazaki, Nobuya Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  12. Dry etched SiO2 Mask for HgCdTe Etching Process

    NASA Astrophysics Data System (ADS)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  13. Patterning enhancement techniques by reactive ion etch

    NASA Astrophysics Data System (ADS)

    Honda, Masanobu; Yatsuda, Koichi

    2012-03-01

    The root causes of issues in state-of-the-arts resist mask are low plasma tolerance in etch and resolution limit in lithography. This paper introduces patterning enhancement techniques (PETs) by reactive ion etch (RIE) that solve the above root causes. Plasma tolerance of resist is determined by the chemical structure of resin. We investigated a hybrid direct current (DC) / radio frequency (RF) RIE to enhance the plasma tolerance with several gas chemistries. The DC/RF hybrid RIE is a capacitive coupled plasma etcher with a superimposed DC voltage, which generates a ballistic electron beam. We clarified the mechanism of resist modification, which resulted in higher plasma tolerance[1]. By applying an appropriate gas to DC superimposed (DCS) plasma, etch resistance and line width roughness (LWR) of resist were improved. On the other hand, RIE can patch resist mask. RIE does not only etch but also deposits polymer onto the sidewall with sedimentary type gases. In order to put the deposition technique by RIE in practical use, it is very important to select an appropriate gas chemistry, which can shrink CD and etch BARC. By applying this new technique, we successfully fabricated a 35-nm hole pattern with a minimum CD variation.

  14. Plasma etching a ceramic composite. [evaluating microstructure

    NASA Technical Reports Server (NTRS)

    Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

    1992-01-01

    Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

  15. Pulsed plasma etching for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Economou, Demetre J.

    2014-07-01

    Power-modulated (pulsed) plasmas have demonstrated several advantages compared to continuous wave (CW) plasmas. Specifically, pulsed plasmas can result in a higher etching rate, better uniformity, and less structural, electrical or radiation (e.g. vacuum ultraviolet) damage. Pulsed plasmas can also ameliorate unwanted artefacts in etched micro-features such as notching, bowing, micro-trenching and aspect ratio dependent etching. As such, pulsed plasmas may be indispensable in etching of the next generation of micro-devices with a characteristic feature size in the sub-10 nm regime. This work provides an overview of principles and applications of pulsed plasmas in both electropositive (e.g. argon) and electronegative (e.g. chlorine) gases. The effect of pulsing the plasma source power (source pulsing), the electrode bias power (bias pulsing), or both source and bias power (synchronous pulsing), on the time evolution of species densities, electron energy distribution function and ion energy and angular distributions on the substrate is discussed. The resulting pulsed plasma process output (etching rate, uniformity, damage, etc) is compared, whenever possible, to that of CW plasma, under otherwise the same or similar conditions.

  16. Reactive Ion Etching for Randomly Distributed Texturing of Multicrystalline Silicon Solar Cells

    SciTech Connect

    ZAIDI, SALEEM H

    2002-05-01

    The quality of low-cost multicrystalline silicon (mc-Si) has improved to the point that it forms approximately 50% of the worldwide photovoltaic (PV) power production. The performance of commercial mc-Si solar cells still lags behind c-Si due in part to the inability to texture it effectively and inexpensively. Surface texturing of mc-Si has been an active field of research. Several techniques including anodic etching [1], wet acidic etching [2], lithographic patterning [3], and mechanical texturing [4] have been investigated with varying degrees of success. To date, a cost-effective technique has not emerged.

  17. A relative humidity sensing probe based on etched thin-core fiber coated with polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Yang, Zaihang; Zhou, Libin; Liu, Nan; Gang, Tingting; Qiao, Xueguang; Hu, Manli

    2015-12-01

    A relative humidity (RH) sensing probe based on etched thin-core fiber (TCF) coated with polyvinyl alcohol (PVA) is proposed and experimentally demonstrated.This sensor is constructed by splicing a section of TCF with a single mode fiber (SMF), then part of the TCF's cladding is etched by hydrofluoric acid solution and finally the tip of TCF is coated with PVA. Experimental results demonstrate that this sensor can measure the ambient RH by demodulating the power variation of reflection spectrum. The power demodulation method make this sensor can ignore the temperature cross-sensitivity and have an extensive application prospect.

  18. Hybrid chemical etching of femtosecond laser irradiated structures for engineered microfluidic devices

    NASA Astrophysics Data System (ADS)

    LoTurco, S.; Osellame, R.; Ramponi, R.; Vishnubhatla, K. C.

    2013-08-01

    We report on the fabrication of 3D buried micro-structures in fused silica glass using the selective chemical etching along femtosecond laser irradiated zones. Specifically, we have exploited a novel approach combining two different etching agents in successive steps. The widely used hydrofluoric acid solution, which provides fast volume removal, and potassium hydroxide solution, which exhibits high selectivity, are used to fabricate microfluidic structures. We demonstrate that this hybrid approach takes advantage of both of the individual etchants’ special characteristics and facilitates prototyping and fabrication of complex geometries for microfluidic devices.

  19. Solderability enhancement of copper through chemical etching

    SciTech Connect

    Stevenson, J.O.; Guilinger, T.R.; Hosking, F.M.; Yost, F.G.; Sorensen, N.R.

    1995-05-01

    Sandia National Laboratories has established a Cooperative Research and Development Agreement with consortium members of the National Center for Manufacturing Sciences (NCMS) to develop fundamental generic technology in the area of printed wiring board materials and surface finishes. Improved solderability of copper substrates is an important component of the Sandia-NCMS program. The authors are investigating the effects of surface roughness on the wettability and solderability behavior of several different types of copper board finishes. In this paper, the authors present roughness and solderability characterizations for a variety of chemically-etched copper substrates. Initial testing on six chemical etches demonstrate that surface roughness can be greatly enhanced through chemical etching. Noticeable improvements in solder wettability were observed to accompany increases in roughness. A number of different algorithms and measures of roughness were used to gain insight into surface morphologies that lead to improved solderability.

  20. Analytical model of plasma-chemical etching in planar reactor

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Bakun, A. D.; Voronov, Yu A.; Kireev, V. Yu; Vasileva, O. V.

    2016-09-01

    The paper discusses an analytical model of plasma-chemical etching in planar diode- type reactor. Analytical expressions of etch rate and etch anisotropy were obtained. It is shown that etch anisotropy increases with increasing the ion current and ion energy. At the same time, etch selectivity of processed material decreases as compared with the mask. Etch rate decreases with the distance from the centre axis of the reactor. To decrease the loading effect, it is necessary to reduce the wafer temperature and pressure in the reactor, as well as increase the gas flow rate through the reactor.

  1. Radicals Are Required for Thiol Etching of Gold Particles.

    PubMed

    Dreier, Timothy A; Ackerson, Christopher J

    2015-08-01

    Etching of gold with an excess of thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is unclear. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initiator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process.

  2. Radicals are required for thiol etching of gold particles

    PubMed Central

    Dreier, Timothy A.

    2016-01-01

    Etching of gold with excess thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is opaque. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process. PMID:26089294

  3. Environmentally benign semiconductor processing for dielectric etch

    NASA Astrophysics Data System (ADS)

    Liao, Marci Yi-Ting

    Semiconductor processing requires intensive usage of chemicals, electricity, and water. Such intensive resource usage leaves a large impact on the environment. For instance, in Silicon Valley, the semiconductor industry is responsible for 80% of the hazardous waste sites contaminated enough to require government assistance. Research on environmentally benign semiconductor processing is needed to reduce the environmental impact of the semiconductor industry. The focus of this dissertation is on the environmental impact of one aspect of semiconductor processing: patterning of dielectric materials. Plasma etching of silicon dioxide emits perfluorocarbons (PFCs) gases, like C2F6 and CF4, into the atmosphere. These gases are super global warming/greenhouse gases because of their extremely long atmospheric lifetimes and excellent infrared absorption properties. We developed the first inductively coupled plasma (ICP) abatement device for destroying PFCs downstream of a plasma etcher. Destruction efficiencies of 99% and 94% can be obtained for the above mentioned PFCs, by using O 2 as an additive gas. Our results have lead to extensive modeling in academia as well as commercialization of the ICP abatement system. Dielectric patterning of hi-k materials for future device technology brings different environment challenges. The uncertainty of the hi-k material selection and the patterning method need to be addressed. We have evaluated the environmental impact of three different dielectric patterning methods (plasma etch, wet etch and chemical-mechanical polishing), as well as, the transistor device performances associated with the patterning methods. Plasma etching was found to be the most environmentally benign patterning method, which also gives the best device performance. However, the environmental concern for plasma etching is the possibility of cross-contamination from low volatility etch by-products. Therefore, mass transfer in a plasma etcher for a promising hi

  4. SEMICONDUCTOR TECHNOLOGY: Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    NASA Astrophysics Data System (ADS)

    Yongliang, Li; Qiuxia, Xu

    2010-03-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 °C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case.

  5. Etching of fused silica fiber by metallic laser-induced backside wet etching technique

    NASA Astrophysics Data System (ADS)

    Vass, Cs.; Kiss, B.; Kopniczky, J.; Hopp, B.

    2013-08-01

    The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τFWHM = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm2, while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm2. The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

  6. Alternative process for thin layer etching: Application to nitride spacer etching stopping on silicon germanium

    SciTech Connect

    Posseme, N. Pollet, O.; Barnola, S.

    2014-08-04

    Silicon nitride spacer etching realization is considered today as one of the most challenging of the etch process for the new devices realization. For this step, the atomic etch precision to stop on silicon or silicon germanium with a perfect anisotropy (no foot formation) is required. The situation is that none of the current plasma technologies can meet all these requirements. To overcome these issues and meet the highly complex requirements imposed by device fabrication processes, we recently proposed an alternative etching process to the current plasma etch chemistries. This process is based on thin film modification by light ions implantation followed by a selective removal of the modified layer with respect to the non-modified material. In this Letter, we demonstrate the benefit of this alternative etch method in term of film damage control (silicon germanium recess obtained is less than 6 A), anisotropy (no foot formation), and its compatibility with other integration steps like epitaxial. The etch mechanisms of this approach are also addressed.

  7. Systematically controlling Kapitza conductance via chemical etching

    NASA Astrophysics Data System (ADS)

    Duda, John C.; Hopkins, Patrick E.

    2012-03-01

    We measure the thermal interface conductance between thin aluminum films and silicon substrates via time-domain thermoreflectance from 100 to 300 K. The substrates are chemically etched prior to aluminum deposition, thereby offering a means of controlling interface roughness. We find that conductance can be systematically varied by manipulating roughness. In addition, transmission electron microscopy confirms the presence of a conformal oxide for all roughnesses, which is then taken into account via a thermal resistor network. This etching process provides a robust technique for tuning the efficiency of thermal transport while alleviating the need for laborious materials growth and/or processing.

  8. Laser etching of enamel for direct bonding with an Er,Cr:YSGG hydrokinetic laser system.

    PubMed

    Uşümez, Serdar; Orhan, Metin; Uşümez, Aslihan

    2002-12-01

    Irradiation of enamel with laser energy changes the physical and chemical characteristics of the enamel surface, and these alterations hold promise for the conditioning of enamel for bonding procedures. This laboratory study examined the influence of laser irradiation of enamel at 2 different power settings with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system (Millennium System, Biolase Technology, Inc; San Clemente, Calif) on the shear bond strength of orthodontic appliances and compared these with that of acid-etching. The prepared surfaces of 40 noncarious, intact, extracted premolars were exposed to laser energy: 20 teeth at 2-W setting (5.6 J/cm(2)) and 20 teeth at 1-W setting (2.7 J/cm(2)) of the commercial laser unit. Twenty teeth were etched with 37% orthophosphoric acid. Brackets were bonded with an orthodontic no-mix adhesive, and shear bond strength was determined with a universal testing machine. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Etched and restored surfaces of an acid-etched tooth and a 2-W laser-irradiated tooth were examined with scanning electron microscopy (SEM). Laser treatment under 2 W resulted in bond strengths of 7.11 +/- 4.56 megapascals (MPa), which was not significantly different from that of acid etching (8.23 +/- 2.30 MPa). Laser irradiation at 1 W resulted in bond strengths of 5.64 +/- 3.19 MPa, which was significantly different from that of acid etching (P <.05). However, large SD and coefficient of variation values of both laser groups made reliability of this method as an enamel conditioner questionable. Scanning electron microscopy studies of the restored irradiated surfaces showed good surface characteristics, whereas the lased surface was still more irregular than the restored acid-etched sample. Although laser devices are effectively used in some other areas of dentistry, enamel conditioning with an Er,Cr:YSGG laser cannot be considered a successful

  9. Laser etching of enamel for direct bonding with an Er,Cr:YSGG hydrokinetic laser system.

    PubMed

    Uşümez, Serdar; Orhan, Metin; Uşümez, Aslihan

    2002-12-01

    Irradiation of enamel with laser energy changes the physical and chemical characteristics of the enamel surface, and these alterations hold promise for the conditioning of enamel for bonding procedures. This laboratory study examined the influence of laser irradiation of enamel at 2 different power settings with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system (Millennium System, Biolase Technology, Inc; San Clemente, Calif) on the shear bond strength of orthodontic appliances and compared these with that of acid-etching. The prepared surfaces of 40 noncarious, intact, extracted premolars were exposed to laser energy: 20 teeth at 2-W setting (5.6 J/cm(2)) and 20 teeth at 1-W setting (2.7 J/cm(2)) of the commercial laser unit. Twenty teeth were etched with 37% orthophosphoric acid. Brackets were bonded with an orthodontic no-mix adhesive, and shear bond strength was determined with a universal testing machine. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Etched and restored surfaces of an acid-etched tooth and a 2-W laser-irradiated tooth were examined with scanning electron microscopy (SEM). Laser treatment under 2 W resulted in bond strengths of 7.11 +/- 4.56 megapascals (MPa), which was not significantly different from that of acid etching (8.23 +/- 2.30 MPa). Laser irradiation at 1 W resulted in bond strengths of 5.64 +/- 3.19 MPa, which was significantly different from that of acid etching (P <.05). However, large SD and coefficient of variation values of both laser groups made reliability of this method as an enamel conditioner questionable. Scanning electron microscopy studies of the restored irradiated surfaces showed good surface characteristics, whereas the lased surface was still more irregular than the restored acid-etched sample. Although laser devices are effectively used in some other areas of dentistry, enamel conditioning with an Er,Cr:YSGG laser cannot be considered a successful

  10. Distinguishing shocked from tectonically deformed quartz by the use of the SEM and chemical etching

    USGS Publications Warehouse

    Gratz, A.J.; Fisler, D.K.; Bohor, B.F.

    1996-01-01

    Multiple sets of crystallographically-oriented planar deformation features (PDFs) are generated by high-strain-rate shock waves at pressures of > 12 GPa in naturally shocked quartz samples. On surfaces, PDFs appear as narrow (50-500 nm) lamellae filled with amorphosed quartz (diaplectic glass) which can be etched with hydrofluoric acid or with hydrothermal alkaline solutions. In contrast, slow-strain-rate tectonic deformation pressure produces wider, semi-linear and widely spaced arrays of dislocation loops that are not glass filled. Etching samples with HF before examination in a scanning electron microscope (SEM) allows for unambiguous visual distinction between glass-filled PDFs and glass-free tectonic deformation arrays in quartz. This etching also reveals the internal 'pillaring' often characteristic of shock-induced PDFs. This technique is useful for easily distinguishing between shock and tectonic deformation in quartz, but does not replace optical techniques for characterizing the shock features.

  11. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    SciTech Connect

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  12. Formation of Mach angle profiles during wet etching of silica and silicon nitride materials

    NASA Astrophysics Data System (ADS)

    Ghulinyan, M.; Bernard, M.; Bartali, R.; Pucker, G.

    2015-12-01

    In integrated circuit technology peeling of masking photoresist films is a major drawback during the long-timed wet etching of materials. It causes an undesired film underetching, which is often accompanied by a formation of complex etch profiles. Here we report on a detailed study of wedge-shaped profile formation in a series of silicon oxide, silicon oxynitride and silicon nitride materials during wet etching in a buffered hydrofluoric acid (BHF) solution. The shape of etched profiles reflects the time-dependent adhesion properties of the photoresist to a particular material and can be perfectly circular, purely linear or a combination of both, separated by a knee feature. Starting from a formal analogy between the sonic boom propagation and the wet underetching process, we model the wedge formation mechanism analytically. This model predicts the final form of the profile as a function of time and fits the experimental data perfectly. We discuss how this knowledge can be extended to the design and the realization of optical components such as highly efficient etch-less vertical tapers for passive silicon photonics.

  13. Compositional and Microtextural Analysis of Basaltic Feedstock Materials Used for the 2010 ISRU Field Tests, Mauna Kea, Hawaii

    NASA Astrophysics Data System (ADS)

    Marin, N.; Farmer, J. D.; Zacny, K.; Sellar, R. G.; Nunez, J.

    2011-12-01

    This study seeks to understand variations in composition and texture of basaltic pyroclastic materials used in the 2010 International Lunar Surface Operation-In-Situ Resource Utilization Analogue Test (ILSO-ISRU) held on the slopes of Mauna Kea Volcano, Hawaii (1). The quantity and quality of resources delivered by ISRU depends upon the nature of the materials processed (2). We obtained a one-meter deep auger cuttings sample of a basaltic regolith at the primary site for feed stock materials being mined for the ISRU field test. The auger sample was subdivided into six, ~16 cm depth increments and each interval was sampled and characterized in the field using the Multispectral Microscopic Imager (MMI; 3) and a portable X-ray Diffractometer (Terra, InXitu Instruments, Inc.). Splits from each sampled interval were returned to the lab and analyzed using more definitive methods, including high resolution Powder X-ray Diffraction and Thermal Infrared (TIR) spectroscopy. The mineralogy and microtexture (grain size, sorting, roundness and sphericity) of the auger samples were determined using petrographic point count measurements obtained from grain-mount thin sections. NIH Image J (http://rsb.info.nih.gov/ij/) was applied to digital images of thin sections to document changes in particle size with depth. Results from TIR showed a general predominance of volcanic glass, along with plagioclase, olivine, and clinopyroxene. In addition, thin section and XRPD analyses showed a down core increase in the abundance of hydrated iron oxides (as in situ weathering products). Quantitative point count analyses confirmed the abundance of volcanic glass in samples, but also revealed olivine and pyroxene to be minor components, that decreased in abundance with depth. Furthermore, point count and XRD analyses showed a decrease in magnetite and ilmenite with depth, accompanied by an increase in Fe3+phases, including hematite and ferrihydrite. Image J particle analysis showed that the

  14. Plasma etching of the Group-III nitrides

    SciTech Connect

    Shul, R.; Pearton, S.J.; Abernathy, C.R.

    1996-01-01

    In reactive ion etching (RIE) of GaN, the ion bombardment can damage the material, so it is necessary to develop plasma etch processes. This paper reports etching of GaN in an ECR (electron cyclotron resonance) etch system using both the ECR/RIE mode and the RIE-only mode. Group III (Ga, In, Al) nitride ECR etching is reviewed as a function of plasma chemistry, power, temperature, and pressure; as the ECR microwave power increased, the ion density and etch rates increased, with the etch rate increasing the most for InN. GaN etch rates > 6500 {angstrom}/min have been observed in the ECR/RIE mode. 2 figs, 6 refs.

  15. Transferring resist microlenses into silicon by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Eisner, Martin; Schwider, Johannes

    1996-10-01

    Reactive ion etching (RIE) is known as an effective technique for high precision anisotropic etching with a minimum loss of the critical dimensions provided by the photoresist or other masking materials. RIE can also be used to transfer continuous forms such as spherical resist microlenses into substrate materials (e.g., quartz glass or silicon). The form of the lenses can be considerably controlled by changing the etch rate ratio between resist and the substrate. This was achieved by varying the etch gas compound, especially the amount of oxygen, during the etching or by changing the applied power. Measured etch rates for silicon are given to demonstrate the possibilities of lens shaping. The surface roughness of the etched lenses was one of the main problems. The roughness could be minimized by adding helium to the etch gases for heat removal and by increasing the resist rinse time after the wet chemical development.

  16. Admittance spectroscopy of CdTe /CdS solar cells subjected to varied nitric-phosphoric etching conditions

    NASA Astrophysics Data System (ADS)

    Proskuryakov, Y. Y.; Durose, K.; Taele, B. M.; Welch, G. P.; Oelting, S.

    2007-01-01

    In this work we investigate the electric and structural properties of CdTe /CdS solar cells subjected to a nitric-phosphoric (NP) acid etching procedure, employed for the formation of a Te-rich layer before back contacting. The etching time is used as the only variable parameter in the study, while admittance spectroscopy is employed for the characterization of the cells' electric properties as well as for the analysis of the defect energy levels. Particular attention was also given to the characteristics of unetched devices and it is shown that despite the larger height of back-contact barrier such samples show well defined admittance spectra, as well as allow for extraction of as much as five defect levels in the range of 0.08-0.9eV above the valence band. In contrast, admittance characteristics of the etched samples show a decrease of the number of the detectable trap levels with increasing etching time. (Hence it is usual for only one or two trap levels to be reported in the literature for finished devices.) The latter leads to the anomalous Arrhenius energy plots as well as the breakdown of low-frequency capacitance characteristics for samples etched with times larger than 30s. The observed effects are attributed to physical thinning of the cells, the etching out of grain boundaries, and the tellurium enrichment of the CdTe surface by NP etching. We also perform analysis of the back-contact barrier height as extracted from dark I-V measurements at different temperatures. The dependence of this barrier height on NP etching time is compared with that of conversion efficiency, from which conclusions are drawn about both positive and negative effects of the nitric-phosphoric etch.

  17. Etch Profile Simulation Using Level Set Methods

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    Etching and deposition of materials are critical steps in semiconductor processing for device manufacturing. Both etching and deposition may have isotropic and anisotropic components, due to directional sputtering and redeposition of materials, for example. Previous attempts at modeling profile evolution have used so-called "string theory" to simulate the moving solid-gas interface between the semiconductor and the plasma. One complication of this method is that extensive de-looping schemes are required at the profile corners. We will present a 2D profile evolution simulation using level set theory to model the surface. (1) By embedding the location of the interface in a field variable, the need for de-looping schemes is eliminated and profile corners are more accurately modeled. This level set profile evolution model will calculate both isotropic and anisotropic etch and deposition rates of a substrate in low pressure (10s mTorr) plasmas, considering the incident ion energy angular distribution functions and neutral fluxes. We will present etching profiles of Si substrates in Ar/Cl2 discharges for various incident ion energies and trench geometries.

  18. Technique for etching monolayer and multilayer materials

    DOEpatents

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  19. Optimization of Track Etched Makrofol Etching Conditions for Short-term Exposure Duration

    NASA Astrophysics Data System (ADS)

    Moreno, V.; Font, Ll.

    Exposure time of nuclear track detectors at humid environments is normally limited to a few weeks because filter used to avoid humidity is not completely waterproof and, after several months, some parts of detector start to degrade. In other really extreme measurement conditions, like high aerosol content, high or low temperatures, etc., the exposure time also requires a reduction. Then detector detection limit becomes a problem, unless radon concentrations were high. In those cases where radon levels are not high enough a better detection efficiency is required. In our laboratory we use passive detectors based on the track etched Makrofol DE foil covered with aluminized Mylar and they are analyzed by means of an electrochemical etching. Our standard etching conditions allow analyzing detectors generally exposed for periods between three and six months. We have optimized our etching conditions to reduce the exposure time down to a month for common radon concentration values.

  20. Anodic etching of p-type cubic silicon carbide

    NASA Technical Reports Server (NTRS)

    Harris, G. L.; Fekade, K.; Wongchotigul, K.

    1992-01-01

    p-Type cubic silicon carbide was anodically etched using an electrolyte of HF:HCl:H2O. The etching depth was determined versus time with a fixed current density of 96.4 mA/sq cm. It was found that the etching was very smooth and very uniform. An etch rate of 22.7 nm/s was obtained in a 1:1:50 HF:HCl:H2O electrolyte.

  1. Multilayer Badges Indicate Depths Of Ion Sputter Etches

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Matossian, J. N.; Garvin, H. L.

    1994-01-01

    Multilayer badges devised to provide rapid, in-place indications of ion sputter etch rates. Badges conceived for use in estimating ion erosion of molybdenum electrodes used in inert-gas ion thrustors. Concept adapted to measure ion erosion in industrial sputter etching processes used for manufacturing of magnetic, electronic, and optical devices. Badge etched when bombarded by energetic ions. Badge layers exposed using mask. Contrast between layers facilitates counting of layers to determine etch depth.

  2. High index contrast polysiloxane waveguides fabricated by dry etching

    SciTech Connect

    Madden, S. J.; Zhang, M. Y.; Choi, D.-Y.; Luther-Davies, B.; Charters, R.

    2009-05-15

    The authors demonstrate the production of low loss enhanced index contrast waveguides by reactive ion etching of IPG trade mark sign polysiloxane thin films. The use of a silica mask and CHF{sub 3}/O{sub 2} etch gas led to large etch selectivity between the silica and IPG trade mark sign of >20 and etch rates of >100 nm/min. This work indicates that compact optical circuits could be successfully fabricated for telecommunication applications using polysiloxane films.

  3. LOCALIZED MECHANICS OF DENTIN SELF-ETCHING ADHESIVE SYSTEM

    PubMed Central

    Anchieta, Rodolfo Bruniera; Rocha, Eduardo Passos; Ko, Ching-Chang; Sundfeld, Renato Herman; Martin, Manoel; Archangelo, Carlos Marcelo

    2007-01-01

    The bond strength of composite resins (CRs) to dentin is influenced by the interfacial microstructure of the hybrid layer (HL) and the resin tags (TAG). The contemporary self-etching primer adhesive systems overcame the inconvenient of the etch-and-rinse protocol. Studies, however, have demonstrated that HL thickness and TAG length vary according to the wetting time and additional use of acid-etching prior to self-etching primers. This study investigated the localized stress distribution in the HL and the dentin/adhesive interface. Two HL thicknesses (3 or 6 μm), two TAG lengths (13 or 17 μm) and two loading conditions (perpendicular and oblique-25o) were investigated by the finite element (FE) analysis. Five two-dimensional FE models (M) of a dentin specimen restored with CR (38 x 64 μm) were constructed: Ml - no HL and no TAG; M2 - 3 μm of HL and 13 μm of TAG; M3 - 3 μm of HL and 17 μm of TAG; M4 - 6 μm of HL and 13 μm of TAG; and M5 - 6 μm of HL and 17 μm of TAG. Two distributed loadings (L) (20N) were applied on CR surface: L1 - perpendicular, and L2 - oblique (25°). Fixed interfacial conditions were assigned on the border of the dentin specimen. Ansys 10.0 (Ansys®, Houston, PA, USA) software was used to calculate the stress fields. The peak of von Mises (σvM) and maximum principal stress (σmax) was higher in L2 than in L1. Microstructures (HL and TAG) had no effect on local stresses for L1. Decreasing HL decreased σvM and σmax in all structures for L2, but the TAG length had influence only on the peributular dentin. The thickness of HL had more influence on the σvM and σmax than TAG length. The peritubular dentin and its adjacent structures showed the highest σvM and σmax, mainly in the oblique loading. PMID:19089152

  4. Dopant Selective Reactive Ion Etching of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Okojie, Robert (Inventor)

    2016-01-01

    A method for selectively etching a substrate is provided. In one embodiment, an epilayer is grown on top of the substrate. A resistive element may be defined and etched into the epilayer. On the other side of the substrate, the substrate is selectively etched up to the resistive element, leaving a suspended resistive element.

  5. CR-39 track etching and blow-up method

    DOEpatents

    Hankins, Dale E.

    1987-01-01

    This invention is a method of etching tracks in CR-39 foil to obtain uniformly sized tracks. The invention comprises a step of electrochemically etching the foil at a low frequency and a "blow-up" step of electrochemically etching the foil at a high frequency.

  6. Characterization of electric discharge machining, subsequent etching and shot-peening as a surface treatment for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Stráský, Josef; Havlíková, Jana; Bačáková, Lucie; Harcuba, Petr; Mhaede, Mansour; Janeček, Miloš

    2013-09-01

    Presented work aims at multi-method characterization of combined surface treatment of Ti-6Al-4V alloy for biomedical use. Surface treatment consists of consequent use of electric discharge machining (EDM), acid etching and shot peening. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. Acid etching by strong Kroll's reagent is capable of removing surface layer of transformed material created by EDM. Acid etching also creates partly nanostructured surface and significantly contributes to the enhanced proliferation of the bone cells. The cell growth could be positively affected by the superimposed bone-inspired structure of the surface with the morphological features in macro-, micro- and nano-range. Shot peening significantly improves poor fatigue performance after EDM. Final fatigue performance is comparable to benchmark electropolished material without any adverse surface effect. The proposed three-step surface treatment is a low-cost process capable of producing material that is applicable in orthopedics.

  7. Modeling Wet Chemical Etching of Surface Flaws on Fused Silica

    SciTech Connect

    Feit, M D; Suratwala, T I; Wong, L L; Steele, W A; Miller, P E; Bude, J D

    2009-10-28

    Fluoride-based wet chemical etching of fused silica optical components is useful to open up surface fractures for diagnostic purposes, to create surface topology, and as a possible mitigation technique to remove damaged material. To optimize the usefulness of etching , it is important to understand how the morphology of etched features changes as a function of the amount of material removed. In this study, we present two geometric etch models that describe the surface topology evolution as a function of the amount etched. The first model, referred to as the finite-difference etch model, represents the surface as an array of points in space where at each time-step the points move normal to the local surface. The second model, referred to as the surface area-volume model, more globally describes the surface evolution relating the volume of material removed to the exposed surface area. These etch models predict growth and coalescence of surface fractures such as those observed on scratches and ground surfaces. For typical surface fractures, simulations show that the transverse growth of the cracks at long etch times scales with the square root of etch time or the net material removed in agreement with experiment. The finite-difference etch model has also been applied to more complex structures such as the etching of a CO{sub 2} laser-mitigated laser damage site. The results indicate that etching has little effect on the initial morphology of this site implying little change in downstream scatter and modulation characteristics upon exposure to subsequent high fluence laser light. In the second part of the study, the geometric etch model is expanded to include fluid dynamics and mass transport. This later model serves as a foundation for understanding related processes such as the possibility of redeposition of etch reaction products during the etching, rinsing or drying processes.

  8. Reactive sputter etching of magnetic materials in an HCl plasma

    SciTech Connect

    Heijman, M.G.J.

    1988-12-01

    In an rf low-pressure HCl plasma NiZn and MnZn ferrite etch up to five times as fast as in an otherwise comparable Ar sputter etch process. Selectivity towards Al/sub 2/O/sub 3/ as an etch mask is of order 10. No redeposited material and very little trenching are seen. The etched slopes have a steepness up to 70/sup 0/, resulting from redeposition and enhanced etching on the sidewalls. This is shown by experiments and by computer simulations.

  9. Research on wet etching at MEMS torsion mirror optical switch

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Wang, Jifeng; Luo, Yuan

    2002-10-01

    Etching is a very important technique at MEMS micromachining. There are two kinds of etching processing, the one is wet etching and the other is dry etching. In this paper, wet selective etching with KOH and tetramethyl ammonium hydroxide (TMAH) etchants is researched in order to make a torsion mirror optical switch. The experiments results show that TMAH with superphosphate is more suitable at MEMS torsion mirror optical switch micromachining than KOH, and it also has good compatibility with IC processing. Also our experiments results show some different with other reported research data. More work will be done to improve the yield rate of MEMS optical switch.

  10. ICP etching of GaAs via hole contacts

    SciTech Connect

    Shul, R.J.; Baca, A.G.; Briggs, R.D.; McClellan, G.B.; Pearton, S.J.; Constantine, C.

    1996-09-01

    Deep etching of GaAs is a critical process step required for many device applications including fabrication of through-substrate via holes for monolithic microwave integrated circuits (MMICs). Use of high-density plasmas, including inductively coupled plasmas (ICP), offers an alternative approach to etching vias as compared to more conventional parallel plate reactive ion etch systems. This paper reports ICP etching of GaAs vias at etch rates of about 5.3 {mu}m/min with via profiles ranging from highly anistropic to conical.

  11. Chemically assisted ion beam etching of polycrystalline and (100)tungsten

    NASA Technical Reports Server (NTRS)

    Garner, Charles

    1987-01-01

    A chemically assisted ion-beam etching technique is described which employs an ion beam from an electron-bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 microns thick with good anisotropy and pattern definition over areas of 30 sq mm, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred-orientation etching, while polycrystalline tungsten films exhibit high etch rates. This technique can be used to pattern the dispenser cathode surfaces serving as electron emitters in traveling-wave tubes to a controlled porosity.

  12. Patterning of platinum (Pt) thin films by chemical wet etching in Aqua Regia

    NASA Astrophysics Data System (ADS)

    Köllensperger, P. A.; Karl, W. J.; Ahmad, M. M.; Pike, W. T.; Green, M.

    2012-06-01

    The chemical and physical properties of platinum (Pt) make it a useful material for microelectromechanical systems and microfluidic applications such as lab-on-a-chip devices. Platinum thin-films are frequently employed in applications where electrodes with high chemical stability, low electrical resistance or a high melting point are needed. Due to its chemical inertness it is however also one of the most difficult metals to pattern. The gold standard for patterning is chlorine RIE etching, a capital-intensive process not available in all labs. Here we present simple fabrication protocols for wet etching Pt thin-films in hot Aqua Regia based on sputtered Ti/Pt/Cr and Cr/Pt/Cr metal multilayers. Chromium (Cr) or titanium (Ti) is used as an adhesion layer for the Pt. Cr is used as a hard masking layer during the Pt etch as it can be easily and accurately patterned with photoresist and withstands the Aqua Regia. The Cr pattern is transferred into the Pt and the Cr mask later removed. Only standard chemicals and cleanroom equipment/tools are required. Prior to the Aqua Regia etch any surface passivation on the Pt is needs to be removed. This is usually achieved by a quick dip in dilute hydrofluoric acid (HF). HF is usually also used for wet-etching the Ti adhesion layer. We avoid the use of HF for both steps by replacing the HF-dip with an argon (Ar) plasma treatment and etching the Ti layer with a hydrogen peroxide (H2O2) based etchant.

  13. Development of Wet-Etching Tools for Precision Optical Figuring

    SciTech Connect

    Rushford, M C; Dixit, S N; Hyde, R; Britten, J A; Nissen, J; Aasen, M; Toeppen, J; Hoaglan, C; Nelson, C; Summers, L; Thomas, I

    2004-01-27

    This FY03 final report on Wet Etch Figuring involves a 2D thermal tool. Its purpose is to flatten (0.3 to 1 mm thickness) sheets of glass faster thus cheaper than conventional sub aperture tools. An array of resistors on a circuit board was used to heat acid over the glass Optical Path Difference (OPD) thick spots and at times this heating extended over the most of the glass aperture. Where the acid is heated on the glass it dissolves faster. A self-referencing interferometer measured the glass thickness, its design taking advantage of the parallel nature and thinness of these glass sheets. This measurement is used in close loop control of the heating patterns of the circuit board thus glass and acid. Only the glass and acid were to be moved to make the tool logistically simple to use in mass production. A set of 4-circuit board, covering 80 x 80-cm aperture was ordered, but only one 40 x 40-cm board was put together and tested for this report. The interferometer measurement of glass OPD was slower than needed on some glass profiles. Sometimes the interference fringes were too fine to resolve which would alias the sign of the glass thickness profile. This also caused the phase unwrapping code (FLYNN) to struggle thus run slowly at times taking hours, for a 10 inch square area. We did extensive work to improve the speed of this code. We tried many different phase unwrapping codes. Eventually running (FLYNN) on a farm of networked computers. Most of the work reported here is therefore limited to a 10-inch square aperture. Researched into fabricating a better interferometer lens from Plexiglas so to have less of the scattered light issues of Fresnel lens groves near field scattering patterns, this set the Nyquest limit. There was also a problem with the initial concept of wetting the 1737 glass on its bottom side with acid. The wetted 1737 glass developed an Achromatic AR coating, spoiling the reflection needed to see glass thickness interference fringes. In response

  14. Porous siliconformation and etching process for use in silicon micromachining

    DOEpatents

    Guilinger, Terry R.; Kelly, Michael J.; Martin, Jr., Samuel B.; Stevenson, Joel O.; Tsao, Sylvia S.

    1991-01-01

    A reproducible process for uniformly etching silicon from a series of micromechanical structures used in electrical devices and the like includes providing a micromechanical structure having a silicon layer with defined areas for removal thereon and an electrochemical cell containing an aqueous hydrofluoric acid electrolyte. The micromechanical structure is submerged in the electrochemical cell and the defined areas of the silicon layer thereon are anodically biased by passing a current through the electrochemical cell for a time period sufficient to cause the defined areas of the silicon layer to become porous. The formation of the depth of the porous silicon is regulated by controlling the amount of current passing through the electrochemical cell. The micromechanical structure is then removed from the electrochemical cell and submerged in a hydroxide solution to remove the porous silicon. The process is subsequently repeated for each of the series of micromechanical structures to achieve a reproducibility better than 0.3%.

  15. Si etching with reactive neutral beams of very low energy

    SciTech Connect

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Iwata, Naotaka; Hara, Tamio

    2014-12-14

    A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

  16. Properties of TNF-1 track etch detector

    NASA Astrophysics Data System (ADS)

    Ogura, K.; Asano, M.; Yasuda, N.; Yoshida, M.

    2001-12-01

    We have developed a new plastic track etch detector labeled TNF-1, which is the copolymer of CR-39 monomer with N-isopropylacrylamide (NIPAAm). It was found that copoly(CR-39/NIPAAm/ antioxidant) composed in weight ratio of 99/1/0.01 is highly sensitive to low linear energy transfer (LET) particles in the region below 10 keV/μm of LET 200 eV. TNF-1 is the most sensitive plastic track etch detector reported so far and is able to record normally incident protons up to the energy of 27 MeV. This paper gives results of our studies on the track responses of TNF-1 as well as the brief results obtained by the performance tests of TNF-1 in various dosimetric experiments such as space radiation dosimetry, dosimetry for heavy ion cancer therapy and neutron dosimetry. These results are compared with the results obtained for CR-39 track detectors.

  17. Geochemical, microtextural and petrological studies of the Samba prospect in the Zambian Copperbelt basement: a metamorphosed Palaeoproterozoic porphyry Cu deposit.

    NASA Astrophysics Data System (ADS)

    Master, Sharad; Mirrander Ndhlovu, N.

    2015-04-01

    Ever since Wakefield (1978, IMM Trans., B87, 43-52) described a porphyry-type meta-morphosed Cu prospect, the ca 50 Mt, 0.5% Cu Samba deposit (12.717°S, 27.833°E), hosted by porphyry-associated quartz-sericite-biotite schists in northern Zambia, there has been controversy about its origin and significance. This is because it is situated in the basement to the world's largest stratabound sediment-hosted copper province, the Central African Copperbelt, which is hosted by rocks of the Neoproterozoic Katanga Supergroup. Mineralization in the pre-Katangan basement has long played a prominent role in ore genetic models, with some authors suggesting that basement Cu mineralization may have been recycled into the Katangan basin through erosion and redeposition, while others have suggested that the circulation of fluids through Cu-rich basement may have leached out the metals which are found concentrated in the Katangan orebodies. On the basis of ca 490-460 Ma Ar-Ar ages, Hitzman et al. (2012, Sillitoe Vol., SEG Spec. Publ., 16, 487-514) suggested that Samba represents late-stage impregnation of copper mineralization into the basement, and that it was one of the youngest copper deposits known in the Central African Copperbelt. If the Samba deposit really is that young, then it would have post-dated regional deformation and metamorphism (560-510 Ma), and it ought to be undeformed and unmetamorphosed. The Samba mineralization consists of chalcopyrite and bornite, occurring as disseminations, stringers and veinlets, found in a zone >1 km along strike, in steeply-dipping lenses up to 10m thick and >150m deep. Our new major and trace element XRF geochemical data (14 samples) show that the host rocks are mainly calc-alkaline metadacites. Cu is correlated with Ag (Cu/Ag ~10,000:1) with no Au or Mo. Our study focused on the microtextures and petrology of the Samba ores. We confirm that there is alteration of similar style to that accompanying classical porphyry Cu mineralization

  18. Shapes of agglomerates in plasma etching reactors

    SciTech Connect

    Huang, F.Y.; Kushner, M.J.

    1997-05-01

    Dust particle contamination of wafers in reactive ion etching (RIE) plasma tools is a continuing concern in the microelectronics industry. It is common to find that particles collected on surfaces or downstream of the etch chamber are agglomerates of smaller monodisperse spherical particles. The shapes of the agglomerates vary from compact, high fractal dimension structures to filamentary, low fractal dimension structures. These shapes are important with respect to the transport of particles in RIE tools under the influence electrostatic and ion drag forces, and the possible generation of polarization forces. A molecular dynamics simulation has been developed to investigate the shapes of agglomerates in plasma etching reactors. We find that filamentary, low fractal dimension structures are generally produced by smaller ({lt}100s nm) particles in low powered plasmas where the kinetic energy of primary particles is insufficient to overcome the larger Coulomb repulsion of a compact agglomerate. This is analogous to the diffusive regime in neutral agglomeration. Large particles in high powered plasmas generally produce compact agglomerates of high fractal dimension, analogous to ballistic agglomeration of neutrals. {copyright} {ital 1997 American Institute of Physics.}

  19. Etching of moldavities under natural conditions

    NASA Technical Reports Server (NTRS)

    Knobloch, V.; Knoblochova, Z.; Urbanec, Z.

    1983-01-01

    The hypothesis that a part of the lechatellierites which originated by etching from a basic moldavite mass became broken off after deposition of moldavite in the sedimentation layer is advanced. Those found close to the original moldavite were measured for statistical averaging of length. The average length of lechatelierite fibers per cubic mm of moldavite mass volume was determined by measurement under a microscope in toluene. The data were used to calculate the depth of the moldavite layer that had to be etched to produce the corresponding amount of lechatelierite fragments. The calculations from five "fields" of moldavite surface, where layers of fixed lechatelierite fragments were preserved, produced values of 2.0, 3.1, 3.5, 3.9 and 4.5. Due to inadvertent loss of some fragments the determined values are somewhat lower than those found in references. The difference may be explained by the fact that the depth of the layer is only that caused by etching after moldavite deposition.

  20. Photoluminescence of etched SiC nanowires

    NASA Astrophysics Data System (ADS)

    Stewart, Polite D., Jr.; Rich, Ryan; Zerda, T. W.

    2010-10-01

    SiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100^oC and 1350^oC. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The compound possesses a high melting point, high thermal conductivity, and excellent wear resistance. The surface of the SiC nanowires after formation is covered by an amorphous layer. The composition of that layer is not fully understood, but it is believed that in addition to amorphous SiC it contains various carbon and silicon compounds, and SiO2. The objective of the research was to modify the surface structure of these SiC nanowires. Modification of the surface was done using the wet etching method. The etched nanowires were then analyzed using Fourier Transform Infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and photoluminescence (PL). FTIR and TEM analysis provided valid proof that the SiC nanowires were successfully etched. Also, the PL results showed that the SiC nanowire core did possess a fluorescent signal.

  1. Pattern inspection of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2015-10-01

    Patterned mask inspection for an etched multilayer (ML) EUV mask was investigated. In order to optimize the mask structure from the standpoint of not only a pattern inspection by using a projection electron microscope (PEM), but also by considering the other fabrication processes using electron beam (EB) techniques such as CD metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients (SEECs) of the candidate materials for conductive layer, we evaluated the image contrast and the influence of charging effect. In the cases of 40-pair-ML, 16 nm sized extrusion and intrusion defects were found to be detectable more than 10 sigma in hp 44 nm, 40 nm, and 32 nm line and space (L/S) patterns. Reducing 40-pair-ML to 20-pair-ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16 nm sized defects remained detectable. These defects were also detected after the etched part was refilled with Si. Moreover, the simulation shows a high sensitivity for detecting the residual-type defects (etching residues). A double layer structure with 2.5-nm-thik B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  2. Laser etching of polymer masked leadframes

    NASA Astrophysics Data System (ADS)

    Ho, C. K.; Man, H. C.; Yue, T. M.; Yuen, C. W.

    1997-02-01

    A typical electroplating production line for the deposition of silver pattern on copper leadframes in the semiconductor industry involves twenty to twenty five steps of cleaning, pickling, plating, stripping etc. This complex production process occupies large floor space and has also a number of problems such as difficulty in the production of rubber masks and alignment, generation of toxic fumes, high cost of water consumption and sometimes uncertainty on the cleanliness of the surfaces to be plated. A novel laser patterning process is proposed in this paper which can replace many steps in the existing electroplating line. The proposed process involves the application of high speed laser etching techniques on leadframes which were protected with polymer coating. The desired pattern for silver electroplating is produced by laser ablation of the polymer coating. Excimer laser was found to be most effective for this process as it can expose a pattern of clean copper substrate which can be silver plated successfully. Previous working of Nd:YAG laser ablation showed that 1.06 μm radiation was not suitable for this etching process because a thin organic and transparent film remained on the laser etched region. The effect of excimer pulse frequency and energy density upon the removal rate of the polymer coating was studied.

  3. Time-varying wetting behavior on copper wafer treated by wet-etching

    NASA Astrophysics Data System (ADS)

    Tu, Sheng-Hung; Wu, Chuan-Chang; Wu, Hsing-Chen; Cheng, Shao-Liang; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2015-06-01

    The wet cleaning process in semiconductor fabrication often involves the immersion of the copper wafer into etching solutions and thereby its surface properties are significantly altered. The wetting behavior of a copper film deposited on silicon wafer is investigated after a short dip in various etching solutions. The etchants include glacial acetic acid and dilute solutions of nitric acid, hydrofluoric acid, and tetramethylammonium hydroxide. It was found that in most cases a thin oxide layer still remains on the surface of as-received Cu wafers when they are subject to etching treatments. However, a pure Cu wafer can be obtained by the glacial acetic acid treatment and its water contact angle (CA) is about 45°. As the pure Cu wafer is placed in the ambient condition, the oxide thickness grows rapidly to the range of 10-20 Å within 3 h and the CA on the hydrophilic surface also rises. In the vacuum, it is surprising to find that the CA and surface roughness of the pure Cu wafer can grow significantly. These interesting results may be attributed to the rearrangement of surface Cu atoms to reduce the surface free energy.

  4. Steady-state damage profiles due to reactive ion etching and ion-assisted etching

    SciTech Connect

    Davis, R.J.; Jha, P.

    1995-03-01

    Ion damage of materials due to reactive ion etching and ion-assisted etching is formulated as a dynamic problem involving the etch rate, damage creation due to ions, diffusion, and ion range effects. The differential equation is solved in the steady-state assuming an exponentially decreasing damage creation function. The ratio {ital D}/{ital a}{epsilon}, where {ital D} is the damage coefficient, {ital a} the inherent depth of ion damage, and {epsilon} the etch rate is shown to be an important parameter determining the steady-state damage profile. Results are examined for situations in which the parameter is much less than or much greater than unity, corresponding to range- and diffusion-dominated profiles, respectively. In both situations, steady-state damage profiles will be quite sensitive to the etch rate of the surface. We suggest some experiments which may elucidate the separate contributions of ion channeling and diffusion to observed damage depth profiles. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  5. Micromorphology of ceramic etching pattern for two CAD-CAM and one conventional feldspathic porcelain and need for post-etching cleaning.

    PubMed

    Onisor, Ioana; Rocca, Giovanni Tommaso; Krejci, Ivo

    2014-01-01

    The aim of this in vitro study was to observe the effect of hydrofluoric acid (HF) on the surface of two glass ceramics for Cerec and to compare it with the effect on a conventional glass ceramic. Discs were cut from a feldspathic ceramic block (VitaMKII) and from a leucite reinforced glass ceramic (IPS EMPRESS CAD) for Cerec. 5% and 9% HF concentrations were used during 1 min and 2 min each. Afterwards samples were thoroughly water rinsed for 30 s. Half of the 9% HF 1 min samples were subsequently submitted to a complex post-etching cleaning. All samples were observed under a scanning electron microscope (SEM). The conventional feldspathic ceramic samples were built up on a refractory die and a platinum foil. They were treated with 9% HF for 2 min and water rinsed for 30 s. Half of the samples were submitted to the same post-etching cleaning protocol. All samples were examined under SEM and EDX. The Cerec ceramic samples and the platinum foil ones were clean and free of any precipitate after 30 s of water rinsing. Acid concentration, times of application and the postetching cleaning treatment did not influence the cleanliness of the samples. A thick layer of deposit was observed only on the refractory die samples. This was only diminished after the post-etching treatment. The EDX analysis detected the presence of fluoride (F) only on the refractory die samples.

  6. Etching characteristics of LiNbO{sub 3} in reactive ion etching and inductively coupled plasma

    SciTech Connect

    Ren, Z.; Yu, S.; Heard, P. J.; Marshall, J. M.; Thomas, P. A.

    2008-02-01

    The etching characteristics of congruent LiNbO{sub 3} single crystals including doped LiNbO{sub 3} and proton-changed LiNbO{sub 3} have been studied in reactive ion etching (RIE) and inductively coupled plasma (ICP) etching tools, using different recipes of gas mixtures. The effects of parameters including working pressure, RIE power, and ICP power are investigated and analyzed by measurement of etching depth, selectivity, uniformity, etched surface state, and sidewall profile by means of focused ion beam etching, energy-dispersive x-ray analysis, secondary ion mass spectroscopy, scanning electron microscopy, and surface profilometry. The effects of a sample carrier wafer coating have also been investigated. Optimized processes with high etching rates, good mask selectivity, and a near-vertical profile have been achieved. Ridge waveguides on proton-exchanged LiNbO{sub 3} have been fabricated and optically measured.

  7. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    SciTech Connect

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  8. Anisotropic Ta{sub 2}O{sub 5} waveguide etching using inductively coupled plasma etching

    SciTech Connect

    Muttalib, Muhammad Firdaus A. Chen, Ruiqi Y.; Pearce, Stuart J.; Charlton, Martin D. B.

    2014-07-01

    Smooth and vertical sidewall profiles are required to create low loss rib and ridge waveguides for integrated optical device and solid state laser applications. In this work, inductively coupled plasma (ICP) etching processes are developed to produce high quality low loss tantalum pentoxide (Ta{sub 2}O{sub 5}) waveguides. A mixture of C{sub 4}F{sub 8} and O{sub 2} gas are used in combination with chromium (Cr) hard mask for this purpose. In this paper, the authors make a detailed investigation of the etch process parameter window. Effects of process parameters such as ICP power, platen power, gas flow, and chamber pressure on etch rate and sidewall slope angle are investigated. Chamber pressure is found to be a particularly important factor, which can be used to tune the sidewall slope angle and so prevent undercut.

  9. NiCr etching in a reactive gas

    SciTech Connect

    Ritter, J.; Boucher, R.; Morgenroth, W.; Meyer, H. G.

    2007-05-15

    The authors have etched NiCr through a resist mask using Cl/Ar based chemistry in an electron cyclotron resonance etch system. The optimum gas mixture and etch parameters were found for various ratios of Ni to Cr, based on the etch rate, redeposits, and the etch ratio to the mask. The introduction of O{sub 2} into the chamber, which is often used in the etching of Cr, served to both increase and decrease the etch rate depending explicitly on the etching parameters. Etch rates of >50 nm min{sup -1} and ratios of >1 (NiCr:Mask) were achieved for NiCr (80:20). Pattern transfer from the mask into the NiCr was achieved with a high fidelity and without redeposits for a Cl/Ar mix of 10% Ar (90% Cl{sub 2}) at an etch rate of {approx_equal}50 nm min{sup -1} and a ratio of 0.42 (NiCr:ZEP 7000 e-beam mask)

  10. Improving UV laser damage threshold of fused silica optics by wet chemical etching technique

    NASA Astrophysics Data System (ADS)

    Ye, Hui; Li, Yaguo; Yuan, Zhigang; Wang, Jian; Xu, Qiao; Yang, Wei

    2015-07-01

    Fused silica is widely used in high-power laser systems because of its good optical performance and mechanical properties. However, laser damage initiation and growth induced by 355 nm laser illumination in optical elements have become a bottleneck in the development of high energy laser system. In order to improve the laser-induced damage threshold (LIDT), the fused silica optics were treated by two types of HF-based etchants: 1.7%wt. HF acid and buffer oxide etchant (BOE: the mixture of 0.4%wt. HF and 12%wt. NH4F), respectively, for varied etching time. Damage testing shows that both the etchants increase the damage threshold at a certain depth of material removal, but further removal of material lowers the LIDT markedly. The etching rates of both etchants keep steady in our processing procedure, ~58 μg/min and ~85 μg/min, respectively. The micro-surface roughness (RMS and PV) increases as etching time extends. The hardness (H) and Young's modulus (E) of the fused silica etched for diverse time, measured by nano-indenter, show no solid evidence that LIDT can be related to hardness or Young's modulus.

  11. Electrolytic Transport Through Cylindrical Etched Pores in Polyethylene Terepthalate Track-Etched Membrane

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Chakarvarti, S. K.

    In the present work, electrolytic transport phenomena is studied for different electrolytes (LiCl, NaCl, KCl of different concentrations) at room temperature (25 ± 2°C) through etched pores with different diameters having cylindrical shape in track-etched membranes of polyethylene terepthalate (PET) with pore density of the order of 106/cm2. Electric potential has been used as the driving force. It has been observed that electrolytic transport through pores is different for different electrolytes, depending strongly on size of cations and is independent of size of anions. In the case of cylindrical pores, there has not been found appreciable change in forward and backward resistances.

  12. Chemical etching and EDAX analysis of beryllium-free nickel-chromium ceramo-metal alloy.

    PubMed

    Atta, O M; Mosleh, I E; Shehata, M T

    1995-10-01

    A chemical etching technique is described for producing etch patterns in beryllium-free nickel chromium ceramo-metal alloy. Disc-shaped samples were chemically etched, evaluated with SEM and analysed by the EDAX technique. Scanning electron micrographs revealed, profound retentive cavities. The EDAX analysis provided a comprehensive interpretation of the etch mechanism. The obtained results show that the developed chemical etching has the potential to produce a highly retentive etched surface with less problematic and less technique sensitive than electrolytic etching.

  13. Spray etching 2 µm features in 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Chatterjee, Sudipta; Ujihara, Motoki; Lee, Dong Gun; Chen, Jerry; Lei, Stanley; Carman, Greg P.

    2006-12-01

    304 stainless steel samples were patterned with either a photoresist (PR) mask or a silicon nitride (Si3Ni4) mask and then subjected to either wet immersion etching or spray etching techniques with ferric chloride (FeCl3). The silicon nitride mask provides much better adhesion to the stainless steel substrate resulting in less undercut compared to the PR mask. When a silicon nitride mask was subjected to spray etching, better adhesion and less undercut enabled features as small as 1.8 µm with an etch depth of 5.6 µm. This is an order of magnitude smaller than current spray etching techniques (20-50 µm) used in the steel industry. This procedure will allow spray etching features for batch fabrication for a variety of metals including steels, aluminum, nickel-based alloys and copper-based alloys with microscale resolution.

  14. Experiment and Results on Plasma Etching of SRF cavities

    SciTech Connect

    Upadhyay, Janardan; Im, Do; Peshl, J.; Vuskovic, Leposova; Popovic, Svetozar; Valente, Anne-Marie; Phillips, H. Lawrence

    2015-09-01

    The inner surfaces of SRF cavities are currently chemically treated (etched or electropolished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.

  15. ECR, ICP, and RIE plasma etching of GaN

    SciTech Connect

    Shul, R.J.; McClellan, G.B.; Rieger, D.J.; Hafich, M.J.

    1996-06-01

    The group III-nitrides continue to generate interest due to their wide band gaps and high dielectric constants. These materials have made significant impact on the compound semiconductor community as blue and ultraviolet light emitting diodes (LEDs). Realization of more advanced devices; including lasers and high temperature electronics, requires dry etch processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {mu}m/min. In this paper, we compare electron cyclotron resonance (ECR), inductively coupled plasma (ICP), and reactive ion etch (RIE) etch results for GaN. These are the first ICP etch results reported for GaN. We also report ECR etch rates for GaN as a function of growth technique.

  16. Reduction of oxide microtrenching by electron beam assisted etching

    NASA Astrophysics Data System (ADS)

    Watanabe, M.; Shaw, D. M.; Collins, G. J.

    2000-10-01

    High density plasma etching of submicron wide oxide trenches often results in non-ideal etched features. For example, microtrenching is the result of higher etch rate near the side wall as compared to the center of the trench. Herein, we apply a previously reported[1] high energy (100 - 900 eV) electron beam directed at the etching wafer surface to reduce microtrenching during the etching of 0.5 micron wide silicon dioxide (SiO2) trench patterns in an inductively coupled fluorocarbon plasma. The directed electron beam neutralizes the positive charge buildup at the bottom of the trench and reduces the microtrench formation. Scanning Electron Microscopy (SEM) images of features etched with and without the electron beam show that the electron beam is effective in reducing microtrenching. [1] D. M. Shaw, M. Watanabe, G. J. Collins, and H. Sugai, Jpn. J. Appl. Phys. 38, 87 (1999).

  17. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanisms and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  18. Etched-multilayer phase shifting masks for EUV lithography

    DOEpatents

    Chapman, Henry N.; Taylor, John S.

    2005-04-05

    A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.

  19. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  20. Photoinduced laser etching of a diamond surface

    SciTech Connect

    Kononenko, V V; Komlenok, M S; Pimenov, S M; Konov, V I

    2007-11-30

    Nongraphitising ablation of the surface of a natural diamond single crystal irradiated by nanosecond UV laser pulses is studied experimentally. For laser fluences below the diamond graphitisation threshold, extremely low diamond etching rates (less than 1nm/1000 pulses) are obtained and the term nanoablation is used just for this process. The dependence of the nanoablation rate on the laser fluence is studied for samples irradiated both in air and in oxygen-free atmosphere. The effect of external heating on the nanoablation rate is analysed and a photochemical mechanism is proposed for describing it. (interaction of laser radiation with matter. laser plasma)

  1. Fabrication of silicon nanowire arrays by macroscopic galvanic cell-driven metal catalyzed electroless etching in aerated HF solution.

    PubMed

    Liu, Lin; Peng, Kui-Qing; Hu, Ya; Wu, Xiao-Ling; Lee, Shuit-Tong

    2014-03-01

    Macroscopic galvanic cell-driven metal catalyzed electroless etching (MCEE) of silicon in aqueous hydrofluoric acid (HF) solution is devised to fabricate silicon nanowire (SiNW) arrays with dissolved oxygen acting as the one and only oxidizing agent. The key aspect of this strategy is the use of a graphite or other noble metal electrode that is electrically coupled with silicon substrate.

  2. Anisotropic etching of Al by a directed Cl2 flux

    NASA Technical Reports Server (NTRS)

    Efremow, N. N.; Geis, M. W.; Mountain, R. W.; Lincoln, G. A.; Randall, J. N.

    1986-01-01

    A new Al etching technique is described that uses an ion beam from a Kaufman ion source and a directed Cl2 flux. The ion beam is used primarily to remove the native oxide and to allow the Cl2 to spontaneously react with the Al film forming volatile Al2Cl6. By controlling both the flux equivalent pressure of Cl2 and the ion beam current, this etching technique makes possible the anisotropic etching of Al with etch rates from 100 nm/min to nearly 10 microns/min with a high degree of selectivity.

  3. Influence of track-etching on polycarbonate membrane permittivity

    NASA Astrophysics Data System (ADS)

    Allaeys, J.-F.; Marcilhac, B.; Mage, J.-C.

    2007-06-01

    The complex dielectric permittivity of track-etched polycarbonate (PC) membranes is measured and compared with raw polymer membranes. Membranes at different steps of the track-etching process are compared. Dielectric loss is a key factor for microwave nanowired substrate devices, and better knowledge of the materials is necessary for choosing the most suited polymer for applications. Our experimental data on track-etched and raw PC are similar, and the PC dielectric loss at every track-etching step is lower than the raw polyimide dielectric loss.

  4. Physics and chemistry of complex oxide etching and redeposition control

    NASA Astrophysics Data System (ADS)

    Margot, Joëlle

    2012-10-01

    Since its introduction in the 1970s, plasma etching has become the universal method for fine-line pattern transfer onto thin films and is anticipated to remain so in foreseeable future. Despite many success stories, plasma etching processes fail to meet the needs for several of the newest materials involved in advanced devices for photonic, electronic and RF applications like ferroelectrics, electro-optic materials, high-k dielectrics, giant magnetoresistance materials and unconventional conductors. In this context, the work achieved over the last decade on the etching of multicomponent oxides thin films such as barium strontium titanate (BST), strontium titanate (STO) and niobate of calcium and barium (CBN) will be reviewed. These materials present a low reactivity with usual etching gases such as fluorinated and chlorinated gases, their etching is mainly governed by ion sputtering and reactive gases sometimes interact with surface materials to form compounds that inhibit etching. The etching of platinum will also be presented as an example of unconventional conductor materials for which severe redeposition limits the achievable etching quality. Finally, it will be shown how simulation can help to understand the etching mechanisms and to define avenues for higher quality patterning.

  5. Molecular Dynamics Simulations Of Nanometer-Scale Feature Etch

    SciTech Connect

    Vegh, J. J.; Graves, D. B.

    2008-09-23

    Molecular dynamics (MD) simulations have been carried out to examine fundamental etch limitations. Beams of Ar{sup +}, Ar{sup +}/F and CF{sub x}{sup +} (x = 2,3) with 2 nm diameter cylindrical confinement were utilized to mimic 'perfect' masks for small feature etching in silicon. The holes formed during etch exhibit sidewall damage and passivation as a result of ion-induced mixing. The MD results predict a minimum hole diameter of {approx}5 nm after post-etch cleaning of the sidewall.

  6. HF-(NH₄)₂S₂O₈-HCl Mixtures for HNO₃- and NOx-free Etching of Diamond Wire- and SiC-Slurry-Sawn Silicon Wafers: Reactivity Studies, Surface Chemistry, and Unexpected Pyramidal Surface Morphologies.

    PubMed

    Stapf, André; Gondek, Christoph; Lippold, Marcus; Kroke, Edwin

    2015-04-29

    The wet-chemical treatment of silicon wafers is an important production step in photovoltaic and semiconductor industries. Solutions containing hydrofluoric acid, ammonium peroxodisulfate, and hydrochloric acid were investigated as novel acidic, NOx-free etching mixtures for texturization and polishing of monocrystalline silicon wafers. Etching rates as well as generated surface morphologies and properties are discussed in terms of the composition of the etching mixture. The solutions were analyzed with Raman and UV/vis spectroscopy as well as ion chromatography (IC). The silicon surfaces were investigated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), diffuse reflection infrared spectroscopy (DRIFT), and X-ray photoelectron spectroscopy (XPS). Surprisingly, pyramidal surface structures were found after etching SiC-slurry as well as diamond wire-sawn monocrystalline Si(100) wafers with hydrochloric acid-rich HF-(NH4)2S2O8-HCl mixtures. Acidic etching solutions are generally not known for anisotropic etching. Thus, the HNO3-free mixtures might allow to replace KOH/i-propanol and similar alkaline solutions for texturization of monosilicon wafers at room temperature with less surface contamination. Besides, common HNO3-based etching mixtures may be replaced by the nitrate-free system, leading to significant economic and ecological advantages.

  7. Aspect-ratio-dependent etching of polymers as interlayer dielectrics

    NASA Astrophysics Data System (ADS)

    Kim, Gusung

    2000-08-01

    The reactive ion etching of the polymer has been studied in CF4-O2, SF6, and N2 plasmas to understand the contributions of aspect-ratio dependent etching (ARDE), an anisotropic etch profiles, and the etch rate for one of low-k polymers, Divinyl bis-benzocyclobutene (BCB, silicon containing spin-on polymer). A new experimental process (Type B) was implemented to determine the ARDE in which the AR remains constant during the entire experiment. These samples showed the uniform etch rate for all trenches. However, in conventional structure (Type A), using a SiO2 hardmask for patterning, ARDE phenomena can be observed. In the range of 30--35% CF4 in O2, BCB shows the maximum etch rate, and this coincides with the maximum in the oxygen concentration. Complete anisotropic profiles can be obtained at low pressure where the fluorine atom concentration is low. The highest etch rates are achieved at the higher pressures where fluorine and oxygen atom concentrations are high, but with an increase in the amount of profile tapering in Type A. In Type B samples, etching gives increased undercutting and bowing with an increase in pressure. At low pressure, the sidewall profile is vertical regardless of the aspect ratio of the pattern. No oxide is exposed to the CF4-O2 plasma and undercutting occurs with an increase of fluorine concentration. In large trenches, polymer residue and micromasking phenomena were observed in both cases. Specifically, the surface roughness of etched BCB in CF 4-O2 was much higher than in SF6 and N2. Lateral etching of the BCB, mask erosion and faceting of the hardmask were more prominently observed with SF6. SF6 produces a very clean surface and no residue at the bottom of a trench. In N2 plasma, the etch rate of BCB is very low due to physical ion bombardment and trenches are formed by mask erosion and micro-trenching.

  8. Novel hydrophilic nanostructured microtexture on direct metal laser sintered Ti-6Al-4V surfaces enhances osteoblast response in vitro and osseointegration in a rabbit model.

    PubMed

    Hyzy, Sharon L; Cheng, Alice; Cohen, David J; Yatzkaier, Gustavo; Whitehead, Alexander J; Clohessy, Ryan M; Gittens, Rolando A; Boyan, Barbara D; Schwartz, Zvi

    2016-08-01

    The purpose of this study was to compare the biological effects in vivo of hierarchical surface roughness on laser sintered titanium-aluminum-vanadium (Ti-6Al-4V) implants to those of conventionally machined implants on osteoblast response in vitro and osseointegration. Laser sintered disks were fabricated to have micro-/nano-roughness and wettability. Control disks were computer numerical control (CNC) milled and then polished to be smooth (CNC-M). Laser sintered disks were polished smooth (LST-M), grit blasted (LST-B), or blasted and acid etched (LST-BE). LST-BE implants or implants manufactured by CNC milling and grit blasted (CNC-B) were implanted in the femurs of male New Zealand white rabbits. Most osteoblast differentiation markers and local factors were enhanced on rough LST-B and LST-BE surfaces in comparison to smooth CNC-M or LST-M surfaces for MG63 and normal human osteoblast cells. To determine if LST-BE implants were osteogenic in vivo, we compared them to implant surfaces used clinically. LST-BE implants had a unique surface with combined micro-/nano-roughness and higher wettability than conventional CNC-B implants. Histomorphometric analysis demonstrated a significant improvement in cortical bone-implant contact of LST-BE implants compared to CNC-B implants after 3 and 6 weeks. However, mechanical testing revealed no differences between implant pullout forces at those time points. LST surfaces enhanced osteoblast differentiation and production of local factors in vitro and improved the osseointegration process in vivo. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2086-2098, 2016.

  9. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, Stephen M.; Tao, Hongyi; Todd-Copley, Judith A.

    1991-01-01

    A process for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength.

  10. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, S.M.; Tao, H.; Todd-Copley, J.A.

    1991-06-11

    A process is disclosed for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength. 1 figure.

  11. Washable and wear-resistant superhydrophobic surfaces with self-cleaning property by chemical etching of fibers and hydrophobization.

    PubMed

    Xue, Chao-Hua; Li, Ya-Ru; Zhang, Ping; Ma, Jian-Zhong; Jia, Shun-Tian

    2014-07-01

    Superhydrophobic poly(ethylene terephthalate) (PET) textile surfaces with a self-cleaning property were fabricated by treating the microscale fibers with alkali followed by coating with polydimethylsiloxane (PDMS). Scanning electron microscopy analysis showed that alkali treatment etched the PET and resulted in nanoscale pits on the fiber surfaces, making the textiles have hierarchical structures. Coating of PDMS on the etched fibers affected little the roughening structures while lowered the surface energy of the fibers, thus making the textiles show slippery superhydrophobicity with a self-cleaning effect. Wettability tests showed that the superhydrophobic textiles were robust to acid/alkaline etching, UV irradiation, and long-time laundering. Importantly, the textiles maintained superhydrophobicity even when the textiles are ruptured by severe abrasion. Also colorful images could be imparted to the superhydrophobic textiles by a conventional transfer printing without affecting the superhydrophobicity.

  12. Development of Localized Plasma Etching System for Failure Analyses in Semiconductor Devices: (3)
    Etching-Monitoring Using Quadrupole Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoshi; Horie, Tomoyuki; Shirayama, Yuya; Yokosuka, Shuntaro; Kashimura, Kenta; Hayashi, Akihiro; Iwase, Chikatsu; Shimbori, Shun'ichiro; Tokumoto, Hiroshi; Naitoh, Yasuhisa; Shimizu, Tetsuo

    Quadrupole mass spectrometry (QMS) has been applied to monitor the etching processes in a localized plasma etching system. An inward plasma was employed for etching in which the etching gas was discharged in the narrow gap between the etched sample and the entrance of an evacuating capillary tube. As the etching products are immediately evacuated through the capillary, a QMS system equipped at the capillary exit is able to analyze the products without any loss in concentration via diffusion into the chamber. Two kinds of samples, thermally grown SiO2 on Si and spin-coated polyimide film on Si, were etched, and the chemical species in the evacuated etching gas were analyzed with QMS, which enables monitoring of the composition of the surface being etched. Samples of thermal SiO2 were etched with CF4 plasma. The peak height of the SiF3+ signal during the SiO2 etching was lower than that observed during etching of the silicon substrate, leading to endpoint detection. The endpoint detection of the polyimide film etching was conducted using two etching gases: pure O2 and pure CF4. When O2 was used, the endpoint was detected by the decrease of the mass peak attributed to CO. When CF4 was employed, the plasma was able to etch both the polyimide film and Si substrate. Then the endpoint was detected by the increase of the mass peak of SiF3+ produced by the etching of the Si substrate.

  13. The influence of varying sputter deposition conditions on the wet chemical etch rate of AlN thin films

    NASA Astrophysics Data System (ADS)

    Ababneh, A.; Kreher, H.; Seidel, H.; Schmid, U.

    2007-05-01

    Aluminium nitride (AlN) reactively sputter deposited from an aluminium target is an interesting compound material due to its CMOS compatible fabrication process and its piezoelectric properties. For the implementation in micromachined sensors and actuators an appropriate patterning technique is needed to form AlN-based elements. Therefore, the influence of different sputtering conditions on the vertical etch rate of AlN thin films with a typical thickness of 600 nm in phosphoric acid (H 3PO 4) is investigated. Under comparable conditions, such as temperature and concentration of the etchant, thin films with a high c-axis orientation are etched substantially slower compared to films with a low degree of orientation. When a high c-axis orientation is present detailed analyses of the etched topologies reveal surface characteristics with a low porosity and hence, low roughness values. From temperature dependant etching experiments an activation energy of 800 (+/- 30) meV is determined showing a reaction-controlled etching regime independent of sputter deposition conditions.

  14. Focused electron-beam-induced etching of silicon dioxide

    SciTech Connect

    Randolph, S.J.; Fowlkes, J.D.; Rack, P.D.

    2005-08-01

    Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO{sub 2} matrix, and subsequently rate limited by XeF{sub 2} availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO{sub 2} to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

  15. Physical mechanisms for anisotropic plasma etching of cesium iodide

    SciTech Connect

    Yang Xiaoji; Hopwood, Jeffrey A.

    2004-11-01

    The physical mechanisms for the interaction between a reactive plasma and a cesium iodide surface are investigated. Under conditions of ion bombardment and elevated substrate temperature, CsI is found to sputter etch slowly (15 nm/min). If atomic fluorine, fluorocarbon radicals, of SF{sub x} radicals are present in the discharge, however, CsI is reactively etched at substantially higher rates (up to 200 nm/min). The roles of plasma radicals and energetic ion bombardment are investigated by first exposing the surface to plasma radicals and then bombarding the surface with argon ions. The optical emission from Cs and I atoms is found to correlate with the etch rate of CsI and is used as an in situ monitor of radical-enhanced etching. Small surface exposures to CF{sub x}, SF{sub x}, and F radicals are shown to enhance the etch rate of CsI. If the exposure of the CsI surface is increased, however, these same radical species act as etch inhibitors. A simple model for reactive etching of CsI is proposed, and this model is shown to compare reasonably well with experimental etch rates.

  16. Differential etching of chalcogenides for infrared photonic waveguide structures

    SciTech Connect

    Riley, Brian J.; Sundaram, S. K.; Johnson, Bradley R.; Saraf, Laxmikant V.

    2007-10-10

    Chemical etching rates for two different chalcogenide glass compositions (As2S3 and As24S38Se38) were studied using sodium hydroxide based etchant solutions. Etching was performed using a variation of standard photolithographic masking and wet-etching techniques. Variations in etch rate with NaOH concentration and glass composition were observed. The depth of etch was characterized using an optical profilometer. Etch rate differences as large as three orders of magnitude between these two glasses were observed at low NaOH concentration (0.053 M). We present a single variable etch rate curve of etch depth per time (nm/s) versus NaOH overall solution concentration (in M) for these two different chalcogenide glasses (As2S3 and As24S38Se38). This technology shows promise for fabricating highly asymmetrical photonic structures and has potential applications in fabricating novel photonic bandgap (PBG) structures that will function in the long-wave infrared (LWIR) regime.

  17. A geometric etch-stop technology for bulk micromachining

    NASA Astrophysics Data System (ADS)

    Amir Parviz, Babak; Najafi, Khalil

    2001-05-01

    This paper describes a new fabrication method for the simultaneous creation of multi-level single-crystalline silicon structures, each with a different thickness. The method combines deep dry etching and wet anisotropic etching of silicon in order to avoid multiple back-side alignment steps and timed etches. The levels are defined in a single lithographic step from the front side. The fabrication involves etching of deep trenches from the front side of the wafer followed by a refill and etch back process. The final structure is defined by maskless wet etching of the bulk silicon. The progress of the anisotropic wet etch is impeded by the geometric pattern at the bottom of the trenches, and thus structures with various thickness ranging from ten to a few hundred micrometres can be implemented. The effect of various design parameters, such as trench geometry, refill material and reactive ion etching lag, are discussed and design rules are established. The capabilities of the method are demonstrated by the fabrication of a number of devices, such as 1200×1200×3.5 µm diaphragms supported by a 40 µm thick rim and (1800×10×3 µm) embedded hot-wire anemometers suspended by a 0.2 µm thick dielectric bridge.

  18. Reactive ion etched substrates and methods of making and using

    DOEpatents

    Rucker, Victor C.; Shediac, Rene; Simmons, Blake A.; Havenstrite, Karen L.

    2007-08-07

    Disclosed herein are substrates comprising reactive ion etched surfaces and specific binding agents immobilized thereon. The substrates may be used in methods and devices for assaying or isolating analytes in a sample. Also disclosed are methods of making the reactive ion etched surfaces.

  19. Focused electron-beam-induced etching of silicon dioxide

    NASA Astrophysics Data System (ADS)

    Randolph, S. J.; Fowlkes, J. D.; Rack, P. D.

    2005-08-01

    Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO2 matrix, and subsequently rate limited by XeF2 availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO2 to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

  20. Laser etching: A new technology to identify Florida grapefruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laser labeling of fruits and vegetables is an alternative means to label produce. Low energy CO2 laser beam etches the surface showing the contrasting underlying layer. These etched surfaces can promote water loss and potentially allowing for pathogen entry. The long term effects of laser labeling o...

  1. Evaluation of bond strength of orthodontic brackets without enamel etching

    PubMed Central

    Boruziniat, Alireza; Motaghi, Shiva; Moghaddas, Mohmmadjavad

    2015-01-01

    Background To compare the shear bond strength of brackets with and without enamel etching. Material and Methods In this study, 60 sound premolars were randomly divided into four different groups: 1- TXE group: Enamel etching+Transbond XT adhesive+ Transbond XT composite. 2- TXS group: Transbond plus self-etch adhesive+ Transbond XT composite. 3- PQ1E group: Enamel etching+ PQ1 adhesive+ Transbond XT composite. 4- PQ1 group: PQ1 adhesive+ Transbond XT composite. The shear bond strengths of brackets were evaluated using universal testing machine at cross head speed of 0.5 mm/min. The Adhesive Remnant Index (ARI) was also measured. One-way ANOVA, Tukey’s post hoc, Kruskal-wallis and Mann-Witney U test were used for data analysis. Results There was a significant difference between etched and unetched groups respect to SBS and ARI (p<0.05), however; no significant difference was observed between unetched group and self-etch adhesive group (p>> 0.05). The shear bond strength of PQ1 group was the least but in acceptable range and its ARI was less than other groups. Conclusions PQ1 adhesive can be used for bracket bonding without enamel etching with adequate bond strength and minimal ARI. Key words:Bracket, shear bond strength, filled-adhesive, self-etch adhesive. PMID:26535100

  2. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    NASA Astrophysics Data System (ADS)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  3. Reactive ion etching (RIE) technique for application in crystalline silicon solar cells

    SciTech Connect

    Yoo, Jinsu

    2010-04-15

    Saw damage removal (SDR) and texturing by conventional wet chemical processes with alkali solution etch about 20 micron of silicon wafer on both sides, resulting in thin wafers with which solar cell processing is difficult. Reactive ion etching (RIE) for silicon surface texturing is very effective in reducing surface reflectance of thin crystalline silicon wafers by trapping the light of longer wavelength. High efficiency solar cells were fabricated during this study using optimized RIE. Saw damage removal (SDR) with acidic mixture followed by RIE-texturing showed the decrease in silicon loss by {proportional_to}67% and {proportional_to}70% compared to conventional SDR and texturing by alkaline solution. Also, the crystalline silicon solar cells fabricated by using RIE-texturing showed conversion efficiency as high as 16.7% and 16.1% compared with 16.2%, which was obtained in the case of the cell fabricated with SDR and texturing with NaOH solution. (author)

  4. Enlargement of halloysite clay nanotube lumen by selective etching of aluminum oxide.

    PubMed

    Abdullayev, Elshad; Joshi, Anupam; Wei, Wenbo; Zhao, Yafei; Lvov, Yuri

    2012-08-28

    Halloysite clay tubes have 50 nm diameter and chemically different inner and outer walls (inner surface of aluminum oxide and outer surface of silica). Due to this different chemistry, the selective etching of alumina from inside the tube was realized, while preserving their external diameter (lumen diameter changed from 15 to 25 nm). This increases 2-3 times the tube lumen capacity for loading and further sustained release of active chemical agents such as metals, corrosion inhibitors, and drugs. In particular, halloysite loading efficiency for the benzotriazole increased 4 times by selective etching of 60% alumina within the tubes' lumens. Specific surface area of the tubes increased over 6 times, from 40 to 250 m(2)/g, upon acid treatment.

  5. Feasibility of atomic layer etching of polymer material based on sequential O{sub 2} exposure and Ar low-pressure plasma-etching

    SciTech Connect

    Vogli, Evelina; Metzler, Dominik; Oehrlein, Gottlieb S.

    2013-06-24

    We describe controlled, self-limited etching of a polystyrene polymer using a composite etching cycle consisting of sequential deposition of a thin reactive layer from precursors produced from a polymer-coated electrode within the etching chamber, modification using O{sub 2} exposure, and subsequent low-pressure Ar plasma etching, which removes the oxygen-modified deposited reactive layer along with Almost-Equal-To 0.1 nm unmodified polymer. Deposition prevents net etching of the unmodified polymer during the etching step and enables self-limited etch rates of 0.1 nm/cycle.

  6. Correction for etch proximity: new models and applications

    NASA Astrophysics Data System (ADS)

    Granik, Yuri

    2001-09-01

    Short-range etch proximity effects increase intra-die CD variability and degrade the IC performance and yield. Tight control of the etch bias is an increasingly critical factor in realizing the ITRS technology nodes. The 2000 technology nodes revision added a new category, the post-etch 'physical' gate length metric, that is 9 - 17% smaller than 'in-resist' gate length. We present new etch proximity correction methods and models designed to reduce negative impact of etch-induced CD variability and increase uniformity of the controlled over- etching. Resolution Enhancement Technologies (RET) design correction methods typically employ 'lumped' process models. We found that an alternative methodology based upon separation of the process factors and the related models may yield better accuracy, performance, and better suit the design and process optimization flows. The contributions from the reticle, the optics, the wafer, and etch are individually determined and then used either separately or in aggregation for the most flexible and optimum correction of their respective contributions. The etch corrections are based on the Variable Etch Bias model (VEB model). This semi-empirical model requires experimental CD information to be collected from the test patterns under fixed process conditions (point-process model). It demonstrates excellent fit to the early experimental CD-SEM data gathered to date, which spans a variety of layout features and process conditions. The VEB model works in conjunction with CalibreR software system's Variable Threshold Resist-Extended (VTR-E) model, however the etching is modeled separately from the optics and the resist processing. This yields better understanding and more accurate explanation of the experiments than those that are produced by the 'lumped' process modeling. The VEB model explains etch- induced bias in terms of the following three proximity characteristics or variables: effective trench width (or pattern separation), pattern

  7. Investigation and simulation of XeF2 isotropic etching of silicon

    NASA Astrophysics Data System (ADS)

    Bahreyni, Behraad; Shafai, C.

    2002-11-01

    Trenching and loading phenomena observed on XeF2-etched (100) silicon wafers are explained in this article. Trenching refers to deeper etching at the side of an etch feature with respect to the middle of the feature. Loading is the reduction in etch depth that adjacent etched regions impose on their respective etch profiles. These two phenomena are especially recognized at locations where the substrate is etched through large mask openings. Both phenomena were reported by other groups, but no explanation was given for them. A novel model explaining these phenomena is developed in this article, and the etching process is simulated in software. The results are compared to several etched samples with varying mask aperture size and etch depth. Good agreement is found between simulated profiles and actual measured etch profiles at given mean-free paths. Furthermore, our simulator predicts that the reaction probability between etchant and substrate molecules influences surface roughness of the etched regions.

  8. UV-photoassisted etching of GaN in KOH

    SciTech Connect

    Cho, H.; Donovan, S.M.; Abernathy, C.R.; Lambers, E.S.; Pearton, S.J.; Auh, K.H.; Han, J.; Shul, R.J.

    1999-03-01

    The etch rate of GaN under ultraviolet-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias, and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n {approximately} 3 {times} 10{sup 16} cm{sup {minus}3}) GaN are {ge} 1,000 {angstrom} {center_dot} min{sup {minus}1}. The etching is diffusion-limited under the conditions with an activation energy of {approximately} 0.8 kCal{center_dot}mol{sup {minus}1}. The etched surfaces are rough, but retain their stoichiometry.

  9. Composition/bandgap selective dry photochemical etching of semiconductor materials

    DOEpatents

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  10. Composition/bandgap selective dry photochemical etching of semiconductor materials

    DOEpatents

    Ashby, Carol I. H.; Dishman, James L.

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  11. Effects of plasma etching solar cell front surfaces

    SciTech Connect

    Taylor, W.E.; Bunyan, S.M.; Olson, C.E.

    1980-01-01

    A front surface plasma etch with Freon 14+8% O/sub 2/ or sulfur hexafluoride (SF/sub 6/) was found to improve terrestrial solar cell output. SEM studies of these samples revealed surface pitting on Freon 14 etched samples. About 50% of the improvement from Freon etched samples can be attributed to the light capturing effects of surface pits. Output increases from SF/sub 6/ plasma etched cells were found to be comparable with Freon etched cells after subtraction of the light trapping effects. The excess output improvement might be attributed to reduced junction depth or removal of near surface lattice damage. Investigations attempting to identify the cause are described. 1 ref.

  12. Consideration of VT5 etch-based OPC modeling

    NASA Astrophysics Data System (ADS)

    Lim, ChinTeong; Temchenko, Vlad; Kaiser, Dieter; Meusel, Ingo; Schmidt, Sebastian; Schneider, Jens; Niehoff, Martin

    2008-03-01

    Including etch-based empirical data during OPC model calibration is a desired yet controversial decision for OPC modeling, especially for process with a large litho to etch biasing. While many OPC software tools are capable of providing this functionality nowadays; yet few were implemented in manufacturing due to various risks considerations such as compromises in resist and optical effects prediction, etch model accuracy or even runtime concern. Conventional method of applying rule-based alongside resist model is popular but requires a lot of lengthy code generation to provide a leaner OPC input. This work discusses risk factors and their considerations, together with introduction of techniques used within Mentor Calibre VT5 etch-based modeling at sub 90nm technology node. Various strategies are discussed with the aim of better handling of large etch bias offset without adding complexity into final OPC package. Finally, results were presented to assess the advantages and limitations of the final method chosen.

  13. Atomic precision etch using a low-electron temperature plasma

    NASA Astrophysics Data System (ADS)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2016-03-01

    Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

  14. Chemical etching of bovine serum albumin-protected Au25 nanoclusters for label-free and separation-free detection of cysteamine.

    PubMed

    Shu, Tong; Su, Lei; Wang, Jianxing; Li, Chenzhong; Zhang, Xueji

    2015-04-15

    This study describes a novel Au nanocluster-based fluorescent sensor for label-free, separation-free and selective detection of cysteamine (CSH). The sensing mechanism is based on CSH etching-induced fluorescence quenching of the bovine serum albumin-protected Au25 nanoclusters (BSAGNCs). A series of characterizations is carried out towards a better understanding of the CSH-induced fluorescence quenching of the BSAGNCs. It is found that CSH can etch the Au25 nanoclusters, exhibiting the potent etching activity. Other thiol-containing compounds such as glutathione and cysteine and other 19 natural amino acids do not interfere with such CSH-induced etching process. The decreases in fluorescence intensity of the BSAGNCs allow sensitive detection of free CSH in the range of 500-10,000nM. The detection limit for CSH is 150nM (S/N=3). The spiked human serum samples can be analyzed with satisfactory results.

  15. In-situ diagnostics and characterization of etch by-product deposition on chamber walls during halogen etching of silicon

    NASA Astrophysics Data System (ADS)

    Rastgar, Neema; Sriraman, Saravanapriyan; Marsh, Ricky; Paterson, Alex

    2014-10-01

    Plasma etching is a critical technology for nanoelectronics fabrication, but the use of a vacuum chamber limits the number of in-situ, real-time diagnostics measurements that can be performed during an etch process. Byproduct deposition on chamber walls during etching can affect the run-to-run performance of an etch process if there is build-up or change of wall characteristics with time. Knowledge of chamber wall evolution and the composition of wall-deposited films are critical to understanding the performance of plasma etch processes, and an in-situ diagnostics measurement is useful for monitoring the chamber walls in real time. We report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to perform in-situ diagnostics of a vacuum chamber's walls during plasma etching. Using ATR-FTIR, we are able to monitor the relative thickness and makeup of chamber wall deposits in real time. We then use this information to develop a chamber wall cleaning process in order to maintain reproducible etching conditions from wafer to wafer. In particular, we report mid-IR (4000-650 cm-1) absorption spectra of chamber wall-deposited silicon byproducts formed during halogen etching of silicon wafers.

  16. Optical diagnostic instrument for monitoring etch uniformity during plasma etching of polysilicon in a chlorine-helium plasma

    SciTech Connect

    Hareland, W.A.; Buss, R.J.

    1993-06-01

    Nonuniform etching is a serious problem in plasma processing of semiconductor materials and has important consequences in the quality and yield of microelectronic components. In many plasmas, etching occurs at a faster rate near the periphery of the wafer, resulting in nonuniform removal of specific materials over the wafer surface. This research was to investigate in situ optical diagnostic techniques for monitoring etch uniformity during plasma processing of microelectronic components. We measured 2-D images of atomic chlorine at 726 nm in a chlorine-helium plasma during plasma etching of polysilicon in a parallel-plate plasma etching reactor. The 3-D distribution of atomic chlorine was determined by Abel inversion of the plasma image. The experimental results showed that the chlorine atomic emission intensity is at a maximum near the outer radius of the plasma and decreases toward the center. Likewise, the actual etch rate, as determined by profilometry on the processed wafer, was approximately 20% greater near the edge of the wafer than at its center. There was a direct correlation between the atomic chlorine emission intensity and the etch rate of polysilicon over the wafer surface. Based on these analyses, 3-D imaging would be a useful diagnostic technique for in situ monitoring of etch uniformity on wafers.

  17. Influence of cross-rolling on the micro-texture and biodegradation of pure iron as biodegradable material for medical implants.

    PubMed

    Obayi, Camillus Sunday; Tolouei, Ranna; Paternoster, Carlo; Turgeon, Stephane; Okorie, Boniface Adeleh; Obikwelu, Daniel Oray; Cassar, Glenn; Buhagiar, Joseph; Mantovani, Diego

    2015-04-01

    Iron-based biodegradable metals have been shown to present high potential in cardiac, vascular, orthopaedic and dental in adults, as well as paediatric, applications. These require suitable mechanical properties, adequate biocompatibility while guaranteeing a low toxicity of degradation products. For example, in cardiac applications, stents need to be made by homogeneous and isotropic materials in order to prevent sudden failures which would impair the deployment site. Besides, the presence of precipitates and pores, chemical inhomogeneity or other anisotropic microstructural defects may trigger stress concentration phenomena responsible for the early collapse of the device. Metal manufacturing processes play a fundamental role towards the final microstructure and mechanical properties of the materials. The present work assesses the effect of mode of rolling on the micro-texture evolution, mechanical properties and biodegradation behaviour of polycrystalline pure iron. Results indicated that cross-rolled samples recrystallized with lower rates than the straight-rolled ones due to a reduction in dislocation density content and an increase in intensity of {100} crystallographic plane which stores less energy of deformation responsible for primary recrystallization. The degradation resulted to be more uniform for cross-rolled samples, while the corrosion rates of cross-rolled and straight-rolled samples did not show relevant differences in simulated body solution. Finally, this work shows that an adequate compromise between biodegradation rate, strength and ductility could be achieved by modulating the deformation mode during cold rolling. PMID:25644452

  18. E-beam inspection of EUV mask defects: To etch or not to etch?

    NASA Astrophysics Data System (ADS)

    Bonam, Ravi; Tien, Hung-Yu; Park, Chanro; Halle, Scott; Wang, Fei; Corliss, Daniel; Fang, Wei; Jau, Jack

    2014-04-01

    EUV Lithography is aimed to be inserted into mainstream production for sub-20nm pattern fabrication. Unlike conventional optical lithography, frequent defectivity monitors (adders, repeaters etc.) are required in EUV lithography. Due to sub-20nm pattern and defect dimensions e-beam inspection of critical pattern areas is essential for yield monitor. In previous work we showed sub-10nm defect detection sensitivity1 on patterned resist wafers. In this work we report 8-10× improvement in scan rates of etched patterns compared to resist patterns without loss in defect detection sensitivity. We observed good etch transfer of sub-10nm resist features. A combination of smart scan strategies with improved etched pattern scan rates can further improve throughput of e-beam inspection. An EUV programmed defect mask with Line/Space, Contact patterns was used to evaluate printability of defects and defect detection (Die-Die and Die-Database) capability of the e-beam inspection tool. Defect inspection tool parameters such as averaging, threshold value were varied to assess its detection capability and were compared to previously obtained results on resist patterns.

  19. Bulk filling of Class II cavities with a dual-cure composite: Effect of curing mode and enamel etching on marginal adaptation

    PubMed Central

    Bortolotto, Tissiana; Roig, Miguel; Krejci, Ivo

    2014-01-01

    Objectives: This study attempted to find a simple adhesive restorative technique for class I and II cavities on posterior teeth. Study Design: The tested materials were a self-etching adhesive (Parabond, Coltène/Whaledent) and a dual-cure composite (Paracore, Coltène/Whaledent) used in bulk to restore the cavities. Class II MO cavities were performed and assigned to 4 groups depending on the orthophosphoric acid (H3PO4) conditioning of enamel and polymerization method used (chemical or dual). Specimens were subjected to quantitative marginal analysis before and after thermo-mechanical loading. Results: Higher percentages of marginal adaptation at the total margin length, both before and after thermo-mechanical loading, were found in groups in which enamel was etched with phosphoric acid, without significant differences between the chemically and dual-cured modes. The restorations performance was similar on enamel and dentin, obtaining low results of adaptation on occlusal enamel in the groups without enamel etching, the lowest scores were on cervical dentin in the group with no ortophosphoric acid and self-cured. Conclusions: A dual-cure composite applied in bulk on acid etched enamel obtained acceptable marginal adaptation results, and may be an alternative technique for the restoration of class II cavities. Key words:Dual-cure composite, bulk technique, class II restoration, selective enamel etching, marginal adaptation. PMID:25674316

  20. Direct Visualization of Etching Trajectories in Metal-Assisted Chemical Etching of Si by the Chemical Oxidation of Porous Sidewalls.

    PubMed

    Yoon, Sung-Soo; Khang, Dahl-Young

    2015-09-29

    We demonstrate a simple method for the visualization of trajectories traced by noble metal nanoparticles during metal-assisted chemical etching (MaCE) of Si. The nanoporous Si layer formed around drilled pores is converted into SiO2 by simple chemical oxidation. Etch removal of the remaining Si using alkali hydroxide leaves SiO2 nanostructures that are the exact replica of those drilled pores or etching trajectories. The differences in etching characteristics between Ag and Au have been investigated using the proposed visualization method. The shape and chemical stability of metal nanoparticles used for MaCE have been found to be critical in determining etching paths. The proposed method would be very helpful in studying the fundamental mechanism of MaCE as well as in micro/nanostructuring of the Si surface for various applications. This approach can also be used for the generation of straight or helical SiO2 nanotubes.

  1. Energy dispersive X-ray spectroscopy analysis of Si sidewall surface etched by deep-reactive ion etching

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Nishioka, Kunio; Sato, Mina

    2016-06-01

    We investigated the composition of a passivation film on a sidewall etched by deep-reactive ion etching (RIE) using SF6/O2 and C4F8 plasma, by energy-dispersive X-ray (EDX) spectroscopy. It was found that the compositions of carbon and fluorine in the passivation film on the etched sidewall depend on the width and depth of the etched trench. It is important to understand both the plasma behavior and the passivation film composition to carry out fabrication by deep-RIE. We consider that these results of the EDX analysis of an etched sidewall will be useful for understanding plasma behavior in order to optimize the process conditions of deep-RIE.

  2. Optimized condition for etching fused-silica phase gratings with inductively coupled plasma technology.

    PubMed

    Wang, Shunquan; Zhou, Changhe; Ru, Huayi; Zhang, Yanyan

    2005-07-20

    Polymer deposition is a serious problem associated with the etching of fused silica by use of inductively coupled plasma (ICP) technology, and it usually prevents further etching. We report an optimized etching condition under which no polymer deposition will occur for etching fused silica with ICP technology. Under the optimized etching condition, surfaces of the fabricated fused silica gratings are smooth and clean. Etch rate of fused silica is relatively high, and it demonstrates a linear relation between etched depth and working time. Results of the diffraction of gratings fabricated under the optimized etching condition match theoretical results well.

  3. Characterization of silicon isotropic etch by inductively coupled plasma etcher for microneedle array fabrication

    NASA Astrophysics Data System (ADS)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin; Sun, Jianbo

    2006-04-01

    This work investigates the isotropic etching properties in inductively coupled plasma (ICP) etcher for microneedle arrays fabrication. The effects of process variables including powers, gas and pressure on needle structure generation are characterized by factorial design of experiment (DOE). The experimental responses of vertical etching depth, lateral etching length, ratio of vertical etching depth to lateral etching length and photoresist etching rate are reported. The relevance of the etching variables is also presented. The obtained etching behaviours for microneedle structure generation will be applied to develop recipes to fabricate microneedles in designed dimensions.

  4. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    DOEpatents

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  5. One-component self-etching primer: a seventh generation of orthodontic bonding system?

    PubMed

    Pithon, Matheus Melo; dos Santos, Rogerio Lacerda; Ruellas, Antônio Carlos de Oliveira; Sant'Anna, Eduardo Franzotti

    2010-10-01

    The purpose of this study was to compare the bond strengths and to evaluate the debonding site using the adhesive remnant index (ARI) provided by a conventional acid-etch conditioner and a new self-etching adhesive system, Xeno IV (Dentsply Caulk). One hundred and eighty bovine lower incisors were randomly divided into six groups (n = 30). In groups 1, 2, and 3, Transbond XT (3M Unitek) composite was used to bond the brackets to enamel samples conditioned with 37 per cent phosphoric acid + XT primer (3M Unitek), Xeno IV + XT primer, or Xeno IV only, respectively. In groups 4, 5, and 6, the bonding procedures were performed using Fuji Ortho LC (GC Corp.) resin-modified glass ionomer cement unconditioned, enamel conditioned with 37 per cent phosphoric acid, or Xeno IV, respectively. All samples underwent thermocycling and then shear bond strength (SBS) testing was performed using a universal testing machine (Emic DL 10.000). Analysis of variance was applied. For the post hoc test, the Tukey's test was used. Kruskal-Wallis and Mann-Whitney U-tests were used to assess ARI scores. The results demonstrated no statistical differences between groups 1, 2, and 3. However, statistically significant differences were found between these samples and groups 4, 5, and 6. With regard to ARI score, the highest mean value was found in group 5 (Fuji Ortho LC + 37 per cent acid conditioning), whereas group 4 (Fuji Ortho LC + no conditioning) had the lowest SBS. Xeno IV self-etching bonding agent was able to bond orthodontic brackets in association with Transbond XT composite as well as with Fuji Ortho LC, thus maximizing bracket bonding.

  6. Etching of oxynitride thin films using inductively coupled plasma

    SciTech Connect

    Kim, Byungwhan; Lee, Dukwoo; Kim, Nam Jung; Lee, Byung Teak

    2005-05-01

    In this study, silicon oxynitride (SiON) has been etched in a C{sub 2}F{sub 6} inductively coupled plasma. The process parameters examined include a radio frequency source power, bias power, pressure, and C{sub 2}F{sub 6} flow rate. For process optimization, a statistical experimental design was employed to investigate parameter effects under various plasma conditions. The etch rate increased almost linearly with increasing the source or bias power. Main effect analysis revealed that the etch rate is dominated by the source power. The C{sub 2}F{sub 6} flow rate exerted the least impact on both etch rate and profile angle. It was estimated that the C{sub 2}F{sub 6} effect is transparent only as the etchant is supplied sufficiently. Depending on the pressure levels, the etch rate varied in a complicated way. Parameter effects on the profile angle were very small and the profile angle varied between 83 deg. and 87 deg. for all etching experiments. In nearly all experiments, microtrenching was observed. The etch rate and profile angle, optimized at 1000 W source power, 30 W bias power, 6 mTorr pressure, and 60 sccm C{sub 2}F{sub 6} flow rate, are 434 nm/min and 86 deg., respectively.

  7. Feedback control of chlorine inductively coupled plasma etch processing

    SciTech Connect

    Lin Chaung; Leou, K.-C.; Shiao, K.-M.

    2005-03-01

    Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2{sup 2} factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained.

  8. UV-Photoassisted Etching of GaN in KOH

    SciTech Connect

    Abernathy, C.R.; Auh, K.H.; Cho, H.; Donovan, S.M.; Han, J.; Lambers, E.S.; Pearton, S.J.; Ren F.; Shul, R.J.

    1998-11-12

    The etch rate of GaN under W-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n - 3x 10^12Gcm-3) GaN are 2 1000 .min-l. The etching is diffusion limited under our conditions with an activation energy of - 0.8kCal.mol-1. The etched surfaces are rough, but retain their stoichiometry. PEC etching is found to selectively reveal grain boundaries in GaN under low light illumination conditions. At high lamp powers the rates increase with sample temperature and the application of bias to the PEC cell, while they go through a maximum with KOH solution molarity. The etching is diffusion-limited, producing rough surface morphologies that are suitable in a limited number of device fabrication steps. The surfaces however appear to remain relatively close to their stoichiometric composition.

  9. Dry etching technologies for the advanced binary film

    NASA Astrophysics Data System (ADS)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Yoshimori, Tomoaki; Azumano, Hidehito; Muto, Makoto; Nonaka, Mikio

    2011-11-01

    ABF (Advanced Binary Film) developed by Hoya as a photomask for 32 (nm) and larger specifications provides excellent resistance to both mask cleaning and 193 (nm) excimer laser and thereby helps extend the lifetime of the mask itself compared to conventional photomasks and consequently reduces the semiconductor manufacturing cost [1,2,3]. Because ABF uses Ta-based films, which are different from Cr film or MoSi films commonly used for photomask, a new process is required for its etching technology. A patterning technology for ABF was established to perform the dry etching process for Ta-based films by using the knowledge gained from absorption layer etching for EUV mask that required the same Ta-film etching process [4]. Using the mask etching system ARES, which is manufactured by Shibaura Mechatronics, and its optimized etching process, a favorable CD (Critical Dimension) uniformity, a CD linearity and other etching characteristics were obtained in ABF patterning. Those results are reported here.

  10. Porous silicon formation during Au-catalyzed etching

    SciTech Connect

    Algasinger, Michael; Bernt, Maximilian; Koynov, Svetoslav; Stutzmann, Martin

    2014-04-28

    The formation of “black” nano-textured Si during the Au-catalyzed wet-chemical etch process was investigated with respect to photovoltaic applications. Cross-sectional scanning electron microscopy (SEM) images recorded at different stages of the etch process exhibit an evolution of a two-layer structure, consisting of cone-like Si hillocks covered with a nano-porous Si (np-Si) layer. Optical measurements confirm the presence of a np-Si phase which appears after the first ∼10 s of the etch process and continuously increases with the etch time. Furthermore, the etch process was investigated on Si substrates with different doping levels (∼0.01–100 Ω cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 Ω cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of “black” Si on various Si substrates, which is of significant interest for photovoltaic applications.

  11. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Yun; Wong, Ching-Ping

    2014-12-01

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag

  12. Rapid recipe formulation for plasma etching of new materials

    NASA Astrophysics Data System (ADS)

    Chopra, Meghali; Zhang, Zizhuo; Ekerdt, John; Bonnecaze, Roger T.

    2016-03-01

    A fast and inexpensive scheme for etch rate prediction using flexible continuum models and Bayesian statistics is demonstrated. Bulk etch rates of MgO are predicted using a steady-state model with volume-averaged plasma parameters and classical Langmuir surface kinetics. Plasma particle and surface kinetics are modeled within a global plasma framework using single component Metropolis Hastings methods and limited data. The accuracy of these predictions is evaluated with synthetic and experimental etch rate data for magnesium oxide in an ICP-RIE system. This approach is compared and superior to factorial models generated from JMP, a software package frequently employed for recipe creation and optimization.

  13. Chlorine-based plasma etching of GaN

    SciTech Connect

    Shul, R.J.; Briggs, R.D.; Pearton, S.J.; Vartuli, C.B.; Abernathy, C.R.; Lee, J.W.; Constantine, C.; Baratt, C.

    1997-02-01

    The wide band gap group-III nitride materials continue to generate interest in the semiconductor community with the fabrication of green, blue, and ultraviolet light emitting diodes (LEDs), blue lasers, and high temperature transistors. Realization of more advanced devices requires pattern transfer processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {micro}m/min. The utilization of high-density chlorine-based plasmas including electron cyclotron resonance (ECR) and inductively coupled plasma (ICP) systems has resulted in improved GaN etch quality over more conventional reactive ion etch (RIE) systems.

  14. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2004-11-16

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  15. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2006-06-27

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  16. Metal-assisted chemical etch porous silicon formation method

    DOEpatents

    Li, Xiuling; Bohn, Paul W.; Sweedler, Jonathan V.

    2004-09-14

    A thin discontinuous layer of metal such as Au, Pt, or Au/Pd is deposited on a silicon surface. The surface is then etched in a solution including HF and an oxidant for a brief period, as little as a couple seconds to one hour. A preferred oxidant is H.sub.2 O.sub.2. Morphology and light emitting properties of porous silicon can be selectively controlled as a function of the type of metal deposited, Si doping type, silicon doping level, and/or etch time. Electrical assistance is unnecessary during the chemical etching of the invention, which may be conducted in the presence or absence of illumination.

  17. Structural and magnetic etch damage in CoFeB

    SciTech Connect

    Krayer, L.; Lau, J. W.; Kirby, B. J.

    2014-05-07

    A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

  18. Ultrasensitive Visual Sensing of Molybdate Based on Enzymatic-like Etching of Gold Nanorods.

    PubMed

    Zhang, Zhiyang; Chen, Zhaopeng; Chen, Lingxin

    2015-08-25

    Here, we have developed a novel approach to the visual detection of molybdate with high sensitivity and selectivity in aqueous media based on the combination of catalytic formation of iodine and iodine-mediated etching of gold nanorods. In weak acid solution, like peroxidase, molybdate can catalyze the reaction between H2O2 and I(-) to produce I2, a moderate oxidant, which then etches gold nanorods preferentially along the longitudinal direction in the presence of hexadecyltrimethylammonium bromide. The etching results in the longitudinal localized surface plasmon resonance extinction peak shifts to short wavelength, accompanied by a color change from blue to red. Under optimal conditions, this sensor exhibits good sensitivity with a detection limit of 1.0 nM. The approach is highlighted by its high selectivity and tolerance to interference, which enables the sensor to detect molybdate directly in real samples, such as tap water, drinking water, and seawater. In addition, perhaps the proposed sensing strategy can be also used for other targets that can selectively regulate the formation of I2 under given conditions. PMID:26226196

  19. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    PubMed

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise. PMID:25958585

  20. Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl{sub 2} ion beam assisted etching

    SciTech Connect

    Anglin, Kevin Goodhue, William D.; Swint, Reuel B.; Porter, Jeanne

    2015-03-15

    A deeply etched, anisotropic 45° and 90° mirror technology is developed for Al{sub x}Ga{sub 1−x}As heterostructures using a Cl{sub 2} ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si{sub 3}N{sub 4}-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar{sup +} ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.

  1. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    PubMed

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

  2. Osteoporotic bone microstructure by collagenase etching.

    PubMed Central

    Mackie, I G; Green, M; Clarke, H; Isaac, D H

    1989-01-01

    Collagenase etching has been used to show the microstructure of bone from patients suffering from primary osteoporosis. Both polished and unpolished surfaces of trabecular bone from femoral heads were treated with collagenase solution before study in the scanning electron microscope. The polished surfaces show the mineral component of this bone as small rounded units approximately 10-20 nm across, which aggregate to form a continuous phase of contiguous spheroidal particles approximately 100 nm across. Lamellations are clearly seen to be due to the removal of collagen fibres up to approximately 200 nm across, fibres in adjacent lamellae being arranged approximately perpendicular to each other. The unpolished surfaces also show small rounded units, which aggregate into rods of mineral approximately 100 nm across. Although these rods form a connected system, they are loosely packed, compatible with their being interspersed with the collagen fibres in vivo. This model for the detailed microstructure of bone is consistent with specimens from a number of other sources and shows no features unique to osteoporosis. Images PMID:2545170

  3. Ion orbits in plasma etching of semiconductors

    SciTech Connect

    Madziwa-Nussinov, Tsitsi G.; Arnush, Donald; Chen, Francis F.

    2008-01-15

    Fabrication of high-speed semiconductor circuits depends on etching submicron trenches and holes with straight walls, guided by sheath accelerated ions, which strike the substrate at a normal angle. Electrons accumulate at the nonconductive entrance of each trench, charging it negatively and preventing the penetration of electrons to the bottom of the trench. This 'electron shading' effect causes an ion charge at the bottom, which is well known to cause damage to thin oxide layers. In addition, the deflection of ions by electric fields in the trench can cause deformation of the trench shape. To study this effect, the ion orbits are computed self-consistently with their charging of the trench walls. It is found that (a) the orbits depend only on the electric fields at the entrance and are sensitive to changes in the shape of the photoresist layer there; (b) there is an 'ion shading' effect that protects part of the wall; and (c) the number of ions striking the wall is too small to cause any deformation thereof.

  4. Pattern inspection of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2015-07-01

    Patterned mask inspection for an etched multilayer (ML) EUV mask was investigated. In order to optimize the mask structure from the standpoint of not only a pattern inspection by using a projection electron microscope (PEM), but also by considering the other fabrication processes using electron beam (EB) techniques such as CD metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients (SEECs) of the candidate materials for conductive layer, we evaluated the image contrast and the influence of charging effect. In the cases of 40-pair-ML, 16 nm sized extrusion and intrusion defects were found to be detectable more than 10 sigma in hp 44 nm, 40 nm, and 32 nm line and space (L/S) patterns. Reducing 40-pair-ML to 20-pair-ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16 nm sized defects remained detectable. A double layer structure with 2.5-nm-thik B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  5. Automated process control for plasma etching

    NASA Astrophysics Data System (ADS)

    McGeown, Margaret; Arshak, Khalil I.; Murphy, Eamonn

    1992-06-01

    This paper discusses the development and implementation of a rule-based system which assists in providing automated process control for plasma etching. The heart of the system is to establish a correspondence between a particular data pattern -- sensor or data signals -- and one or more modes of failure, i.e., a data-driven monitoring approach. The objective of this rule based system, PLETCHSY, is to create a program combining statistical process control (SPC) and fault diagnosis to help control a manufacturing process which varies over time. This can be achieved by building a process control system (PCS) with the following characteristics. A facility to monitor the performance of the process by obtaining and analyzing the data relating to the appropriate process variables. Process sensor/status signals are input into an SPC module. If trends are present, the SPC module outputs the last seven control points, a pattern which is represented by either regression or scoring. The pattern is passed to the rule-based module. When the rule-based system recognizes a pattern, it starts the diagnostic process using the pattern. If the process is considered to be going out of control, advice is provided about actions which should be taken to bring the process back into control.

  6. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  7. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  8. Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

    PubMed

    Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

    2014-02-01

    The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding. PMID:24372961

  9. Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

    PubMed

    Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

    2014-02-01

    The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding.

  10. Reactive Ion Etching in a VHF Parallel Plate Reactor

    NASA Technical Reports Server (NTRS)

    Dahi, H.; Murnick, D. E.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    VHF (very high frequency) capacitive plasma reactors may allow development of new RIE (reactive ion etching) systems with high etch rates, excellent uniformity and anisotropy and low damage. High ion and radical fluxes can be obtained by raising the RF (radio frequency) frequency which increases plasma density dramatically at a fixed voltage. The effects of variation in frequency (25-120 MHz), pressure (10-250 mTorr), and flow rate (1-100 sccm) in a CF4 discharge have been investigated. The RF current versus voltage characteristics and spatially resolved optical emission are used as diagnostics. Experiments on etch rates, etch uniformity and anisotropy in silicon, silicon dioxide and silicon nitride will be discussed. Results of fluid model simulations are used to interpret the experimental data.

  11. Summary of Chalcogenide Glass Processing: Wet-Etching and Photolithography

    SciTech Connect

    Riley, Brian J.; Sundaram, S. K.; Johnson, Bradley R.; Saraf, Laxmikant V.

    2006-12-01

    This report describes a study designed to explore the different properties of two different chalcogenide materials, As2S3 and As24S38Se38, when subjected to photolithographic wet-etching techniques. Chalcogenide glasses are made by combining chalcogen elements S, Se, and Te with Group IV and/or V elements. The etchant was selected from the literature and was composed of sodium hydroxide, isopropyl alcohol, and deionized water and the types of chalcogenide glass for study were As2S3 and As24S38Se38. The main goals here were to obtain a single variable etch rate curve of etch depth per time versus NaOH overall solution concentration in M and to see the difference in etch rate between a given etchant when used on the different chalcogenide stoichiometries. Upon completion of these two goals, future studies will begin to explore creating complex, integrated photonic devices via these methods.

  12. Influence of doping on the etching of Si(111)

    NASA Astrophysics Data System (ADS)

    Winters, Harold F.; Haarer, D.

    1987-10-01

    Exposure of solid surfaces to reactive gases (or radicals) often leads to chemical reactions which produce volatile products. These are frequently called etching reactions. The example discussed in this paper involves the reaction of XeF2 with Si(111) to produce SiF4(gas). It will be shown that the etch rate depends strongly upon the concentration and type of dopant. It also depends upon the thickness of the fluorosilyl (SiFx) layer on the surface. The trends previously observed in plasma-assisted etching environments are shown to also occur in the XeF2-Si reaction. A simple model will be developed which indicates a strong correlation between the number of negative ions on the surface and the etch rate. The model is based upon some of the ideas originally proposed by Mott and Cabrera to describe oxide growth and on the Poisson-Boltzmann equation which describes the space charge at a semiconductor interface.

  13. Restoration of canine disocclusion by using etched porcelain onlays.

    PubMed

    Glaser, C G; Nagy, W W

    1991-03-01

    The restoration of a progressive delayed disocclusion on periodontally healthy canines by etched porcelain onlays has been presented as a suitable treatment alternative to interrupt bruxism and reverse destructive occlusal neuroses.

  14. Visible luminescence from silicon wafers subjected to stain etches

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; George, T.; Ksendzov, A.; Vasquez, R. P.

    1992-01-01

    Etching of Si in a variety of solutions is known to cause staining. These stain layers consist of porous material similar to that produced by anodic etching of Si in HF solutions. In this work, photoluminescence peaked in the red from stain-etched Si wafers of different dopant types, concentrations, and orientations produced in solutions of HF:HNO3:H2O was observed. Luminescence is also observed in stain films produced in solutions of NaNO2 in HF, but not in stain films produced in solutions of CrO3 in HF. The luminescence spectra are similar to those reported recently for porous Si films produced by anodic etching in HF solutions. However, stain films are much easier to produce, requiring no special equipment.

  15. Polishing of quartz by rapid etching in ammonium bifluoride.

    PubMed

    Vallin, Orjan; Danielsson, Rolf; Lindberg, Ulf; Thornell, Greger

    2007-07-01

    The etch rate and surface roughness of polished and lapped AT-cut quartz subjected to hot (90, 110, and 130 degrees C), concentrated (50, 65, 80 wt %) ammonium bi-fluoride have been investigated. Having used principal component analysis to verify experimental solidity and analyze data, we claim with confidence that this parameter space does not, as elsewhere stated, allow for a polishing effect or even a preserving setting. Etch rates were found to correlate well, and possibly logarithmically, with temperature except for the hottest etching applied to lapped material. Roughness as a function of temperature and concentration behaved well for the lapped material, but lacked systematic variation in the case of the polished material. At the lowest temperature, concentration had no effect on etch rate or roughness. Future efforts are targeted at temperatures and concentrations closer to the solubility limit.

  16. 6. Photocopy of etching (from collection of New Hampshire Historical ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of etching (from collection of New Hampshire Historical Society, Concord, New Hampshire), post 1870 VIEW SOUTHEAST SHOWING WEST FRONT (ELEVATION) - Merchants' Exchange Block, 94-102 North Main Street, Concord, Merrimack County, NH

  17. Highly chemical reactive ion etching of gallium nitride

    SciTech Connect

    Karouta, F.; Jacobs, B.; Moerman, I.; Jacobs, K.; Weyher, J.L.; Porowski, S.; Crane, R.; Hageman, P.R.

    2000-07-01

    A highly chemical reactive ion etching process has been developed for MOVPE-grown GaN on sapphire. The key element for the enhancement of the chemical property during etching is the use of a fluorine containing gas in a chlorine based chemistry. In the perspective of using GaN substrates for homo-epitaxy of high quality GaN/AlGaN structures they have used the above described RIE process to smoothen Ga-polar GaN substrates. The RMS value, measured by AFM, went from 20 {angstrom} (after mechanical polishing) down to 4 {angstrom} after 6 minutes of RIE. Etching N-polar GaN resulted in a higher etch rate than Ga-polar materials (165 vs. 110 nm/min) but the resulting surface was quite rough and suffers from instability problems. Heat treatment and HCl dip showed a partial recovery of Schottky characteristics after RIE.

  18. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, Robert J.; Mayer, Steven T.; Tarte, Lisa A.

    1996-01-01

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment.

  19. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, R.J.; Mayer, S.T.; Tarte, L.A.

    1996-01-23

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment. 6 figs.

  20. 1. Photocopy of an early etching (Original in collection of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Photocopy of an early etching (Original in collection of the Historical Society of Montana) BROADWAY AND JACKSON ELEVATIONS - Second Masonic Temple, Broadway & Jackson Streets, Helena, Lewis and Clark County, MT

  1. 157. Copy of Louis Rosenberg Etching (original in the Tower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    157. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) TERMINAL TOWER UNDER CONSTRUCTION, STEEL FRAMEWORK OF THE SOUTHWEST WING, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

  2. Origin of electrical signals for plasma etching endpoint detection

    SciTech Connect

    Sobolewski, Mark A.

    2011-11-14

    Electrical signals are used for endpoint detection in plasma etching, but the origin of the electrical changes observed at endpoint is not known. They may be caused by changes in the gas-phase densities of etch products and reactants or by changes in substrate surface properties such as photoemitted or ion-induced electron yield. To investigate these effects, experiments were performed in an inductively coupled, rf-biased reactor, during CF{sub 4}/Ar etches of SiO{sub 2} films on Si wafers. The rf bias impedance was measured vs. time during etching, simultaneous with Langmuir probe measurements. At endpoint, a decrease in impedance coincided with increases in ion current and electron energy. The data, analyzed by a numerical model of the discharge, indicate that changes in electron emission yield were relatively insignificant or entirely absent. Thus the impedance change is not a surface effect but is, instead, predominantly or entirely a gas-phase phenomenon.

  3. Analysis of machining characteristics in electrochemical etching using laser masking

    NASA Astrophysics Data System (ADS)

    Shin, Hong Shik; Chung, Do Kwan; Park, Min Soo; Chu, Chong Nam

    2011-12-01

    Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.

  4. Catalytic etching of synthetic diamond crystallites by iron

    NASA Astrophysics Data System (ADS)

    Ohashi, Tatsuya; Sugimoto, Wataru; Takasu, Yoshio

    2012-08-01

    For the expansion of the functionality of diamond crystallites by modification of surface morphology, catalytic etching of synthetic diamond crystallites at 1173 K by iron, which were loaded by the impregnation method using an aqueous solution of iron nitrate; in a streaming mixed gas (pH2=0.1   MPa, pN2=0.9   MPa), has been investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The dependence of the crystal planes {1 1 1} and {1 0 0}, of the diamond crystallites and the loading amount of iron on the diamond on the etching behavior by iron particles, the morphology of the etch pits, and potential formation of iron carbide through the catalytic etching, were discussed.

  5. Photoluminescence from stain-etched polycrystalline Si thin films

    NASA Astrophysics Data System (ADS)

    Steckl, A. J.; Xu, J.; Mogul, H. C.

    1993-04-01

    Visible room-temperature photoluminescence has been observed from stain-etched polycrystalline Si thin films. Poly-Si thin films deposited on oxidized Si and quartz substrates became porous (PoSi) after stain-etching in a 1:3:5 solution of HF:HNO3:H2O. Under UV excitation, the stain-etched doped and undoped poly-Si films produce uniform orange-red (about 650 nm) luminescence very similar to that obtained from stain-etched crystalline Si substrates. Stained amorphous thin films did not exhibit photoluminescence. Luminescent patterns with sub-micrometer (about 0.6 micron) dimensions have been obtained for the first time from PoSi produced from poly-Si films.

  6. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    SciTech Connect

    Wang, Yufeng; Zeng, Yongbin Qu, Ningsong; Zhu, Di

    2015-07-15

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained.

  7. Advantages of p++ polysilicon etch stop layer versus p++ silicon

    NASA Astrophysics Data System (ADS)

    Charavel, Remy; Laconte, Jean; Raskin, Jean Pierre

    2003-04-01

    Boron highly doped silicon is now widely used as etch stop layer in MicroElectroMechanical Systems (MEMS) devices fabrication. The present paper shows the advantages of replacing the p++ Si etch stop layer by a p++ polysilicon layer. The etch rate of Tetramethylammoniunhydroxide (TMAH) is measured for LPCVD polysilicon and silicon doped with Boron at concentrations from 8.1018 up to 4.1020 atoms/cm3 which is the Boron solubility limit into Si. TMAH etch being often used during back-end process, selectivity to aluminium is usually needed. The etch selectivity of various TMAH solutions for p++ Si, p++ Poly and aluminium have been measured, from 25 % to 5 % TMAH pure and mixed with silicon powder and ammonium persulfate. Contrarily to silicon, polysilicon is etched isotropically in TMAH solution which constitutes a great advantage when cavities with vertical walls have to be opened. Although the polysilicon etch rate is higher than the silicon one, the selectivity (doped/undoped) is the same for the both materials, allowing identical uses. Another great advantage of polysilicon is that it can be deposited at any process step and does not require clever epitaxy steps or wafer bonding as for silicon. The surface roughness of the etched Poly region is considerably decreased with TMAH mixed with silicon powder and ammonium persulfate mixture compared to pure 25 % TMAH solution. The definition of buried masks in polysilicon layer through Boron implant is the main foreseen application. The p++ Poly buried mask brings solutions for the fabrication of self-aligned double gate MOS, microfluidic or optical networks in MEMS field.

  8. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    DOEpatents

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  9. Micro-textures and in situ sulfur isotopic analysis of spheroidal and zonal sulfides in the giant Jinding Zn-Pb deposit, Yunnan, China: Implications for biogenic processes

    NASA Astrophysics Data System (ADS)

    Xue, Chunji; Chi, Guoxiang; Fayek, Mostafa

    2015-05-01

    The Jinding deposit in Yunnan, southwest China, is the largest sandstone- and conglomerate-hosted Zn-Pb deposit in the world. In this paper, we report various micro-textures of spheroidal and zonal sulfides, such as pellet-shaped and colloform aggregates of pyrite and sphalerite, from the deposit and interpret them to be possibly related to micro-colonies of sulfate reducing bacteria, probably supporting an in situ BSR hypothesis. Micro-scale sulfur isotope analysis in different parts of the spheroidal and zonal sulfide aggregates, using secondary ion mass spectrometry (SIMS), revealed δ34S (VCDT) values as low as -48.4‰ for sulfides formed in the early-main stage disseminated ores in the western part of the deposit, possibly suggesting maximum sulfur isotopic fractionation through BSR. Relatively elevated δ34S (VCDT) values (-7.7‰ to -34.8‰, mainly from -10‰ to -20‰) for the late-stage, cavity-filling ores in the eastern part of the deposit, are interpreted to be possibly related to elevated temperatures close to the hydrothermal conduit and elevated δ34S values of the remaining sulfates resulting from the preceding BSR processes. The apparent discrepancy between the low temperatures required for BSR and the high temperatures indicated by fluid inclusions (>120 °C) may be reconciled through invoking episodic influx of ore-forming hydrothermal fluids into a shallow, relatively cool environment. It is proposed that the host rocks of the Jinding deposit have not been buried to great depths (⩽1 km), which, combined with the availability of hydrocarbons in the Jinding dome (a paleo-oil and gas reservoir), provides an ideal environment for BSR. Episodic influx of metal-carrying hydrothermal fluids temporarily and locally suppressed BSR and promoted thermo-chemical sulfate reduction (TSR), resulting in deposit- and micro-scale variations of δ34S.

  10. Integrated reactive ion etching to pattern cross-linked hydrophilic polymer structures for protein immobilization

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Parijat; Strickland, Aaron D.; Kim, Il; Malliaras, George G.; Batt, Carl A.

    2007-04-01

    Patterning of cross-linked hydrophilic polymer features using reactive ion etching (RIE) capable of covalently immobilizing proteins has been achieved. Projection photolithography was used to pattern photoresist to create micromolds. Vapor phase molecular self-assembly of polymerizable monolayer in molds allowed covalent binding of hydrogel on surface during free-radical polymerization. Excess hydrogel blanket film was consumed with oxygen RIE resulting into hydrogel pattern of 1μm size aligned to prefabricated silicon oxide structures. Proteins were finally coupled through their primary amine groups selectively to acid functionalized hydrogel features through stable amide linkages using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride and N-hydroxysulfosuccinimide.

  11. Hydrogen Bubbles and Formation of Nanoporous Silicon during Electrochemical Etching

    SciTech Connect

    Saraf, Laxmikant V.; Baer, Donald R.; Wang, Zheming; Young, James S.; Engelhard, Mark H.; Thevuthasan, Suntharampillai

    2005-06-01

    Many nanoporous Si structures, including those formed by common electrochemical etching procedures, produce a uniformly etch nanoporous surface. If the electrochemical etch rate is slowed down, details of the etch process can be explored and process parameters may be varied to test hypotheses and obtain controlled nanoporous and defect structures. For example, after electrochemical etching of a heavily n-doped (R = 0.05-0.5 ? -cm) <100> silicon at a current density of 10 mA/cm? in buffer oxide etch (BOE) electrolyte solution defect craters, containing textured nanopores, were observed to occur in ring shaped patterns of rings. The defect craters apparently originate at the hydrogen-BOE bubble interface, which forms during hydrogen evolution in the reaction. The slower hydrogen evolution due to low current density allows sufficient bubble residence time so that a high defect density appears at the bubble edges where local reaction rates are highest. Current carrying Si-OH species are most likely responsible for the widening in the craters. Reducing the defect/doping density in silicon lowers the defect concentration and thereby the density of nanopores. Measurements of photoluminescence lifetime and intensity show a distinct feature when the low density of nanopores formed at ring edges are isolated from each other. Overall features observed in photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) intensity strongly emphasize the role of surface oxide that influences these properties.

  12. Recouping etch rates in pulsed inductively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Stout, Phillip J.; Banna, Samer; Rauf, Shahid; Collins, Ken

    2011-01-15

    Pulsed rf plasmas are increasingly being employed for plasma etching at future technological nodes. Although the plasma uniformity usually improves with pulsing, the lower time-averaged power decreases the etch rate and the lower throughput is undesirable. It is therefore important to evaluate different strategies to restore higher etch rates while retaining the advantages of pulsed plasmas. In this work, the impact of varying pulsing modes in an inductively coupled plasma on plasma characteristics and feature profile evolution are discussed using the results from a two-dimensional reactor scale plasma model coupled to a Monte Carlo based feature profile model. Results are discussed for poly-Si etching in an Ar/Cl{sub 2} gas mixture. The consequences of source-only and bias-only pulsing modes on discharge characteristics, ion energy distributions (IEDs) to the wafer, and feature profile evolution are discussed. Although the etch depth rates were found to be higher for source-only pulsing compared to the synchronized (source and bias) pulsing mode, the higher ion energies in the afterglow period during source-only pulsing may also increase ion bombardment damage. Compensation of power may allow for increased etch depth rates while retaining the benefits of synchronized pulsing. Further, power compensation level can be varied to achieve fine tuning of the IEDs to the wafer.

  13. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Paetzelt, H.; Böhm, G.; Arnold, Th

    2015-04-01

    Local plasma-assisted etching of crystalline silicon by fine focused plasma jets provides a method for high accuracy computer controlled surface waviness and figure error correction as well as free form processing and manufacturing. We investigate a radio-frequency powered atmospheric pressure He/N2/CF4 plasma jet for the local chemical etching of silicon using fluorine as reactive plasma gas component. This plasma jet tool has a typical tool function width of about 0.5 to 1.8 mm and a material removal rate up to 0.068 mm3 min-1. The relationship between etching rate and plasma jet parameters is discussed in detail regarding gas composition, working distance, scan velocity and RF power. Surface roughness after etching was characterized using atomic force microscopy and white light interferometry. A strong smoothing effect was observed for etching rough silicon surfaces like wet chemically-etched silicon wafer backsides. Using the dwell-time algorithm for a deterministic surface machining by superposition of the local removal function of the plasma tool we show a fast and efficient way for manufacturing complex silicon structures. In this article we present two examples of surface processing using small local plasma jets.

  14. The grand challenges of plasma etching: a manufacturing perspective

    NASA Astrophysics Data System (ADS)

    Lee, Chris G. N.; Kanarik, Keren J.; Gottscho, Richard A.

    2014-07-01

    Plasma etching has been enabling nano-electronic fabrication since the 1980s; during this time, transistor size has shrunk by nearly two orders of magnitude, starting at 1.0 µm in the mid 80s to ˜0.01 µm today. The manufacturing of these devices requires overcoming a series of challenges, ranging from continuous innovation on device integration to extend Moore's law to breaking tradeoffs on the perennial challenge of aspect ratio-dependent etching. In this paper, we will review four key areas in etch manufacturing: uniformity, defects, surface precision and ‘sticky’/non-volatile etch materials. In the uniformity section, we will discuss the challenges for microscopic uniformity, such as localized feature dimension variations; macroscopic uniformity, such as performance at the extreme edge of the wafer; and repeatable uniformity, meaning wafer-to-wafer, lot-to-lot and chamber-to-chamber performance. While defect management is successful with in situ plasma cleans, one must be cognizant of the choice of clean chemistry. In surface precision, we look at the approach of atomic layer etching and how it can be successful in a manufacturing environment. Finally, in the non-volatile material section, we review technology drivers for DRAM (dynamic random access memory) and NAND flash memory in the microelectronics Si industry, with focus on the utilization of such materials and what it means to etch equipment manufacturers.

  15. Etching of germanium-tin using ammonia peroxide mixture

    SciTech Connect

    Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia; Zhang, Zheng; Pan, Jisheng; Tok, Eng-Soon

    2015-12-28

    The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

  16. Vapor etching of nuclear tracks in dielectric materials

    DOEpatents

    Musket, Ronald G.; Porter, John D.; Yoshiyama, James M.; Contolini, Robert J.

    2000-01-01

    A process involving vapor etching of nuclear tracks in dielectric materials for creating high aspect ratio (i.e., length much greater than diameter), isolated cylindrical holes in dielectric materials that have been exposed to high-energy atomic particles. The process includes cleaning the surface of the tracked material and exposing the cleaned surface to a vapor of a suitable etchant. Independent control of the temperatures of the vapor and the tracked materials provide the means to vary separately the etch rates for the latent track region and the non-tracked material. As a rule, the tracked regions etch at a greater rate than the non-tracked regions. In addition, the vapor-etched holes can be enlarged and smoothed by subsequent dipping in a liquid etchant. The 20-1000 nm diameter holes resulting from the vapor etching process can be useful as molds for electroplating nanometer-sized filaments, etching gate cavities for deposition of nano-cones, developing high-aspect ratio holes in trackable resists, and as filters for a variety of molecular-sized particles in virtually any liquid or gas by selecting the dielectric material that is compatible with the liquid or gas of interest.

  17. Plasma etching of polymers like SU8 and BCB

    NASA Astrophysics Data System (ADS)

    Mischke, Helge; Gruetzner, Gabi; Shaw, Mark

    2003-01-01

    Polymers with high viscosity, like SU8 and BCB, play a dominant role in MEMS application. Their behavior in a well defined etching plasma environment in a RIE mode was investigated. The 40.68 MHz driven bottom electrode generates higher etch rates combined with much lower bias voltages by a factor of ten or a higher efficiency of the plasma with lower damaging of the probe material. The goal was to obtain a well-defined process for the removal and structuring of SU8 and BCB using fluorine/oxygen chemistry, defined using variables like electron density and collision rate. The plasma parameters are measured and varied using a production proven technology called SEERS (Self Excited Electron Resonance Spectroscopy). Depending on application and on Polymer several metals are possible (e.g., gold, aluminum). The characteristic of SU8 and BCB was examined in the case of patterning by dry etching in a CF4/O2 chemistry. Etch profile and etch rate correlate surprisingly well with plasma parameters like electron density and electron collision rate, thus allowing to define to adjust etch structure in situ with the help of plasma parameters.

  18. Controlled Layer-by-Layer Etching of MoS₂.

    PubMed

    Lin, TaiZhe; Kang, BaoTao; Jeon, MinHwan; Huffman, Craig; Jeon, JeaHoo; Lee, SungJoo; Han, Wei; Lee, JinYong; Lee, SeHan; Yeom, GeunYoung; Kim, KyongNam

    2015-07-29

    Two-dimensional (2D) metal dichalcogenides like molybdenum disulfide (MoS2) may provide a pathway to high-mobility channel materials that are needed for beyond-complementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS2 devices. In this study, we propose a layer-by-layer removal of MoS2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar)(+) ion-beam desorption. MoS2 etching was not observed with only the Cl-radical adsorption or low-energy (<20 eV) Ar(+) ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar(+) ion-beam desorption step resulted in the complete etching of one monolayer of MoS2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer of MoS2 with each ALET cycle; therefore, the number of MoS2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS2.

  19. Laser etching technique using bubble jet impact for glass substrates

    NASA Astrophysics Data System (ADS)

    Weng, Tsu-Shien; Tsai, Chwan-Huei

    2015-03-01

    The purpose of this paper is to propose a new laser etching technique using bubble jet impact for glass substrates. An Nd:YAG laser is applied to the backside of the substrate which is partially submerged in water. A metal plate is placed below the glass substrate. The metal vaporizes the water and generates a turbulent bubble flow. The bubble nozzle is proposed to enhance the impact of the bubble jet. The glass surface will first be softened, and then expelled by the shock wave resulting from the jet impact. The phenomena of bubble nucleation, growth, collapse, and jet impact were studied in this paper. The formation of the etching cavity can be divided into three types: double-petal, triple-petal, and four-petal. The etching pits expanded and combined to form a complete cavity. The needed laser power does not exceed 5 W. The proposed laser etching method was successfully demonstrated for etching a cavity of 5-20 µm in depth and 50-250 µm in diameter. The bubble jet of the small nozzle diameter is well concentrated, creating a strong jet impact on the glass surface. A greater nozzle depth can enhance the impact of the bubble jet. The proposed etching technique has great potential to provide an improved solution for the micro-machining of glass.

  20. Etching of photoresist with an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    West, Andrew; van der Schans, Marc; Xu, Cigang; Gans, Timo; Cooke, Mike; Wagenaars, Erik

    2014-10-01

    Low-pressure oxygen plasmas are commonly used in semiconductor industry for removing photoresist from the surface of processed wafers; a process known as plasma ashing or plasma stripping. The possible use of atmospheric-pressure plasmas instead of low-pressure ones for plasma ashing is attractive from the point of view of reduction in equipment costs and processing time. We present investigations of photoresist etching with an atmospheric-pressure plasma jet (APPJ) in helium gas with oxygen admixtures driven by radio-frequency power. In these experiments, the neutral, radical rich effluent of the APPJ is used for etching, avoiding direct contact between the active plasma and the sensitive wafer, while maintaining a high etch rate. Photoresist etch rates and etch quality are measured for a range of plasma operating parameters such as power input, driving frequency, flow rate and wafer temperature. Etch rates of up to 10 micron/min were achieved with modest input power (45 W) and gas flow rate (10 slm). Fourier Transform Infrared (FTIR) spectroscopy showed that the quality of the photoresist removal was comparable to traditional plasma ashing techniques. This work was supported by the UK Engineering and Physical Sciences Research Council Grant EP/K018388/1.

  1. Integration of Nanotubes, Etch Tracks, and Nanoribbons in Crystallographic Alignment

    NASA Astrophysics Data System (ADS)

    Boland, Mathias J.; Hunley, D. Patrick; Sundrarajan, Abhishek; Nasseri, Mohsen; Strachan, Douglas R.

    2015-03-01

    Three nanomaterial components, carbon nanotubes (CNTs), few-layer graphene (FLG), and etch tracks exposing insulating SiO2 regions, are integrated to form crystallographically-aligned nanoscale systems. These integrated systems consist of CNTs grown across nanogap etch tracks and nanoribbons formed within the FLG films as a result of chemical vapor deposition (CVD) processing. Each nanoscale component is aligned along the underlying graphene lattice, resulting in their orientations being locked into precise values, with CNTs maintaining alignment even after crossing etch tracks. The growth of aligned CNTs across nanogap etch tracks and nanoribbons suggests that integrated formations can be achieved by growing CNTs directly over nanogap etch tracks and nanoribbons. This is supported by calculations of the vibrational energy of CNTs indicating that they should be capable of maintaining atomic registry with an underlying graphene lattice as they grow across a typical etch track, in agreement with our experimental results. Thus, this work is relevant to the integration of semiconducting, conducting, and insulating nano-materials all together into precise nano-electronic systems.

  2. The influence of H2O2 concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Omar, Hafsa; Jani, Abdul Mutalib Md.; Rusop, Mohamad; Abdullah, Saifollah

    2016-07-01

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

  3. Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation

    NASA Technical Reports Server (NTRS)

    Kane, R. D.; Petrovic, J. J.; Ebert, L. J.

    1975-01-01

    Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

  4. Metal-oxide-semiconductor characterization of silicon surfaces thermally oxidized after reactive ion etching and magnetically enhanced reactive ion etching

    SciTech Connect

    Settlemyer, K.T. Jr.; Ruzyllo, J.; Hwang, D.K.

    1993-03-01

    In this study the performance of reactive ion etching (RIE) and magnetically enhanced reactive ion etching (MERIE) processes in pregate oxidation etching of the field oxide are compared. The comparison is carried out through metal-oxide-semiconductor (MOS) characterization of oxides and interfaces formed on etched silicon surfaces. The results revealed differences in the outcome of RIE and MERIE processes with the latter displaying overall superior characteristics. MERIE induced surface damage is shallower, and is mostly removed during oxide growth. RIE damage propagates deeper into the Si bulk and still influences the MOS devices even after the top Si layers are converted into the oxide. The results obtained emphasize the importance of adequate cleaning of silicon surfaces following RIE/MERIE processes. 5 refs., 4 figs.

  5. Comparison of acidulated phosphate fluoride gel and hydrofluoric acid etchants for porcelain-composite repair.

    PubMed

    Tylka, D F; Stewart, G P

    1994-08-01

    Hydrofluoric acid etches porcelain to produce a porous surface visible under scanning electron microscopy when compared to an acidulated phosphate fluoride gel. Some investigators have suggested the greater porosity of the hydrofluoric acid etch produces a greater composite-to-porcelain bond. This investigation tested that assumption with two common fluoride etchants. The etched surfaces were first viewed under scanning electron microscopy to ensure that a characteristic etch was achieved. Both etchants yielded bond strengths that produced cohesive failure of all samples. This suggested that the intraoral use of hydrofluoric acid is no more effective than the less dangerous acidulated phosphate fluoride gel.

  6. A randomized control clinical trial of fissure sealant retention: Self etch adhesive versus total etch adhesive

    PubMed Central

    Aman, Nadia; Khan, Farhan Reza; Salim, Aisha; Farid, Huma

    2015-01-01

    Context: There are limited studies on comparison of Total etch (TE) and Self etch (SE) adhesive for placement of sealants. Aims: The aim of the study was to compare the retention of fissure sealants placed using TE adhesive to those sealants placed using SE (seventh generation) adhesive. Settings and Design: The study was conducted in the dental section, Aga Khan University Hospital. This study was a randomized single blinded trial with a split mouth design. Materials and Methods: The study included 37 patients, 101 teeth were included in both study groups. The intervention arm was treated with SE Adhesive (Adper Easy One, 3M ESPE, US). Control arm received TE adhesive (Adper Single Bond 2, 3M ESPE, US) before sealant application. The patients were followed after 6 months for assessment of sealant retention. Statistical analysis used: Interexaminer agreement for outcome assessment was assessed by Kappa Statistics and outcome in intervention group was assessed by McNemar's test. Results: Ninety-one pairs of molar (90%) were reevaluated for sealant retention. Complete retention was 56% in TE arm and 28% in SE arm with an odds ratio (OR) of 3.7. Conclusions: Sealants applied with TE adhesives show higher rate of complete sealant retention than SE adhesive. PMID:25657521

  7. Split-it!: from litho etch litho etch to self-aligned double patterning decomposition

    NASA Astrophysics Data System (ADS)

    Badr, Yasmine A.; Wassal, Amr G.; Hammouda, Sherif

    2012-11-01

    Double Patterning (DP) is still the most viable lithography option for sub-22nm nodes. The two main types of DP are Litho Etch Litho Etch (LELE) and Self-Aligned Double Patterning (SADP). Of those two, SADP has the advantage of lower sensitivity to overlay error. However SADP imposes a lot of restrictions on the layout. One of the ways to do SADP decomposition is to use an LELE decomposer while prohibiting stitches, and to generate mandrel and trim masks from LELE masks using some Boolean characterization equations. In this paper, we propose an SADP decomposer based on an LELE decomposer that is used to decide which target polygons are mandrel and which are non-mandrel. However the core of the LELE decomposer has been made SADP-aware, such that it gives less priority to pairs of polygons separated by spacing values that are prohibited by SADP. Then, a mandrel and trim masks generator uses the LELE decomposer output and produces the final mandrel and trim masks. Experimental results show that adding SADPawareness to the core of the decomposer has decreased the average number of coloring conflicts by 38%. The proposed decomposer is faster than the previous SADP decomposition approaches that use Integer Linear Programming (ILP) and Satisfiability (SAT).

  8. Evaluating the shear bond strength of enamel and dentin with or without etching: A comparative study between dimethacrylate-based and silorane-based adhesives

    PubMed Central

    Hajizadeh, Hila; Nasseh, Atefeh; Rahmanpour, Naim

    2015-01-01

    Background Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching. Material and Methods 40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- Filtek P90 composite and Silorane adhesive. Each group divided into two subgroups: with or without additional etching. For additional etching, 37% acid phosphoric was applied before bonding procedure. A cylinder of the composite was bonded to the surface. After 24 hours storage and 500 thermo cycling between 5-55°C, shear bond strength was assessed with the cross head speed of 0.5 mm/min. Then, bonded surfaces were observed under stereomicroscope to determine the failure mode. Data were analyzed with two-way ANOVA and Fischer exact test. Results Shear bond strength of Filtek P60 composite was significantly higher than Filtek P90 composite both in enamel and dentin surfaces (P<0.05). However, additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites (P>0.05). There was no interaction between composite type and additional etching (P>0.05). Failure pattern was mainly adhesive and no significant correlation was found between failure and composite type or additional etching (P>0.05). Conclusions Shear bond strength of methacrylate-based composite was significantly higher than silorane-based composite both in enamel and dentin surfaces and additional etching had no significant effect on shear bond strength in enamel or dentin for

  9. Reactive ion etching of silicon using low-power plasma etcher

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Bakun, A. D.; Voronov, Yu A.

    2016-09-01

    The paper is devoted to the study of deep reactive ion etching of silicon using diode plasma etcher system with a low-power source. Silicon wafers were etched in a sulfur hexafluoride plasma and sulfur hexafluoride/oxygen plasma. The maximum achieved silicon etch rate was about 2 μm/min. The expediency of using dry reactive ion etching in combination with wet anisotropic etching of silicon for manufacturing of microelectromechanical systems (MEMS) was demonstrated.

  10. Evaluation of a chemical etching solution for nickel-chromium-beryllium and chromium-cobalt alloys.

    PubMed

    Ferrari, M; Cagidiaco, M C; Borracchini, A; Bertelli, E

    1989-11-01

    Two chemical etching solutions were capable of providing micromechanical retention in two nickel-chromium-beryllium alloys and in a chromium-cobalt alloy. A resin matrix was used to verify the quality of etching on the metal surfaces. The chemical etching solutions created high microretentive surfaces in nickel-chromium-beryllium alloy but the chromium-cobalt alloy surfaces after etching were less retentive. Improved chemical etching technique should encourage expanded use of the resin-bonded retainers.

  11. Parallel preparation of plan-view transmission electron microscopy specimens by vapor-phase etching with integrated etch stops.

    PubMed

    English, Timothy S; Provine, J; Marshall, Ann F; Koh, Ai Leen; Kenny, Thomas W

    2016-07-01

    Specimen preparation remains a practical challenge in transmission electron microscopy and frequently limits the quality of structural and chemical characterization data obtained. Prevailing methods for thinning of specimens to electron transparency are serial in nature, time consuming, and prone to producing artifacts and specimen failure. This work presents an alternative method for the preparation of plan-view specimens using isotropic vapor-phase etching with integrated etch stops. An ultrathin amorphous etch-stop layer simultaneously serves as an electron transparent support membrane whose thickness is defined by a controlled growth process such as atomic layer deposition with sub-nanometer precision. This approach eliminates the need for mechanical polishing or ion milling to achieve electron transparency, and reduces the occurrence of preparation induced artifacts. Furthermore, multiple specimens from a plurality of samples can be thinned in parallel due to high selectivity of the vapor-phase etching process. These features enable dramatic reductions in preparation time and cost without sacrificing specimen quality and provide advantages over wet etching techniques. Finally, we demonstrate a platform for high-throughput transmission electron microscopy of plan-view specimens by combining the parallel preparation capabilities of vapor-phase etching with wafer-scale micro- and nanofabrication.

  12. Etching properties and electrical characterization of surfaces of silicon-on-insulator substrates in presence of halogens

    SciTech Connect

    Abbadie, A.; Hamaide, G.; Chaupin, M.; Brunier, F.; Mariolle, D.; Martinez, E.; Maehliss, J.

    2012-03-15

    We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I{sup -}, Br{sup -}...) in HF/HNO{sub 3}/CH{sub 3}COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br{sup -}, I{sup -}..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.

  13. Method for Fabricating Textured High-Haze ZnO:Al Transparent Conduction Oxide Films on Chemically Etched Glass Substrates.

    PubMed

    Park, Hyeongsik; Nam, Sang-Hun; Shin, Myunghun; Ju, Minkyu; Lee, Youn-Jung; Yu, Jung-Hoon; Jung, Junhee; Kim, Sunbo; Ahn, Shihyun; Boo, Jin-Hyo; Yi, Junsin

    2016-05-01

    We developed a technique for forming textured aluminum-doped zinc oxide (ZnO:Al) transparent conductive oxide (TCO) films on glass substrates, which were etched using a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids. The etching depth and surface roughness increased with an increase in the HF content and the etching time. The HF-based residues produced insoluble hexafluorosilicate anion- and oxide impurity-based semipermeable films, which reduced the etching rate. Using a small amount of HCl dissolved the Ca compounds, helping to fragment the semipermeable film. This formed random, complex structures on the glass substrates. The angled deposition of three layers of ZnO:Al led to the synthesis of multiscaled ZnO:Al textures on the glass substrates. The proposed approach resulted in textured ZnO:Al TCO films that exhibited high transmittance (-80%) and high haze (> 40%) values over wavelengths of 400-1000 nm, as well as low sheet resistances (< 18 Ω/sq)..Si tandem solar cells based on the ZnO:Al textured TCO films exhibited photocurrents and cell efficiencies that were 40% higher than those of cells with conventional TCO films. PMID:27483840

  14. Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching

    PubMed Central

    2011-01-01

    Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics. PMID:21711891

  15. Etching properties and electrical characterization of surfaces of silicon-on-insulator substrates in presence of halogens

    NASA Astrophysics Data System (ADS)

    Abbadie, A.; Hamaide, G.; Mariolle, D.; Chaupin, M.; Brunier, F.; Martinez, E.; Mähliß, J.

    2012-03-01

    We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I-, Br-…) in HF/HNO3/CH3COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br-, I-..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.

  16. Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

    PubMed

    Weinreich, Wenke; Acker, Jörg; Gräber, Iris

    2007-03-30

    In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control. PMID:19071540

  17. A high efficiency industrial polysilicon solar cell with a honeycomb-like surface fabricated by wet etching using a photoresist mask

    NASA Astrophysics Data System (ADS)

    Zhang, Hong; Ding, Bin; Chen, Tianhang

    2016-11-01

    In this paper, an effective and low cost method of texturization was introduced into the fabrication process for industrial multicrystalline silicon solar cell production. The purpose of the method was to reduce reflectance by creating a honeycomb-like textured surface using a masked wet etching process. A negative photoresist film was selected as an etching mask. Although large surface roughness of wafer was considered to affect the adhesion and acid resistance of etching mask, a honeycomb-like textured surface with a pitch of 18 μm was fabricated successfully. The etched pits had a nearly smooth spherical segment surface, an average aperture of 15.1 μm, and a depth of 6.5 μm. This regular textured surface had a low light reflectivity of approximately 20.5% and greatly increased the carrier lifetime. Compared with multicrystalline silicon solar cells textured by conventional acid etching, the average short circuit current increased by 2.2% and the average efficiency increased from 17.41% to 17.75%, a net gain of 0.34%. And a high throughput above 2400 pieces per hour was obtained. This texturing technique is expected to promote the application of diamond-wire cut multicrystalline silicon wafers with the low saw-damage in the future.

  18. Preliminary surface analysis of etched, bleached, and normal bovine enamel

    SciTech Connect

    Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C. )

    1990-09-01

    X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

  19. Advanced Simulation Technology to Design Etching Process on CMOS Devices

    NASA Astrophysics Data System (ADS)

    Kuboi, Nobuyuki

    2015-09-01

    Prediction and control of plasma-induced damage is needed to mass-produce high performance CMOS devices. In particular, side-wall (SW) etching with low damage is a key process for the next generation of MOSFETs and FinFETs. To predict and control the damage, we have developed a SiN etching simulation technique for CHxFy/Ar/O2 plasma processes using a three-dimensional (3D) voxel model. This model includes new concepts for the gas transportation in the pattern, detailed surface reactions on the SiN reactive layer divided into several thin slabs and C-F polymer layer dependent on the H/N ratio, and use of ``smart voxels''. We successfully predicted the etching properties such as the etch rate, polymer layer thickness, and selectivity for Si, SiO2, and SiN films along with process variations and demonstrated the 3D damage distribution time-dependently during SW etching on MOSFETs and FinFETs. We confirmed that a large amount of Si damage was caused in the source/drain region with the passage of time in spite of the existing SiO2 layer of 15 nm in the over etch step and the Si fin having been directly damaged by a large amount of high energy H during the removal step of the parasitic fin spacer leading to Si fin damage to a depth of 14 to 18 nm. By analyzing the results of these simulations and our previous simulations, we found that it is important to carefully control the dose of high energy H, incident energy of H, polymer layer thickness, and over-etch time considering the effects of the pattern structure, chamber-wall condition, and wafer open area ratio. In collaboration with Masanaga Fukasawa and Tetsuya Tatsumi, Sony Corporation. We thank Mr. T. Shigetoshi and Mr. T. Kinoshita of Sony Corporation for their assistance with the experiments.

  20. Range and etching behaviour of swift heavy ions in polymers

    NASA Astrophysics Data System (ADS)

    Singh, Lakhwant; Singh, Mohan; Samra, Kawaljeet Singh; Singh, Ravinder

    Aliphatic (CR-39) and aromatic (Lexan polycarbonate) polymers have been irradiated with a variety of heavy ions such as 58Ni, 93Nb, 132Xe, 139La, 197Au, 208Pb, 209Bi, and 238U having energy ranges of 5.60-8.00 MeV/n in order to study the range and etching kinetics of heavy ion tracksE The ion fluence (range ˜104-105 ions/cm2) was kept low to avoid the overlapping of etched tracks. The measured values of maximum etched track length were corrected due to bulk etching and over etching to obtain the actual range. The experimental results of range profiles were compared with those obtained by the most used procedures employed in obtaining range and stopping power. The range values of present ions have been computed using the semiempirical codes (SRIM-98, SRIM-2003.26, and LISE++:0-[Hub90]) in order to check their accuracy. The merits and demerits of the adopted formulations have been highlighted in the present work. It is observed that the range of heavy ions is greater in aromatic polymers (Lexan polycarbonate) as compared to the aliphatic polymers (CR-39) irradiated with similar ions having same incident energies. The SRIM-98 and SRIM2003.26 codes don't show any significant trend in deviations, however, LISE++:0-[Hub90] code provides overall good agreement with the experimental values. The ratio of track etch rate (along projectile trajectory) to the bulk etch rate has also been studied as a function of energy loss of heavy ions in these polymers.

  1. Laser-assisted dry etching of III-nitride wide band gap semiconductor materials

    NASA Astrophysics Data System (ADS)

    Leonard, Robert Tyler

    Laser assisted dry etching is a materials processing technique capable of producing highly anisotropic etch features with precise etch depth control and little contamination. The technique is simple: laser radiation is combined with a gaseous chemical etchant to remove material in pattern selected regions. The advantages of laser etching include the removal of etch products with photonic energy instead of ion bombardment, potential of projected patterning to combine growth and etching in situ without exposure to air, production of distinct sidewall etch features for device structures, and precise control of etching with a highly directional pulsed laser energy source. The use of pulsed laser radiation allows for pulsed etch depth control, ultimately resulting in atomic layer control. Laser assisted dry HCl etching of GaN, AlGaN and InGaN optical device materials was first demonstrated in our laboratory at North Carolina State University in a modified UHV vacuum chamber and ArF (193nm) excimer laser. Effective masking materials of Al and SiOsb2 were determined to be resistant to laser heating and HCl environment for laser etching. The process variables of laser intensity and HCl pressure were found to be dominant with the necessary condition that no etching occurs without both the excimer laser and HCl present. Successful laser etching of GaN, AlGaN, and InGaN was demonstrated indicating that deep etch features with distinct sidewall features are possible with this technique. Laser etching of a III-Nitride quantum well double heterostructure resulted in no degradation of the photoluminescence response. Also, reduction of etch damage with laser etching may be possible in comparison to ion etching. Finally, a proposed model for the etching mechanism includes the photothermal release of nitrogen from the GaN surface resulting in a Ga-rich surface which is removed by the HCl etchant.

  2. Dry etch development of W/WSi short Gate MESFETs

    SciTech Connect

    Shul, R.J.; Sherwin, M.E.; Baca, A.G.; Zolper, J.C.; Rieger, D.J.

    1996-01-01

    The use of refractory metal thin films in the fabrication of high-speed, high-density GaAs field effect transistors (FETs) are prominent with applications as interconnects, via plugs, and ohmic and Schottky contacts. Tungsten and tungsten silicide can be used in a self-aligned gate process as the ion implantation mask during the formation of source and drain regions for metal-semiconductor FETs (MESFETs). The gate etch must be highly anisotropic to accurately define the implant region. Reactive ion etch (RIE) techniques have been used to etch W and WSi films in fluorine-based discharges. The etch mechanism tends to be very chemical and often results in severe undercutting of the feature due to the lateral attack of the refractory metal. The undercut is often so severe that critical dimensions are not maintained and gate profiles do not properly align to the implant region resulting in poor device characteristics. As device design rules shrink, the etch requirements and patterning techniques become even more critical.

  3. Plasma chemistry dependent ECR etching of GaN

    SciTech Connect

    Shul, R.J.; Ashby, C.I.H.; Rieger, D.J.

    1995-12-31

    Electron cyclotron resonance (ECR) etching of GaN in Cl{sub 2}/H{sub 2}/Ar, C1{sub 2}/SF{sub 6}/Ar, BCl{sub 3}/H{sub 2}/Ar and BCl{sub 3}/SF{sub 6}/Ar plasmas is reported as a function of percent H{sub 2} and SF{sub 6}. GaN etch rates were found to be 2 to 3 times greater in Cl{sub 2}/H{sub 2}/Ar discharges than in BCl{sub 3}/H{sub 2}/Ar discharges independent of the H{sub 2} concentration. In both discharges, the etch rates decreased as the H{sub 2} concentration increased above 10%. When SF{sub 6} was substituted for H{sub 2}, the GaN etch rates in BCl{sub 3}-based plasmas were greater than those for the Cl{sub 2}-based discharges as the SF{sub 6} concentration increased. GaN etch rates were greater in Cl{sub 2}/H{sub 2}/Ar discharges as compared to Cl{sub 2}SF{sub 6}/Ar discharges whereas the opposite trend was observed for BCl{sub 3}-based discharges. Variations in surface morphology and near-surface stoichiometry due to plasma chemistries were also investigated using atomic force microscopy and Auger spectroscopy, respectively.

  4. Environmental photostability of SF6-etched silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Liptak, R. W.; Yang, J.; Kramer, N. J.; Kortshagen, U.; Campbell, S. A.

    2012-10-01

    We report on the long-term environmental stability of the photoluminescent (PL) properties of silicon nanocrystals (SiNCs). We prepared sulfur hexafluoride (SF6) etched SiNCs in a two-stage plasma reactor and investigated their PL stability against UV irradiation in air. Unlike SiNCs with hydrogen-passivated surfaces, the SF6-etched SiNCs exhibit no photobleaching upon extended UV irradiation despite surface oxidation. Furthermore, the PL quantum yield also remains stable upon heating the SF6-etched SiNCs up to 160 °C. The observed thermal and UV stability of SF6-etched SiNCs combined with their PL quantum yields of up to ˜50% make them attractive candidates for UV downshifting to enhance the efficiency of solar cells. Electron paramagnetic spin resonance indicates that the SF6-etched SiNCs have a lowered density of defect states, both as-formed and after room temperature oxidation in air.

  5. Etching Effects During the Chemical Vapor Deposition of (100) Diamond

    SciTech Connect

    Battaile, C.C.; Srolovitz, D.J.; Oleinik, I.I.; Pettifor, D.G.; Sutton, A.P.; Harris, S.J.; Butler, J.E.

    1999-08-02

    Current theories of CVD growth on (100) diamond are unable to account for the numerous experimental observations of slow-growing, locally smooth (100)(2x1) films. In this paper they use quantum mechanical calculations of diamond surface thermochemistry and atomic-scale kinetic Monte Carlo simulations of deposition to investigate the efficacy of preferential etching as a mechanism that can help to reconcile this discrepancy. This etching mechanism allows for the removal of undercoordinated carbon atoms from the diamond surface. In the absence of etching, simulated growth on the (100)(2x1) surface is faster than growth on the (110) and (111) surfaces, and the (100) surface is atomically rough. When etching is included in the simulations, the (100) growth rates decrease to values near those observed experimentally, while the rates of growth on the other surfaces remain largely unaffected and similar to those observed experimentally. In addition, the etching mechanism promotes the growth of smooth (100) surface regions in agreement with numerous scanning probe studies.

  6. Dry-wet digital etching of Ge1-xSnx

    NASA Astrophysics Data System (ADS)

    Shang, Colleen K.; Wang, Vivian; Chen, Robert; Gupta, Suyog; Huang, Yi-Chiau; Pao, James J.; Huo, Yijie; Sanchez, Errol; Kim, Yihwan; Kamins, Theodore I.; Harris, James S.

    2016-02-01

    The development of a precise micromachining process for Ge1-xSnx has the potential to enable both the fabrication and optimization of Ge1-xSnx-based devices in photonics and microelectromechanical systems. We demonstrate a digital etching scheme for Ge0.922Sn0.078 based on a two-stage, highly selective CF4 plasma dry etch and HCl wet etch. Using X-Ray Reflectivity, we show consistent etch control as low as 1.5 nm per cycle, which is defined as one dry etch step followed by one wet etch step. The etch rate increases to 3.2 nm per cycle for a longer dry etch time due to physical sputtering contributions, accompanied by an increase in RMS surface roughness. By operating within a regime with minimal sputtering, we demonstrate that good digital etch depth control and surface quality can be achieved using this technique.

  7. Photonic crystal membrane reflectors by magnetic field-guided metal-assisted chemical etching

    SciTech Connect

    Balasundaram, Karthik; Mohseni, Parsian K.; Li, Xiuling E-mail: xiuling@illinois.edu; Shuai, Yi-Chen; Zhao, Deyin; Zhou, Weidong E-mail: xiuling@illinois.edu

    2013-11-18

    Metal-assisted chemical etching (MacEtch) is a simple etching method that uses metal as the catalyst for anisotropic etching of semiconductors. However, producing nano-structures using MacEtch from discrete metal patterns, in contrast to interconnected ones, has been challenging because of the difficulties in keeping the discrete metal features in close contact with the semiconductor. We report the use of magnetic field-guided MacEtch (h-MacEtch) to fabricate periodic nanohole arrays in silicon-on-insulator (SOI) wafers for high reflectance photonic crystal membrane reflectors. This study demonstrates that h-MacEtch can be used in place of conventional dry etching to produce ordered nanohole arrays for photonic devices.

  8. Dissolution kinetics and etch pit studies of potassium aluminium sulphate

    NASA Astrophysics Data System (ADS)

    van der Hoek, B.; Van Enckevort, W. J. P.; Van Der Linden, W. H.

    1983-03-01

    The dissolution process of the {111} faces of potash alum is studied, both by microtopographic examinations of the etch pit patterns and by measurement of the dissolution kinetics in a rotating disc crystallizer. Both methods showed that the Cabrera-Levine dissolution theory holds for the two most common dislocation types ending on the {111} faces of potash alum. On the basis of the rotating disc experiments, the interfacial supersaturation of the etch pit experiments was roughly estimated. Using this, it was found that at interfacial supersaturations below -0.6% (dislocations with <110> Burgers vector) or below -0.85% (dislocations with <100> Burgers vector) numerous etch pits related to those dislocation types appeared. Below those undersaturations the dissolution process is mainly determined by volume diffusion. From the critical undersaturation, determined in the rotating disc crystallizer, the value of the edge free energy of a step was found to be approximately 0.01 J/m 2.

  9. Novel diamantane polymer platform for enhanced etch resistance

    NASA Astrophysics Data System (ADS)

    Padmanaban, Munirathna; Chakrapani, Srinivasan; Lin, Guanyang; Kudo, Takanori; Parthasarathy, Deepa; Rahman, Dalil; Anyadiegwu, Clement; Antonio, Charito; Dammel, Ralph R.; Liu, Shenggao; Lam, Frederick; Waitz, Anthony; Yamagchi, Masao; Maehara, Takayuki

    2007-03-01

    The dominant current 193 nm photoresist platform is based on adamantane derivatives. This paper reports on the use of derivatives of diamantane, the next higher homolog of adamantane, in the diamondoid series, as monomers in photoresists. Due to their low Ohnishi number and incremental structural parameter (ISP), such molecules are expected to enhance dry etch stability when incorporated into polymers for resist applications. Starting from the diamantane parent, cleavable and non-cleavable acrylate/methacrylate derivatives of diamantane were obtained using similar chemical steps as for adamantane derivatization. This paper reports on the lithographic and etch performance obtained with a number of diamantane-containing monomers, such as 9-hydroxy-4-diamantyl methacrylate (HDiMA), 2-ethyl-2- diamantyl methacrylate (EDiMA), and 2-methyl-2-diamantyl methacrylate (MDiMA). The etch advantage, dry and wet lithographic performance of some of the polymers obtained from these diamantane-containing polymers are discussed.

  10. Profile etching for prefiguring X-ray mirrors.

    PubMed

    Liu, Chian; Qian, Jun; Assoufid, Lahsen

    2015-03-01

    A method to pre-shape mirror substrates through etching with a broad-beam ion source and a contoured mask is presented. A 100 mm-long elliptical cylinder substrate was obtained from a super-polished flat Si substrate with a 48 nm root-mean-square (r.m.s.) figure error and a 1.5 Å r.m.s. roughness after one profile-etching process at a beam voltage of 600 V without iteration. A follow-up profile coating can be used to achieve a final mirror. Profile etching and profile coating combined provide an economic way to make X-ray optics, such as nested Kirkpatrick-Baez mirrors.

  11. Surface Modification of Nitinol by Chemical and Electrochemical Etching

    NASA Astrophysics Data System (ADS)

    Yang, Zhendi; Wei, Xiaojin; Cao, Peng; Gao, Wei

    2013-07-01

    In this paper, Nitinol, an equiatomic binary alloy of nickel and titanium, was surface modified for its potential biomedical applications by chemical and electrochemical etching. The main objective of the surface modification is to reduce the nickel content on the surface of Nitinol and simultaneously to a rough surface microstructure. As a result, better biocompatibility and better cell attachment would be achieved. The effect of the etching parameters was investigated, using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectrometry (XPS). The corrosion property of modified Nitinol surfaces was investigated by electrochemical work station. After etching, the Ni content in the surface layer has been reduced and the oxidation of Ti has been enhanced.

  12. Study of etching rate uniformity in SRF cavities

    SciTech Connect

    Janardan Upadhyay, Svetozar Popovic, Leposova Vuskovic, H. Phillips, Anne-Marie Valente

    2012-07-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in the gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and chlorine concentration in the Argon/Chlorine gas mixtures.

  13. Method and apparatus for spatially uniform electropolishing and electrolytic etching

    DOEpatents

    Mayer, Steven T.; Contolini, Robert J.; Bernhardt, Anthony F.

    1992-01-01

    In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed.

  14. Method and apparatus for spatially uniform electropolishing and electrolytic etching

    DOEpatents

    Mayer, S.T.; Contolini, R.J.; Bernhardt, A.F.

    1992-03-17

    In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed. 6 figs.

  15. Fabrication of sub-15 nm aluminum wires by controlled etching

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Marković, N.

    2014-04-01

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  16. Plasma etching of superconducting Niobium tips for scanning tunneling microscopy

    SciTech Connect

    Roychowdhury, A.; Dana, R.; Dreyer, M.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.

    2014-07-07

    We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 μm diameter are dry etched in an SF₆ plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100), and Nb(100), as well as a doped topological insulator Bi₂Se₃ at temperatures ranging from 30 mK to 9 K.

  17. Method of plasma etching Ga-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2012-12-25

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

  18. Method of plasma etching GA-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2013-01-01

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

  19. Effect of thermocycling on the durability of etch-and-rinse and self-etch adhesives on dentin.

    PubMed

    Sangwichit, Ketkamon; Kingkaew, Ruksaphon; Pongprueksa, Pong; Senawongse, Pisol

    2016-01-01

    The objective was to compare bond strengths of adhesives with/without thermocycling and to analyze the micromorphology of resindentin interfaces. Flat dentin surfaces were prepared and divided into eight groups to bond with four etch-and-rinse adhesives (Optibond FL, Adper Scotchbond Multi-Purpose, Optibond Solo Plus, and Single Bond 2) and four self-etch adhesives (Clearfil SE Bond, Adper SE Plus, Clearfil S(3) Bond and Adper Easy Bond). Specimens were further divided into two subgroups subjected for with/without thermocycling and then subjected to both micro-tensile test and resin-dentin interface evaluation. The results revealed that there were significant differences in bond strength between the groups with and without thermocycling for all etch-and-rinse groups and for the Adper Easy Bond self-etch group (p<0.01). Clearfil SE Bond demonstrated highly durable bond strengths. Furthermore, more silver ion uptake was observed at the resin-dentin interfaces for all etch-and-rinse adhesives and Adper SE Plus and Adper Easy Bond after thermocycling. PMID:27251990

  20. pH-controlled selective etching of Al2O3 over ZnO.

    PubMed

    Sun, Kaige G; Li, Yuanyuan V; Saint John, David B; Jackson, Thomas N

    2014-05-28

    We describe pH-controlled selective etching of atomic layer deposition (ALD) Al2O3 over ZnO. Film thickness as a function of etch exposure was measured by spectroscopic ellipsometry. We find that alkaline aqueous solutions with pH between about 9 and 12 will etch Al2O3 at useful rate with minimal attack of ZnO. Highly selective etching of Al2O3 over ZnO (selectivity >400:1) and an Al2O3 etch rate of ∼50 nm/min can be obtained using a pH 12 etch solution at 60 °C. PMID:24818868