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Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers  

Microsoft Academic Search

The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses\\u000a in order to release and roll up InGaAs\\/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching\\u000a regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds\\u000a as expected and one

Ruxandra M. Costescu; Christoph Deneke; Dominic J. Thurmer; Oliver G. Schmidt



Mitigation of surface damage growth by hydrofluoric acid etching combined with carbon dioxide laser treatment  

NASA Astrophysics Data System (ADS)

Damage sites as large as 600 ?m in fused silica surface were successfully mitigated with a new protocol by hydrofluoric acid (HF) etching combined with carbon dioxide laser treatment. The damage sites were first etched in 40% HF solution to blunt the fractures, and then the etched damage sites were smoothed with a CO2 laser. It has been found that the etching rate of damaged material in the lateral direction is larger than in the longitudinal direction; thus, an optimized etching time was chosen to etch the damage sites based on the etching ratio. Three types of damage test methods were used to confirm the mitigation efficiency of the protocol. The results indicate that the damage resistance capability of mitigated sites can recover to the level of pristine substrate.

Jiang, Yong; Yuan, Xiaodong; He, Shaobo; Zheng, Wanguo; Wang, Haijun; Lü, Haibing; Ren, Wei; Luo, Chengsi; Liu, Chunming; Xiang, Xia; Zu, Xiaotao



Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers  

NASA Astrophysics Data System (ADS)

The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

Costescu, Ruxandra M.; Deneke, Christoph; Thurmer, Dominic J.; Schmidt, Oliver G.



Masking effect of copper during anisotropic etching of silicon in buffered hydrofluoric acid solutions  

NASA Astrophysics Data System (ADS)

The etching characteristics of silicon samples of (100) orientation in buffered hydrofluoric acid (BHF) solutions containing different levels of dissolved copper were studied systematically using atomic force microscopy, total reflection x-ray fluorescence, inductively coupled plasma mass spectroscopy and transmission electron microscopy techniques. It was found that the presence of trace amounts of copper ions in BHF solutions can cause not only metallic contamination but also very severe surface roughness. Copper deposits onto the silicon surfaces in the form of submonoatomic layer clusters which act as masks during silicon anisotropic etching in BHF solutions. Surface roughness as high as 12 nm was generated in 30 min of etching in buffered hydrofluoric acid solution containing 100 ppb Cu2+. Cross-sectional TEM micrographs showed that silicon was etched anisotropically in BHF solutions containing Cu2+ ions. Etching rates as high as 1.0 nm/min were obtained on the (100) planes of p-type silicon in the presence of a 100 ppb Cu2+. The size of the etching structures depends on the Cu2+ concentration in solution and the etching time.

Li, Guangming; Jiao, Jun; Seraphin, Supapan; Raghavan, Srini; Jeon, Joong S.



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


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 reproducible for the SPME of PAHs. PMID:19445486

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



Focus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid  

E-print Network

characterized by weight loss, brittle bones, anemia, and general ill health. Safe use If possible, avoid workingFocus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid Hydrofluoric acid (HF bone. Skin exposure to highly concentrated HF (48% or greater) immediately results in serious

Wilcock, William


Deep Wet Etching in Hydrofluoric Acid, Nitric Acid, and Acetic Acid of Cavities in a Silicon Wafer  

NASA Astrophysics Data System (ADS)

This paper reports an experimental investigation of deep isotropic etching in HF:HNO3:CH3COOH solution for the fabrication of large microcavities in a silicon wafer. The effects of different practical parameters, e.g., back protective layer, etch window diameter and agitation method, are evaluated experimentally and then discussed. Results show that, for the conditions used, the back protective layer has little influence on the etched depth. Experimental etched profiles are in agreement with the mathematical model of Kuiken's assuming a purely diffusion-controlled etching. Vertical anisotropy and asymmetry of etched profiles were observed. A 100 µm deep hemispherical microcavity was obtained for a 60 min etching with magnetic agitation at room temperature.

Yifan, Zhou; Sihai, Chen; Edmond, Samson; Bosseboeuf, Alain



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


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. PMID:23388452

Ahmad, Muthanna; Grime, Geoffrey W



40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.  

...Applicability; description of the hydrofluoric acid production subcategory. 415.80 Section...MANUFACTURING POINT SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.80 Applicability; description of the hydrofluoric acid production subcategory. The...



Physics Division ESH Bulletin 2007-01 Working with Hydrofluoric Acid Solutions  

E-print Network

Physics Division ESH Bulletin 2007-01 Working with Hydrofluoric Acid Solutions The Physics Division has a procedure, Using Hydrofluoric Acid, that must be followed when working with this acid with hydrofluoric acid. Definition: Hydrofluoric acid (HF) is a very corrosive solution of hydrogen fluoride


Hydrofluoric acid burn: latent period was key factor  

SciTech Connect

To clean oxidation from silver soldering on a copper component, a technician used a commercial solution containing 15% hydrofluoric acid. At 9:30 a.m., the technician finished the job. The solution was used for approximately 1 hr. He removed his protective clothing and washed up, but not thoroughly (since there was no indication of anything out of the ordinary). It was not until 5:30 p.m. that he felt a burning sensation in one hand and his fingers started turning white (indicative of an acid burn). Because of the one day lapse of time since the exposure, specific hydrofluoric acid emergency treatment was not given. The next morning he saw the hand surgeon who injected calcium gluconate into the burned area. Later the wounds were debrided. Serious damage to the fingers could have resulted had the hydrofluoric acid reached the bone. Fortunately, the hydrofluoric acid had not penetrated as far as expected and, after debridement of the upper tissue, only a few minor scars remained. Three months after the accident, his hand was still swollen, and the use and dexterity of his fingers had not fully returned. After seven months, dexterity had returned although some swelling remained.

Stencel, J.R.; Tobin, J.S.



Hydrofluoric acid burn: latent period was key factor  

Microsoft Academic Search

To clean oxidation from silver soldering on a copper component, a technician used a commercial solution containing 15% hydrofluoric acid. At 9:30 a.m., the technician finished the job. The solution was used for approximately 1 hr. He removed his protective clothing and washed up, but not thoroughly (since there was no indication of anything out of the ordinary). It was

J. R. Stencel; J. S. Tobin



Title: Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Prepared By: Associate Director, WSEP  

E-print Network

Title: Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Prepared By: Associate Director, WSEP........................................................................................................ 6 #12;Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Date effective: July 21, 2010 Workplace DF #12;Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Date effective: July 21, 2010 Workplace

Saskatchewan, University of


Nanopores in GaN by electrochemical anodization in hydrofluoric acid: Formation and mechanism  

NASA Astrophysics Data System (ADS)

We report the use of hydrofluoric acid (HF) as an electrolyte in etching and porosifying GaN. HF is found to be effective in rendering a wide range of nanoporous morphology, from curved branches to highly parallel straight pores. Under suitable conditions, the porosification proceeds at a rate greater than 100 ?m/min. To elucidate the etching mechanism, cyclic voltammetry is performed, together with a parametric mapping of electrolysis variables such as the doping of GaN, the concentration of HF electrolyte, and the anodization voltage. We demonstrate that the formation of nanoporous structures is largely due to the local breakdown of the reverse-biased semiconductor junction. A quantitative agreement between the estimated width of space-charge region and the observed variation in morphology lends support to a depletion layer model developed previously in the etching of porous-Si.

Chen, Danti; Xiao, Hongdi; Han, Jung



Distillation Separation of Hydrofluoric Acid and Nitric Acid from Acid Waste Using the Salt Effect on Vapor-Liquid Equilibrium  

NASA Astrophysics Data System (ADS)

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor-liquid equilibrium for acid aqueous solutions and acid mixtures. The vapor-liquid equilibrium of hydrofluoric acid + salt systems (fluorite, potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed a salting-out effect on the vapor-liquid equilibrium of the hydrofluoric acid-water system. Fluorite and potassium nitrate showed a salting-in effect on the hydrofluoric acid-water system. Separation of hydrofluoric acid from an acid mixture containing nitric acid and hydrofluoric acid was tested by the simple distillation treatment using the salt effect of cesium nitrate (45 mass%). An acid mixture of nitric acid (5.0 mol · dm-3) and hydrofluoric acid (5.0 mol · dm-3) was prepared as a sample solution for distillation tests. The concentration of nitric acid in the first distillate decreased from 5.0 mol · dm-3 to 1.13 mol · dm-3, and the concentration of hydrofluoric acid increased to 5.41 mol · dm-3. This first distillate was further distilled without the addition of salt. The concentrations of hydrofluoric acid and nitric acid in the second distillate were 7.21 mol · dm-3 and 0.46 mol · dm-3, respectively. It was thus found that the salt effect on vapor-liquid equilibrium of acid mixtures was effective for the recycling of acids from acid mixture wastes.

Yamamoto, Hideki; Sumoge, Iwao



Balloon-borne observations of mid-latitude hydrofluoric acid  

NASA Technical Reports Server (NTRS)

Measurements of stratospheric hydrofluoric acid (HF) have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35 deg N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N2O profiles, indicate an average rate of HF increase of (5.5 +/- 0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements.

Sen, B.; Toon, G. C.; Blavier, J.-F.; Szeto, J. T.; Fleming, E. L.; Jackman, C. H.



Effect of hydrofluoric acid (HF) concentration to pores size diameter of silicon membrane.  


This paper studies parameters which affect the pore size diameter of a silicon membrane. Electrochemical etching is performed in characterise the parameter involved in this process. The parameter has been studied is volume ratio of hydrofluoric acid (HF) and ethanol as an electrolyte aqueous for electrochemical etch. This electrolyte aqueous solution has been mixed between HF and ethanol with volume ratio 3:7, 5:5, 7:3 and 9:1. As a result, the higher volume of HF in this electrolyte gives the smallest pore size diameter compared to the lower volume of HF. These samples have been dipped into HF and ethanol electrolyte aqueous with supplied 25 mA/cm2 current density for 20, 30, 40, and 50 minutes. The samples will inspect under Scanning Electron Microscope (SEM) to execute the pore formations on silicon membrane surface. PMID:25226919

Burham, Norhafizah; Hamzah, Azrul Azlan; Majlis, Burhanuddin Yeop




Microsoft Academic Search

Stress corrosion cracking (SCC) of Monel 400 in hydrofluoric acid vapour has been investigated by slow strain rate testing. The effect of grain size, cold work and galvanic coupling has been studied. The as-received hot rolled material has shown intergranular cracking, the 50% cold worked material transgranular cracking with decreased susceptibility and the 60% material immunity to SCC. A decrease

R. Kumar; U. K. Chatterjee


A study to determine the efficacy of treatments for hydrofluoric acid burns.  


Hydrofluoric acid burns are characterized by progressive tissue destruction and severe pain. Fluoride ion chelators, such as salts of calcium and magnesium, have been used to treat these burns. This study was designed to compare the efficacy of several treatment methods that involve the use of these salts. Standard hydrofluoric acid burns were produced on the shaved hindquarters of rats. After being rinsed with water, the chemical burns were treated by one of seven experimental methods. The progress of the chemical burn damage was observed for 1 week by measuring the surface areas of the burns. Calcium gluconate burn jelly, 20% calcium gluconate in water, and 50% aqueous dimethyl sulfoxide did not significantly slow the spread of the burn area. However, subcutaneous injections of calcium gluconate or magnesium sulfate and topical applications of calcium gluconate in a solution of dimethyl sulfoxide significantly slowed the progress of the burns during the first 24 hours and enhanced tissue recovery for the remainder of the observation period. These results indicate that subcutaneous injections of magnesium or calcium salts appear to be more effective than conventional topical applications in the treatment of hydrofluoric acid burns. More significantly, topically applied calcium gluconate combined with a penetration enhancer, such as dimethyl sulfoxide, is as effective as injection treatments in reducing damage caused by hydrofluoric acid. PMID:7673304

Seyb, S T; Noordhoek, L; Botens, S; Mani, M M



Detection of hydrofluoric acid by a SiO2 sol-gel coating fiber-optic probe based on reflection-based localized surface plasmon resonance.  


A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO(2) sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO(2) sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations. PMID:22319388

Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang



Adhesion of resin composite to hydrofluoric acid-exposed enamel and dentin in repair protocols.  


Intraoral repairs of ceramic fixed-dental-prostheses (FDP) often include cervical recessions that require pretreatment of the exposed tooth surfaces either before or after the ceramic is conditioned with hydrofluoric (HF) acid gel. The sequence of repair protocol may cross-contaminate the exposed etched enamel or dentin surfaces during the application or rinsing process and thereby affect the adhesion. This study evaluated the influence of HF acid gel with two concentrations on bond strengths of composite to enamel and dentin. Human third molars (N=100, n=10 per group) with similar sizes were selected and randomly divided into 10 groups. Flat surfaces of enamel and dentin were created by wet ground finishing. Before or after the enamel (E) or dentin (D) was conditioned with phosphoric acid (P), substrate surfaces were conditioned with either 9.5% HF (HF(9.5)) or 5% HF (HF(5)). Subsequently, a bonding agent (B) was applied. The experimental groups by conditioning sequence were as follows where the first letter of the group abbreviation represents the substrate (E or D) followed by the acid type and concentration: group 1 (EPHF(9.5)), group 2 (EPHF(5)), group 3 (EHF(9.5)P), group 4 (EHF(5)P), group 5 (DPHF(9.5)), group 6 (DPHF(5)), group 7 (DHF(9.5)P), and group 8 (DHF(5)P). Group 9 (EPB) and group 10 (DPB) acted as the control groups. Repair resin was adhered incrementally onto the conditioned enamel and dentin in polyethylene molds. Each layer was photo-polymerized for 40 seconds. All specimens were thermocycled (×1000, 5°-55°C) and subjected to shear test (universal testing machine, 1 mm/min). Specimens that debonded during thermocycling were considered as 0 MPa. The bond strength data were analyzed using Kruskal-Wallis test and failure types using the chi-square test (?=0.05). Overall, the bond results (MPa) were lower on dentin than on enamel (p<0.01). EPB (25.6 ± 6.6) and DPB (20.2 ± 4.9) control groups showed significantly higher results than those of other groups (p<0.05). While higher mean bond strengths were obtained in group 1 (EPHF(9.5)) (11.5 ± 2.1) and group 2 (EPHF(5)) (7.3 ± 0.6), lower results were obtained when HF acid gels were applied prior to phosphoric acid (EHF(9.5)P: 5.0 ± 1.1, EHF(5)P: 3.6 ± 0.1) (p<0.05). On dentin, the results were the lowest in group 8 (DHF(5)P: 1.5 ± 1.6), being significantly lower than those of group 5 (DPHF(9.5)) (p<0.05). Scanning electron microscope (SEM) images revealed predominantly mixed failures with less than half of the composite left on both enamel and dentin surfaces (64 out of 80) (p<0.05), indicating that in general, adhesion was not ideal. Contamination of the enamel or dentin surfaces with HF acid gel impairs the bond strength of composites. Considering both the bond strength results and failure types, when dental tissues are to be repaired next to ceramic, application of phosphoric acid before HF acid gel application can be recommended. HF acid gel concentration did not influence the results except on enamel. PMID:21859315

Saracoglu, A; Ozcan, M; Kumbuloglu, O; Turkun, M



Mechanical Properties of Thermoplastic Polyurethanes Laminated Glass Treated by Acid Etching Combined with Cold Plasma  

NASA Astrophysics Data System (ADS)

To overcome the problem of interlaminar delamination of thermoplastic polyurethane laminated glass, silicate glass was etched with hydrofluoric acid and thermoplastic polyurethane was then treated with cold plasma. Compared with the untreated samples, the interlaminar shear strength of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 97%, 84% and 341%, respectively. Acid etching combined with cold plasma-treated samples exhibited a higher flexural strength and strain as compared with the untreated samples. The impact energy of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 8.7%, 8.1% and 11.6%, respectively, in comparison with the untreated samples. FT-IR analysis showed that a large number of –C=O, –CO–N and –CO–O–C– groups appeared on the surface of cold plasma-treated thermoplastic polyurethane, which resulted in the formation of hydrogen bonds. SEM results showed that some pittings formed on the surface of the silicate glass treated by acid etching, which resulted in the formation of a three-dimensional interface structure between the silicate glass and polyurethane. Hydrogen bonds combined with the three-dimensional interface between silicate glass and polyurethanes co-improved the mechanical properties of thermoplastic polyurethanes laminated glass.

Li, Xibao; Lu, Jinshan; Luo, Junming; Zhang, Jianjun; Ou, Junfei; Xu, Haitao



Intra-Arterial Calcium Gluconate Treatment After Hydrofluoric Acid Burn of the Hand  

SciTech Connect

Hydrofluoric acid (HF) is a colorless corrosive acid used in different industrial branches. Exposure to HF typically results from spills, and most often the hand or fingers are involved. Tissue damage through cutaneous HF exposure occurs through corrosive burns due to the free hydrogen ions and through skin penetration of the fluoride ions, causing a depletion of calcium in the deep tissue layers, ultimately leading to cell death and tissue necrosis. Treatment of HF burns consists of thoroughly flushing the exposed area with water and applying calcium gluconate gel to the skin. If topical treatment does not suffice, subcutaneous injections, as well as intravascular-both intravenous and intra-arterial-calcium gluconate therapy, have been advocated. We report for the first time a case of HF burn of the hand and digits associated with vasospasm. Pain and vasospasm were successfully treated by repeated intra-arterial calcium gluconate injection. We conclude that intra-arterial calcium gluconate injection is a successful and well-tolerated therapy for HF burn associated with Raynaud's syndrome. Intra-arterial injection allows for well-controlled delivery of therapy as well as assessment of the vascular status.

Thomas, D., E-mail:; Jaeger, U. [Radiologische Universitaetsklinik, Universitaet Bonn (Germany); Sagoschen, I. [Klinikum der Johannes Gutenberg Universitaet, Poison Control Center, Medizinische Klinik und Poliklinik II (Germany); Lamberti, C. [Universitaet Bonn, Medizinische Klinik und Poliklinik I (Germany); Wilhelm, K. [Radiologische Universitaetsklinik, Universitaet Bonn (Germany)



EXAFS Study of the Speciation of Protactinium(V) in Aqueous Hydrofluoric Acid Solutions.  


The speciation of protactinium(V) in hydrofluoric acid (HF) solutions was studied using X-ray absorption spectroscopy. Extended X-ray absorption fine structure measurements were performed on an aqueous solution of 0.05 M protactinium(V) with various HF concentrations ranging from 0.5 to 27 M in order to probe the protactinium coordination sphere with respect to the identity and number of coordinating ligands. The resulting fits to the spectra suggest the presence of an eight-coordinate homoleptic fluoro complex in highly concentrated fluoride solutions (27 M), with equilibrium between seven- and eight-coordinate fluoro complexes at moderate acidities, and in more dilute solutions, results indicate that one water molecule is likely to replace a fluoride in the first coordination sphere, at a distance of 2.54-2.57 Å. Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed. PMID:25389749

De Sio, Stéphanie M; Wilson, Richard E



Successful extracorporeal life support after potentially fatal pulmonary oedema caused by inhalation of nitric and hydrofluoric acid fumes.  


Two patients presented with potentially fatal pulmonary oedema after accidental exposure to nitric and hydrofluoric acid fumes during electroplating. Despite aggressive respiratory support, one succumbed to respiratory failure 3.5h after inhalation. The other patient also rapidly progressed to respiratory failure. Extracorporeal life support (ECLS) was started 5h after exposure at the ED. During ECLS, hypoxia improved, but pulmonary oedema shown by chest radiography became aggravated. N-Acetyl cysteine and calcium gluconate were given i.v. on the first day of admission and nebulised for 48 h after exposure. Pulmonary secretions were significantly reduced 24 h after the nebulising therapy began. Ultimately, the patient was discharged without serious pulmonary or neurological complications after 28 days of hospitalisation. In this case, early ECLS, nebulised antioxidant and antidote were available to treat potentially fatal pulmonary oedema after exposure to nitric and hydrofluoric acid fumes. PMID:17507140

Shin, Jae Seung; Lee, Sung-Woo; Kim, Nak-Hoon; Park, Jon-Su; Kim, Kwang Ja; Choi, Sung-Hyuk; Hong, Yun-Sik



Study of the effect of DCCA and hydrofluoric acid contents on metric and topological parameters of silica membranes  

Microsoft Academic Search

In this work we studied the effects of drying control chemical additive (DCCA's), for instance formamide, N,N-dimethylformamide and propylene carbonate as well as the effect of hydrofluoric acid on structural parameters related to the evaluation of pore connectivity and permeability of sol-gel membranes. In order to study the effect of drying additives, we used a molar ratio additive\\/alkoxide of 1\\/1.

R. F. S. Lenza; W. L. Vasconcelos



Galvanically coupled gold/silicon-on-insulator microstructures in hydrofluoric acid electrolytes: finite element simulation and morphological analysis of electrochemical corrosion  

NASA Astrophysics Data System (ADS)

During the post-processing of silicon (Si) microsystems in hydrofluoric acid (HF)-based solutions, a galvanic couple is formed between the Si (anode) and metallic overlayers (cathode), such as gold (Au). Electrochemical etching (corrosion) of the exposed Si results in a porous silicon (PS) film and substantial degradation of mechanical and electrical properties occur. Focused ion beam milling (FIB) of micro-scale silicon-on-insulator (SOI) devices post-processed using HF solutions is used to determine the depth uniformity of the PS as a function of the geometry of the device. As the dopant concentration of the Si is critical to corrosion, dynamic SIMS is employed to assess the dopant concentration profile in SOI. As a means to model corrosion, we present a finite element method (FEM) enabled simulation to model the galvanic corrosion process on Si microsystems exposed to HF. The model uses an analogy to heat transfer to represent electrical conduction and accounts for electrochemical kinetics using the Tafel equation to represent empirical electrochemical measurements of Au and Si in HF. The model reproduces the current-limited condition resulting from the finite surface area of metal relative to silicon and predicts the uniform etch rate across the device for surfactant-enhanced HF solutions as seen in FIB. This work can be extended to applications where forming PS using a galvanic method may be advantageous.

Becker, C. R.; Miller, D. C.; Stoldt, C. R.



Development of a continuous process for adjusting nitrate, zirconium, and free hydrofluoric acid concentrations in zirconium fuel dissolver product  

SciTech Connect

In the Fluorinel Dissolution Process (FDP) upgrade, excess hydrofluoric acid in the dissolver product must be complexed with aluminum nitrate (ANN) to eliminate corrosion concerns, adjusted with nitrate to facilitate extraction, and diluted with water to ensure solution stability. This is currently accomplished via batch processing in large vessels. However, to accommodate increases in projected throughput and reduce water production in a cost-effective manner, a semi-continuous system (In-line Complexing (ILC)) has been developed. The major conclusions drawn from tests demonstrating the feasibility of this concept are given in this report.

Cresap, D.A.; Halverson, D.S.



In vitro evaluation of microleakage under orthodontic brackets using two different laser etching, self etching and acid etching methods  

Microsoft Academic Search

This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted\\u000a human premolars were divided randomly into four equal groups and received the following treatment: group 1, acid etching;\\u000a group 2, self-etching primer (SEP); group 3, erbium:yttrium–aluminum–garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium–scandium–gallium–garnet\\u000a (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept

Nihal Hamamc?; At?l?m Akkurt; Güvenç Ba?aran



Improved corrosion resistance of Hastelloy G-30 in nitric/hydrofluoric acid solutions by welding with Inconel 72 weld wire  

SciTech Connect

When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0{sub 3}) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution anneal and water quench is necessary to assure that these phases redissolve into the solid. When a post weld solution anneal and water quench is not feasible, improved corrosion resistance can be obtained by welding with INCO 72 weld wire. When welding Hastelloy G-30 with INCO 72, there can be a region at the weldmetal/base-metal interface that does not benefit from the INCO 72 weld wire. This region consists of melted and resolidified Hastelloy G-30. This unmixed zone can be preferentially attacked in HN03 solutions contaminated with minor amounts of HF. Long term corrosion immersion tests have shown that the rate of attack at the weld-metal/base-metal interface can be as high as 50 mpy. Welding techniques that increase the mixing of the melted Hastelloy G-30 with the INCO 72 weld wire can reduce the interface corrosion rate.

Norby, B.C.



Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives  

PubMed Central

Objective: To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin. Material and Methods: Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12) as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100) were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37ºC, 100% humidity) with a testing machine (Ultra-tester) at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis. Results: Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05). Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05) only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa) and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa) among all tested groups (p<0.05). Conclusion: The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin. PMID:23559113




Low-cost PDMS seal ring for single-side wet etching of MEMS structures  

Microsoft Academic Search

We describe a new O-ring setup for wet-etching processes of microelectromechanical systems (MEMS). Our new low-cost approach using siloxane-based seal rings entails the single-side etching of silicon and silicon dioxide using potassium hydroxide and buffered hydrofluoric acid, respectively. With this approach, the wafer is not immersed into the etching solution, but only the side to be etched is in contact

J. Brugger; G. Beljakovic; M. Despont; H. Biebuyck; N. F. de Rooij; P. Vettiger



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

NASA Astrophysics Data System (ADS)

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.

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



Laboratory-scale fracture conductivity created by acid etching  

E-print Network

Success of acid fracturing treatment depends greatly on the created conductivity under closure stress. In order to have sufficient conductivity, the fracture face must be non-uniformly etched while the fracture strength maintained to withstand...

Pournik, Maysam



Part 2. Comparison of emergency washing solutions in 70% hydrofluoric acid-burned human skin in an established ex vivo explants model  

PubMed Central

Background: Hydrofluoric acid (HF) is a small and partially dissociated acid (pKa 3.2), able to deeply penetrate into human skin in addition to the corrosiveness of the hydrogen ion (H+) and the toxicity of the fluoride ion (F-). However, there has been a lack of experimental studies to objectively characterize the results of human HF skin exposure decontamination. Methodology/principal findings: A previously established experimental method using a human skin explants ex vivo model (Part 1. Experimental 70% hydrofluoric acid (HF) burns: Histological observations in an established human skin explants ex vivo model) described the lesions that appeared following 70% HF penetration. Within 5min, 70% HF penetrates to the dermis. Using the same experimental conditions, a comparison study of two different washing protocols was performed: water + topical calcium gluconate (CaG) versus Hexafluorine®. In these conditions, washing for 15min with running tap water followed by topical CaG ointment only delayed burn onset, while severe tissue damage appeared later. In contrast, after washing with Hexafluorine® over 10 min, no histological lesions developed. These results are in accordance with the results of accidental human industrial case reports. Conclusion/significance: Amphoteric and hypertonic Hexafluorine® can deactivate H+ and chelate F- ions. Based on these results, it should be considered as a promising first-aid decontamination solution to prevent or minimize significant local and systemic consequences of concentrated HF skin exposures. PMID:21083510

Burgher, Francois; Mathieu, Laurence; Lati, Elian; Gasser, Philippe; Peno-Mazzarino, Laurent; Blomet, Joel; Hall, Alan H; Maibach, Howard I



[Effect of acid etching on the primary enamel smooth surfaces. (3) A study of the etching times].  


The purpose of this study was to investigate the influence of etching times for the effect of acid etching on the primary enamel smooth surfaces. Fifty labial surfaces of the extracted or exfoliated caries-free primary anterior teeth were used. The cleaning and polishing pretreatment used in this study was polishing with a brush cone (Howe-Neos-Dental Co.) with water at a low speed (600-6000 r.p.m.). The etchant used in this study was 40% phospholic acid gel and the etching times were 10, 30, 60, 90 and 120 seconds. All specimens were washed with an air water spray for 30 seconds after etching. The following observations were obtained using the SEM. 1. The shorter the etching time, the higher was the rate of the cases which did not show any prism structure. 2. The numbers of the cases which did not show any prism structure were: 4 (40%) out of the 10 in 10 seconds etching, 2 (20%) out of the 10 in 30 seconds etching and 1 (10%) out of the 10 in 60 seconds etching. All cases showed prism structure in 90 seconds and 120 seconds etching. 3. The most common etching patterns in all etching times were poorly structured etching patterns. 4. The longer the etching time, the higher was the rate of the cases which showed peripheral etching patterns. 5. Tooth to tooth differences in the etching effects and patterns were observed under the same etching times. Various etching effects and patterns on the same enamel surface were observed. 6. Among the etching times used in this study, 90 seconds was an adequate time for etching on the unground primary enamel smooth surfaces polished with a brush cone. PMID:2489874

Hosoya, Y; Goto, G



Sulfuric acid-methanol electrolytes as an alternative to sulfuric-hydrofluoric acid mixtures for electropolishing of niobium  

SciTech Connect

Attainment of the greatest possible interior surface smoothness is critical to meeting the performance demands placed upon niobium superconducting radiofrequency (SRF) accelerator cavities by next generation projects. Electropolishing with HF-H{sub 2}SO{sub 4} electrolytes yields cavities that meet SRF performance goals, but a less-hazardous, more environmentally-friendly process is desirable. Reported studies of EP on chemically-similar tantalum describe the use of sulfuric acid-methanol electrolytes as an HF-free alternative. Reported here are the results of experiments on niobium samples with this electrolyte. Voltammetry experiments indicate a current plateau whose voltage range expands with increasing acid concentration and decreasing temperature. Impedance spectroscopy indicates that a compact salt film is responsible for the current plateau. Equivalent findings in electropolishing chemically-similar tantalum with this electrolyte were interpreted due to as mass transfer limitation by diffusion of Ta ions away from the anode surface. We infer that a similar mechanism is at work here. Conditions were found that yield leveling and brightening comparable to that obtained with HF-H{sub 2}SO{sub 4} mixtures.

Zhao, Xin [JLAB; Corcoran, Sean G. [Virginia Tech; Kelley, Michael J. [W& amp; M, JLAB



Reactivation of inactivated endogenous proteolytic activities in phosphoric acid-etched dentine by etch-and-rinse adhesives  

Microsoft Academic Search

Auto-degradation of collagen matrices occurs in resin-infiltrated dentine by the slow action of host-derived matrix metalloproteinases. As phosphoric acid-etching inactivates these endogenous enzymes, it is puzzling how hybrid layers created by simplified etch-and-rinse adhesives can degrade in vivo. This study tested the null hypothesis that there are no differences in the relative proteolytic activities of mineralised dentine, acid-etched dentine, and

Annalisa Mazzoni; David H. Pashley; Yoshihiro Nishitani; Lorenzo Breschi; Ferdinando Mannello; Leo Tjäderhane; Manuel Toledano; Edna L. Pashley; Franklin R. Tay



Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium.  


A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere. PMID:18960775

Donaldson, E M



Extraction of Nd3+-doped LiYF4 phosphor from sol-gel-derived oxyfluoride glass ceramics by hydrofluoric acid treatment  

NASA Astrophysics Data System (ADS)

Nd3+-doped oxyfluoride glass ceramics were synthesized by the sol-gel method. LiYF4 crystallites were deposited in an amorphous matrix consisting mainly of silica by heat treatment at middle temperature of 400-600 °C in air. A hydrofluoric acid (HF) treatment was carried out on the glass ceramics, resulting in the extraction of LiYF4 crystallites from the amorphous matrix. The photoluminescent (PL) properties were investigated for the sample before and after HF treatment. The results indicated that the Nd3+ ions were predominantly incorporated in LiYF4, and the extraction of LiYF4 crystallites was successfully carried out without changing the PL properties of Nd3+ ions.

Kawamura, G.; Yoshimura, R.; Ota, K.; Oh, S. Y.; Muto, H.; Hayakawa, T.; Matsuda, A.



Use of dilute hydrofluoric acid and deep eutectic solvent systems for back end of line cleaning in integrated circuit fabrication  

NASA Astrophysics Data System (ADS)

Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by plasma etching of low-k dielectric layers to form vias and trenches, and this process typically leaves behind polymer-like post etch residues (PER) containing copper oxides, copper fluorides and fluoro carbons, on underlying copper and sidewalls of low-k dielectrics. Effective removal of PER is crucial for achieving good adhesion and low contact resistance in the interconnect structure, and this is accomplished using wet cleaning and rinsing steps. Currently, the removal of PER is carried out using semi-aqueous fluoride based formulations. To reduce the environmental burden and meet the semiconductor industry's environmental health and safety requirements, there is a desire to completely eliminate solvents in the cleaning formulations and explore the use of organic solvent-free formulations. The main objective of this work is to investigate the selective removal of PER over copper and low-k (Coral and Black DiamondRTM) dielectrics using all-aqueous dilute HF (DHF) solutions and choline chloride (CC) -- urea (U) based deep eutectic solvent (DES) system. Initial investigations were performed on plasma oxidized copper films. Copper oxide and copper fluoride based PER films representative of etch products were prepared by ashing g-line and deep UV photoresist films coated on copper in CF4/O2 plasma. PER removal process was characterized using scanning electron microscopy and X-ray photoelectron spectroscopy and verified using electrochemical impedance spectroscopy measurements. A PER removal rate of ~60 A/min was obtained using a 0.2 vol% HF (pH 2.8). Deaeration of DHF solutions improved the selectivity of PER over Cu mainly due to reduced Cu removal rate. A PER/Cu selectivity of ~20:1 was observed in a 0.05 vol% deaerated HF (pH 3). DES systems containing 2:1 U/CC removed PER at a rate of ~10 and ~20 A/min at 40 and 70°C respectively. A mixture of 10-90 vol% de-ionized water (W) with 2:1 U/CC in the temperature range of 20 to 40°C also effectively removed PER. Importantly, etch rate of copper and low-k dielectric in DES formulations were lower than that in conventional DHF cleaning solutions.

Padmanabhan Ramalekshmi Thanu, Dinesh


Fissure Sealants: The Susceptibility to Dissolution of Acid-Etched and Subsequently Abraded Enamel in vitro  

Microsoft Academic Search

Since the enamel surface is etched with an acid solution prior to the application of a fissure sealant, eventual loss of material may expose a surface more susceptible to caries. The purpose of this in vitro study was to assess the susceptibility to dissolution of enamel surfaces which had been (1) acid-etched, (2) etched and exposed to saliva and (3)

Leon M. Silverstone



Modeling Acid Transport and Non-Uniform Etching in a Stochastic Domain in Acid Fracturing  

E-print Network

Success of acid fracturing depends on uneven etching along the fracture surfaces caused by heterogeneities such as variations in local mineralogy and variations in leakoff behavior. The heterogeneities tend to create channeling characteristics...

Mou, Jianye



Mechanical Behavior of Small-Scale Channels in Acid-etched Fractures  

E-print Network

The conductivity of acid-etched fractures highly depends on spaces along the fracture created by uneven etching of the fracture walls remaining open after fracture closure. Formation heterogeneities such as variations of mineralogy and permeability...

Deng, Jiayao



Molecular evaluation of soil organic matter characteristics in three agricultural soils by improved off-line thermochemolysis: the effect of hydrofluoric acid demineralisation treatment.  


The molecular composition of soil organic matter (SOM) in three agricultural fields under different managements, was evaluated by off-line thermochemolysis followed by gas chromatography mass spectrometry analysis (THM-GC-MS). While this technique enabled the characterization of SOM components in coarse textured soil, its efficiency in heavy textured soils was seriously affected by the interference of clay minerals, which catalyzed the formation of secondary artifacts in pyrolysates. Soil demineralization with hydrofluoric acid (HF) solutions effectively improved the reliable characterization of organic compounds in clayey soils by thermochemolysis, while did not alter significantly the results of coarse textured soil. A wide range of lignin monomers and lipids molecules, of plant and microbial origin, were identified in the pyrograms of HF treated soils, thereby revealing interesting molecular differences between SOM management practices. Our results indicated that clay removal provided by HF pretreatment enhanced the capacity of thermochemolysis to be a valuable and accurate technique to study the SOM dynamics also in heavy-textured and OC-depleted cultivated soils. PMID:24176504

Spaccini, Riccardo; Song, XiangYun; Cozzolino, Vincenza; Piccolo, Alessandro



Multiscale, Multifunction Diffractive Structures Wet Etched into Fused Silica for High-Laser Damage Threshold Applications  

Microsoft Academic Search

We combined functionalities of two diffractive optics with almost 100 lateral and vertical scale-length difference onto a single fused-silica surface. Fine-scale (2- m-period) gratings for beam sampling were printed in photoresist by interference lithography and transferred to the substrate by a hydrofluoric acid etch. Subsequently, 115- m-linewidth stairstep gratings for color separation at focus were proximity printed and wet etched

Jerald A. Britten; Leslie J. Summers



Multiscale, multifunction diffractive structures wet etched into fused silica for high-laser damage threshold applications  

Microsoft Academic Search

We combined functionalities of two diffractive optics with almost 100à lateral and vertical scale-length difference onto a single fused-silica surface. Fine-scale (2-μm-period) gratings for beam sampling were printed in photoresist by interference lithography and transferred to the substrate by a hydrofluoric acid etch. Subsequently, 115-μm-linewidth stairstep gratings for color separation at focus were proximity printed and wet etched in a

Jerald A. Britten; Leslie J. Summers



Biomimetic Remineralization of Resin-bonded Acid-etched Dentin  

PubMed Central

Degradation of denuded collagen within adhesive resin-infiltrated dentin is a pertinent problem in dentin bonding. A biomimetic remineralization scheme that incorporates non-classic crystallization pathways of fluidic amorphous nanoprecursors and mesoscopic transformation has been successful in remineralizing resin-free, acid-etched dentin, with evidence of intrafibrillar and interfibrillar remineralization. This study tested the hypothesis that biomimetic remineralization provides a means for remineralizing incompletely infiltrated resin-dentin interfaces created by etch-and-rinse adhesives. The remineralization medium consists of a Portland cement/simulated body fluid that includes polyacrylic acid and polyvinylphosphonic acid biomimetic analogs for amorphous calcium phosphate dimension regulation and collagen targeting. Both interfibrillar and intrafibrillar apatites became readily discernible within the hybrid layers after 2-4 months. In addition, intra-resin apatite clusters were deposited within the porosities of the adhesive resin matrices. The biomimetic remineralization scheme provides a proof-of-concept for the adoption of nanotechnology as an alternative strategy to extend the longevity of resin-dentin bonds. PMID:19734458

Tay, F.R.; Pashley, D.H.



Fabrication of Circular-Type Microchannel Using Photoresist Reflow and Isotropic Etching for Microfluidic Devices  

NASA Astrophysics Data System (ADS)

In this study, we fabricated circular channels using photoresist reflow and isotropic etching. A silicon substrate, using Si3N4 as a mask, was selectively etched using the hydrofluoric acid, nitric acid, acetic acid (HNA) etching system for fabricating the bottom hemisphere of the channels. Photoresist reflow was used to make the top of the channels round. Then Si3N4 was deposited on the reflowed photoresist. Since the deposited Si3N4 was approximately 6000 Å thick, it was possible to observe the inside of the channel. We expect to apply such circular channels to simple bio-systems and microfluidic devices in which optical detection is required.

Seo, Chang-Taeg; Bae, Chang-Hyun; Eun, Duk-Soo; Shin, Jang-Kyoo; Lee, Jong-Hyun



In vitro bracket bond strength to acid-etched or air-abraded enamel  

Microsoft Academic Search

Purpose: This study evaluated, in vitro, the capacity of a den- tin bonding agent to improve the bond strength of orthodontic brackets using air abrasion enamel preparation. Methods: Each of the enamel surfaces received a different treat- ment prior to bonding procedures. Group 1 received acid-etched with 38% phosphoric acid for 30 seconds. Group 2 received acid- etched with 38%

Kathy Mulcahey; Angelo A. Caputo; Donald F. Duperon



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


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

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



Interfacial morphology and bond strength of self-etching adhesives to primary dentin with or without acid etching.  


The aim of the study was to determine the interfacial morphology and bond strength of three current self-etching adhesives (SEAs) to primary dentin and to evaluate the effect of introducing an additional step of phosphoric acid etching. Three human primary molars were assigned to each adhesive group for testing microtensile bond strength (microTBS) and three for studying interface morphology. Groups were: group 1, Excite, a total-etch adhesive (control); group 2, Adhese (ASE); group 3, Adper-Prompt-L-Pop (APLP), and group 4: Xeno III (XE) SEAs; groups 5-7 received application of 37% phosphoric acid for 15 s before applying ASE, APLP, and XE, respectively. A class I cavity was performed in each molar to study the interface morphology. Two halves of each tooth were used for examination either by optical microscopy, using Masson's trichromic dye technique, or by scanning electron microscopy. For microTBS determination, composite/dentin bars (1 mm(2) section) were obtained from each tooth, and tested in tension until debonding. The microTBS was significantly lower in the APLP than in the rest of the groups. The performance of SEAs on primary dentin depends on the product. Inclusion of dentin pre-etching step did not significantly modify microTBS results. All SAEs achieved greater decalcification depth on etched versus nonetched dentin. PMID:18506828

Bolaños-Carmona, Victoria; González-López, Santiago; De Haro-Muñoz, Cristina; Briones-Luján, María T



Square-wave anodic-stripping voltammetric determination of Cd, Pb, and Cu in a hydrofluoric acid solution of siliceous spicules of marine sponges (from the Ligurian Sea, Italy, and the Ross Sea, Antarctica)  

Microsoft Academic Search

Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead,\\u000a and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution (?0.55 mol L?1 HF, pH ?1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc\\u000a support was used. The optimum experimental conditions, evaluated also in terms of the

C. Truzzi; A. Annibaldi; S. Illuminati; E. Bassotti; G. Scarponi



Behavior of acid etching on titanium: topography, hydrophility and hydrogen concentration.  


Since acid etching is easily controlled and effective, it has become one of the most common methods of surface modification. However, the behavior of etching is seldom discussed. In this study, different surfaces of titanium were prepared by changing the etching temperature and time. Surface topography, roughness, contact angles, surface crystalline structure, hydrogen concentration and mechanical properties were observed. As a result, surface topography and roughness were more proportional to etching temperature; however, diffusion of hydrogen and tensile strength are more time-related to titanium hydride formation on the surface. Titanium becomes more hydrophilic after etching even though the micropits were not formed after etching. More and deeper cracks were found on the specimens with more hydrogen diffusion. Therefore, higher temperature and shorter time are an effective way to get a uniform surface and decrease the diffusion of hydrogen to prevent hydrogen embrittlement. PMID:24343349

Lin, Xi; Zhou, Lei; Li, Shaobing; Lu, Haibin; Ding, Xianglong



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

PubMed Central

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

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



Nanoparticle-based etching of silicon surfaces  


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.

Branz, Howard (Boulder, CO); Duda, Anna (Denver, CO); Ginley, David S. (Evergreen, CO); Yost, Vernon (Littleton, CO); Meier, Daniel (Atlanta, GA); Ward, James S. (Golden, CO)



Acid Solutions for Etching Corrosion-Resistant Metals  

NASA Technical Reports Server (NTRS)

New study characterized solutions for etching austenitic stainless steels, nickel-base alloys, and titanium alloys (annealed). Solutions recommended for use remove at least 0.4 mil of metal from surface in less than an hour. Solutions do not cause intergranular attack on metals for which they are effective, when used under specified conditions.

Simmons, J. R.



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


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. PMID:22414518

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



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


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 ?( 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. PMID:22663196

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



Porous silicon layers prepared by electrochemical etching for application in silicon thin film solar cells  

NASA Astrophysics Data System (ADS)

In this paper, multilayer structures of porous silicon were fabricated by using electrochemical etching and characterized for its optical properties and surface morphology. Samples of monolayer of porous silicon were grown to study the characteristics of porous layer formation with respect to applied current density, etching time and hydrofluoric acid concentrations. Photoluminescence peaks of red emission at wavelength 695 and 650 nm were observed from multilayer porous silicon structures. By atomic force microscopy measurement, hillocks like surface were clearly observed within the host material, which confirmed the formation of pores.

Dubey, R. S.; Gautam, D. K.



Effect of different monomer-based composites and acid etching pre-treatment of enamel on the microleakage using self-etch adhesives systems.  


Abstract Objective. To evaluate quantitatively the marginal microleakage of restorations carried out with self-etching adhesives with or without prior phosphoric enamel acid etching of silorane or methacrylate resin-based composite restorations subjected to thermal cycling. Materials and methods. Forty cavities were prepared at the proximal surface of bovine incisors and randomly divided according to the etching of the enamel and restorative system used. The groups were restored with methacrylate [Adper SE Plus adhesive (3M ESPE) + Filtek Z250 (3M ESPE)] or silorane [Filtek LS adhesive (3M ESPE) + Filtek LS composite (3M ESPE)] restorative systems, light-cured using a LED unit (Bluephase 16i, Vivadent). After restorative procedure and thermocycling (1000 cycles), the specimens were immersed in methylene blue for 2 h. The specimens were triturated and the powder was used for analysis in an absorbance spectrophotometer. Data were statistically analyzed by 2-way ANOVA (alpha = 0.05). Results. No statistical difference between the restorative materials tested with or without previous acid etching of enamel in Class II marginal microleakage was observed (p > 0.05). Conclusions. The use of acid etching prior to self-etching adhesives did not interfere on the microleakage of methacrylate- or silorane-based restorations. PMID:24580091

Catelan, Anderson; Giorgi, Maria Cecília Caldas; Soares, Giulliana Panfiglio; Lima, Debora Alves Nunes Leite; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio



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

PubMed Central

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

Saks?, Mikkel; Jakobsen, Stig S; Saks?, Henrik; Baas, J?rgen; Jakobsen, Thomas; S?balle, Kjeld



Formation of nanostructured silicon surfaces by stain etching  

PubMed Central

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.



Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning*  

PubMed Central

Objective: This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths (?TBSs) of conventional and resin-modified glass ionomer cements (GICs/RMGICs). Methods: Forty-eight bovine incisors were prepared into rectangular blocks. Highly-polished labial enamel surfaces were either acid-etched, conditioned with liquids of cements, or not further treated (control). Subsequently, two matching pre-treated enamel surfaces were cemented together with one of four cements [two GICs: Fuji I (GC), Ketac Cem Easymix (3M ESPE); two RMGICs: Fuji Plus (GC), RelyX Luting (3M ESPE)] in preparation for ?TBS tests. Pre-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy (SEM). Results: Phosphoric acid etching significantly increased the enamel ?TBS of GICs/RMGICs. Conditioning with the liquids of the cements produced significantly weaker or equivalent enamel ?TBS compared to the control. Regardless of etching, RMGICs yielded stronger enamel ?TBS than GICs. A visible hybrid layer was found at certain enamel-cement interfaces of the etched enamels. Conclusions: Phosphoric acid etching significantly increased the enamel ?TBSs of GICs/RMGICs. Phosphoric acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays, using GICs/RMGICs to improve the bond strengths. RMGICs provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength. PMID:24190447

Zhang, Ling; Tang, Tian; Zhang, Zhen-liang; Liang, Bing; Wang, Xiao-miao; Fu, Bai-ping



Metal etching composition  

NASA Technical Reports Server (NTRS)

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.

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



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

NASA Astrophysics Data System (ADS)

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 ?m 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/ ??, 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.

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



In vitro short-term bonding performance of zirconia treated with hot acid etching and primer conditioning etching and primer conditioning.  


This study aimed to investigate and compare the resin bond strengths of zirconia conditioned as follows: alumina sandblasting; alumina sandblasting+application of 10-MDP-containing primer; alumina sandblasting+application of Z-Prime Plus or Metal/Zirconia Primer (new zirconia primers); tribochemical silica coating+silanization; hot acid etching in three different combinations [H2SO4/(NH4)2SO4, HF/HNO3, H2SO4/HF/HNO3]+application of 10-MDP-containing primer. Shear bond strengths (SBS) after water storage for 24 h and 40 days were measured to assess resin bonding performance. Surface and chemical properties of conditioned zirconia surfaces and primers were characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and atomic force microscopy. Surface roughness ranked in descending order was: hot acid etching > tribochemical silica coating > alumina sandblasting. Combination of tribochemical silica coating and silanization showed the highest initial SBS (12.46±2.13 MPa) (P<0.01). Etching with H2SO4/(NH4)2SO4 (13.15±3.24 MPa) and HF/HNO3 (13.48±2.15 MPa) showed significantly better bond durability (P<0.01). Hot acid etching seemed to be a promising surface roughening treatment to improve resin-zirconia bonding. PMID:24240899

Xie, Haifeng; Chen, Chen; Dai, Wenyong; Chen, Gang; Zhang, Feimin



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

PubMed Central

A carbon dioxide laser operating at the highly absorbed wavelength of 9.3?m with a pulse duration of 10–15?s 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

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



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


A carbon dioxide laser operating at the highly absorbed wavelength of 9.3?m with a pulse duration of 10-15?s 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

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



Etching process for improving the strength of a laser-machined silicon-based ceramic article  


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.

Copley, S.M.; Tao, H.; Todd-Copley, J.A.



Analysis methods for meso- and macroporous silicon etching baths  

NASA Astrophysics Data System (ADS)

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.

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



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

NASA Astrophysics Data System (ADS)

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 ?A cm-2). By local etching, straight nanopores with aspect ratios above 1000 (˜19 ?m 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.

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



Selective Removal of Dry-Etching Residue Derived from Polymer Sacrificial Layer for Microelectromechanical-System Device Fabrication  

NASA Astrophysics Data System (ADS)

A selective removal of dry-etching residue using hydrofluoric acid (HF) vapor is described in relation to the fabrication of microelectromechanical-system (MEMS) devices. Auger electron spectroscopy (AES) analysis of residue after dry etching of polymer sacrificial layers reveals that the residue is mainly composed of silicon oxides. HF vapor removes the dry-etching residue, and raising the vapor temperature enables the selective removal of the residue without damaging silicon dioxide (SiO2), which is often used as the insulator for MEMS devices. Direct-contact-type MEMS switches with SiO2 insulators fabricated using polymer sacrificial layers demonstrate the effectiveness of removing the dry-etching residue selectively.

Takagahara, Kazuhiko; Kuwabara, Kei; Sakata, Tomomi; Ishii, Hiromu; Sato, Yasuhiro; Jin, Yoshito



Guidance Document SafeHandlingofHydrofluoricAcid  

E-print Network

or store in glass. Very small spills may be neutralized and absorbed with calcium carbonate or calcium clothing while flushing with water. Apply calcium gluconate gel to the exposed tissues. Seek medical


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

PubMed Central

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 (? ?0.05). Results. There were no significant differences between the groups in term of ?E 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

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



Nanofabrication on monocrystalline silicon through friction-induced selective etching of Si3N4 mask  

PubMed Central

A new fabrication method is proposed to produce nanostructures on monocrystalline silicon based on the friction-induced selective etching of its Si3N4 mask. With low-pressure chemical vapor deposition (LPCVD) Si3N4 film as etching mask on Si(100) surface, the fabrication can be realized by nanoscratching on the Si3N4 mask and post-etching in hydrofluoric acid (HF) and potassium hydroxide (KOH) solution in sequence. Scanning Auger nanoprobe analysis indicated that the HF solution could selectively etch the scratched Si3N4 mask and then provide the gap for post-etching of silicon substrate in KOH solution. Experimental results suggested that the fabrication depth increased with the increase of the scratching load or KOH etching period. Because of the excellent masking ability of the Si3N4 film, the maximum fabrication depth of nanostructure on silicon can reach several microns. Compared to the traditional friction-induced selective etching technique, the present method can fabricate structures with lesser damage and deeper depths. Since the proposed method has been demonstrated to be a less destructive and flexible way to fabricate a large-area texture structure, it will provide new opportunities for Si-based nanofabrication. PMID:24940174



Morphological field emission-SEM study of the effect of six phosphoric acid etching agents on human dentin  

Microsoft Academic Search

Objectives. This study evaluated the effects of six phosphoric acid-etching agents on dentin, the independent variables being two acid concentrations (10% and 32%–37%) and three thickener conditions (no thickener, silica, and polymer). The tested hypothesis was that the use of different etchants with similar concentrations of phosphoric acid would result in similar depths of dentin demineralization.Methods. Thirty dentin disks were

Jorge Perdigão; Paul Lambrechts; Bart Van Meerbeek; Ângelo R. Tomé; Guido Vanherle; Augusto B. Lopes



Multiscale, Multifunction Diffractive Structures Wet Etched into Fused Silica for High-Laser Damage Threshold Applications  

NASA Astrophysics Data System (ADS)

We combined functionalities of two diffractive optics with almost 100 lateral and vertical scale-length difference onto a single fused-silica surface. Fine-scale (2- m-period) gratings for beam sampling were printed in photoresist by interference lithography and transferred to the substrate by a hydrofluoric acid etch. Subsequently, 115- m-linewidth stairstep gratings for color separation at focus were proximity printed and wet etched in a two-mask process. Line shapes of the lamellar sampling grating are remarkably preserved following etching of the much deeper color separation grating structures with this nominally isotropic etch process. Model simulations of isotropic etching of topographical features show good agreement with the measured shape evolution of the sampling grating profiles, and the simulations reveal the sensitivity of the final feature shape to its initial aspect ratio. As a rule of thumb, lamellar grating profiles can be etched approximately 0 . 08 A 2 times their modulation depth, where A is their initial aspect ratio (height width), before they evolve into a cusplike shape and begin to lose height.

Britten, Jerald A.; Summers, Leslie J.



Multiscale, multifunction diffractive structures wet etched into fused silica for high-laser damage threshold applications  

SciTech Connect

We combined functionalities of two diffractive optics with almost 100{times} lateral and vertical scale-length difference onto a single fused-silica surface. Fine-scale (2-{mu}m-period) gratings for beam sampling were printed in photoresist by interference lithography and transferred to the substrate by a hydrofluoric acid etch. Subsequently, 115-{mu}m-linewidth stairstep gratings for color separation at focus were proximity printed and wet etched in a two-mask process. Line shapes of the lamellar sampling grating are remarkably preserved following etching of the much deeper color separation grating structures with this nominally isotropic etch process. Model simulations of isotropic etching of topographical features show good agreement with the measured shape evolution of the sampling grating profiles, and the simulations reveal the sensitivity of the final feature shape to its initial aspect ratio. As a rule of thumb, lamellar grating profiles can be etched approximately 0.08A{sup {minus}2} times their modulation depth, where {ital A} is their initial aspect ratio (height/width), before they evolve into a cusplike shape and begin to lose height. {copyright} 1998 Optical Society of America

Britten, J.A.; Summers, L.J. [Lawrence Livermore National Laboratory, P.O. Box 808, L-439, Livermore, California 94550 (United States)



Multiscale, multifunction diffractive structures wet etched into fused silica for high-laser damage threshold applications.  


We combined functionalities of two diffractive optics with almost 100x lateral and vertical scale-length difference onto a single fused-silica surface. Fine-scale (2-mum-period) gratings for beam sampling were printed in photoresist by interference lithography and transferred to the substrate by a hydrofluoric acid etch. Subsequently, 115-mum-linewidth stairstep gratings for color separation at focus were proximity printed and wet etched in a two-mask process. Line shapes of the lamellar sampling grating are remarkably preserved following etching of the much deeper color separation grating structures with this nominally isotropic etch process. Model simulations of isotropic etching of topographical features show good agreement with the measured shape evolution of the sampling grating profiles, and the simulations reveal the sensitivity of the final feature shape to its initial aspect ratio. As a rule of thumb, lamellar grating profiles can be etched approximately 0.08A(-2) times their modulation depth, where A is their initial aspect ratio (height/width), before they evolve into a cusplike shape and begin to lose height. PMID:18301523

Britten, J A; Summers, L J



Optimization of HNA etching parameters to produce high aspect ratio solid silicon microneedles  

NASA Astrophysics Data System (ADS)

High aspect ratio solid silicon microneedles with a concave conic shape were fabricated. Hydrofluoric acid-nitric acid-acetic acid (HNA) etching parameters were characterized and optimized to produce microneedles that have long and narrow bodies with smooth surfaces, suitable for transdermal drug delivery applications. The etching parameters were characterized by varying the HNA composition, the optical mask's window size, the etching temperature and bath agitation. An L9 orthogonal Taguchi experiment with three factors, each having three levels, was utilized to determine the optimal fabrication parameters. Isoetch contours for HNA composition with 0% and 10% acetic acid concentrations were presented and a high nitric acid region was identified to produce microneedles with smooth surfaces. It is observed that an increase in window size indiscriminately increases the etch rate in both the vertical and lateral directions, while an increase in etching temperature beyond 35 °C causes the etching to become rapid and uncontrollable. Bath agitation and sample placement could be manipulated to achieve a higher vertical etch rate compared to its lateral counterpart in order to construct high aspect ratio microneedles. The Taguchi experiment performed suggests that a HNA composition of 2:7:1 (HF:HNO3:CH3COOH), window size of 500 µm and agitation rate of 450 RPM are optimal. Solid silicon microneedles with an average height of 159.4 µm, an average base width of 110.9 µm, an aspect ratio of 1.44, and a tip angle and diameter of 19.2° and 0.38 µm respectively were successfully fabricated.

Hamzah, A. A.; Abd Aziz, N.; Yeop Majlis, B.; Yunas, J.; Dee, C. F.; Bais, B.



Comparison of separation performance of laser-ablated and wet-etched microfluidic devices  

PubMed Central

Laser ablation of glass allows for production of microfluidic devices without the need of hydrofluoric acid and photolithography. The goal of this study was to compare the separation performance of microfluidic devices produced using a low-cost laser ablation system and conventional wet etching. During laser ablation, cracking of the glass substrate was prevented by heating the glass to 300°C. A range of laser energy densities was found to produce channel depths ranging from 4 – 35 ?m and channel widths from 118 – 162 ?m. The electroosmotic flow velocity was lower in laser-ablated devices, 0.110 ± 0.005 cm s?1, as compared to wet-etched microfluidic chips, 0.126 ± 0.003 cm s?1. Separations of both small and large molecules performed on both wet- and laser-ablated devices were compared by examining limits of detection, theoretical plate count, and peak asymmetry. Laser-induced fluorescence detection limits were 10 pM fluorescein for both types of devices. Laser-ablated and wet-etched microfluidic chips had reproducible migration times with ? 2.8% RSD and peak asymmetries ranging from 1.0 – 1.8. Numbers of theoretical plates were between 2.8- and 6.2-fold higher on the wet-etched devices compared to laser-ablated devices. Nevertheless, resolution between small and large analytes was accomplished, which indicates that laser ablation may find an application in pedagogical studies of electrophoresis or microfluidic devices, or in settings where hydrofluoric acid cannot be used. PMID:20827468

Baker, Christopher A.; Bulloch, Rayford; Roper, Michael G.



Scanning acoustic microscopy investigation of frequency-dependent reflectance of acid-etched human dentin using  

E-print Network

hal-00555784,version1-14Jan2011 #12;2 Abstract Composite restorations in modern restorative dentistry-etched human dentin surface plays a significant role in modern restorative dentistry. Composite restorations

Paris-Sud XI, Université de


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

NASA Astrophysics Data System (ADS)

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.

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



TMAH wet etching of silicon micro- and nano-fins for selective sidewall epitaxy of III-Nitride semiconductors  

NASA Astrophysics Data System (ADS)

We describe formation of silicon micro- and nano-fins, with (111)-plane sidewall facets, for selective sidewall epitaxy of III-Nitride semiconductors. The fins are produced by wet etching (110)-oriented silicon wafers. Silicon dioxide is deposited using plasma enhanced chemical vapor deposition for producing a hard mask. The silicon dioxide is patterned using photo- and electron-beam lithography for micro- and nano-fins, respectively, followed by wet etching in hydrofluoric acid. Wet etching to produce the silicon fins is carried out using tetramethyl ammonium hydroxide (TMAH) diluted with isopropyl alcohol (IPA). Atomic force microscopy and scanning electron microscopy are used to determine morphology including the surface roughness of the area between fins and the etching rate of silicon. We tune the etching time, temperature, and percentage of IPA in order to get the best surface on both (111) and (110) planes. Adding IPA is found to alter the etch rate and improve the surface between the fins without adversely affecting the sidewall morphology.

Liu, Lianci; Myasishchev, Denis; Kuryatkov, Vladimir; Nikishin, Sergey; Holtz, Mark; Harris, Rusty



Illumination-dependent HF Etching of AlAs Sacrificial Layers for the Formation of ``Rolled Up'' Nanotubes from Strained InGaAs/GaAs Films  

NASA Astrophysics Data System (ADS)

"Rolled-up" nanostructures formed from lattice mismatched III-V heterojunction films by taking advantage of a strain-induced self-rolling mechanism represent a useful type of building blocks for nanotechnology, with possible applications in high-speed microelectronic and optoelectronic devices. This work investigated the effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up MBE grown InGaAs/GaAs bilayers. Based on this "etch suppression effect" (ESE), we propose an illumination-assisted technique that offers an advantage over other methods of rolling up nano-objects on a substrate from inherently strained films because it allows control over the positioning of rolled-up micro- and nanotubes independently from lithographic methods. For thicknesses of AlAs below 10 nm, we found two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The "etch suppression" area is well defined by the illumination spot, which can be used to realize well-controlled heterogeneously etched regions on the same sample.

Costescu, Ruxandra M.



Deep wet etching of borosilicate glass and fused silica with dehydrated AZ4330 and a Cr/Au mask  

NASA Astrophysics Data System (ADS)

This research highlights a superior glass-wet-etch technique which enables a glass wafer to be etched for more than 20 h in 49 wt% hydrofluoric acid (HF) only with Cr/Au film and a common positive photoresist, AZ4330. We demonstrated that pits on the wet-etched glass wafer were generated not only due to HF diffusion through the Cr/Au film but also due to pinholes on the Cr/Au films created by the diffusion of the Cr/Au etchant through a photoresist etching-mask during the Cr/Au wet etching process. These two types of diffusion, HF diffusion and Cr/Au etchant diffusion, were eliminated by the thermal curing of a photoresist (PR), AZ4330, before the Cr/Au wet etching process. The curing process allowed the PR to dehydrate, increased the hydrophobicity, and prevented the diffusion of the hydrophilic HF and Cr/Au etchant. Optimization of the curing process was performed, showing that curing at 130 °C for 20 min was the proper condition. With the optimized process, a 525 µm thick borosilicate glass wafer was penetrated with 49%wt HF. A fused silica wafer 525 µm thick was also wet-etched and penetrated with 49 wt% HF at 10 h. Moreover, no pits were found in wet etching of the fused silica for 20 h in 49 wt% HF. These findings demonstrate that the proposed technique allows the wet etching of a glass wafer for more than 20 h in 49%wt HF, the best result thus far. We fabricated a glass substrate with a 217.0 µm deep cavity and a penetrating through-via using the proposed technique, proving the feasibility of the product as an optical component with a surface roughness of 45.5 Å in the cavity.

Jin, Joo-Young; Yoo, Sunghyun; Bae, Jae-Sung; Kim, Yong-Kweon



Investigations of AlGaN/GaN HFETs utilizing post-metallization etching by nitric acid treatment  

NASA Astrophysics Data System (ADS)

This work investigates AlGaN/GaN heterostructure field-effect transistors (HFETs) processed by using a simple post-metallization etching (PME) treatment. Decreased gate length (LG) can be achieved by using nitric acid (HNO3) PME treatment owing to the high etching selectivity of HNO3 of Ni against the Au and GaN layer. Influences on LG, etched gate profiles and device characteristics with respect to different PME processing parameters by HNO3 treatment are systematically investigated. Optimum device performance is obtained as LG was reduced to 0.5 µm by using a 1 µm long gate mask by immersing the device into a 45% diluted HNO3 solution for 35 s. Improved device performances, including maximum drain-source current density (IDS, max: 657.6 mA mm-1 ? 898.5 mA mm-1), drain-source saturation current density at zero gate bias (IDSS0: 448.3 mA mm-1 ? 653.4 mA mm-1), maximum extrinsic transconductance (gm, max: 158.3 mS mm-1 ? 219.2 mS mm-1), unity-gain cut-off frequency (fT: 12.35 GHz ? 22.05 GHz), maximum oscillation frequency (fmax: 17.55 GHz ? 29.4 GHz) and power-added efficiency (P.A.E.: 26.3% ? 34.5%) compared to the untreated reference device, have been successfully achieved.

Chou, Bo-Yi; Hsu, Wei-Chou; Lee, Ching-Sung; Liu, Han-Yin; Tsai, Chih-Ming; Ho, Chiu-Sheng



Micromorphology of ceramic etching pattern for two CAD-CAM and one conventional feldspathic porcelain and need for post-etching cleaning.  


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. PMID:24757699

Onisor, Ioana; Rocca, Giovanni Tommaso; Krejci, Ivo



Morphological evolution of silver nanoparticles and its effect on metal-induced chemical etching of silicon.  


In this report, we have demonstrated the morphological evolution of the silver nanoparticles (AgNPs) by controlling the growth conditions and its effect on morphology of silicon (Si) during metal-induced electroless etching (MICE). Self-organized AgNPs with peculiarly shape were synthesized by an electroless plating method in a conventional aqueous hydrofluoric acid (HF) and silver nitrate (AgNO3) solution. AgNP nuclei were densely created on Si wafer surface, and they had a strong tendency to merge and form continuous metal films with increasing AgNO3 concentrations. Also, we have demonstrated that the fabrication of aligned Si nanowire (SiNW) arrays in large area of p-Si (111) substrates by MICE in a mixture of HF and hydrogen peroxide (H2O2) solution. We have found that the morphology of the initial AgNPs and oxidant concentration (H2O2) greatly influence on the shape of the SiNW etching profile. The morphological results showed that AgNP shapes were closely related to the etching direction of SiNWs, that is, the spherical AgNPs preferred to move vertical to the Si substrate, whereas non-spherical AgNPs changed their movement to the [100] directions. In addition, as the etching activity was increased at higher H2O2 concentrations, AgNPs had a tendency to move from the original [111] direction to the energetically preferred [100] direction. PMID:23858934

Baek, Seong-Ho; Kong, Bo Hyun; Cho, Hyung Koun; Kim, Jae Hyun



Surface characteristics and biocompatibility of sandblasted and acid-etched titanium surface modified by ultraviolet irradiation: an in vitro study.  


Sandblasting with large grit and acid-etching (SLA) treatment is considered to be a reliable modification to achieve excellent titanium surface. However, contamination of hydrocarbons would make SLA surface hydrophobic and influence its bioactivity. Thus, appropriate methods of preservation or further treatments could be used for improvement. In present study, preservation in deionized water (dH(2)O) and ultraviolet (UV) irradiation were, respectively, applied to achieve modSLA and UV-SLA surfaces. Surface characteristics were assessed by scanning electron microscopy, optical profilometer and x-ray photoelectron spectroscopy as well as wettability by optical contact angle analyzer. Additionally, biocompatibility was evaluated by the response to osteoblast-like MG63 cells. Prevented from further contamination, modSLA surface with fewer hydrocarbons (25.31%) remained hydrophilic and showed better affinity to mineralization of MG63 cells than hydrophobic polluted SLA surface (p < 0.01). Furthermore, with the lowest content of hydrocarbons (14.26%) and super-hydrophilicity, UV-SLA surface, which had the hydrocarbons effectively decomposed by photocatalysis and meanwhile acquired abundant hydroxyl groups, had most greatly promoted the attachment, proliferation, differentiation, and mineralization of MG63 cells (p < 0.05). Therefore, hydrocarbons were found to be an important influencing factor to compatibility of biomaterials. In addition, UV irradiation was recognized as a trustworthy method for surface cleaning without change of topography and roughness and could ever lead to greater biocompatibility of sandblasted and acid-etched titanium surface. PMID:22707456

Li, Shaobing; Ni, Jia; Liu, Xiangning; Zhang, Xueyang; Yin, Shiheng; Rong, Mingdeng; Guo, Zehong; Zhou, Lei



Optimal acidulated phosphate fluoride gel etching time for surface treatment of feldspathic porcelain: on shear bond strength to resin composite  

PubMed Central

Objectives: This in vitro study evaluated the shear bond strength (SBS) of resin composite to feldspathic porcelain after acidulated phosphate fluoride (APF) gel treatment over different periods of time. Methods: One hundred and fifty-six feldspathic specimens were divided into 12 groups. Group C received no treatment (control group). Groups APF1 through APF10, ten experimental groups, were treated with 1.23% APF gel. Each group obtained 1 to 10 minutes of etching time in 1 minute increments, respectively. Group HF2 was treated with 9.6% hydrofluoric acid (HF) for 2 minutes. All specimens were then bonded to a resin composite cylinder using Adper Scotchbond Multi-purpose (3M ESPE) after silane (Monobond-S, Ivoclar Vivadent AG) application. Specimens were stored at 37ºC for 24 hours before the SBS was performed and were recorded in MPa at fracture. Data were analyzed using one-way ANOVA and Tukey’s test (?=.05). Results: HF etching yielded the highest SBS (18.0 ± 1.5 MPa), which was not significantly different from APF gel etching for 6 to 10 minutes (16.0 ± 2.1 to 17.2 ± 1.6 MPa) (P>.05). Conclusions: APF gel etching for 6 minutes might be used as an alternative etchant to HF acid for bonding resin composite to silanized feldspathic porcelain. PMID:22229009

Kukiattrakoon, Boonlert; Thammasitboon, Kewalin



Assessment and comparison of microleakage of a fluoride-releasing sealant after acid etching and Er: YAG laser treatment - An in vitro study  

PubMed Central

Aim: The aim of the present study was to estimate and compare the microleakage of a pit and fissure sealant after etching and Er:YAG laser treatment. Materials and Methods: Twenty non-carious premolars extracted for orthodontic reasons were equally divided into two groups. Samples in Group- I were treated with 37% phosphoric acid. Samples in Group II were irradiated with Er: YAG laser at 400 mJ at 4 Hz. Sealant was placed and light cured. Then, the samples were subjected to thermocycling. The samples were then immersed in 1% methylene blue. The samples were sectioned and examined under stereomicroscope at ×10 magnification. Results: Acid etched samples showed significantly less microleakage when compared to laser etching and it was statistically significant (P<0.01). PMID:22557900

Vijayaraghavan, R.; Rao, V. Arun Prasad; Reddy, N. Venugopal; Krishnakumar, R.; Sugumaran, D. K.; Mohan, G.



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

PubMed Central

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

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



Versatile route to gapless microlens arrays using laser-tunable wet-etched curved surfaces.  


This work reveals a cost-efficient and flexible approach to various microlens arrays on polymers, which is essential to micro-optics elements. An 800-nm femtosecond laser is employed to control the hydrofluoric (HF) acid etching process on silica glasses, and concave microstructures with smooth curved surfaces are produced by this method. Then, the micro-structured glass templates can serve as molds for replicating microlenses on polymers. In this paper, a high-ordered microlens array with over 16,000 hexagonal-shaped lenses is fabricated on poly (dimethyl siloxane) [PDMS], and its perfect light-gathering ability and imaging performance are demonstrated. The flexibility of this method is demonstrated by successful preparation of several concave molds with different patterns which are difficult to be obtained by other methods. This technique provides a new route to small-scaled, smooth and curved surfaces which is widely used in micro-optics, biochemical analysis and superhydrophobic interface. PMID:22714321

Hao, Bian; Liu, Hewei; Chen, Feng; Yang, Qing; Qu, Pubo; Du, Guangqing; Si, Jinhai; Wang, Xianhua; Hou, Xun



Three-dimensional Modeling of Acid Transport and Etching in a Fracture  

E-print Network

Acid fracture stimulation generates higher well production but requires engineering design for treatment optimization. To quantify the cost and benefit of a particular acid fracture treatment an engineer must predict the resulting fracture’s...

Oeth, Cassandra V



Influence of acid-etched splinting methods on discoloration of dental enamel in four media: an in vitro study.  


The aim of this in vitro study was to assess the staining of enamel in relation to fixation of luxated teeth. Color changes induced by chlorhexidine, red wine, tea, and coffee were detected with a Minolta Chroma Meter (CR-121) after extracted teeth were treated to simulate construction of dental splinting. L*a*b* color readings were made before and after 7 days of incubation in the above-mentioned media in teeth treated 1) by acid-etching, 2) by acid-etching followed by resin, 3) by resin and composite, 4) by Triad Gel, and 5) by Protemp. L* is an indicator of black (0) and white (100). The a* values relate to the red (+100)-green (-100) color axes, and the b* values to the yellow (+100) and blue (-100) axes. Untreated teeth served as controls. One-way analysis of variance of mean L* values revealed no statistically significant differences in treatment. Discoloration was observed in all teeth, including the control ones. However, Protemp yielded the largest changes in mean L* values. Analysis of variance of mean L* values revealed statistically significant differences between incubation liquids because no increase in staining of enamel was noted after 7 days' incubation in chlorhexidine. Red wine increased the mean L* values more than coffee or tea. Changes in a*b* readings were toward red (+a*) after incubation in red wine, except in the case of teeth treated with resin. The color of all such teeth changed more toward yellow (+b*), because the resin used was yellow.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7871352

Oikarinen, K S; Nieminen, T M



Asphaltene damage in matrix acidizing  

E-print Network

were acidized with three stage treatments of 15% hydrochloric acid (HCl), 12% HCL-3% hydrofluoric acid (HF) and 15% HCL. No additives were used in the acid. Comparisons were made between cores acidized with a variety of saturating fluids. Petrographic...

Hinojosa, Roberto Antonio



Novel and low reflective silicon surface fabricated by Ni-assisted electroless etching and coated with atomic layer deposited Al2O3 film  

NASA Astrophysics Data System (ADS)

In this paper, nickel nanoparticles (Ni NPs) were deposited on planar silicon and pyramidal silicon wafers by the magnetron sputtering method, and then these Ni NP-covered samples were etched in a hydrofluoric acid, hydrogen peroxide, and deionized water mixed solution at room temperature to fabricate a low reflective silicon surface. An alumina (Al2O3) film was then deposited on the surface of the as-etched pyramidal sample by atomic layer deposition to further reduce the reflectance. The morphologies and compositions of these samples were studied by using a field emission scanning electron microscope attached to an energy-dispersive X-ray spectrometer. The surface reflectance measurements were carried out with a UV-Vis-NIR spectrophotometer in a wavelength range of 200-1100 nm. The SEM images show that the as-etched planar and pyramidal silicon samples were covered with many rhombic nanostructures and that some nanostructures on the planar silicon surface were ready to exhibit a flower-like burst. The reflectances of the as-etched planar and pyramidal silicon samples were 5.22 % and 3.21 % in the wavelength range of 400-800 nm, respectively. After being coated with a 75-nm-thick Al2O3 film, the etched pyramidal silicon sample showed an even lower reflectance of 2.37 % from 400 nm to 800 nm.

Yue, Zhihao; Shen, Honglie; Jiang, Ye; Wang, Wei; Jin, Jiale



Characterisation and comparison of microfluidic chips formed using abrasive jet micromachining and wet etching  

NASA Astrophysics Data System (ADS)

The electro-osmotic flow limit of detection and separation efficiency of glass channels machined using abrasive jet micromachining (AJM) were measured and compared with those for channels machined using conventional wet etching with hydrofluoric acid. It was found that the electro-osmotic mobility in AJM channels was similar to that in wet-etched channels, ˜4 × 10-4 cm2 V-1 s-1 for 20 µm channels, despite a two-decade difference in surface roughness. Similarly, limits of detection measured on the two types of chips were roughly comparable to each other and on the order of 1 nM (injected sample concentration). The separation efficiency calculated from TAMRA dye injections in AJM channels, however, was found to be significantly lower, ˜0.2-0.25 times, than that in wet-etched channels. The effect of surface roughness on the separation efficiency and electro-osmotic mobility in micro-channels is discussed in the context of the literature. Furthermore, experimental data concerning the effect of the AJM process conditions on the surface roughness are presented and discussed with the aim of exploring methods to improve surface quality in AJM. Commercially available self-adhesive elastomeric masks were found to be particularly suitable for rapid prototyping as they provided reasonably high resolution and machining flexibility.

Ghobeity, Amin; Crabtree, H. John; Papini, Marcello; Spelt, Jan K.



Photopolymerization of phosphoric acid ester-based self-etch dental adhesives  

PubMed Central

The objective of the study was to gain more understanding on the photopolymerization mechanism and the role of individual monomers in the polymerization behavior of a PAE-based self-etch adhesive system with the presence of HAp and water. The photo-polymerization process of the model adhesive system (2MP / HEMA) was monitored by using real-time attenuated total reflectance Fourier transform infrared (ATR/FT-IR) technique. The effect of monomer ratio, HAp incorporation, and water content were investigated. The degree of conversion (DC) and the polymerization rate (PR) of the adhesives were determined to evaluate the polymerization efficacy. The results showed that the DC and PR increased consistently as the 2MP content increased from 30% to 70%, while they declined drastically as the 2MP content was further elevated to 100%. The incorporation of HAp considerably increased the DC and PR; however, the increase in water content was found to have negative influence on the photopolymerization. PMID:23370865

ZHANG, Ying; WANG, Yong



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


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. PMID:22298375

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



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

PubMed Central

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

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



Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid  

SciTech Connect

Describes general synthetic strategies developed under this grant to control interchain electronic communications within conjugated polymers (CPs). Novel chemical architectures built on iptycenes, metallorotaxanes, and canopied pyrroles restrict the dimensionality of electronic structures responsible for excition and charge transport. Structure-property relationships emerging from studies of selected systems are discussed, focusing on their implications for the sensitivity of these materials as sensors.

Timothy M. Swager



vwDepartment of Geoscience Hydrofluoric Acid Policy  

E-print Network

must not be left in open containers, plastic ware or wash bottles. HF must be neutralized before to the Safety Office as mixed chemical waste. Under no circumstances will HF residue be left in an open topped

Habib, Ayman


Amino acid substitutions within the Cys-rich domain of the tobacco etch potyvirus HC-Pro result in loss of transmissibility by aphids  

Microsoft Academic Search

Summary.  ?We examined the role of several amino acid residues located at the N-terminus of the tobacco etch potyvirus (TEV) helper\\u000a component-proteinase (HC-Pro) in virus transmissibility by aphids. Site-directed mutagenesis resulted in changes affecting\\u000a amino acids that appear highly conserved among a number of potyviruses. The TEV HC-Pro amino acid residues Gly343, Val345,\\u000a Ala346, Ile348, Pro355, Lys358, and Ile359 were arranged

C. Llave; B. Martínez; J. R. Díaz-Ruíz; D. López-Abella



Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation  

NASA Astrophysics Data System (ADS)

In-situ functionalization of polar GaN was performed by adding cysteamine to a phosphoric acid etchant in order to study its effect on photoluminescence and oxide formation on the surfaces. The functionalization was characterized by atomic force microscopy, x-ray photoelectron spectroscopy, photoluminescence (PL), and water contact angle measurements. Two sets of polar GaN samples with different dislocation densities were evaluated, thin GaN layers residing on sapphire and thick free-standing GaN separated from sapphire substrate aiming to reveal the effect of material quality on in-situ functionalization. The addition of cysteamine to the phosphoric acid solution was found to result in: (i) decreased surface roughness, (ii) no change to hydrophobicity, (iii) decreased oxygen content especially at high-temperature treatments. The effect of the in-situ functionalization on the PL efficiency was more pronounced in the free-standing sample than in the film residing on the sapphire, which was attributed to a higher crystal quality free from strain.

Wilkins, S. J.; Paskova, T.; Ivanisevic, A.



Preparation of substrates for EUV blanks using an etch clean process to meet HVM challenges  

NASA Astrophysics Data System (ADS)

Achieving mask blanks with defectivity less than 0.03 defects/cm2 at 30 nm SiO2 equivalent and above is one of the key goals for accomplishing high volume manufacturing capability for EUV lithography. Defect free blanks for lithography start from defect free substrates. Currently, defects on both LTEM and quartz substrates are dominated by pits, scratches, particles and residues left by the polishing processes used to achieve the roughness and flatness specifications of the substrates. Normally, such defects are extremely difficult to be removed and particles often leave pits as they are removed by cleaning. Standard cleaning processes relying on megasonic cavitations for particle removal are insufficient for removing such defects from substrates. It is well known that hydrofluoric acid is an etchant of fused silica (quartz) and buffered HF in different concentrations has been used in the past for cleaning quartz and silicon substrates. Ideally, an etch clean process should not increase the roughness of the substrate while cleaning. However, in the process of etching and removing the defects, the roughness of the substrates is invariably increased which is undesirable. The rate of roughness change is directly dependent on the concentration and time of exposure, which also affects the etch rate and defect removal rate. In this paper we report that a post polishing etch clean process has been developed for ULE and quartz substrates which meet the defectivity, roughness and flatness specifications for EUV blanks. We also examine the effects of substrate roughness on blank roughness, and inspection capability of substrates and blanks at different roughness levels using a defect inspection tool capable of inspecting defects down to 35 nm SiO2 equivalent size. Defect smoothing using etch clean processes have been proposed and demonstrated in the past using an anisotropic etch mechanism. This study focuses on complete removal of defects from EUV substrates, and therefore smoothing is not an issue. Multilayer blank deposition process is known to decorate defects on substrates. We use this as a technique to identify any defects that might be left on the substrate surface after etch cleaning. In most cases, we find that the substrates have low defectivity and do not affect the EUV requirements. We demonstrate that the etch clean process can be used to increase the yield of high quality ULE substrates to meet the high volume production requirements of euv masks.

Kadaksham, Arun J.; Teki, Ranganath; Harris-Jones, Jenah; Lin, C. C.



Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method  

NASA Astrophysics Data System (ADS)

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 ?m with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

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



Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method  

PubMed Central

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 ?m with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.



Role of preliminary etching for one-step self-etch adhesives.  


The aim of this study was to analyse the effect of preliminary phosphoric acid etching of enamel and dentine before the application of two, one-step self-etch adhesive systems. The systems were applied onto acid-etched or smear-layer-covered enamel and dentine. The treatment groups were as follows: group 1, Adper Easy Bond (3M ESPE) on etched substrate; group 2, Adper Easy Bond (control); group 3, iBond Self-Etch (Heraeus Kulzer) on etched substrate; and group 4, iBond Self-Etch (control). Enamel and dentine bond strengths were calculated using microshear and microtensile bond-strength tests. Additional specimens were prepared to evaluate nanoleakage at the dentine-adhesive interface and were investigated using light microscopy or transmission electron microscopy. Both adhesives demonstrated higher microshear bond strengths when enamel was pre-acid-etched with phosphoric acid (Adper Easy Bond 28.7 ± 4.8 MPa; iBond Self-Etch 19.7 ± 3.6 MPa) compared with controls (Adper Easy Bond 19.2 ± 3.3 MPa; iBond Self-Etch 17.5 ± 2.7 MPa) and increased microtensile bond strength when applied on acid-etched (Adper Easy Bond 35.8 ± 5.7 MPa; iBond Self-Etch 24.3 ± 7.9 MPa) vs. smear-layer-covered dentine (Adper Easy Bond 26.9 ± 6.2 MPa; iBond Self-Etch 17.6 ± 4.3 MPa). Adper Easy Bond showed lower nanoleakage than iBond Self-Etch, irrespective of preliminary etching. The results of this study support the use of phosphoric acid etching before the application of one-step self-etch adhesive systems. PMID:20831587

Taschner, Michael; Nato, Fernando; Mazzoni, Annalisa; Frankenberger, Roland; Krämer, Norbert; Di Lenarda, Roberto; Petschelt, Anselm; Breschi, Lorenzo



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.  


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 (??=?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 dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections. PMID:24671257

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



Dry Etching Overview What is dry etching?  

E-print Network

· No unintentional prolongation of etching · Better process control · Ease of automation (e.g., cassette loading Etch-Processes for IC Manufacturing #12;6 Disadvantages of RIE · Conflict between etching rate

Wang, Deli


High-quality near-field optical probes by tube etching Raoul Stockle, Christian Fokas, Volker Deckert, and Renato Zenobia)  

E-print Network

the polymer coating off the optical fiber before etching, the cladded fiber end is dipped into a hydrofluoric is presented. Tip formation occurs inside a cylindrical cavity formed by the polymer coating of an optical is the adiabatic pulling of optical fibers during heating with a CO2 laser.8,9 Recently, microfabricated tips have

La Rosa, Andres H.


Repair strength of etched vs silica-coated metal-ceramic and all-ceramic restorations.  


The purpose of this in vitro study was to examine shear bond strengths of composite resin to metal-exposed porcelain-fused-to-metal (PFM) and all-ceramic restorations after silica coating or etching with 5% hydrofluoric acid (HF). Specimens were fabricated for each of the following groups: two all-ceramic materials [a feldspathic porcelain (Vita Mark II) and a leucite-reinforced glass-ceramic (IPS Empress)], and one noble metal-ceramic (Orplid Keramik I alloy; Vita VMK 68 N felspathic veneer ceramic). These groups were repaired with resin composites after different pretreatment methods. In one metal-ceramic subgroup the surface exhibited a 50% metal and 50% ceramic exposure. In the silica-coating groups, the specimen surfaces were air abraded with silica acid-modified Al2O3 (CoJet Sand) and treated corresponding to the porcelain repair with resin composite. For control groups, the surfaces were etched with 5% HF for 60 seconds and treated in the same way as the silica-coated groups. After 24 hours of storage (distilled water, 37 degrees C) and an additional 24 hours of thermocycling (1150 x 5 degrees C/55 degrees C) the specimens were debonded using a shear bond strength test (n = 15). In all groups the silica coat repair achieved equal or significantly higher bond strengths than did the etching technique (p < 0.05, Mann-Whitney U test). In the metal-exposed group, the mean bond strength increased from 7.3 MPa to 16.3 MPa following the silica-coat repair. Results indicated that silica coating represents a suitable treatment for the intraoral repair of the materials tested in the present study. PMID:11203818

Frankenberger, R; Krämer, N; Sindel, J



Atmospheric-pressure argon plasma etching of spin-coated 3,4-polyethylenedioxythiophene:polystyrenesulfonic acid (PEDOT:PSS) films for cupper phtalocyanine (CuPc)\\/C 60 heterojunction thin-film solar cells  

Microsoft Academic Search

Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated 3,4-polyethylenedioxythiophene:polystyrenesulfonic acid (PEDOT:PSS) films were investigated by real-time characterization by the spectroscopic ellipsometry (SE) during argon plasma etching at atmospheric pressure. Spectral analysis revealed that homogeneous etching occurred within 10–15nm of the top surface, followed by the appearance of a conductive PEDOT phase and surface roughning, which

Tomohisa Ino; Tatsuya Hayashi; Keiji Ueno; Hajime Shirai



Acid-etch interval and shear bond strength of Er,Cr:YSGG laser-prepared enamel and dentin.  


The formation of a superficial layer of tiny flakes has been observed on teeth prepared by Erbium lasers. It has been suggested that removing this layer (mechanically or chemically) may increase the bond strength of the resin composite. The purpose of this study is to evaluate the effect of various etching times on bond strength of resin composite to enamel and dentin prepared by Er,Cr:YSGG laser. Sixty previously flattened human molars were irradiated for 10 s by an Er,Cr:YSGG laser. Enamel (E) specimens were etched with 37% H(3)PO(4) for 20, 40 or 60 s and dentin (D) specimens were etched for 15 or 30 s. All specimens were prepared for a standard shear bond strength (SBS) test (1 mm/min). Data were analyzed [ANOVA, Tukey post-hoc, a < 0.05)] and the failure mode was studied under SEM. Mean SBS+/-sd (MPa) for each group was 16.97 +/- 7.77 (E20s), 21.34 +/- 3.55 (E40s), 14.08 +/- 4.77 (E60s), 13.62 +/- 7.28 (D15s) and 13.15 +/- 6.25 (D30s). SBS for E40s was significantly higher than E60s (p = 0.023). No difference was noted between the dentin groups. SEM evaluation showed predominantly cohesive failure. Within the limits of this study, etching time significantly influenced the SBS of composite resin to laser-prepared enamel. SEM showed subsurface cracks, fissures, and deformities leading to predominantly cohesive failure in both enamel and dentin. PMID:19288054

Obeidi, Ali; Liu, Perng-Ru; Ramp, Lance C; Beck, Preston; Gutknecht, Norbert



State of the art etch-and-rinse adhesives  

Microsoft Academic Search

Objectives: The aim of this study was to explore the therapeutic opportunities of each step of 3-step etch-and-rinse adhesives. Methods: Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. Acid-etching, using 32–37% phosphoric acid (pH

David H. Pashley; Franklin R. Tay; Lorenzo Breschi; Leo Tjäderhane; Ricardo M. Carvalho; Marcela Carrilho; Arzu Tezvergil-Mutluay



Depth Profile Characterization of Spin-Coated Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonic acid) Films for Thin-Film Solar Cells during Argon Plasma Etching by Spectroscopic Ellipsometry  

NASA Astrophysics Data System (ADS)

Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films were investigated by real-time characterization by spectroscopic ellipsometry (SE) during argon plasma etching at atmospheric pressure. Spectral analysis revealed that homogeneous etching occurred within 10-15 nm of the top surface, followed by the appearance of a conductive PEDOT phase and surface roughening, which originated from the depth profile of the PEDOT-to-PSS molar concentration ratio. The use of the plasma-etched PEDOT:PSS layer relatively improved the performance of the cupper phthalocyanine (CuPc)/C60 organic thin-films solar cells as a hole-transport layer with higher optical transmittance by adjusting the plasma etching condition.

Ino, Tomohisa; Hayashi, Tatsuya; Ueno, Keiji; Shirai, Hajime



Morphology of resin-dentin interfaces after Er,Cr:YSGG laser and acid etching preparation and application of different bonding systems.  


The goal of this study was to show the modifications in the ultrastructure of the dentin surface morphology following different surface treatments. The stability of the adhesive compound with dentin after laser preparation compared with conventional preparation using different bonding agents was evaluated. An Er,Cr:YSGG laser and 36% phosphoric acid in combination with various bonding systems were used. A total of 100 caries-free human third molars were used in this study. Immediately after surgical removal teeth were cut using a band saw and 1-mm thick dentin slices were created starting at a distance of 4 mm from the cusp plane to ensure complete removal of the enamel. The discs were polished with silicon carbide paper into rectangular shapes to a size of 6 × 4 mm (±0,2 mm).The discs as well as the remaining teeth stumps were stored in 0.9% NaCl at room temperature. The specimens were divided into three main groups (group I laser group, group II etch group, group III laser and etch group) and each group was subdivided into three subgroups which were allocated to the different bonding systems (subgroup A Excite, subgroup B Scotchbond, subgroup C Syntac). Each disc and the corresponding tooth stump were treated in the same way. After preparation the bonding composite material was applied according to the manufacturers' guidelines in a hollow tube of 2 mm diameter to the disc as well as to the corresponding tooth stump. Shear bond strength testing and environmental scanning electron microscopy were used to assess the morphology and stability of the resin-dentin interface. The self-etching bonding system showed the highest and the most constant shear values in all three main groups, thus enabling etching with phosphoric acid after laser preparation to be avoided. Thus we conclude that laser preparation creates a surface texture that allows prediction of the quality of the restoration without the risk of negative influences during the following treatment steps. This can easily and repeatedly be achieved. PMID:21948398

Beer, Franziska; Buchmair, Alfred; Körpert, Wolfram; Marvastian, Leila; Wernisch, Johann; Moritz, Andreas



Self-etch and etch-and-rinse adhesive systems in clinical dentistry.  


Current adhesive systems follow either an "etch-and-rinse" or "self-etch" approach, which differ in how they interact with natural tooth structures. Etch-and-rinse systems comprise phosphoric acid to pretreat the dental hard tissues before rinsing and subsequent application of an adhesive. Self-etch adhesives contain acidic monomers, which etch and prime the tooth simultaneously. Etch-and-rinse adhesives are offered as two- or three-step systems, depending on whether primer and bonding are separate or combined in a single bottle. Similarly, self-etch adhesives are available as one- or two-step systems. Both etch-and-rinse and self-etch systems form a hybrid layer as a result of resins impregnating the porous enamel or dentin. Despite current trends toward fewer and simpler clinical application steps, one-step dentin bonding systems exhibit bonding agent lower bond strengths and seem less predictable than multi-step etch-and-rinse and self-etch systems. The varying evidence available today suggests that the choice between etch-and-rinse and self-etch systems is often a matter of personal preference. In general, however, phosphoric acid creates a more pronounced and retentive etching pattern in enamel. Therefore, etch-and-rinse bonding systems are often preferred for indirect restorations and when large areas of enamel are still present. Conversely, self-etch adhesives provide superior and more predictable bond strength to dentin and are, consequently, recommended for direct composite resin restorations, especially when predominantly supported by dentin. PMID:23550327

Ozer, Fusun; Blatz, Markus B



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


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. PMID:23134519

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



From hypo- to hypersuppression: effect of amino acid substitutions on the RNA-silencing suppressor activity of the Tobacco etch potyvirus HC-Pro.  


RNA silencing participates in several important functions: from the regulation of cell metabolism and organism development to sequence-specific antiviral defense. Most plant viruses have evolved proteins that suppress RNA silencing and that in many cases are multifunctional. Tobacco etch potyvirus (TEV) HC-Pro protein suppresses RNA silencing and participates in aphid-mediated transmission, polyprotein processing, and genome amplification. In this study, we have generated 28 HC-Pro amino acid substitution mutants and quantified their capacity as suppressors of RNA silencing in a transient expression assay. Most mutations either had no quantitative effect or completely abolished silencing suppression (10 in each class), 3 caused a significant decrease in the activity, and 5 significantly increased it, revealing an unexpected high frequency of mutations conferring hypersuppressor activity. A representative set of the mutant alleles, containing both hypo- and hypersuppressors, was further analyzed for their effect on TEV accumulation and the strength of induced symptoms. Whereas TEV variants with hyposuppressor mutants were far less virulent than wild-type TEV, those with hypersuppressor alleles induced symptoms that were not more severe than those characteristic of the wild-type virus, suggesting that there is not a perfect match between suppression and virulence. PMID:18780745

Torres-Barceló, Clara; Martín, Susana; Daròs, José-Antonio; Elena, Santiago F



Controlled-release of bone morphogenetic protein-2 from a microsphere coating applied to acid-etched Ti6AL4V implants increases biological bone growth in vivo.  


A central clinical challenge regarding the surgical treatment of bone and joint conditions is the eventual loosening of an orthopedic implant as a result of insufficient bone ingrowth at the bone-implant interface. We investigated the in vivo effectiveness of a coating containing recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded microspheres applied to acid-etched Ti6Al4V cylinders for implantation. Three groups of rabbits (24 per group) were used for implantation: (1) acid-etched Ti6Al4V implants coated with a mixture of rhBMP-2-loaded microspheres (125?ng rhBMP-2/mg microspheres) and ?-butyl cyanoacrylate; (2) acid-etched, uncoated implants; and (3) bare, smooth uncoated implants. After implantation, 12 rabbits from each group were used for bone ingrowth determination at 4, 5, 6, 7, 8, and 12 weeks (2 rabbits per time point), while the remainder were used for histological analysis and push-out testing at 12 weeks. Scanning electron microscopy showed significant improvement in bone growth of the rhBMP-2 microspheres/?-butyl cyanoacrylate group compared with the other groups (p<0.01). Histological analysis and push-out testing also demonstrated enhanced bone growth of the rhBMP-2 group over that in the other two groups (p<0.01). The rhBMP-2 group showed the most significant bone growth, suggesting that coating acid-etched implants with a mixture of rhBMP-2-loaded microspheres and ?-butyl cyanoacrylate may be an effective method to improve the osseointegration of orthopedic implants. PMID:24536004

Fu, Yangmu; Zhang, Qiang; Sun, Yong; Liao, Weixiong; Bai, Xiaowei; Zhang, Lili; Du, Lina; Jin, Yiguang; Wang, Qi; Li, Zhongli; Wang, Yan



Investigation of the neutral-solution etch process for refractive SOE antireflective surfaces  

SciTech Connect

Antireflection of optically clear glass used in photovoltaic concentrator refractive secondary optical elements (SOE's) was investigated using the neutral-solution etch process developed by Schott Glass. Test coupons and SOE's made from barium zinc glass, which does not solarize under ultraviolet exposure, were successfully etched at the center point process variable conditions of 87{degrees}C and 24 hours. Reflectance of the plano-plano dropped from 7.7% to 0.8%, with a corresponding increase in transmission from 91.7% to 98.5%. The etching process uses non-hydrofluoric, relatively non-toxic chemicals in a low-cost process well suited for use by photovoltaic system manufacturers during production. 10 refs., 4 figs., 1 tab.

Maish, A.B.



The use of reduced healing times on ITI implants with a sandblasted and acid-etched (SLA) surface: early results from clinical trials on ITI SLA implants.  


ITI dental implants are available with two bone-anchoring surfaces, a titanium plasma-sprayed (TPS) surface, and a recently introduced sandblasted and acid-etched (SLA) surface. Cell culture and animal tests demonstrate that the SLA surface stimulates bone cell differentiation and protein production, has large amounts of bone-to-implant contact, and results in large removal torque values in functional testing of the bone contact. As a result of these studies, a prospective human clinical trial was initiated to determine whether the 4.1 mm diameter SLA ITI solid screw implants could be predictably and safely restored as early as six weeks after implant placement surgery. The protocol restricted the use of the reduced healing time to a) healthy patients with sufficient bone volume to surround the implant, and b) those patients who had good bone quality (classes I-III) at the implant recipient site. Patients with poorer bone quality (class IV) did not have restorations until 12 weeks after implant placement. The clinical trial is an ongoing multicenter trial, with six centers in four countries, and with follow-up over five years. The primary outcome variable was abutment placement with a 35 Ncm force, with no countertorque and no pain or rotation of the implant. A secondary outcome was implant success, as defined by no mobility, no persistent pain or infection, and no peri-implant radiolucency. To date, 110 patients with 326 implants have completed the one-year post-loading recall visit, while 47 patients with 138 implants have completed the two-year recall. Three implants were lost prior to abutment connection. Prosthetic restoration was commenced after shortened healing times on 307 implants. The success rate for these implants, as judged by abutment placement, was 99.3% (with an average healing time of 49 days). Life table analyses demonstrated an implant success rate of 99.1%, both for 329 implants at one year and for 138 implants at two years. In the 24-month period after restoration, no implant losses were reported for the 138 implants. These results demonstrate that, under defined conditions, solid screw ITI implants with an SLA endosseous surface can be restored after approximately six weeks of healing with a high predictability of success, defined by abutment placement at 35 Ncm without countertorque, and with subsequent implant success rates of greater than 99% two years after restoration. PMID:11952734

Cochran, David L; Buser, Daniel; ten Bruggenkate, Christian M; Weingart, Dieter; Taylor, Thomas M; Bernard, Jean-Pierre; Peters, Françoise; Simpson, James P



Controlled ion track etching  

NASA Astrophysics Data System (ADS)

It is a common practice since long to follow the ion track-etching process in thin foils via conductometry, i.e . by measurement of the electrical current which passes through the etched track, once the track breakthrough condition has been achieved. The major disadvantage of this approach, namely the absence of any major detectable signal before breakthrough, can be avoided by examining the track-etching process capacitively. This method allows one to define precisely not only the breakthrough point before it is reached, but also the length of any non-transient track. Combining both capacitive and conductive etching allows one to control the etching process perfectly. Examples and possible applications are given.

George, J.; Irkens, M.; Neumann, S.; Scherer, U. W.; Srivastava, A.; Sinha, D.; Fink, D.



Gate etch process control  

NASA Astrophysics Data System (ADS)

Studies on photomask Cr and MoSi etch processes were carried out and etch kinetics and modeling were performed. The photomasks were etched using an AMAT Centura II DPS and compared with a Unaxis VLE 770 ICP etcher. Mask metrology to support theoretical suppositions was performed on several tools: a KLA-Tencor P-12 profiler was used for depth measurement, while the KLA-Tencor 8250XP-R SEM was used for CD metrology and process characterization. The Toshiba EBM3500 50KeV writing system on positive chemically amplified resist was used for pattern creation. Cr and MoSi loading - etch rate equations were theoretically proposed and experimentally tested. It was found that the calculated Cr and MoSi etch rates agreed well with the experimental results. The equations can be used for etch time calculations and endpoint determinations of extremely low Cr load photomasks. Cr and MoSi local etch rates versus local loading on one photomask were studied and kinetic equations were proposed, showing good agreement with experimental results. Cr and MoSi etch CD movements versus local load on one photomask were also investigated. It was found that load effects on Cr and MoSi etch CD movements could be controlled in opposite directions and then a compensation consideration was proposed in MoSi optimization instead of using a point-to-point 3? as the optimization parameter. By using this compensation method, the final MoSi CD unformity of 100-110 nm technology node photomasks is in the range of 8.5 to 10.1 nm. This final CD uniformity is similar to those etched using VLR 770 ICP etcher.

Krogh, Ole; Freeland, Mark; Mori, Ron; Chowdhury, Tito



Glass-ceramic Flexural Strength after Hydrofluoric Acid and Unfilled Resin Treatment Sumana Posritong1  

E-print Network

Department of Restorative Dentistry / Division of Dental Biomaterials,Indiana University School of Dentistry. Mentor: Marco C. Bottino, Department of Restorative Dentistry / Division of Dental Biomaterials, Indiana University School of Dentistry, Indianapolis, IN #12;

Zhou, Yaoqi


Ion beam sputter etching  

NASA Technical Reports Server (NTRS)

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.

Banks, Bruce A.; Rutledge, Sharon K.



INVESTIGATION OF CORROSION INHIBITORS FOR FUMING NITRIC ACID. Period covered November 21, 1955 to June 7, 1957  

Microsoft Academic Search

Development of a corrosion inhibitor for fuming nitric acid that has ; corrosion-inhibiting and scale and sludge-formation properties superior to those ; of hydrofluoric acid was investigated. Amonium hexafluorophosphate in amount ; equivalent to 0.30% by weight hydrofluoric acid was found to provide better ; inhibition to the corrosion of 61S-T6 aluminum alloy and 17-7PH and AISI Type ; 304L

W. H. Bergdorf; E. J. Jr. Kinsey



Using white light interferometry to measure etching of dental enamel  

Microsoft Academic Search

A new method has been developed where white light interferometry (WLI) is used to study the progression of dental erosions. Six specimens of human enamel were imaged during stepwise etching in 0.01M hydrochloric acid for 2+2+2min at room temperature. Amalgam fillings were used as reference surfaces. Computer based analysis of the topographic images gave detailed information about the etching response.

Børge Holme; Lene Hystad Hove; Anne Bjørg Tveit



Effect of Acetic, Lactic and other Organic Acids on the Formation of Artificial Carious Lesions  

Microsoft Academic Search

Artificial carious lesions were produced in human enamel using a diphosphonate\\/organíc acid system over periods up to 30 days, and progress assessed by depth measurement. Acids studied were lactic, acetic, propionic, isobutyric, succinic, tartaric, hydrochloric and hydrofluoric. The rate of lesion progress was found to be a function of calculated unionized acid concentration, and acid dissociation constant. Acetic acid made

J. D. B. Featherstone; B. E. Rodgers



Grafting on nuclear tracks using the active sites that remain after the etching process  

NASA Astrophysics Data System (ADS)

Poly(propylene) foils were irradiated with Ag ions and then chemically etched to produce samples with structured surfaces. After the etching procedure the active sites that remain on the latent track were used to graft acrylic acid. Nuclear tracks before grafting were visualised using a transmission electron microscope. The grafting yields were determined by weight measurements as a function of ion fluence, etching and grafting time, and were also analysed using Fourier transform infrared spectroscopy. Both measurements suggest that the acrylic acid was grafted on etched tracks using the active sites produced by the swift heavy ion beam.

Mazzei, R.; Bermúdez, G. García; Chappa, V. C.; del Grosso, M. F.; Fernandez, A.



Deep, Precise Etching in Semiconductors  

NASA Technical Reports Server (NTRS)

Semiconductors made to accept precise etching after pretreatment. Combination of material destabilization and anisotropic etching permits formation of precise perpendicular-wall cavities in silicon wafers and other semiconductors. New technique extends capabilities of current micromachining technology to fabrication of submillimeter waveguide arrays and filters. Pre-etching process currently used to fabricate thin-walled arrays of submillimeter waveguides for use as dichroic bandpass filters. Possible applications include integration of sensor probes and processing of circuitry on same silicon chip.

Shlichta, P. J.; Barth, P. W.



ZERODUR: bending strength data for etched surfaces  

NASA Astrophysics Data System (ADS)

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.

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



Bond strength with various etching times on young permanent teeth  

SciTech Connect

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.

Wang, W.N.; Lu, T.C. (School of Dentistry, National Defense Medical Center, Taipei, Taiwan (China))



Submicron patterned metal hole etching  


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.

McCarthy, Anthony M. (Menlo Park, CA); Contolini, Robert J. (Lake Oswego, OR); Liberman, Vladimir (Needham, MA); Morse, Jeffrey (Martinez, CA)



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

PubMed Central

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

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



Effects of radical-distribution control on etching-profile uniformity in dielectric etching  

Microsoft Academic Search

Uniformity control of etching profile and etching rate across a wafer during damascene etching was investigated using a UHF-ECR etching apparatus with a dual-zone gas-injection system. Uniform etching rate was obtained under various conditions by controlling magnetic field distribution. It was found that etching profile could be controlled without affecting etching-rate uniformity by changing the ratio of inner- to outer-nitrogen-gas

Hiroyuki Kobayashi; Ken'etsu Yokogawa; Kenji Maeda; Tadamitsu Kanekiyo; Masaru Izawa



Decontamination of metals using chemical etching  


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.

Lerch, Ronald E. (Kennewick, WA); Partridge, Jerry A. (Richland, WA)



Etching and Growth of GaAs  

NASA Technical Reports Server (NTRS)

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.

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



Microtrenching during polysilicon plasma etch  

NASA Astrophysics Data System (ADS)

Micro-trenching occurs during plasma polysilicon etch for features with sub 0.5 micrometers spaces and thin gate dielectric. The trenches, which form near the base of etched features as a series of holes through the gate dielectric and into the underlying silicon, are the result of ion scattering off the resist/polysilicon sidewall. By studying structures with varying feature spacing and resist thicknesses we were able to determine that the depth and location of the trenches are related to the aspect ratio (height:width) of the structure, the sidewall profile of the resist/polysilicon line, and the process conditions during over-etch. Ion scattering which causes the micro-trenching is enhanced under conditions of increasing aspect ratio and decreasing sidewall angle of the etched feature.

Swan, Steve W.; Corliss, Daniel A.



Etching Of Semiconductor Wafer Edges  


A novel method of etching a plurality of semiconductor wafers is provided which comprises assembling said plurality of wafers in a stack, and subjecting said stack of wafers to dry etching using a relatively high density plasma which is produced at atmospheric pressure. The plasma is focused magnetically and said stack is rotated so as to expose successive edge portions of said wafers to said plasma.

Kardauskas, Michael J. (Billerica, MA); Piwczyk, Bernhard P. (Dunbarton, NH)



State of the art etch-and-rinse adhesives  

PubMed Central

Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. This review explores the therapeutic opportunities of each separate step. Acid-etching, using 32-37% phosphoric acid (pH 0.1-0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria. Some etchants include anti-microbial compounds such as benzalkonium chloride that also inhibits matrix metalloproteinases (MMPs) in dentin. Primers are usually water and HEMA-rich solutions that ensure complete expansion of the collagen fibril meshwork and wet the collagen with hydrophilic monomers. However, water alone can re-expand dried dentin and can also serve as a vehicle for protease inhibitors or protein cross-linking agents that may increase the durability of resin-dentin bonds. In the future, ethanol or other water-free solvents may serve as dehydrating primers that may also contain antibacterial quaternary ammonium methacrylates to inhibit dentin MMPs and increase the durability of resin-dentin bonds. The complete evaporation of solvents is nearly impossible. Manufacturers may need to optimize solvent concentrations. Solvent-free adhesives can seal resin-dentin interfaces with hydrophobic resins that may also contain fluoride and antimicrobial compounds. Etch-and-rinse adhesives produce higher resin-dentin bonds that are more durable than most 1 and 2-step adhesives. Incorporation of protease inhibitors in etchants and/or cross-linking agents in primers may increase the durability of resin-dentin bonds. The therapeutic potential of etch-and-rinse adhesives has yet to be fully exploited. PMID:21112620

Pashley, David H; Tay, Franklin R; Breschi, Lorenzo; Tjaderhane, Leo; Carvalho, Ricardo M; Carrilho, Marcela; Tezvergil-Mutluay, Arzu



Wet Chemical Etching Survey of III-Nitrides  

SciTech Connect

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.

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.



Materials Modification in Nanotechnology: Advanced Etch Systems  

NSDL National Science Digital Library

This PowerPoint created and presented by the Nanotechnology Applications and Career Knowledge (NACK) Center discusses etch systems. The presentation provides descriptions and examples of nine different system classifications, including Horizontal Plate RIE, Parallel Plate Etch, Microwave Etch, Electron Cyclotron Resonance (ECR) Etch, Hexode RIE, MERIE, Inductively Coupled Plasma (ICP) Etch, Ion Beam Etch, and Advanced Strip and Passivation (ASP). This presentation also has a cluster tools section, explaining their function and configuration. This is a great resource for any classroom looking at nanofabrication modifications. This and all other valuable resources from the NACK Center require a fast, easy, free log-in.



Surface texturing of p-GaN layer for efficient GaN LED by maskless selective etching  

Microsoft Academic Search

The maskless selective wet etching of p-GaN layer with KOH in ethylene glycol (KE) and H3PO4\\/H2SO4 (HH) acids was developed for the highly efficient light-emitting diodes (LEDs). The p-GaN surfaces textured by the selective wet etching process without using etch mask showed hexagonal and stripe shapes in the KE and HH solutions, respectively. The current-voltage (I-V) characteristics of the LED

Seok-In Na; Dae-Seob Han; Seok-Soon Kim; Jae-Hong Lim; Ja-Yeon Kim; Seong-Ju Park



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

NASA Astrophysics Data System (ADS)

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 ?/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 J sc of 37 mAcm-2, open circuit voltage ( V oc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on V oc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with J sc of 36.90 mAcm-2, V oc of 625.7 mV, and efficiency of 17.60%.

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



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

PubMed Central

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

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya



Incubation time of etch pits at dislocation outcrops  

NASA Astrophysics Data System (ADS)

The incubation time for etch pit formation on single crystals of willemite was estimated for the first time by making successive optical measurements of the etch pit growth rate and then calculating incubation times by extrapolating the length vs. time curve for the etch pits back to zero width. Incubation times were estimated for the (0001) faces of willemite (containing minor impurities of Fe 2+, Mg 2+, and Al 3+) after dissolution in acidic solutions (pH = 0-5) at 30°C. Shorter incubation times at lower pH were attributed to the pH dependence of leaching rates of the inhibitors (e.g., Fe 2+), which in acidic solutions should accumulate rapidly at dislocation outcrops and maintain the near surface undersaturation of willemite, thus allowing etch pits to develop at these high energy sites. Dissolution (pH = 2) experiments with various cations (Mn 2+, Fe 2+, Co 2+, Ni 2+, Cu 2+, Mg 2+, Al 3+, Fe 3+) already present in the etchant indicated that incubation times were indeed related to the dissolution-inhibiting cations. Spiking of etchant (pH = 2) beyond a critical concentration of Fe 2+ (0.01 M) significantly lowered the dissolution rates (especially along the < 2 overline110 > and the < 10 overline1O >, i.e., normal to the sides of pit opening) and shortened the incubation time as measured by static immersion experiments.

Lin, Chung-Cherng; Shen, Pouyan



The effect of additional etching and curing mechanism of composite resin on the dentin bond strength  

PubMed Central

PURPOSE The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives. MATERIALS AND METHODS Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ×20 magnification. The data was analyzed using a one-way ANOVA and Scheffe's post-hoc test (?=.05). RESULTS Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond. CONCLUSION The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin. PMID:24353889

Lee, In-Su; Son, Sung-Ae; Hur, Bock; Kwon, Yong-Hoon



Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements  

PubMed Central

Objective This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. Material and Methods Conventional (KetacTM Molar Quick ApplicapTM) or resin-modified (PhotacTM Fil Quick AplicapTM) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (AdperTM Single Bond 2) or single-step self-etching adhesive (AdperTM PromptTM L-PopTM) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (FiltekTM Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. Results The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. Conclusions The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal. PMID:23329245

PAMIR, Tijen; SEN, Bilge Hakan; EVCIN, Ozgur



Using Hydrofluoric Acid for Morphological Investigations of Zoanthids (Cnidaria: Anthozoa): A Critical Assessment of Methodology and Necessity  

Microsoft Academic Search

Zoanthids comprise an order of benthic, generally colonial cnidarians, which can usually be distinguished from other hexacorallians\\u000a by embedded sand and detritus in their mesoglea to help strengthen their structure. These animals are becoming increasingly\\u000a important research subjects in biochemistry and other research fields. Their inclusion of both calcium and silica results\\u000a in the need for both decalcification and desilification

James Davis Reimer; Shu Nakachi; Mamiko Hirose; Euichi Hirose; Shinji Hashiguchi



Apparatus for edge etching of semiconductor wafers  

NASA Technical Reports Server (NTRS)

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.

Casajus, A.



Solution control for hybrid microcircuit etching  

Microsoft Academic Search

Methods were developed for monitoring the photoresistant developer and ; gold etchant used in hybrid microcircuit etching. The developer color, which ; darkens with use, was monitored using a spectrophotometric procedure. The gold ; concentration in the gold etch was found to be very critical to the etch rate. ; Measurement of solution density was found to be effective in




Etching Magnetic Tunnel Junction with Metal Etchers  

Microsoft Academic Search

Etch performances of inductory-coupled plasma (ICP) metal etchers with several gas systems are examined under constant ion energy condition to evaluate extendibility to the 300 mm wafer magnetic tunnel junction (MTJ) etch process. The ICP-Ar sputter etch affects little on magnetic properties, and shows about the same magnetoresistive (MR) ratio with conventional Ar ion milling. Major issue is the electrical

Keizo Kinoshita; Hiroaki Utsumi; Katsumi Suemitsu; Hiromitsu Hada; Tadahiko Sugibayashi



Secret of formulating a selective etching or cleaning solution for boron nitride (BN) thin film  

NASA Astrophysics Data System (ADS)

Boron nitride thin film has a very unique characteristic of extremely high chemical inertness. Thus, it is a better hard mask than silicon nitride for aggressive etching solutions, such as the isotropic HF/HNO3/CH3COOH (or HNA) etchant for silicon. However, because of its high chemical inertness, it is also difficult to remove it. Plasma etching with Freon gases can etch the boron nitride film, but it is unselective to silicon, silicon dioxide or silicon nitride. Cleaning up the boron nitride film with plasma etching will usually leave a damaged or foggy surface. A special wet chemical solution has been developed for etching or cleaning boron nitride film selectively. It can etch boron nitride, but not the coatings or substrates of silicon, silicon nitride and silicon dioxide. It is a very strong oxidizing agent consisting of concentrated sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), but different from the common Piranha Etch. It may be even more interesting to understand the logic or secret behind of how to formulate a new selective etching solution. Various chemical and chemical engineering aspects were considered carefully in our development process. These included creating the right electrochemical potential for the etchant, ensuring large differences in chemical kinetics to make the reactions selective, providing proper mass transfer for removing the by products, etc.

Hui, Wing C.



Investigation of etch characteristics of non-polar GaN by wet chemical etching  

NASA Astrophysics Data System (ADS)

We characterized the surface defects in a-plane GaN, grown onto r-plane sapphire using a defect-selective etching (DSE) method. The surface morphology of etching pits in a-plane GaN was investigated by using different combination ratios of H 3PO 4 and H 2SO 4 etching media. Different local etching rates between smooth and defect-related surfaces caused variation of the etch pits made by a 1:3 ratio of H 3PO 4/H 2SO 4 etching solution. Analysis results of surface morphology and composition after etching by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) demonstrated that wet chemical etching conditions could show the differences in surface morphology and chemical bonding on the a-plane GaN surface. The etch pits density (EPD) was determined as 3.1 × 10 8 cm -2 by atom force microscopy (AFM).

Hsu, Hsiao-Chiu; Su, Yan-Kuin; Cheng, Shin-Hao; Huang, Shyh-Jer; Cao, Jia-Ming; Chen, Kuan-Chun



Reduction of etch pit density on GaN by InGaN-strained SQW  

Microsoft Academic Search

We found that the etch pit density (EPD) formed by a mixed acid of H3PO3+H2SO4 on a GaN surface was reduced from 4×107 to 6×106cm?2 by overlaying the GaN surface with an InGaN-strained SQW structure. However, a cross-sectional TEM observation of a wet etched sample revealed that the reduction effect of SQW structure on threading dislocations was not significant, and

Yoshinobu Ono; Yasushi Iyechika; Tomoyuki Takada; Katsumi Inui; Teruyuki Matsue



Plasmoids for etching and deposition  

NASA Astrophysics Data System (ADS)

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.

Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter



Laser-driven fusion etching process  


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.

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



Etching method for photoresists or polymers  

NASA Technical Reports Server (NTRS)

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.

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



Etch challenges for DSA implementation in CMOS via patterning  

NASA Astrophysics Data System (ADS)

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.

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.



Staining etched epoxy resin sections for light microscopy.  


Staining of etched sections for light microscopy is described. Azan staining was successful after treatment with potassium dichromate and the use of concentrated dye solutions. To remove osmium for hematoxylin-eosin staining, removal by reduction with ferrocene was used instead of oxidation. Highly selective differentiation after hematoxylin staining was achieved using p-toluenesulfonic acid-DMSO. To enhance eosin staining, a 2-bromoethylamine link between eosin and the tissue was used. Ferrocene also facilitated counterstaining of nuclei with hematoxylin after the PAS reaction. Periodic acid-methenamine silver staining was carried out without modification. PMID:7578588

Iwadare, T; Arai, T



Selective etching characteristics of the AgInSbTe phase-change film in laser thermal lithography  

NASA Astrophysics Data System (ADS)

In the current work, the etching selectivity of the AgInSbTe phase-change film in laser thermal lithography is reported for the first time. Film phase change induced by laser irradiation and etching selectivity to crystalline and amorphous states in different etchants, including hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, sodium hydroxide, sodium sulfide, ammonium sulfide and ammonium hydroxide, are investigated. The results indicated that ammonium sulfide solvent (2.5 mol/L) had excellent etching selectivity to crystalline and amorphous states of the AgInSbTe film, and the etching characteristics were strongly influenced by the laser power density and laser irradiation time. The etching rate of the crystalline state of the AgInSbTe film was 40.4 nm/min, 20 times higher than that of the amorphous state under optimized irradiation conditions (power density: 6.63 mW/?m2 and irradiation time: 330 ns), with ammonium sulfide solvent (2.5 mol/L) as etchant. The step profile produced in the selective etching was clear, and smooth surfaces remained both on the step-up and step-down with a roughness of less than 4 nm (10×10 ?m). The excellent performance of the AgInSbTe phase-change film in selective etching is significant for fabrication of nanostructures with super-resolution in laser thermal lithography.

Li, Hao; Geng, Yongyou; Wu, Yiqun



Dry etching technologies for reflective multilayer  

NASA Astrophysics Data System (ADS)

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.

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



Etching Magnetic Tunnel Junction with Metal Etchers  

NASA Astrophysics Data System (ADS)

Etch performances of inductory-coupled plasma (ICP) metal etchers with several gas systems are examined under constant ion energy condition to evaluate extendibility to the 300 mm wafer magnetic tunnel junction (MTJ) etch process. The ICP-Ar sputter etch affects little on magnetic properties, and shows about the same magnetoresistive (MR) ratio with conventional Ar ion milling. Major issue is the electrical short by redeposition. The etch uniformity over the wafer and precise etch end-point detection are important. The Cl2 addition to the ICP-Ar etch plasma shows serious pattern deformation and degradation of loop offset (Hoff). Methanol (Me-OH) etch shows slightly lower MR-ratio due to material degradation. However, better Hoff is observed probably due to the ion protection effect by thin carbon layer over the etched surface. Dilution of Me-OH with Ar improves MR ratio. Ar/Me-OH and ICP-Ar etch processes would be the candidate for 300 mm process at present.

Kinoshita, Keizo; Utsumi, Hiroaki; Suemitsu, Katsumi; Hada, Hiromitsu; Sugibayashi, Tadahiko



Advanced silicon trench etching in MEMS applications  

NASA Astrophysics Data System (ADS)

A high performance silicon dry etch process (STS Advanced Silicon Etch ASE) which in many cases is a beneficial replacement for the usual anisotropic wet etch methods like KOH etching is presented. During fabrication of Micro-Electro- Mechanical Systems (MEMS) the patterning of silicon is an essential step. Conventional wet or dry etching processes used up to now cannot meet the majority of future MEMS patterning needs. The process described in this paper allows a wide range of possible geometries and freedom of design and mask layout for novel MEMS applications. The installed etch system is working with an inductively coupled plasma source (ICP) which produces high plasma densities at low pressure to achieve deep silicon etching (greater than 200 micrometer) with high etch rates up to 5 micrometer/min and a high passivation layer selectivity. The new ASE process uses only fluorine based chemistry and operates at room temperature. ASE uses photoresists and silicon oxid layers as an etch passivation and allows the manufacturing of silicon structures with nearly vertical side walls in bulk and surface micromachining illustrated by several MEMS applications carried out at the Fraunhofer Institute for Solid State Technology. With depths up to 100 micrometer realized at the institute now and an excellent anisotropic profile control ASE is obviously the tool, useful from device development to volume production of microsystems.

Kuehl, Karl; Vogel, Steffan; Schaber, Ulrich; Schafflik, Rainer; Hillerich, Bernhard



Anisotropic etching of surfactant-added TMAH solution  

Microsoft Academic Search

The anisotropic silicon etching characteristics of surfactant-added tetramethyl ammonium hydroxide (TMAH) solution were investigated. It was found that the etch rate of the (110) crystal plane abruptly decreases by more than one order of magnitude and that the etch rate ratio of the etch rate of the (100) crystal plane to the etch rate of the (110) crystal plane is

Masayuki Sekimura; Komukai Toshiba-cho



Preliminary observations of lung injury produced by instillation of HF in acidic and neutral buffer  

SciTech Connect

Perfluoroisobutylene (PFIB) is an extremely toxic organofluoride that can be produced during pyrolysis of tetrafluoroethylene polymers, including Teflon{reg sign}. Inhalation of PFIB at very low concentrations causes acute lung injury, the hallmark of which is pulmonary edema. Several lines of evidence have suggested that hydrolysis of PFIB and resulting production of hydrofluoric acid may be responsible for pulmonary damage. In order to investigate the potential involvement of hydrofluoric acid in producing lung injury and its relationship to the mechanism of fluorocarbon toxicity, we have compared the pulmonary injury produced by PFIB, by dissociated (H{sup +} and F{sup {minus}}), and by undissociated (HF) hydrofluoric acid in the deep lung. By delivering hydrofluoric acid by intratracheal instillation in neutral buffer, we demonstrate that F{sup {minus}} produces no significant pulmonary injury as assessed by increased in lung weight and ultrastructural changes. Similarly, instillation of acid buffer alone demonstrated that H{sup +} did not produce detectable lung injury. Instillation of HF produced changes in lung weight and ultrastructure similar to those observed in PFIB-treated rats. However, the ultrastructural studies show that in contrast to inhalation of PFIB, which produces both endothelial and epithelial cell damage, instillation of HF appears to exert its injurious effects only upon epithelial cells. 9 refs., 1 fig.

Brainard, J.R.; Kinkead, S.A.; Kober, E.M.; Sebring, R.J.; Stavert, D.M.; Lehnert, B.E.



Wet etching of InSb surfaces in aqueous solutions: Controlled oxide formation  

NASA Astrophysics Data System (ADS)

This paper investigates the wet etching of InSb surfaces by two different oxidant agents: Br2 and H2O2 and the consecutive oxides generation onto the surfaces. The strong dependence between the chemical composition of the etching baths and the nature of the final surface chemistry of this low band-gap III-V semiconductor will be especially highlighted. One aqueous etching solution combined hydrobromic acid and Bromine (HBr-Br2:H2O) with adjusted concentrations. The other solution combines orthophosphoric and citric acids with hydrogen peroxide (H3PO4-H2O2:H2O). Depending on its composition, each formulation gave rise to variable etching rate. The dosage of Indium traces in the etching solution by atomic absorption spectroscopy (AAS) gives the kinetic variation of the dissolution process. The variations on etching rates are associated to the properties and the nature of the formed oxides on InSb surfaces. Surface characterization is specifically performed by X-ray photoelectron spectroscopy (XPS). A clear evidence of the differences between the formed oxides is highlighted. Atomic force microscopy is used to monitor the surface morphology and pointed out that very different final morphologies can be reached. This paper presents new results on the strong variability of the InSb oxides in relation with the InSb reactivity toward environment interaction.

Aureau, D.; Chaghi, R.; Gerard, I.; Sik, H.; Fleury, J.; Etcheberry, A.



Subsurface defects characterization and laser damage performance of fused silica optics during HF-etched process  

NASA Astrophysics Data System (ADS)

Subsurface defects of fused silica optics would vary with HF-etched process. In this paper, the subsurface defects characteristics of HF-etched fused silica optics and their effects on laser induced damage were investigated. The results suggest that most of metal impurities defects (especially Ce element) of fused silica optics can be dissolved in strong acid solution. Subsurface damage can be removed by submerging fused silica optics in HF-based etchants. Laser damage resistance is improved through the removal of metal impurities and subsurface damage. Optical thermal absorption describes the laser absorption characterization of fused silica subsurface layer. A good correlation between optical thermal absorption and laser-induced damage performance is shown in this paper. Laser damage performance deteriorates when the HF-based etching depth exceeds one value, which can be explained by the impurities redeposition and surface roughness increase. Research results have a guiding significance for HF-based etching process technology of fused silica optics.

Liu, Hongjie; Ye, Xin; Zhou, Xinda; Huang, Jin; Wang, Fengrui; Zhou, Xiaoyan; Wu, Weidong; Jiang, Xiaodong; Sui, Zhan; Zheng, Wanguo



The effects of acid contact time and rock surfaces on acid fracture conductivity  

E-print Network

The conductivity created in acid fracturing is a competition between two phenomena: etching of the rock surface and weakening of the rock. This study presents experimental results of acid fracturing conductivity experiments with polymer gelled acid...

Melendez Castillo, Maria Georgina



Nanoscale etching and flattening of metals with ozone water.  


Etchants used for metal etching are generally harmful to the environment. We propose an environmentally friendly method that uses ozone water to etch metals. We measured the dependencies of ozone water etching on the temperature and ozone concentration for several metals and evaluated the surface roughness of the etched surfaces. The etching rate was proportional to the dissolved ozone concentration, and the temperature and the surfaces were smoothed by etching. PMID:22591392

Hatsuki, Ryuji; Yamamoto, Takatoki



Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions  

EPA Science Inventory

Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...


Etching Behavior of Aluminum Alloy Extrusions  

NASA Astrophysics Data System (ADS)

The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

Zhu, Hanliang



A feature-to-wafer-scale model of etch-rate non-uniformity in deep reactive ion etching/  

E-print Network

Deep Reactive Ion Etching (DRIE) is an inherently complex dry etching process commonly used in the semiconductor manufacturing industry. This work presents a new modeling approach to capture global etch rate variation in ...

Diaz, Jaime O. (Jaime Oscar Diaz Villamil)



Effects of potassium oxalate on knoop hardness of etch-and-rinse adhesives.  


The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives-two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])-were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; p<0.05). Regardless of the adhesive, the treatment with potassium oxalate reduced the adhesives' KHN (p<0.05), with the OS system exhibiting the lowest KHN compared with the MP and SB systems. PMID:22335301

Silva, S M A; Malacarne-Zanon, J; Carvalho, R M; Alves, M C; De Goes, M F; Anido-Anido, A; Carrilho, M R



Etch-a-Sketch Nanoelectronics  

NASA Astrophysics Data System (ADS)

The popular children's toy Etch-a-Sketch has motivated the invention of a new material capable of writing and erasing wires so small they approach the spacing between atoms. The interface between two normally insulating materials, strontium titanate and lanthanum aluminate, can be switched between the insulating and conducting state with the use of the sharp metallic probe of an atomic-force microscope. By ``sketching'' this probe in various patterns, one can create electronic materials with remarkably diverse properties. This material system shows promise both for ultra-high density storage and as possible replacements for silicon-based logic (CMOS). This work is supported by the National Science Foundation, Defense Advanced Research Projects Agency, Army Research Office and Air Force Office of Scientific Research.

Levy, Jeremy



High density plasma etching of magnetic devices  

NASA Astrophysics Data System (ADS)

Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3-rich to achieve the highest etch rates. Several different mask materials were investigated, including photoresist, thermal oxide and deposited oxide. Photoresist etches very rapidly in CO/NH 3 and use of a hard mask is necessary to achieve pattern transfer. Due to its physically dominated nature, the CO/NH3 chemistry appears suited to shallow etch depth (?0.5mum) applications, but mask erosion leads to sloped feature sidewalls for deeper features.

Jung, Kee Bum


Investigation of defects and surface polarity in GaN using hot wet etching together with microscopy and diffraction techniques  

SciTech Connect

The availability of reliable and quick methods to determine defect density and polarity in GaN films is of great interest. We have used photo-electrochemical (PEC) and hot wet etching using H{sub 3}PO{sub 4} and molten KOH to estimate the defect density in GaN films grown by hydride vapor phase epitaxy (HVPE) and molecular beam epitaxy (MBE). Free-standing whiskers and hexagonal etch pits are formed by PEC and wet etching respectively. Using Atomic Force Microscopy (AFM), we found the whisker density to be similar to etch pit densities for samples etched under precise conditions. Additionally Transmission Electron Microscopy (TEM) observations confirmed dislocation densities obtained by etching which increased our confidence in the consistency of methods used. Hot wet etching was used also to investigate the polarity of GaN films together with Convergent Beam Electron Diffraction (CBED) and AFM imaging. We found that hot H{sub 3}PO{sub 4} etches N-polarity GaN films very quickly resulting in the complete removal or drastic change of surface morphology as revealed by AFM or optical microscopy. On the contrary, the acid attacks only defect sites in Ga-polarity films producing nanometer-scale pits but leaving the defect-free GaN intact and the morphology unchanged. Additionally, the polarity assignments were related to the as-grown morphology and to the growth conditions of the buffer layer and the subsequent GaN layer.

Visconti, P.; Huang, D.; Reshchikov, M.A.; Yun, F.; Cingolani, R.; Smith, D.J.; Jasinski, J.; Swider, W.; Liliental-Weber, Z.; Morkoc, H.



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

SciTech Connect

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.

Rosli, Siti Azlina; Aziz, A. Abdul [Nano Optoelectronics Research and Technology Laboratory (N.O.R) School of Physics, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang (Malaysia)



Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments.  


We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor-liquid-solid grown InAs nanowires with embedded InP segments of 10-60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap. PMID:25360747

Schukfeh, M I; Storm, K; Hansen, A; Thelander, C; Hinze, P; Beyer, A; Weimann, T; Samuelson, L; Tornow, M



Dry etching method for compound semiconductors  


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.

Shul, R.J.; Constantine, C.



Method of sputter etching a surface  


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.

Henager, Jr., Charles H. (Seattle, WA)



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

PubMed Central

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

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



Femtosecond laser assisted etching of quartz: microstructuring from inside  

Microsoft Academic Search

In quartz crystal substrates, microchannels were made by femtosecond laser assisted etching, i.e., irradiation of focused femtosecond laser pulses followed by wet etching. By the use of wet etching, the laser irradiated region was selectively etched out, and a microchannel was formed inside the quartz substrate. The laser irradiated region was found to be amorphous by transmission electron microscopy. Anisotropy

S. Matsuo; Y. Tabuchi; T. Okada; S. Juodkazis; H. Misawa



Method for anisotropic etching in the manufacture of semiconductor devices  


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.

Koontz, Steven L. (Seabrook, TX); Cross, Jon B. (Santa Fe, NM)



Inductively Coupled Plasma Etching of Bulk Titanium for MEMS Applications  

E-print Network

Inductively Coupled Plasma Etching of Bulk Titanium for MEMS Applications E. R. Parker,a, * B. J the characterization of bulk titanium deep etching using Cl2/Ar chemistry with an inductively coupled plasma ICP source or biocompatibility. The bulk titanium etch rate, TiO2 mask etch rate, and surface roughness in an inductively coupled

MacDonald, Noel C.


Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala  

E-print Network

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala Department plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having

Kushner, Mark


Epoxy bond and stop etch fabrication method  


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.

Simmons, Jerry A. (Sandia Park, NM); Weckwerth, Mark V. (Pleasanton, CA); Baca, Wes E. (Albuquerque, NM)



Uniform Etching For Polycrystalline Photoconductor Films  

NASA Technical Reports Server (NTRS)

Prewetting surface overcomes problem of nonuniformity of etching often occuring in polycrystalline films at PbS and PbSe. Believed prewetting causes etchant to attack film uniformly. Because process involves wet chemistry, inexpensive and easy to use.

Barrett, John



Anisotropic reactive ion etching of vanadium dioxide  

E-print Network

ANISOTROPIC REACTIVE ION ETCHING OF VANADIUM DIOXIDE A Thesis by BYRON K. RADLE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1990... to a photoresist mask which was another favorable attribute. The effects of the independent variables such as pressure and dc bias on etch rate, anisotropy, selectivity, and surface quality were analyzed using a two-level factorial approach...

Radle, Byron K



Investigation of Nitride Morphology After Self-Aligned Contact Etch  

NASA Technical Reports Server (NTRS)

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.

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



Scanning electron microscope study of the effects of soft drinks on etched and sealed enamel  

Microsoft Academic Search

The purpose of this study was to determine the effects of cola and other acidic drinks on etched tooth enamel in a simulated oral environment. The test beverages were cola, orange soda, lemon soda, and sparkling mineral water. Sixty extracted premolars were divided into an experimental group (n = 40) and a control group (n = 20). Half of the

Banu Dinçer; Serpil Hazar; Bilge Hakan Sen



Cr photomask etch performance and its modeling  

NASA Astrophysics Data System (ADS)

Mathematical prediction of dry etch results have been difficult, if not impossible, over the years due to the complexity inherent in plasma processing. With device requirements tightening combined with the high cost of running test masks, it becomes even more important for process engineers to have some means by which to model accurately this increasingly complex activity. In this paper, a correlation between a novel, plasma chrome etch model and empirical data will be presented. Practical effects of chrome loading are also discussed. From the empirical data side, studies on the photomask chrome etch process using e-beam resists were carried out following strict design of experiments (DOE) format. Photomask chrome etch processes with different resists (ZEP and positive CAR) were investigated using a Unaxis VLR 770 ICP etcher and an AMAT Tetra etcher. A Toshiba EBM-3500B (50KeV) was used for the pattern writing on positive CAR resist. A KLA-Tencor P12-EX profiler, Leica LWM 250 UV CD optical measurement system, and a KLA-Tencor 8250XP-R CD SEM were used for metrology and product characterization. Significant etch performance differences were shown on these etchers irrespective of the resist type used. A special measurable number was defined and found to have a linear relationship with etch movement on both AMAT and VLR etchers.

Wu, Banqiu; Chan, David Y.



Sapphire etching with BCl 3\\/HBr\\/Ar plasma  

Microsoft Academic Search

The etching of (0001) sapphire wafer was studied in an inductively coupled plasma etcher using BCl3\\/HBr\\/Ar plasmas. The qualitative relationship between etch rate and inductive power and d.c. bias voltage was studied to obtain high sapphire etch rate. The etch rate was increased almost linearly with the increase of inductive power and d.c. bias voltage. The etch selectivity over photoresist

C. H. Jeong; D. W. Kim; H. Y. Lee; H. S. Kim; Y. J. Sung; G. Y. Yeom



Experimental Study of Acid Fracture Conductivity of Austin Chalk Formation  

E-print Network

Acid fracture conductivity and the effect of key variables in the etching process during acid fracturing can be assessed at the laboratory scale. This is accomplished by using an experimental apparatus that simulates acid injection fluxes comparable...

Nino Penaloza, Andrea



The electronic structure of anodized and etched aluminum alloy surfaces  

NASA Astrophysics Data System (ADS)

Specimens of 6061 and 5052 aluminum alloys which had been anodized and etched by several commonly used procedures were examined by means of bias-reference X-ray photoelectron spectroscopy (XPS). The spectra were compared with those obtained from single crystals of pure aluminum oxides. The chemical shifts observed from the A12p surface oxide lines were interpreted as differences in the Fermi energy levels relative to those in the bulk oxide crystals, and the Fermi energy levels of the surface oxides were thus determined. Using an earlier experimental correlation obtained for values of the point of zero charge (pzc) with Fermi energy levels in aluminum oxide powders, a value of the pzc of the surface oxide was then determined. The surface exhibited the maximum alkalinity, pzc = 8.9, after a caustic etch, and the maximum acidity, pzc = 3.6, after a phosphoric acid anodizing treatment. The significance of these pzc values in the adhesive bonding of aluminum alloys is discussed.

Mullins, W. M.; Averbach, B. L.



Matrixes of unconventional micro-optical components molded with etched silicon  

NASA Astrophysics Data System (ADS)

This paper reports on a process to create microlenses characterized by unconventional footprints, spherical profiles and a wide range of sizes. Fabricated shapes such as squares, rectangles, ellipses, triangles and hexagons are tested alone as well as in matrix with high fulfill factors. The technique is based on molds from which microlenses are fabricated by UV-molding replication. The molds are produced by silicon wet isotropic etching in an acid solution. The process is mainly steered by temperature and etching concentration. The use of the proposed technology opens a wide range of geometries allowing the fabrication of microlenses matrices with high fulfill factors as well as microlenses for beam-shaping.

Albero, J.; Gorecki, C.; Nieradko, L.; Päivänranta, B.; Gomez, V.; Thienpont, H.; Passilly, N.



High-etch-rate anisotropic deep silicon plasma etching for the fabrication of microsensors  

NASA Astrophysics Data System (ADS)

Dry plasma etching can offer many advantages in the fabrication of MEMS because of its anisotropic etching behavior, high etch rate, and its compatibility with traditional IC processing. A patented high density inductively coupled RFIC plasma source with independent source power and substrate bias control has been developed by Alcatel for deep etching of silicon. With the optimization of hardware and process parameters in a Fluorine based chemistry, processes with silicon etch rate up to 6 micrometers/min, etch uniformity better than +/- 5 percent, Si:SiO2 selectivity of more than 150:1, Si:photoresist selectivity of more than 50:1, etch depths of greater than 250 mm and profile angels of +/- 1 degree have been demonstrated. The silicon etch rate increases with increasing source power and Si:SiO2 selectivity increases with decreasing substrate bias. Substrate temperature can be maintained between -120 to +20 C during processing. The process parameters can be adjusted to give the desired performance for a particular application. Process results obtained at room temperature and at lower temperatures for different applications will be presented. The results indicate that this technology is a promising candidate for micromachining. The tool can be configured for production applications with vacuum loadlock and automated wafer handling.

Pandhumsoporn, Tam; Feldbaum, Michael; Gadgil, Prashant; Puech, Michel; Maquin, Philippe



Etch-induced damage of HgCdTe caused by inductively coupled plasma etching technique  

NASA Astrophysics Data System (ADS)

HgCdTe third-generation infrared focal plane arrays such as avalanche photodiodes, two-color detectors and multi-color detectors require isolation of high aspect ratio trenches with admissible etch induced damage at the surface and sidewalls. Dry etch has many advantages compare with wet etch such as high anisotropy, good uniformity and good reproducibility. Inductively coupled plasma (ICP) etching is most widely used for its low etch induced damage which is a new high density plasma technique. It's very important to understand etching mechanisms and reduce etch induced damage for the low damage threshold of HgCdTe which is due to weak Hg-Te bond and low volatility of CdTe component. The main work of this paper is researching the influence of etch induced damage caused by different mask technique using inductively coupled plasma etching instrument with a feasible technics. In this experiment we used two different masks, one only has a film of silicon dioxide which we called thin mask, its thickness is less than one micrometer, and the other is composed of resist and silicon dioxide which we called complex thick mask, its thickness is several micrometers. We tested the current-voltage (I-V) characteristics of a chip which has a special structure achieved by dry etch and about one micrometer wet etch to remove the etch induced damage film. Then we found that in a same condition the I-V characteristics of the chip which used complex thick mask is distinctly better than the chip which used thin mask. Resist and silicon dioxide complex thick mask can effectively reduce etch induced damage. The reasons for this result have two aspects, in one hand, the grown process of silicon dioxide can cause damage of HgCdTe surface, make a thick resist between HgCdTe and silicon dioxide can reduce the damage of HgCdTe surface, in the other hand, complex thick mask can hold up the damage of trench sidewall in etch process.

Yin, Wenting; Zhou, Wenzhong; Huang, Jian



Enhanced photoelectrochemical-response in highly ordered TiO 2 nanotube-arrays anodized in boric acid containing electrolyte  

Microsoft Academic Search

We examine the photoelectrochemical properties of highly ordered titanium dioxide nanotube-array photoanodes, fabricated by anodization of titanium in a nitric acid\\/hydrofluoric acid electrolyte, with and without the addition of boric acid. Under UV–Vis illumination the photocurrent densities achieved with TiO2 nanotube-arrays fabricated in the H3BO3–HNO3–HF electrolyte are a factor of seven greater than the TiO2 nanotube-array samples obtained in the

Chuanmin Ruan; Maggie Paulose; Oomman K. Varghese; Craig A. Grimes



Three-dimensional simulation of sacrificial etching  

NASA Astrophysics Data System (ADS)

Sacrificial etching is one of the most important process steps in Micro-Electro-Mechanical Systems (MEMS) technology, since it enables the generation of free-standing structures. These structures are often the main part of micro-mechanical devices, intended to sense or induce a mechanical movement. The etching process transforms an initial multi-segmented geometry and depends on material properties and several process conditions. One of the crucial issues for etching is the etching selectivity on different materials. The major task for the simulation is to give an answer, how sacrificial layer surfaces regress in time under the influence of process parameters and to which magnitude surrounding material segments are affected by the etching process. For this purpose we have developed a full three-dimensional topography simulation tool, Etcher-Topo3D, which is capable to deal with realistic process conditions. The main concept is demonstrated in this work. During simulation the topography of the initial multi- segment geometry is changed which is handled by a level-set algorithm. After a simulation is finished, the level-set representation has usually to be converted back to a mesh representation to enable further analysis. For illustrating the main features of our simulation tool several examples of a MEMS structure with a sacrificial layer are presented.

Cervenka, Johann; Ceric, Hajdin; Selberherr, Siegfried



Pulsed plasma etching for semiconductor manufacturing  

NASA Astrophysics Data System (ADS)

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.

Economou, Demetre J.



Maskless micro/nanofabrication on GaAs surface by friction-induced selective etching  

NASA Astrophysics Data System (ADS)

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface.

Tang, Peng; Yu, Bingjun; Guo, Jian; Song, Chenfei; Qian, Linmao



Evaluation of Cu Ion Concentration Effects on Cu Etching Rate in Chemical-Mechanical Polishing Slurry  

NASA Astrophysics Data System (ADS)

The effects of Cu ion concentration of the different solutions on Cu etching rate were investigated. From the dipping experiment of Cu substrates in different solutions of malic acid, hydrogen peroxide (H2O2), benzotriazole (BTA), and Cu ions, it was revealed that Cu etching rate is increased if the concentration of Cu(II) ions added in the solution is high. This is considered to be caused by the effect of Cu(II) ions on H2O2 molecules. In the solution of pH 7, the Cu etching rate increased markedly between 1.7× 10-4 and 3.4× 10-4 M Cu(II) ion concentrations. The maximum increase in the etching rate was from 990 to 2200 nm/min at a H2O2 concentration of 2 wt %. In the solution of pH 3, a marked change in the etching rate was not observed. Our results show that the concentration of Cu ions on the polishing pad in chemical-mechanical polishing (CMP) process is very important.

Nishizawa, Hideaki; Sugiura, Osamu; Matsumura, Yoshiyuki; Kinoshita, Masaharu



Surface-dependent, ligand-mediated photochemical etching of CdSe nanoplatelets.  


Photochemical etching of CdSe nanoplatelets was studied to establish a relationship between the nanocrystal surface and the photochemical activity of an exciton. Nanoplatelets were synthesized in a mixture of octylamine and oleylamine for the wurtzite (W) lattice or in octadecene containing oleic acid for the zinc-blende (ZB) lattice. For photochemical etching, nanoplatelets were dispersed in chloroform containing oleylamine and tributylphosphine in the absence or presence of oleic acid and then irradiated with light at the band-edge absorption maxima. Etching phenomena were characterized using UV-vis absorption spectroscopy and transmission electron microscopy. The absorption spectra of both W and ZB CdSe nanoplatelets showed that the exciton was confined in one dimension along the thickness. However, the two nanoplatelets presented different etching kinetics and erosion patterns. The rate of etching for W CdSe nanoplatelets was much faster than that for ZB nanoplatelets. Small holes were uniformly perforated on the planar surface of W nanoplatelets, whereas the corners and edges of ZB nanoplatelets were massively eroded without a significant perforation on the planar surface. This suggests that the amine-passivated surface of trivalent cadmium atoms on CdSe nanoplatelets is photochemically active, but the carboxylate-passivated surface of divalent cadmium atoms is not. Hence, the ligand, which induces the growth of W or ZB CdSe nanoplatelets, mediates the surface-dependent photochemical etching. This result implies that an electron-hole pair can be extracted from the planar surface of amine-passivated W nanoplatelets but from the corners and edges of carboxylate-passivated ZB nanoplatelets. PMID:22540946

Lim, Sung Jun; Kim, Wonjung; Shin, Seung Koo



Selective lateral electrochemical etching of a GaN-based superlattice layer for thin film device application  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a selective lateral electrochemical etching using a superlattice as the etch-sacrificial layer. Differing from the previous methods that require a special etch-sacrificial layer and therefore deteriorate the epilayer grown atop, our method simplifies the epi-growth without compromising the epi-quality. At the reverse bias voltage of 20 V in 0.3 M oxalic acid electrolyte, a 50-nm-thick InGaN/AlGaN superlattice was etched laterally at the rate of ˜0.8 ?m/min. Our method is efficient enough for the epitaxial lift-off process: an array of 80 ?m × 80 ?m square platelets is completely detached from substrate, with quantum-well emission properties preserved intact.

Kim, Dong-Uk; Chang, Hojun; Cha, Hyungrae; Jeon, Heonsu; Jeon, Seong-Ran



Characterization of electric discharge machining, subsequent etching and shot-peening as a surface treatment for orthopedic implants  

NASA Astrophysics Data System (ADS)

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.

Stráský, Josef; Havlíková, Jana; Ba?áková, Lucie; Harcuba, Petr; Mhaede, Mansour; Jane?ek, Miloš



Practical applications of backside silicon etching  

SciTech Connect

As the complexity of the integrated circuits increases, deprocessing becomes a challenging job due to multilevel metallization and planarization processes. Deprocessing issues associated with failure analysis of the trench capacitors in DRAM devices are well known and various techniques to inspect the trenches from the backside have been widely published. These backside etching techniques can also be applied to failure analysis of other multilayer metallization devices for efficient inspection of gate oxide and contacts. This paper compares backside silicon etch (BSE) techniques using several etchants as well as various sample preparation methods. Practical applications of backside silicon etching of different devices have been described for DRAM and SRAM single cell failures and silicide contact failures where deprocessing from the top side is difficult. These examples show how BSE can be a very useful technique to characterize defects in a wide variety of devices.

Corum, D.; Chowdhury [Texas Instruments, Houston, TX (United States)



Thermally controlled widening of droplet etched nanoholes  

PubMed Central

We describe a method to control the shape of nanoholes in GaAs (001) which combines the technique of local droplet etching using Ga droplets with long-time thermal annealing. The cone-like shape of inverted nanoholes formed by droplet etching is transformed during long-time annealing into widened holes with flat bottoms and reduced depth. This is qualitatively understood using a simplified model of mass transport incorporating surface diffusion and evaporation. The hole diameter can be thermally controlled by varying the annealing time or annealing temperature which provides a method for tuning template morphology for subsequent nanostructure nucleation. We also demonstrate the integration of the combined droplet/thermal etching process with heteroepitaxy by the thermal control of hole depth in AlGaAs layers. PMID:24948902



Etching Damages on AlGaN, GaN and InGaN Caused by Hybrid Inductively Coupled Plasma Etch and Photoenhanced Chemical Wet Etch by Schottky Contact Characterizations  

Microsoft Academic Search

The surface damaging effects of the inductively coupled plasma (ICP) etch and the photoenhanced chemical (PEC) wet etch on AlGaN, GaN and InGaN were systematically investigated. The surface morphologies and the etch rates after ICP etch and PEC wet etch were explored to achieve optimum conditions for a hybrid etch technique. The etch rates increased with the ICP power or

Chao-Yi Fang; Weng-Jung Huang; Edward Yi Chang; Chia-Feng Lin; Ming-Shiann Feng



Etching Silicon Films With Xenon Difluoride  

NASA Technical Reports Server (NTRS)

Microscopic circuit structures prepared for probing. Xenon difluoride removes relatively large amounts of silicon from integratedcircuit or solar-cell structures while leaving SiO2, Si3N4, Al2O3, and other compounds intact. In Etching Apparatus, solid XeF2 sublimated in vacuum, then allowed to flow over sample at controlled rate and pressure. Wafer etched from back to expose SiO2 and Al layers for spectroscopic analysis of SiO2/Al interface. Using XeF2 technique, silicon wafer with oxide layer reduced in thickness from standard 300 micrometer to as little as 10 nanometer without adversely affecting oxide.

Hecht, M. H.



Etching of Graphene Devices with a Helium Ion Beam  

E-print Network

We report on the etching of graphene devices with a helium ion beam, including in situ electrical measurement during lithography. The etching process can be used to nanostructure and electrically isolate different regions ...

Baugher, Britton William Herb


Multilayer Badges Indicate Depths Of Ion Sputter Etches  

NASA Technical Reports Server (NTRS)

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.

Beattie, J. R.; Matossian, J. N.; Garvin, H. L.



Quantitative evaluation of microleakage in Class V cavities using one-bottle and self-etching adhesive systems.  


The aim of this in vitro study was to evaluate quantitatively the microleakage in Class V cavities restored with one-bottle and self-etching adhesive systems with and without previous acid etching. Two one-bottle adhesive systems (Single Bond and Prime & Bond 2.1) and one self-etching adhesive system (Clearfil Mega Bond) were used in this study. One hundred and twenty sound human premolar teeth were randomly divided into 6 groups, and 20 Class V restorations were prepared in the root dentin to test each bonding system. Each bonding system was used with and without acid etching. Specimens were prepared, dyed with 2% methylene blue, sectioned, triturated, and evaluated with an absorbance spectrophotometer test in order to quantify the infiltrated dye. Results were statistically evaluated by ANOVA and Tukey-Kramer test. No statistically significant differences were found among the adhesive systems when no etching agent was used. However, the Single Bond adhesive system showed statistically significant lower microleakage means than Clearfil Mega Bond and Prime & Bond 2.1 when 37% phosphoric acid was used. Single Bond and Clearfil Mega Bond adhesive systems presented similar behavior when the manufacturers' instructions were followed. PMID:15619881

França, Fabiana Mantovani Gomes; Aguiar, Flávio Henrique Baggio; dos Santos, Alex José Souza; Lovadino, José Roberto



Graphene as an etch mask for silicon  

NASA Astrophysics Data System (ADS)

We are using graphene as a hard etch mask for silicon. The error introduced by its edges is hypothesized to be far less compared to innate issues of photolithography (e.g. undercut, sidewall hardening). This presents the possibility of making a highly precise etch mask. We lithographically pattern a graphene layer transferred to a Si(100) surface and fluorinate the sample to demonstrate the selective etching on exposed regions. The graphene layer becomes fluorinated, but shields the silicon underneath. The Si(100) with selective graphene coating was subjected to isotropic etching by xenon difluoride (at 1.0 Torr, and N2 at 35.0 Torr) for 180 s to remove approximately 190 nm of silicon. Raman spectroscopy confirms the onset of sp^3 hybridization of carbon atoms in the hexagonal lattice, brought on by covalent C--F bonding. Along with the possibility of producing highly precise silicon structures, the monolayer mask has added advantages, such as not requiring as many processing steps as the conventional method involving photoresist.

Rangarajan, Aniruddh; Wood, Joshua; Koepke, Justin; Lyding, Joseph



Glass etching to bridge micro- and nanofluidics.  


In this study, a simple and economical fabrication technique bridging micro- and nanostructures is proposed. Glass molds with micro-nanostructures are fabricated by glass microlithography. The microlithography provides flexibility for structure design, and the glass etching contributes to transform the micro glass ridge to the nanoscale. Glass ridge structures with triangular cross sections are generated by undercutting, which coupled the isotropic character of glass and the shield effect of the top Cr layer upon HF etching. Further etching induced the height of the glass ridges to shrink from micro- to nanometres due to the edge effects. At the late etching stage, the geometrical change of the glass greatly slows down, which gives better control over the size of the glass ridge. By glass structure mold-copy, well repeatable, mechanically stable and tunable polydimethylsiloxane (PDMS) channels and cones are fabricated. Scanning electron microscopy (SEM) and laser interferometry (LI) are carried out to characterize the micro-nanostructures. To demonstrate their workability, sample preconcentration to a single nanochannel level is carried out. PMID:22068964

Xu, Bi-Yi; Yan, Xiao-Na; Zhang, Jia-Dong; Xu, Jing-Juan; Chen, Hong-Yuan



Dynamic observation of electrochemical etching in silicon  

SciTech Connect

The authors have designed and constructed a TEM specimen holder in order to observe the process of pore formation in silicon. The holder incorporates electrical feedthroughs and a sealed reservoir for the electrolyte and accepts lithographically patterned silicon specimens. The authors describe the system and present preliminary, ex situ observations of the etching process.

Ross, F.M. [Lawrence Berkeley Lab., CA (United States). National Center for Electron Microscopy; Searson, P.C. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering



Chromium Etching Revised: 2009-12-15  

E-print Network

Chromium Etching Revised: 2009-12-15 Source: www. Chromium Chromium is a hard metal with good adhesion to many materials. Therefore, in the field of micro- structuring chromium is used for photo masks and as adhesion promotor for subsequently coated materials

Yoo, S. J. Ben


Etch Profile Simulation Using Level Set Methods  

NASA Technical Reports Server (NTRS)

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.

Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)



Comparative evaluation of antibacterial activity of total-etch and self-etch adhesive systems: An ex vitro study  

PubMed Central

Aim: The aim of this ex vivo study was to compare the antibacterial activity of total-etch and self-etch adhesive systems against Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces viscosus through disk diffusion method. Materials and Methods: The antibacterial effects of Single Bond (SB) and Adper Prompt (AP) and aqueous solution of chlorhexidine 0.2% (positive control) were tested against standard strain of S. mutans, L. acidophilus, and A. viscosus using the disk diffusion method. The diameters of inhibition zones were measured in millimeters. Data was analyzed using Kruskal-Wallis test. Mann-Whitney U test was used for pairwise comparison. Result: Of all the materials tested, AP showed the maximum inhibitory action against S. mutans and L. acidophilus. Aqueous solution of chlorhexidine 0.2% showed the maximum inhibitory action against A. viscosus. Very minimal antibacterial effect was noted for SB. Conclusion: The antibacterial effects observed for the tested different dentin bonding systems may be related to the acidic nature of the materials. PMID:24944452

Amin, Swathi; Shetty, Harish K.; Varma, Ravi K.; Amin, Vivek; Nair, Prathap M. S.



Etched core fiber Bragg grating sensor integrated with microfluidic channel  

Microsoft Academic Search

We demonstrate an etched-core fiber Bragg grating sensor for detection of bio-chemical agents. The fiber Bragg grating of the sensor is etched to a diameter of 7 mum. The transition between the etched and the unetched core consists of an asymmetric taper resulting in excitation of multiple modes. The different excited modes respond differently to change in refractive index, temperature

Sang-Mae Lee; Myung-Yung Jeong; Simarjeet S. Saini



Studies of Gas Discharges for Dry Etching Modeling and Diagnostics  

Microsoft Academic Search

Modeling of dry etching processes requires knowledge of the etchant species and the energetic ion distribution incident at the wafer surface. Since plasma chemistry in low-pressure dry etching discharges is initiated by highly energetic electrons formed in the discharge, a comprehensive model for dry etching must include electrical discharge physics, gas phase kinetics, species transport and surface reactions. Numerical simulators

Ajit Pramod Paranjpe



Cryogenic dry etching for high aspect ratio microstructures  

Microsoft Academic Search

Cryogenic reactive ion etching (RIE) has been used to fabricate microstructures. The cryogenic system has a cathode stage that is temperature controlled from 0 to -140°C. A magnetic field and a narrow gap between electrodes are introduced to increase plasma density. The etching behavior of silicon and polyimide film has been investigated. Directional etching was achieved at low temperature. The

Kenji Murakami; Yuji Wakabayashi; Kazuyuki Minami; Masayoshi Esashi



Subliming Ice Surfaces: Freeze-Etch Electron Microscopy  

Microsoft Academic Search

Vacuum sublimation of oriented single crystals of ice at temperatures from -110 to -60 degrees Celsius was studied by electron microscopy with the freeze-etch technique. Sublimation etches the ice surface to produce pits and asperities and above -85 degrees Celsius causes extreme surface roughening. The etch pits are ascribed to surface dislocations, and the extreme roughening is ascribed to the

J. Gordon Davy; Daniel Branton



CR-39 track etching and blow-up method  


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.

Hankins, Dale E. (Livermore, CA)



Microfabrication of Magnetic Tunnel Junctions Using CH OH Etching  

Microsoft Academic Search

The 100-nm-scale CoFeB\\/MgO\\/CoFeB magnetic tunnel junctions (MTJs) were fabricated using a CH3OH etching process. These MTJs have steep side walls and show clear MR loops. The distributions of magnetic properties of CH3OH etched MTJs were smaller than those of conventional Ar ion etched MTJs

Y. Otani; H. Kubota; A. Fukushima; H. Maehara; T. Osada; S. Yuasa; K. Ando



Bonding of Self-etch and Total-etch Adhesives to Carious Dentin  

Microsoft Academic Search

Carious dentin is partially demineralized and contains mineral crystals in the tubules. This may permit the deeper etching of intertubular dentin but prevent resin tag formation during bonding. We hypothesize that resin adhesives will produce lower bond strengths to caries-infected and caries-affected dentin compared with normal dentin. We tested this by measuring the microtensile bond strength of a total-etch adhesive

M. Yoshiyama; F. R. Tay; J. Doi; Y. Nishitani; T. Yamada; K. Itou; R. M. Carvalho; M. Nakajima; D. H. Pashley



Effect of application mode on interfacial morphology and chemistry between dentin and self-etch adhesives  

PubMed Central

Objective To investigate the influence of application mode on the interfacial morphology and chemistry between dentin and self-etch adhesives with different aggressiveness. Methods The occlusal one-third of the crown was removed from un-erupted human third molars, followed by abrading with 600 grit SiC under water. Rectangular dentin slabs were prepared by sectioning the tooth specimens perpendicular to the abraded surfaces. The obtained dentin slabs were treated with one of the two one-step self-etch adhesives: Adper Easy Bond (AEB, PH~2.5) and Adper Prompt L-Pop (APLP, PH~0.8) with (15s, active application) or without (15s, inactive application) agitation. The dentin slabs were fractured and the exposed adhesive/dentin (A/D) interfaces were examined with micro-Raman spectroscopy and scanning electron microscopy (SEM). Results The interfacial morphology, degree of dentin demineralization (DD) and degree of conversion (DC) of the strong self-etch adhesive APLP showed more significant dependence on the application mode than the mild AEB. APLP exhibited inferior bonding at the A/D interface if applied without agitation, evidenced by debonding from the dentin substrate. The DDs and DCs of the APLP with agitation were higher than those of without agitation in the interface, in contrast to the comparable DD and DC values of two AEB specimen groups with different application modes. Raman spectral analysis revealed the important role of chemical interaction between acid monomers of self-etch adhesives and dentin in the above observations. Conclusion The chemical interaction with dentin is especially important for improving the DC of the strong self-etching adhesive at the A/D interface. Agitation could benefit polymerization efficacy of the strong self-etch adhesive through enhancing the chemical interaction with tooth substrate. PMID:23153573

Zhang, Ying; Wang, Yong



Vertical etching with isolated catalysts in metal-assisted chemical etching of silicon.  


Metal assisted chemical etching with interconnected catalyst structures has been used to create a wide array of organized nanostructures. However, when patterned catalysts are not interconnected, but are isolated instead, vertical etching to form controlled features is difficult. A systematic study of the mechanism and catalyst stability of metal assisted chemical etching (MACE) of Si in HF and H(2)O(2) using Au catalysts has been carried out. The effects of the etchants on the stability of Au catalysts were examined in detail. The role of excess electronic holes as a result of MACE was investigated via pit formation as a function of catalyst proximity and H(2)O(2) concentration. We show that a suppression of excess holes can be achieved by either adding NaCl to or increasing the HF concentration of the etching solution. We demonstrate that an electric field can direct most of the excess holes to the back of the Si wafer and thus reduce pit formation at the surface of Si between the Au catalysts. The effect of hydrogen bubbles, generated as a consequence of MACE, on the stability of Au catalysts has also been investigated. We define a regime of etch chemistry and catalyst spacing for which catalyst stability and vertical etching can be achieved. PMID:23099475

Lianto, Prayudi; Yu, Sihang; Wu, Jiaxin; Thompson, C V; Choi, W K



Enhanced resist and etch CD control by design perturbation  

NASA Astrophysics Data System (ADS)

Etch dummy features are used in the mask data preparation flow to reduce critical dimension (CD) skew between resist and etch processes and improve the printability of layouts. However, etch dummy rules conflict with SRAF (Sub-Resolution Assist Feature) insertion because each of the two techniques requires specific spacings of poly-to-assist, assist-to-assist, active-to-etch dummy and dummy-to-dummy. In this work, we first present a novel SRAF-aware etch dummy insertion method (SAEDM) which optimizes etch dummy insertion to make the layout more conducive to assist-feature insertion after etch dummy features have been inserted. However, placed standard-cell layouts may not have the ideal whitespace distribution to allow for optimal etch dummy and assist-feature insertions. Since placement of cells can create forbidden pitch violations, the placer must generate assist-correct and etch dummy-correct placements. This can be achieved by intelligent whitespace management in the placer. We describe a novel dynamic programming-based technique for etch-dummy correctness (EtchCorr) which can be combine with the SAEDM in detailed placement of standard-cell designs. Our algorithm is validated on industrial testcases with respect to wafer printability, database complexity and device performance.

Gupta, Puneet; Kahng, Andrew B.; Park, Chul-Hong



Wet Etching of ?-Ga2O3 Substrates  

NASA Astrophysics Data System (ADS)

Wet etching of (100)-oriented ?-Ga2O3 single crystal substrates was carried out using H3PO4 and H2SO4. The etching reactions followed the Arrhenius equation, but the etching in H2SO4 at a high temperature of 190 °C was disturbed by the formation of sulfates on the surface. Considering the higher etching rate over the temperature range of 100-194 °C, H3PO4 is more preferable as an etchant for ?-Ga2O3. Although the isotropic etching led to side etching, a grid pattern in the order of µm was successfully fabricated. These results indicate that this simple and low-cost wet etching using H3PO4 is suitable for isolating devices or patterning structures on ?-Ga2O3 substrates.

Oshima, Takayoshi; Okuno, Takeya; Arai, Naoki; Kobayashi, Yasushi; Fujita, Shizuo



Wet chemical etching of AlN in KOH solution  

NASA Astrophysics Data System (ADS)

In this work we investigated the influence of the AlN material quality on the etching rate in KOH-based solutions. Thus, AlN layers were deposited by three different methods on sapphire and silicon substrates (i) by metal organic chemical vapor deposition (MOCVD), (ii) by molecular beam epitaxy (MBE), and (iii) by reactive sputter deposition. The etch rate is strongly dependent on crystal quality and etch temperatures. The high quality MBE-AlN could be etch anisotropic with a preferred lateral component in [110] direction at 60 °C while the polycrystalline AlN layers we etched isotropic and homogenously already at room temperature. The wet chemical etching in KOH solution is mainly an etching along defects and grain boundaries.

Cimalla, I.; Foerster, Ch.; Cimalla, V.; Lebedev, V.; Cengher, D.; Ambacher, O.



A Novel Model for Fracture Acidizing with Important Thermal Effects  

E-print Network

Fracture acidizing is a well stimulation technique used to improve the productivity of low-permeability reservoirs, and to bypass deep formation damage. The reaction of injected acid with the rock matrix forms etched channels (that depend...

Lyons, John



Depth-resolved subsurface defects in chemically etched SrTiO3  

Microsoft Academic Search

Depth-resolved cathodoluminescence spectroscopy of atomically flat TiO2-terminated SrTiO3 single crystal surfaces reveals dramatic differences in native point defects produced by conventional etching with buffered HF (BHF) and an alternative procedure using HCl-HNO3 acidic solution (HCLNO), which produces three times fewer oxygen vacancies before and nearly an order of magnitude fewer after pure oxygen annealing. BHF-produced defect densities extend hundreds of

Jun Zhang; D. Doutt; T. Merz; J. Chakhalian; M. Kareev; J. Liu; L. J. Brillson



Fabrication of Semiconductors by Wet Chemical Etch  

E-print Network

etching will use InGaAsSb wafers. However, because indium is the most di#cult layer to etch, InGaP is a good starting point. Epi Layer Structures of V3338 350 Å GaAs 5E18 Si Doping (Top) 400 Å GaAs 1E17 Si Doping 160 Å InGaP not intentionly doped... (i) Delta Si Doping 4.4E12/cm2 30 Å AlGaAs not intentionally doped (i) 130 Å InGaAs not intentionally doped (i) 30 Å AlGaAs not intentionally doped (i) Delta Si Doping 1.1E12/cm2 Superlattice Buffer GaAs Buffer S.I. GaAs Substrate Epi Layer Structures...

Francoviglia, Laura



Properties of TNF-1 track etch detector  

NASA Astrophysics Data System (ADS)

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/?m 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.

Ogura, K.; Asano, M.; Yasuda, N.; Yoshida, M.



Profiles: isotropic & anisotropic Applications: Si, Silicon nitride, silicon dioxide, metal  

E-print Network

­ Hot Phos #12;4 Acid: ·HNA (Hydrofluoric acid + Nitric acid + Acetic acid) Base: ·KOHetch ·NaOH etch in glass pan, place pan on hot plate and heat to 50 C (plate Temp set at 100 C) Etch Rate ~ 1.66 µm®) ·High resistance to chemicals and temperature ·Can be used in wet chemistry processes (RCA clean, BOE

Wang, Deli


Etch Overview for Microsystems Learning Module  

NSDL National Science Digital Library

This page from the Southwest Center for Microsystems Education features a learning module which presents a general overview of various etch processes used in the construction of microsystems. A participant guide, instructor guide (both in PDF format) and a comprehensive powerpoint presentation are included. Furthermore, an additional presentation describes the rainbow wafer activity which teaches students to interpret graphs and charts related to silicon dioxide thickness on a silicon wafer



Characterization of aluminum surfaces: Sorption and etching  

NASA Astrophysics Data System (ADS)

Aluminum, due to its low density and low cost, is a key material for future lightweight applications. However, like other structural materials, aluminum is subject to various forms of corrosion damage that annually costs the United States approximately 5% of its GNP [1]. The main goal is to investigate the effects of various solution anions on aluminum surfaces, and specifically probe pit initiation and inhibition. Using surface analysis techniques including X-ray photoelectron spectroscopy, Auger electron spectroscopy, and scanning electron microscopy, results have been correlated with those obtained from electrochemical methods and a radiolabeling technique developed in the Wieckowski laboratory. Analysis of data has indicated that important variables include type of anion, solution pH, and applied electrode potential. While aggressive anions such as chloride are usually studied to elucidate corrosion processes to work ultimately toward inhibition, its corrosive properties can be successfully utilized in the drive for higher energy and smaller-scale storage devices. Fundamental information gained regarding anion interaction with the aluminum surface can be applied to tailor etch processes. Standard electrochemical techniques and SEM are respectively used to etch and analyze the aluminum substrate. Aluminum electrolytic capacitors are comprised of aluminum anode foil covered by an anodically grown aluminum oxide dielectric film, electrolytic paper impregnated with electrolyte, and aluminum cathode foil. Two main processes are involved in the fabrication of aluminum electrolytic capacitors, namely etching and anodic oxide formation. Etching of the anode foil results in a higher surface area (up to 20 times area enlargement compared to unetched foil) that translates into a higher capacitance gain, permitting more compact and lighter capacitor manufacture. Anodic oxide formation on the anode, creates the required dielectric to withstand high voltage operation. A detailed investigation of variables such as solution temperature, solution composition, and supplied charge used in these processes can lead to improved foil design and ultimately a better product.

Polkinghorne, Jeannette Clera


Hydrolysis of Functional Monomers in a Single-bottle Self-etching Primer—Correlation of 13C NMR and TEM Findings  

Microsoft Academic Search

Self-etching primers\\/adhesives that combine acidic methacrylate monomers with water in a single bottle are hydrolytically unstable and require refrigeration to extend their shelf-lives. This study tested the null hypothesis that one year of intermittent refrigeration of a 4-MET-containing simplified self-etching primer does not result in hydrolytic changes that are identifiable by transmission electron microscopy and 13C NMR spectroscopy. Human dentin

N. Nishiyama; F. R. Tay; K. Fujita; D. H. Pashley; K. Ikemura; N. Hiraishi; N. M. King



Near ultraviolet InGaN\\/GaN MQWs grown on maskless periodically grooved sapphire substrates fabricated by wet chemical etching  

Microsoft Academic Search

In the paper, we describe the fabrication and characteristics of near ultraviolet InGaN\\/GaN multiple quantum wells (MQWs) grown on maskless periodically grooved sapphire, which was obtained by wet chemical etching. Hot acid etching combining with atomic force microscopy (AFM), transmission electron microscopy (TEM) were adopted to characterize the films quality. Compared with the MQWs grown on planar sapphire, the sample

N. S. Yu; L. W. Guo; H. Chen; Z. G. Xing; B. H. Ge; J. Wang; X. L. Zhu; M. Z. Peng; J. F. Yan; H. Q. Jia; J. M. Zhou



Reactive Ion Etching of Carbon Nanowalls  

NASA Astrophysics Data System (ADS)

Two-dimensionally standing graphene sheets, i.e., carbon nanowalls (CNWs), were synthesized on a Si substrate employing a capacitively coupled fluorocarbon plasma-enhanced chemical vapor deposition system together with H radical injection. To apply CNWs in electronic devices and/or membrane filters, we have demonstrated the reactive ion etching (RIE) of CNWs. RIE employing H2/N2 gases showed that the CNW films were anisotropically etched at a relatively high rate of more than 250 nm/min. However, the 10-nm-thick interface layer between a CNW film and the Si substrate remained and the interface layer was not completely etched. In contrast, RIE employing Ar/H2 gases enabled us to completely remove the interface layer. Ar/H2 RIE was also carried out from the bottom surface of CNW films after exfoliating them from the Si substrate. As a result, a free-standing CNW film of 550 nm thickness without an interface layer as a membrane filter was successfully formed.

Kondo, Shingo; Kondo, Hiroki; Miyawaki, Yudai; Sasaki, Hajime; Kano, Hiroyuki; Hiramatsu, Mineo; Hori, Masaru



3D characterization of acidized fracture surfaces  

E-print Network

with the dynamic interaction of variables. This thesis presents a new study of acidized surface textures by means of a laser profilometer to improve our understanding of the remaining etched surface topography and its hydraulic response. Visualization plots...

Malagon Nieto, Camilo



*Additional SOPs available, see: 1. PPE Choice and Cleaning 2. Work Station Cleaning 3. Pouring and Mixing 4. Hotplates 5. Hydrofluoric Acid 6. Haz Waste Management  

E-print Network

. Replace the gauze regularly. - If bleeding stops, apply antiseptic to a bandaid or the surrounding skin (do not apply antiseptic into a cut), and apply bandaid. Your cut will likely need stitches if the cut

Woodall, Jerry M.


Combining lithography and etch models in OPC modeling  

NASA Astrophysics Data System (ADS)

With constant shrinking of device critical dimensions (CD), the quality of pattern transfer in IC fabrication depends on the etch process and the exposure process fidelities, and the interaction of lithographic and etching processes is no longer negligible. Etch effect correction with accurate models has become an important component in optical proximity correction (OPC) modeling and related applications. It is now commonly accepted that the lithographic and etch effects should be modeled and corrected in a sequential and staged way: a resist (or lithographic) model should be created and used for lithographic effect compensation, and an etch model should be created and used for etch effect compensation. However, there can be various degrees of separation of these two modeling stages. In order to optimally capture the significant variation in the post-development resist patterns and post-etching patterns, it is helpful to integrate these two processes together for the OPC model calibration practice. In this paper, we analyze the integrated simulation approach in OPC modeling where the entire resist model information is made fully accessible in the etch modeling stage to allow the possibility of resist and etch co-optimization, e.g. through adjusting the resist model to optimally fit the etch data. Furthermore, the integrated simulation technique is integrated into a verification flow to simplify the conventional staged flow.

Zavyalova, Lena V.; Luan, Lan; Song, Hua; Schmoeller, Thomas; Shiely, James P.



Improving aluminum nitride plasma etch process for MEMS applications  

NASA Astrophysics Data System (ADS)

We present a new plasma etch process optimized for etching piezoelectric aluminum nitride (AlN) film deposited on thin molybdenum (Mo) metal electrode. Such film stack finds application in the integration of AlN-based RF microelectromechanical systems devices. The process is based on Cl2/BCl3/Ar gas chemistry with added buffer gas in inductively coupled plasma reactive ion etching system. The new gas mixture overcomes a generic problem of etched surface roughness without significant drop in AlN etch rate. Using design of experiment, the process window is optimized for improving selectivity to Mo and reducing microtrenching while maintaining smooth etched surface. Finally, an etching rate of 280 nm min-1 with reliable etch stop on Mo electrode and smooth bottom surface is reported. The integration suitability of the developed etch process is tested by etching 2.0 to 5.0 µm size square shaped via holes in 1.0 µm thick (0 0 2) oriented piezoelectric AlN on 0.2 µm thick Mo electrode while integrating contour mode resonators.

Bliznetsov, Vladimir; Johari, Badrul Hisam Bin; Tahar Chentir, Mohamed; Li, Wei Hong; Wong, Lai Yin; Merugu, Srinivas; Zhang, Xiao Lin; Singh, Navab



Extreme ultraviolet lithography mask etch study and overview  

NASA Astrophysics Data System (ADS)

An overview of extreme ultraviolet lithography (EUVL) mask etch is presented and a EUVL mask etch study was carried out. Today, EUVL implementation has three critical challenges that hinder its adoption: extreme ultraviolet (EUV) source power, resist resolution-line width roughness-sensitivity, and a qualified EUVL mask. The EUVL mask defect challenges result from defects generated during blank preparation, absorber and multilayer deposition processes, as well as patterning, etching and wet clean processes. Stringent control on several performance criteria including critical dimension (CD) uniformity, etch bias, micro-loading, profile control, defect control, and high etch selectivity requirement to capping layer is required during the resist pattern duplication on the underlying absorber layer. EUVL mask absorbers comprise of mainly tantalum-based materials rather than chrome- or MoSi-based materials used in standard optical masks. Compared to the conventional chrome-based absorbers and phase shift materials, tantalum-based absorbers need high ion energy to obtain moderate etch rates. However, high ion energy may lower resist selectivity, and could introduce defects. Current EUVL mask consists of an anti-reflective layer on top of the bulk absorber. Recent studies indicate that a native oxide layer would suffice as an anti-reflective coating layer during the electron beam inspection. The absorber thickness and the material properties are optimized based on optical density targets for the mask as well as electromagnetic field effects and optics requirements of the patterning tools. EUVL mask etch processes are modified according to the structure of the absorber, its material, and thickness. However, etch product volatility is the fundamental requirement. Overlapping lithographic exposure near chip border may require etching through the multilayer, resulting in challenges in profile control and etch selectivity. Optical proximity correction is applied to further enhance the resolution. Other resolution enhancement techniques, such as phase shifting, are also in consideration for EUVL. Phase-shifting will involve partial etching of the multilayer. The trend to use shorter EUV wavelength (e.g., 6.7 nm) for enhancing resolution will use new multilayer and absorber compositions, and will require new etch process development efforts. TaBO/TaBN absorber layers (features down to 40 nm) were etched with vertical profiles, low etch CD bias, and 1.7 nm etch CD uniformity (3?). In the light shed application, Mo/Si multilayer etching yielded vertical profiles and high etch selectivity.

Wu, Banqiu; Kumar, Ajay; Chandrachood, Madhavi; Sabharwal, Amitabh



Wet-Chemical Etching Revised: 2012-02-11  

E-print Network

reactions summarize the basic etch mechanism for isotropic silicon etching (steps 1-4), and SiO2 (only step 2 NO2 + H2 O (2) Oxidation of silicon by NO2 : 2 NO2 + Si Si2+ + 2 NO2 - (3) Formation of SiO2 : Si2 (strong temperature de- pendency of the etch rate) of Si via the oxidation (1) - (3), while low HF : HNO3

Yoo, S. J. Ben


Design, fabrication, and characterization of deep-etched waveguide gratings  

Microsoft Academic Search

One-dimensional (1-D) deep-etched gratings on a specially grown AlGaAs wafer were designed and fabricated. The gratings were fabricated using state-of-the-art electron beam lithography and high-aspect-ratio reactive ion etching (RIE) in order to achieve the required narrow deep air slots with good accuracy and reproducibility. Since remarkable etch depths (up to 1.5 ?m), which completely cut through the waveguide core layer,

Todd C. Kleckner; Daniele Modotto; Andrea Locatelli; Jessica P. Mondia; Stefan Linden; Roberto Morandotti; C. De Angelis; C. R. Stanley; H. M. van Driel; J. S. Aitchison



Model for a multiple-step deep Si etch process  

NASA Astrophysics Data System (ADS)

A multiple-step deep Si etch process involving separate etching and polymerization steps is often employed for fabrication of microelectromechanical systems, microfluidics devices, and other assorted deep structures in Si. An integrated plasma equipment-feature evolution model for this multiple-step deep Si etch process is described in this article. In the two-dimensional plasma equipment model, the etching (SF6/O2) and polymerization octafluorocyclobutane(c-C4F8) chemistries are separately simulated assuming steady-state conditions. The outputs of the equipment simulations are combined in a string-based feature profile evolution model to simulate the multiple-step deep Si etch process. In the plasma equipment models, detailed gas phase plasma chemistries including electron impact processes, ion-molecule reactions, and neutral chemistry have been considered for both the etching and polymerization gas mixtures. The plasma-surface interaction mechanisms in the feature profile evolution model are based on qualitative information available in literature and the correlation of modeling results with experimental data. Under the relevant operating conditions, F is assumed to be the primary Si etchant, film deposition in c-C4F8 is due to sticking of C, CF2, and C2F4 under ion bombardment, and the polymer is etched by energetic ions through physical sputtering. It is demonstrated that predictions of the resulting model are in close agreement with experiments. The validated model is used to understand the dynamics of the multiple-step deep Si etch process and how etching characteristics can be controlled using a variety of process parameters. Etching characteristics have been found to be quite sensitive to gas pressure, coil power, bias power, and relative step time during both etching and polymerization processes. The Si etch rate and feature sidewall angle are coupled to each other over a wide range of operating conditions. copyright 2002 American Vacuum Society.

Rauf, Shahid; Dauksher, William J.; Clemens, Stephen B.; Smith, Kenneth H.



Ion beam sputter etching and deposition of fluoropolymers  

NASA Technical Reports Server (NTRS)

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.

Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.



Cyclic deep reactive ion etching with mask replenishment  

NASA Astrophysics Data System (ADS)

A multi-step reactive ion etching (MS-RIE) process for silicon was developed for the fabrication of deep anisotropic, closely packed structures with vertical sidewalls. This process used repeated cycles of etching and the replenishment of masking layers, similar to the Bosch process (Laermer and Schilp 1996 US Patent 5,498,312) [1] that is employed in specialized etching tools. The process described here, however, can be used on conventional RIE tools, and is based on the isotropic deposition of an etch-inhibiting polymer to protect sidewalls, its anisotropic removal from the bottom etch front, and a subsequent isotropic etch into deeper layers. A conventional parallel plate etcher without fast gas management, cryogenic substrate cooling, or inductively coupled plasma density enhancement, produced these steps. Each process step was optimized for the maximal etch rate, minimal mask erosion, deposition of the thinnest polymer required to protect the sidewalls, and was tailored for use with 2 µm thick photoresist as the initial mask layer. This cyclic RIE process was used to fabricate photonic devices with high aspect ratios of etched depths over 100 µm and etch widths near 1 µm.

Adam, T. N.; Kim, S.; Lv, P.-C.; Xuan, G.; Ray, S. K.; Troeger, R. T.; Prather, D.; Kolodzey, J.



Developments of Plasma Etching Technology for Fabricating Semiconductor Devices  

NASA Astrophysics Data System (ADS)

Plasma etching technologies such as reactive ion etching (RIE), isotropic etching, and ashing/plasma cleaning are the currently used booster technologies for manufacturing all silicon devices based on the scaling law. The needs-driven conversion from the wet etching process to the plasma/dry etching process is reviewed. The progress made in plasma etching technologies is described from the viewpoint of requirements for the manufacturing of devices. The critical applications of RIE, isotropic etching, and plasma ashing/cleaning to form precisely controlled profiles of high-aspect-ratio contacts (HARC), gate stacks, and shallow trench isolation (STI) in the front end of line (FEOL), and also to form precise via holes and trenches used in reliable Cu/low-k (low-dielectric-constant material) interconnects in the back end of line (BEOL) are described in detail. Some critical issues inherent to RIE processing, such as the RIE-lag effect, the notch phenomenon, and plasma-induced damage including charge-up damage are described. The basic reaction mechanisms of RIE and isotropic etching are discussed. Also, a procedure for designing the etching process, which is strongly dependent on the plasma reactor configuration, is proposed. For the more precise critical dimension (CD) control of the gate pattern for leading-edge devices, the advanced process control (APC) system is shown to be effective.

Abe, Haruhiko; Yoneda, Masahiro; Fujiwara, Nobuo



Use of Sirtl etch for silicon-slice evaluation.  

NASA Technical Reports Server (NTRS)

An investigation was conducted to explore the possibility of using Sirtl etch as a nondestructive evaluation step for categorizing silicon wafers before device fabrication is begun. It is known that chromium is deposited as a residue during the chemical reaction associated with etching silicon in Sirtl etch. There has been concern that the use of Sirtl etch could result in the diffusion of chromium into the silicon slice during subsequent high-temperature processing steps. The investigation revealed, however, that residual chromium resides only on the surface of the slice and can easily be removed.

Porter, W. A.; Gupta, A.; Swindle, D. L.



Release-etch modeling for complex surface micromachined structures  

SciTech Connect

A release etch model for etching sacrificial oxides in aqueous HF solutions is presented. This model is an extension of work done by Monk et al. and Liu et al. The model is inherently one dimensional, but can be used to model the etching of complex three dimensional parts. Solutions and boundary conditions are presented for a number of geometries. Knowledge of release-etch kinetics is essential for designing manufacturing processes for large surface micromachined structures such as sealed diaphragms and cavities and flow channels.

Eaton, W.P.; Smith, J.H.; Jarecki, R.L.



Crystallographic wet chemical etching of GaN  

NASA Astrophysics Data System (ADS)

We demonstrate well-controlled crystallographic etching of wurtzite GaN grown on c-plane sapphire using H3PO4, molten KOH, KOH dissolved in ethylene glycol, and NaOH dissolved in ethylene glycol between 90 and 180 °C, with etch rates as high as 3.2 ?m/min. The crystallographic GaN etch planes are {0001}, {101¯0}, {101¯ 1¯}, {101¯ 2¯}, and {101¯3}. The vertical {101¯0} planes appear perfectly smooth when viewed with a field-effect scanning electron microscope. The activation energy is 21 kcal/mol, indicative of reaction-rate limited etching.

Stocker, D. A.; Schubert, E. F.; Redwing, J. M.



Wet etching for the mitigation of laser damage growth in fused silica  

NASA Astrophysics Data System (ADS)

On the 3? part of the LIL laser many optical components will have to sustain fluences above 10J/cm2. Even if progress in silica substrate technology decreases the number of defects/cm2 which can induce a damage under such a laser flux, tens of damaged sites will appear on large surface optics. Knowing that these damaged sites grow exponentially with the number of laser shots, it is a necessity to stop the growth of these defects before the use of the optical component is impaired. In this paper we have used wet chemical etching as a way to circumvent the growth of laser-induced surface damages. SEM characterization of damages at all stages of the process has been carried out. We show that at a reduced damage creation fluence, the use of a highly concentrated HF acid leads to a 93% mitigation rate for those damaged sites that need mitigation. Due to the etching anisotropy, the HF acid concentration is more important than etch depth"s for the mitigation rate of laser induced surface damage in silica.

Bouchut, Philippe; Garrec, Pierre; Pelle, Catherine



Capillary flow in sacrificially etched nanochannels  

PubMed Central

Planar nanochannels are fabricated using sacrificial etching technology with sacrificial cores consisting of aluminum, chromium, and germanium, with heights ranging from 18 to 98 nm. Transient filling via capillary action is compared against the Washburn equation [E. W. Washburn, Phys. Rev. 17, 273 (1921)], showing experimental filling speeds significantly lower than classical continuum theory predicts. Departure from theory is expressed in terms of a varying dynamic contact angle, reaching values as high as 83° in channels with heights of 18 nm. The dynamic contact angle varies significantly from the macroscopic contact angle and increases with decreasing channel dimensions. PMID:21772934

Hamblin, Mark N.; Hawkins, Aaron R.; Murray, Dallin; Maynes, Daniel; Lee, Milton L.; Woolley, Adam T.; Tolley, H. Dennis



Observation of inverse reactive ion etching lag for silicon dioxide etching in inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

The slowdown of the oxide etch rate with width of submicrometer structures is known as reactive ion etching (RIE) lag and has been explained by ion shadowing and differential charging of the sidewalls, among other effects [R. A. Gottscho and co-workers, J. Vac. Sci. Technol. B 10, 2133 (1992)]. Here we show for an inductively coupled high density plasma reactor working in the pressure regime from 6 to 20 mTorr that inverse RIE lag is primarily observed, i.e., the etch rates increase as the width of the microstructures decrease. Inverse RIE lag, which was first discussed by Vitkavage et al. [Tegal Plasma Proceedings Symposium, San Francisco, 1991 (unpublished)], may be explained by considering the neutral flux distribution at the structure bottom. The neutral flux has a stronger dependence on the aspect ratio than the ion flux due to its isotropic velocity distribution. The neutral flux distribution has been modeled and is consistent with etching profiles observed at high pressure.

Doemling, M. F.; Rueger, N. R.; Oehrlein, G. S.



Fabrication of honeycomb texture on poly-Si by laser interference and chemical etching  

NASA Astrophysics Data System (ADS)

In this paper, we present a laser-interference method to fabricate honeycomb textures on poly-Si wafer for reflection reduction. When exposed to three interfering pulsed laser beams at 532 nm, the Si surface was periodically melted in accordance with the interference pattern. As a result, concave holes were generated on the surface because the melted material overflowed and condensed at the periphery. Subsequent acid etching revealed uniform and clean honeycomb textures. The texture depth could be controlled by varying the irradiation condition and a minimum reflectance of 10% was obtained. Transmission electron microscopy analysis showed that no irradiation-induced damage remained after etching. This approach can be a cost-effective alternative to lithographic processes for fabricating high-efficiency poly-Si solar cells.

Yang, Bogeum; Lee, Myeongkyu



Depth-resolved subsurface defects in chemically etched SrTiO3  

NASA Astrophysics Data System (ADS)

Depth-resolved cathodoluminescence spectroscopy of atomically flat TiO2-terminated SrTiO3 single crystal surfaces reveals dramatic differences in native point defects produced by conventional etching with buffered HF (BHF) and an alternative procedure using HCl-HNO3 acidic solution (HCLNO), which produces three times fewer oxygen vacancies before and nearly an order of magnitude fewer after pure oxygen annealing. BHF-produced defect densities extend hundreds of nanometers below the surface, whereas the lower HCLNO-treated densities extend less than 50 nm. This "Arkansas" HCLNO etch and anneal method avoids HF handling and provides high-quality SrTiO3 surfaces with low native defect density for complex oxide heterostructure growth.

Zhang, Jun; Doutt, D.; Merz, T.; Chakhalian, J.; Kareev, M.; Liu, J.; Brillson, L. J.



Microfabrication of Si and GaAs by Plasma Etching Process Using Bacterial Cells as an Etching Mask Material  

NASA Astrophysics Data System (ADS)

We demonstrated that bacterial cells can be used as a mask material for microfabrication of GaAs and Si by a Cl2 inductively coupled plasma (ICP) etching process. The etching rate of Escherichia coli cells was similar to that of electron beam resist or nanoimprint resist. We also demonstrated the degradation of bacterial cells by low-pressure plasma treatment using O2, Ar, air, and H2O for removal of bacterial cells as the etching mask material. Bacterial cells were efficiently degraded by ions in the low-pressure discharge plasma. The proposed process using bacterial cells can be expected to be applied to semiconductor dry etching processes.

Matsutani, Akihiro; Takada, Ayako



Inorganic Bi/In Thermal Resist as a High Etch Ratio Patterning Layer for CF4/CHF3/O2 Plasma Etch  

E-print Network

Inorganic Bi/In Thermal Resist as a High Etch Ratio Patterning Layer for CF4/CHF3/O2 Plasma Etch mask layers for Si anisotropic etch and plasma etch. Keywords: inorganic photoresist, thermal resist, such as Bi/In, have been found to form highly sensitive thermal resists. They can be exposed by lasers

Chapman, Glenn H.


Advanced etching of silicon based on deep reactive ion etching for silicon high aspect ratio microstructures and three-dimensional micro- and nanostructures  

Microsoft Academic Search

Different processes involving an inductively coupled plasma reactor are presented either for deep reactive ion etching or for isotropic etching of silicon. On one hand, high aspect ratio microstructures with aspect ratio up to 107 were obtained on sub-micron trenches. Application to photonic MEMS is presented. Isotropic etching is also used either alone or in combination with anisotropic etching to

F. Marty; L. Rousseau; B. Saadany; B. Mercier; O. Français; Y. Mita; T. Bourouina



40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.  

Code of Federal Regulations, 2013 CFR

... Applicability: Description of the chemical etching and milling subcategory. 413...ELECTROPLATING POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling subcategory....



40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.  

Code of Federal Regulations, 2012 CFR

... Applicability: Description of the chemical etching and milling subcategory. 413...ELECTROPLATING POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling subcategory....



40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.  

... Applicability: Description of the chemical etching and milling subcategory. 413...ELECTROPLATING POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling subcategory....



Feasibility of atomic layer etching of polymer material based on sequential O{sub 2} exposure and Ar low-pressure plasma-etching  

SciTech Connect

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.

Vogli, Evelina; Metzler, Dominik; Oehrlein, Gottlieb S. [Department of Material Science and Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Material Science and Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)



Rapid Dry Etching Of Photoresists Without Toxic Gases  

NASA Technical Reports Server (NTRS)

Experimental dry etching technique strips photoresists from semiconductor wafers without damaging semiconductor materials. Makes use of afterglow existing downstream from plasma generated by radio-frequency electric field. Constituents of afterglow react with sacrificial polymer to make reactive gases that quickly etch-away photoresist. Strips quickly at room temperature; not necessary to heat substrates. No hazardous or toxic chemicals used.

Lerner, Narcinda R.; Wydeven, Theodore




E-print Network

PATTERN DENSITY BASED PREDICTION FOR DEEP REACTIVE ION ETCH (DRIE) Tyrone F. Hill, Hongwei Sun Cambridge CB2 1PZ, UK ABSTRACT A quantitative model capturing Deep Reactive Ion Etch (DRIE) pattern density die- level interactions resulting from pattern density and reactant species consumption [1]. Several

Boning, Duane S.


Ga(+) beam lithography for nanoscale silicon reactive ion etching.  


By using a dry etch chemistry which relies on the highly preferential etching of silicon, over that of gallium (Ga), we show resist-free fabrication of precision, high aspect ratio nanostructures and microstructures in silicon using a focused ion beam (FIB) and an inductively coupled plasma reactive ion etcher (ICP-RIE). Silicon etch masks are patterned via Ga(+) ion implantation in a FIB and then anisotropically etched in an ICP-RIE using fluorinated etch chemistries. We determine the critical areal density of the implanted Ga layer in silicon required to achieve a desired etch depth for both a Pseudo Bosch (SF(6)/C(4)F(8)) and cryogenic fluorine (SF(6)/O(2)) silicon etching. High fidelity nanoscale structures down to 30 nm and high aspect ratio structures of 17:1 are demonstrated. Since etch masks may be patterned on uneven surfaces, we utilize this lithography to create multilayer structures in silicon. The linear selectivity versus implanted Ga density enables grayscale lithography. Limits on the ultimate resolution and selectivity of Ga lithography are also discussed. PMID:20484788

Henry, M D; Shearn, M J; Chhim, B; Scherer, A



Features of copper etching in chlorine-argon plasma  

Microsoft Academic Search

Chlorine mixtures with inert gases including argon exhibit promise as plasma feed gases for etching metals and semiconductors in the microelectronics industry. It was shown that even strong dilution of reactive gas with an inert gas (up to 80-90% of the latter) has virtually no effect in decreasing the rate of plasma etching of materials such as silicon and gallium

A. M. Efremov; V. I. Svettsov



Laser Etching: A Novel Technology to Label Florida Grapefruit  

E-print Network

Laser Etching: A Novel Technology to Label Florida Grapefruit Preeti Sood1 , Chris Ference2 , Jan, produce labeling SUMMARY. Laser labeling of fruit and vegetables is an alternative means of labeling produce in which a low-energy carbon dioxide laser beam etches the surface and reveals a contrasting

Etxeberria, Edgardo


Reactive ion etched substrates and methods of making and using  


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.

Rucker, Victor C. (San Francisco, CA); Shediac, Rene (Oakland, CA); Simmons, Blake A. (San Francisco, CA); Havenstrite, Karen L. (New York, NY)



High aspect ratio plasma etching of bulk lead zirconate titanate  

NASA Astrophysics Data System (ADS)

Lead Zirconate Titanate (PZT) is a high energy density active material with good piezoelectric coefficient and electromechanical coupling constant making it highly suitable for microsystems applications. In this paper, we present a rapid anisotropic high aspect ratio etching process for defining micron size features in PZT. We used an inductively coupled plasma reactive ion etching (ICP-RIE) system employing sulfur hexafluoride (SF6) and argon (Ar) based chemistry. A seed layer of Au/Cr was lithographically patterned onto fine lap finished PZT-4 substrates followed by electrodeposition of a thick 2-5 ?m nickel on the seed layer, which acts as a hard mask during the etching process. The demonstrated technique was used to etch bulk PZT ceramic substrates, thereby opening possibilities for integration of bulk PZT substrates and structures into microsystems. A maximum etch rate of 19 ?m/hr on PZT-4 and 25 ?m/hr for PZT-5A compositions was obtained using 2000 W of ICP power, 475 W of substrate power, 5 sccm of SF 6, and 50 sccm of Ar on PZT substrate. We have also demonstrated a high aspect ratio etch (>5:1) on a 3 ?m feature size. Detailed analysis of the effects of ICP power, substrate power, and the etch gas composition on the etch rate of PZT are also presented in this article.

Subasinghe, Srimath S.; Goyal, Abhijat; Tadigadapa, Srinivas A.



3D via etch development for 3D circuit integration in FDSOI  

Microsoft Academic Search

This paper describes the development of the 3D via etch process.The oxide via etch was developed in a Trikon Technologies low pressure, high density, helicon-based cluster tool. A response surface design-of-experiments (DOE) was performed varying etch pressure and wafer bias to examine their effect on etch profile and etch rates. An anisotropic etch is essential for high packing density. There

J. M. Knecht; D. R. W. Yost; J. A. Burns; C. K. Chen; C. L. Keast; K. Warner



High rate ECR etching of III-V nitride materials  

NASA Astrophysics Data System (ADS)

The III-V nitride compound semiconductors are attracting considerable attention for blue and ultraviolet light emitting diodes (LED's) and lasers as well as high temperature electronics due to their wide band gaps and high dielectric constants. The recent progress observed in the growth of these materials has not been matched by progress in processing techniques to fabricate more highly sophisticated devices. Patterning these materials has been especially difficult due to the relatively inert chemical nature of the group-III nitrides. The authors review dry etch techniques which have been used to pattern these materials including electron cyclotron resonance (ECR), reactive ion etch (RIE), and chemically assisted ion beam etching (CAIBE). ECR etch rates greater than 3800 A/min for InN, 3500 A/min for GaN, and 1170 A/min for AlN are reported. Etch anisotropy, surface morphology, and near-surface stoichiometry are discussed.

Shul, R. J.; Howard, A. J.; Kilcoyne, S. P.; Pearton, S. J.; Abernathy, C. R.; Vartuli, C. B.; Barnes, P. A.; Bozack, M. J.


Composition/bandgap selective dry photochemical etching of semiconductor materials  


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.

Ashby, C.I.H.; Dishman, J.L.



Composition/bandgap selective dry photochemical etching of semiconductor materials  


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.

Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)



KrF excimer laser etching of diamondlike carbon films  

NASA Astrophysics Data System (ADS)

Diamond-like carbon films with mass density, ranging from 1.7 g/cm3 to 2.4 g/cm3, deposited onto Si in RF glow discharge plasma in benzene were characterized by various techniques in order to obtain a correlation between mechanical, electrical, optical, and thermal properties of the films. Microhardness and optical absorption increase, while electrical resistivity and thermal diffusivity decrease with film density. Etching of DLC films by UV pulses of KrF excimer laser radiation in air was studied. The etch rate was found to decrease with film density. Two etch mechanisms have been identified: (1) carbon oxidation, which provides etch rates V < 5 nm/pulse, and (2) ablation dominating at high fluences (E > 500 mJ/cm2) with V exceeding 100 nm/pulse. Micron-sized patterns in carbon films fabricated by laser etching technique are demonstrated.

Kononenko, Taras V.; Konov, Vitali I.; Ralchenko, Victor G.; Strelnitsky, V. E.



Using masks to obtain uniform ion etch rates  

NASA Astrophysics Data System (ADS)

For milling over large areas there is need for broad ion beam sources with a uniform etch rate profile. Currently uniform ion beam density is obtained in the central portion of the ion source by manipulating the grids and the magnets in the ion source. We have designed and implemented specially shaped hard masks to a rotating substrate holder. This mask is able to transform the Gaussian etch rate profile of a 150-mm-diam Oxford ion source to a flat profile. The flat profile decreases the etch rate in the central portion while maintaining the same etch rate along the edge. The deviation in the ion beam etch rate is within 5% in the flat region.

Gnanarajan, S.



Characterization of silicon isotropic etch by inductively coupled plasma etcher for microneedle array fabrication  

NASA Astrophysics Data System (ADS)

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.

Ji, Jing; Tay, Francis E. H.; Miao, Jianmin; Sun, Jianbo



Optical diagnostic instrument for monitoring etch uniformity during plasma etching of polysilicon in a chlorine-helium plasma  

SciTech Connect

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.

Hareland, W.A.; Buss, R.J.



Optical measurement for the concentrations of the pickling acid with near infrared spectroscopy in steel making industry  

NASA Astrophysics Data System (ADS)

In the manufacturing process of stainless steel, it is essential to pickle the oxide layer of steel surface for high corrosion resistance and fine surface quality. Pickling liquor of stainless steel is commonly composed of mixed hydrofluoric and nitric acid. Real time monitoring of concentrations of each acid is crucial to optimize pickling process. It also reduces cost of production and decreases the generation of waste acid. We used non-contact near infrared spectroscopy technique and rapid analysis method, for the quantification of each acid in an on-line manner. Multivariate calibration such as partial least square regression method is employed for the better prediction results.

Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik



Comparision of Shear Bond Strength of Stainless Steel and Ceramic Brackets at 24 Hours after Etching Enamel with Different Proportions of Acidulated Phosphate Fluoride  

PubMed Central

Aims and Objectives: To evaluate and compare the shear bond strength of stainless steel brackets and ceramic brackets at 24h after etching the enamel with acidulated phosphate fluoride gel (1.23% APF) at different proportions (40%,30%,20%) incorporated in conventional etchant (37% phosphoric acid). Materials and Methods: Eighty premolars (maxillary and mandibular first and second premolars) extracted for orthodontic purpose has been selected for the study and samples were divided into 4 groups containing 10 teeth each. Comprised of teeth etched Group 1 with 40% of APF gel etchant is Group 2 teeth etched with 30% of APF gel in Group 3 teeth etched with 20% of APF gel etchant and Group 4 teeth were etched with conventional etchant (37% phosphoric acid). Results: The experimental group of Acidulated Phosphate Fluoride (APF) at different proportion (40%, 30%, 20%) incorporated with etchant application for 40s on the enamel surface at 24h indicated that group 4 showed the higher bond strength of all other remaining groups and the groups 1, 2 and 3 showed satisfactory bond strength. The statistical evaluation also revealed that the bond strength of control group (37% phosphoric acid) was greater than those of experimental groups. Conclusion: The present study results shows that the ceramic brackets have higher bond strength than stainless steel brackets (material wise). PMID:25302260

Abinaya; Karthikeyan; Sarvanan; Vikram, Raj



Histologic Evaluation of Human Pulp Response to Total Etch and Self Etch Adhesive Systems  

PubMed Central

Background To investigate pulp response to the application of two types adhesive systems (total-etch and self-etch) in human premolar teeth. Materials and Methods Cavities limited to enamel walls in all margins with 2.5 mm depth were prepared on buccal surfaces of thirty three human premolars. The cavities were treated with the following adhesive. Single Bond (SB) and Prompt L-Pop (PLP). The teeth were extracted after 30 days and prepared due to histological technique. Results Pulp responses were evaluated in three field including inflammatory cell response, pulp tissue disorganization and restorative dentin formation. There were no differences in histological response of the pulp tissue (P > 0.05). Conclusion Both adhesive systems showed good biological compatibility. PMID:24349733

Malekipour, Mohammad Reza; Razavi, Sayed Mohammad; Khazaei, Saber; Kazemi, Shantia; Behnamanesh, Maryam; Shirani, Farzaneh



Front-to-backside alignment using resist-patterned etch control and one etching step  

Microsoft Academic Search

A processing technique that aligns features on the front side of a wafer to those on its backside has been developed for bulk micromachining. A 30 ?m-square and 1.6 ?m-thick diaphragm serves as an alignment pattern. At the same time that the alignment diaphragm is made, much thicker, large-area diaphragms can be partially etched using `mesh' masking patterns in these

Eun Sok Kim; Richard S. Muller; Raif S. Hijab



Etching Behavior of GaN Using Chemically-Assisted Ion-Beam Etching  

Microsoft Academic Search

For the experiments we have used undoped GaN with good surface morphology grown by metal-organic vapor-phase epitaxy (MOVPE) on c-plane sapphire substrates. The samples have been dry-etched in a CAIBE system equipped with an electron-cyclotron-resonance (ECR) ion-beam source and a load lock. The substrate is located on a rotatable stage, that can be temper ature controlled in the range of

F. Eberhard; M. Schauler; E. Deichsel; C. Kirchner


Solid polymer electrolyte composite membrane comprising plasma etched porous support  


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.

Liu, Han (Waltham, MA); LaConti, Anthony B. (Lynnfield, MA)



Justification for Selecting Level A vs. Level B Personal Protective Equipment to Remediate a Room Containing Concentrated Acids, Bases and Radiological Constituents  

SciTech Connect

Selecting the appropriate personal protective equipment (PPE) is based on providing an adequate level of employee protection relative to the task-specific conditions and hazards. PPE is categorized into four ensembles, based on the degree of protection afforded; e.g., Levels A (most restrictive), B, C, and D (least restrictive). What is often overlooked in preparing an ensemble is that the PPE itself can create significant worker hazards; i.e., the greater the level of PPE, the greater the associated risks. Furthermore, there is confusion as to whether a more ''conservative approach'' should always be taken since Level B provides the same level of respiratory protection as Level A but less skin protection. This paper summarizes the Occupational Safety and Health Administration regulations addressing Level A versus Level B, and provides justification for selecting Level B over Level A without under-protecting the employee during a particular remediation scenario. The scenario consisted of an entry team performing (1) an initial entry into a room containing concentrated acids (e.g., hydrofluoric acid), bases, and radiological constituents; (2) sampling and characterizing container contents; and (3) retrieving characterized containers. The invasive nature of the hydrofluoric acid sampling and characterization scenario created a high potential for splash, immersion, and exposure to hazardous vapors, requiring additional skin protection. The hazards associated with this scenario and the chemical nature of hydrofluoric acid provided qualitative evidence to justify Level A. Once the hydrofluoric acid was removed from the room, PPE performance was evaluated against the remaining chemical inventory. If chemical breakthrough from direct contact was not expected to occur and instrument readings confirmed the absence of any hazardous vapors, additional skin protection afforded by wearing a vapor-tight, totally-encapsulated suit was not required. Therefore, PPE performance and instrument data provided quantitative evidence to justify Level B.

Hylko, J. M.; Thompson, A. L.; Walter, J. F.; Deecke, T. A.



Dry etching technologies for the advanced binary film  

NASA Astrophysics Data System (ADS)

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.

Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Yoshimori, Tomoaki; Azumano, Hidehito; Muto, Makoto; Nonaka, Mikio



Super-selective cryogenic etching for sub-10 nm features.  


Plasma etching is a powerful technique for transferring high-resolution lithographic masks into functional materials. Significant challenges arise with shrinking feature sizes, such as etching with thin masks. Traditionally this has been addressed with hard masks and consequently additional costly steps. Here we present a pathway to high selectivity soft mask pattern transfer using cryogenic plasma etching towards low-cost high throughput sub-10 nm nanofabrication. Cryogenic SF(6)/O(2) gas chemistry is studied for high fidelity, high selectivity inductively coupled plasma etching of silicon. Selectivity was maximized on large features (400 nm-1.5 ?m) with a focus on minimizing photoresist etch rates. An overall anisotropic profile with selectivity around 140:1 with a photoresist mask for feature size 1.5 ?m was realized with this clean, low damage process. At the deep nanoscale, selectivity is reduced by an order of magnitude. Despite these limits, high selectivity is achieved for anisotropic high aspect ratio 10 nm scale etching with thin polymeric masks. Gentler ion bombardment resulted in planar-dependent etching and produced faceted sub-100 nm features. PMID:23220824

Liu, Zuwei; Wu, Ying; Harteneck, Bruce; Olynick, Deirdre



Porous silicon formation during Au-catalyzed etching  

NASA Astrophysics Data System (ADS)

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 ? 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 ? 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.

Algasinger, Michael; Bernt, Maximilian; Koynov, Svetoslav; Stutzmann, Martin



Effect of etching time on porous silicon processing  

NASA Astrophysics Data System (ADS)

The fabrication of porous silicon (PS) layers based on the crystalline silicon wafer n-type of (100) orientation using electrochemical etching process was conducted. The effect of various etching times on the structural and optical properties of the PS layers was investigated. The surface morphology of the PS layers was characterized using Scanning Electron Microscopy (SEM). Photoluminescence measurements of the PS layers were performed at room temperature. Additionally, the reflectance of the PS layers was obtained using an optical reflectometer. The results revealed that the PS layer at 10 min etching time exhibited excellent light trapping of a wide wavelength spectrum, which is expected to enhance the efficiency of optoelectronic devices.

Salman, Khaldun A.; Omar, Khalid; Hassan, Z.



Laser etching rates of sapphire glass using metal targets  

NASA Astrophysics Data System (ADS)

Q-switched Nd:YAG laser with an output power of 40 watts has been used to study LIPAA etch rates of Sapphire glass in air with different target materials including stainless steel, brass and mild steel. Experiments showed that an ablation depth of 50?m has been achieved in sapphire at a zero target-substrate gap at ambient pressure. The etch depth versus laser scan speed and laser power have also been studied. An etched depth of 200?m is achieved at a scan speed of 20mm/sec with stainless steel as target.

Hamdani, A. H.; Nasir, A.; Sarwar, S.; Ansar, A.; Akhter, R.; Aslam, M.



Inductively coupled plasma etching of HgCdTe  

Microsoft Academic Search

The high-density inductively coupled plasma (ICP) etching technique has been applied to HgCdTe. The HgCdTe etch rate was studied\\u000a as a function of key process variables commonly used in high-density plasma etching: chamber pressure, direct current (DC)\\u000a bias, and ICP-source power. Mesa profiles were characterized using scanning electron microscopy (SEM), and the profiles for\\u000a the process conditions used were found

E. P. G. Smith; J. K. Gleason; L. T. Pham; E. A. Patten; M. S. Welkowsky



CDU improvement technology of etching pattern using photo lithography  

NASA Astrophysics Data System (ADS)

Semiconductor manufacturing technology has shifted towards finer design rules, and demands for critical dimension uniformity (CDU) of resist patterns have become greater than ever. One of the methods for improving Resist Pattern CDU is to control post-exposure bake (PEB) temperature. When ArF resist is used, there is a certain relationship between critical dimension (CD) and PEB temperature. By utilizing this relationship, Resist Pattern CDU can be improved through control of within-wafer temperature distribution in the PEB process. Resist Pattern CDU improvement contributes to Etching Pattern CDU improvement to a certain degree. To further improve Etching Pattern CDU, etcher-specific CD variation needs to be controlled. In this evaluation, 1. We verified whether etcher-specific CD variation can be controlled and consequently Etching Pattern CDU can be further improved by controlling resist patterns through PEB control. 2. Verifying whether Etching Pattern CDU improvement through has any effect on the reduction in wiring resistance variation. The evaluation procedure is as follows.1. Wafers with base film of Doped Poly-Si (D-Poly) were prepared. 2. Resist patterns were created on them. 3. To determine etcher-specific characteristics, the first etching was performed, and after cleaning off the resist and BARC, CD of etched D-Poly was measured. 4. Using the obtained within-wafer CD distribution of the etching patterns, within-wafer temperature distribution in the PEB process was modified. 5. Resist patterns were created again, followed by the second etching and cleaning, which was followed by CD measurement. We used Optical CD Measurement (OCD) for measurement of resist patterns and etching patterns as OCD is minimally affected by Line Edge Roughness (LER). As a result, 1. We confirmed the effect of Resist Pattern CD control through PEB control on the reduction in etcher-specific CD variation and the improvement in Etching Pattern CDU. 2. The improvement in Etching Pattern CDU has an effect on the reduction in wiring resistance variation. The method for Etching Pattern CDU improvement through PEB control reduces within-wafer variation of MOS transistor's gate length. Therefore, with this method, we can expect to observe uniform within-wafer MOS transistor characteristics.

Tadokoro, Masahide; Shinozuka, Shinichi; Jyousaka, Megumi; Ogata, Kunie; Morimoto, Tamotsu; Konishi, Yoshitaka



Microleakage after Thermocycling of Three Self-Etch Adhesives under Resin-Modified Glass-Ionomer Cement Restorations  

PubMed Central

This study was designed to evaluate microleakage that appeared on Resin-Modified Glass-Ionomer Cement (RMGIC) restorations. Sixty class V cavities (h × w × l = 2?mm × 2?mm × 3?mm) were cut on thirty extracted third molars, which were randomly allocated to three experimental groups. All the buccal cavities were pretreated with polyacrylic acid, whereas the lingual cavities were treated with three one-step Self-Etch adhesives, respectively, Xeno III (Dentsply Detrey GmbH, Konstanz, Germany), iBond exp (Heraeus Kulzer gmbH & Co. KG, Hanau, Germany), and Adper Prompt-L-Pop (3M ESPE AG, Dental products Seefeld, Germany). All cavities were completely filled with RMGIC, teeth were thermocycled for 800 cycles, and leakage was evaluated. Results were expressed as means ± standard deviations (SDs). Microleakage scores were analysed by means of generalized linear mixed models (GLMMs) assuming an ordinal logistic link function. All results were considered to be significant at the 5% critical level (P < .05). The results showed that bonding RMGIC to dentin with a Self-Etch adhesive rather than using polyacrylic acid did not influence microleakage scores (P = .091), except for one tested Self-Etch adhesive, namely, Xeno III (P < .0001). Nevertheless, our results did not show any significant difference between the three tested Self-Etch adhesive systems. In conclusion, the pretreatment of dentin with Self-Etch adhesive system, before RMGIC filling, seems to be an alternative to the conventional Dentin Conditioner for the clinicians as suggested by our results (thermocycling) and others (microtensile tests). PMID:20628510

Geerts, Sabine O.; Seidel, Laurence; Albert, Adelin I.; Gueders, Audrey M.



An In Vitro Evaluation of Leakage of Two Etch and Rinse and Two Self-Etch Adhesives after Thermocycling  

PubMed Central

Our experiment evaluated the microleakage in resin composite restorations bonded to dental tissues with different adhesive systems. 40 class V cavities were prepared on the facial and lingual surfaces of each tooth with coronal margins in enamel and apical margins in cementum (root dentin). The teeth were restored with Z100 resin composite bonded with different adhesive systems: Scotchbond Multipurpose (SBMP), a 3-step Etch and Rinse adhesive, Adper Scotchbond 1 XT (SB1), a 2-step Etch and Rinse adhesive, AdheSE One (ADSE-1), a 1-step Self-Etch adhesive, and AdheSE (ADSE), a 2-step Self-Etch adhesive. Teeth were thermocycled and immersed in 50% silver nitrate solution. When both interfaces were considered, SBMP has exhibited significantly less microleakage than other adhesive systems (resp., for SB1, ADSE-1 and ADSE, P = 0.0007, P < 0.0001 and P < 0.0001). When enamel and dentin interfaces were evaluated separately, (1) for the Self-Etch adhesives, microleakage was found greater at enamel than at dentin interfaces (for ADSE, P = 0.024 and for ADSE-1, P < 0.0001); (2) for the Etch and Rinse adhesive systems, there was no significant difference between enamel and dentin interfaces; (3) SBMP was found significantly better than other adhesives both at enamel and dentin interfaces. In our experiment Etch and Rinse adhesives remain better than Self-Etch adhesives at enamel interface. In addition, there was no statistical difference between 1-step (ADSE-1) and 2-step (ADSE) Self-Etch adhesives. PMID:22675358

Geerts, Sabine; Bolette, Amandine; Seidel, Laurence; Gueders, Audrey



Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components  

NASA Technical Reports Server (NTRS)

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.



Negative Impact of Etched Si Area on Selectivity and Positive Impact of Photoelectric Current on Etched Profile in Gate Etching with Different Wafer Bias Frequencies  

NASA Astrophysics Data System (ADS)

The effect of wafer-bias frequency on the dummy-gate fabrication of fin-shaped field-effect transistor (Fin-FET) was investigated. The clear difference in the selectivity of polycrystalline silicon to SiO2 between 400 kHz and 13.56 MHz decreased when the etched Si area increased. On the other hand, a higher frequency increased such selectivity when Si area decreased. These results can be explained by the effect of by-product deposition. As for the etched profile, the amount of side etching was much larger at 13.56 MHz than at 400 kHz. It was reported that this phenomenon is caused by local charging. It was also suggested that the charging should be suppressed by reducing the ratio of ion saturation current to photoelectric current. Therefore, in this study, we investigated the effect of such current ratio on side etching. The result confirmed that a reduction in current ratio induced by increasing gas pressure decreases the amount of side etching.

Kamibayashi, Masami; Kofuji, Naoyuki; Mori, Masahito; Negishi, Nobuyuki



Protein adsorption and cell adhesion on three-dimensional polycaprolactone scaffolds with respect to plasma modification by etching and deposition techniques  

NASA Astrophysics Data System (ADS)

In this work, protein adsorption and cell adhesion on three-dimensional (3D) polycaprolactone (PCL) scaffolds treated by plasma etching and deposition were performed. The 3D PCL scaffold used as a substrate of a bone tissue was fabricated by recent rapid prototype techniques. To increase surface properties, such as hydrophilicity, roughness, and surface chemistry, through good protein adhesion on scaffolds, oxygen (O2) plasma etching and acrylic acid or allyamine plasma deposition were performed on the 3D PCL scaffolds. The O2 plasma etching induced the formation of random nanoporous structures on the roughened surfaces of the 3D PCL scaffolds. The plasma deposition with acrylic acid and allyamine induced the chemical modification for introducing a functional group. The protein adsorption increased on the O2 plasma-etched surface compared with an untreated 3D PCL scaffold. MC3T3-E1 cells adhered bioactively on the etched and deposited surface compared with the untreated surface. The present plasma modification might be sought as an effective technique for enhancing protein adsorption and cell adhesion.

Myung, Sung Woon; Ko, Yeong Mu; Kim, Byung Hoon



Profile Control of a Borosilicate-Glass Groove Formed by Deep Reactive Ion Etching  

Microsoft Academic Search

Deep reactive ion etching (DRIE) of borosilicate glass and profile control of an etched groove are reported. DRIE was carried out using an anodically bonded silicon wafer as an etching mask. We controlled the groove profile, namely improving its sidewall angle, by removing excessively thick polymer film produced by carbon- fluoride etching gases during DRIE. Two fabrication processes were experimentally

T. Akashi; Y. Yoshimura



Gerald Leslie Brockhurst: Etchings from the William P. Brumfield Memorial Collection.  

ERIC Educational Resources Information Center

Provides background information on the life and career of Gerald Brockhurst, an artist known for his etchings. Includes information on his etchings. Describes the travelling exhibition of Brockhurst's etchings "Gerald Leslie Brockhurst: Etchings from the William P. Brumfield Memorial Collection." (CMK)

Johnson, Mark M.



A method for tapered deep reactive ion etching using a modified Bosch process  

NASA Astrophysics Data System (ADS)

This paper presents a method for etching tapered sidewalls in silicon using deep reactive ion etching. The method is based on consecutive switching between anisotropic etching using the Bosch process and isotropic dry etching. By controlling the etch depths of the anisotropic and isotropic etch sessions, the sidewall angle can be controlled over a relatively large range. Tapered sidewalls are useful in microfabrication processes such as metal coating of 3D structures (e.g. for electrical connections or vias), mold tool fabrication or as a tool to compensate for reentrant etching. The method was tested and characterized by etching basic test structures in silicon wafers. Based on the investigated anisotropic and isotropic etch depths the sidewall angle could be varied between 0° (straight vertical) and 36°. The sidewall angle was well predicted by a model using the etch depths as parameters. Due to the alternating etch procedure a scalloping pattern is generated on the sidewalls. By frequent switching and short etch sessions this scalloping can be reduced to less than 1 µm. The process represents an easy method to tailor the sidewall angle in deep etching of silicon. The etch scheme is run in a single etch system and can be implemented in ICP systems of most manufactures. The method can also be used in conjunction with the standard Bosch process as demonstrated herein, where the method was applied to compensate for reentrant etching of high out-of-plane mesa-structures.

Roxhed, Niclas; Griss, Patrick; Stemme, Göran



Measurement of calcium carbonate deposition in molluscs by controlled etching of radioactively labeled shells  

Microsoft Academic Search

Rates of calcium carbonate removal from shell pieces of Argopecten irradians (Say) and Mercenaria mercenaria (L.) were dependent on the type of etching fluid used and not shell origin. Etching was uniform over the entire shell surface, but surface morphology differed with etching fluids. Peak radioactivity was in early eluant fractions of shells etched immediately after radioactive labeling, and in

R. M. Dillaman; S. E. Ford




E-print Network

HIGH-ASPECT-RATIO INDUCTIVELY COUPLED PLASMA ETCHING OF BULK TITANIUM FOR MEMS APPLICATIONS E. R titanium etch rate and TiO2 mask selectivity in an Inductively Coupled Plasma (ICP) as a function of bulk titanium deep etching using Cl2/Ar chemistry with an Inductively Coupled Plasma (ICP) source. Etch

MacDonald, Noel C.


High-rate laser-direct-write dry etching of titanium  

Microsoft Academic Search

Titanium surfaces can be etched spatially selective in a chlorine atmosphere under 488 nm cw Ar+-laser irradiation focused to 3 µm with well-controlled etch depth and high etch rate. By scanning the substrate, patterns can be generated by laser direct writing with high scan speed. The dependence of the etch rate on various parameters, such as laser power, scan speed

O. Lehmann; M. Stuke



Evaluation of unsaturated fluorocarbons for dielectric Etch applications  

E-print Network

The semiconductor industry is currently faced with the problem of the use and emissions of strong global warming compounds, known as perfluorocompounds (PFCs) for dielectric etch applications. The release of global warming ...

Chatterjee, Ritwik, 1974-



Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene  

E-print Network

We demonstrate anisotropic etching of single-layer graphene by thermally activated nickel nanoparticles. Using this technique, we obtain sub-10-nm nanoribbons and other graphene nanostructures with edges aligned along a ...

Campos, Leonardo


Reactive Ion Etching in a VHF Parallel Plate Reactor  

NASA Technical Reports Server (NTRS)

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.

Dahi, H.; Murnick, D. E.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)



Origin of electrical signals for plasma etching endpoint detection  

SciTech Connect

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.

Sobolewski, Mark A.



Visible luminescence from silicon wafers subjected to stain etches  

NASA Technical Reports Server (NTRS)

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.

Fathauer, R. W.; George, T.; Ksendzov, A.; Vasquez, R. P.



Detail of "German Prisoner of War" etched in concrete. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of "German Prisoner of War" etched in concrete. - Naval Supply Annex Stockton, Drainage Canals, Along Davis Avenue & at intersection of Humphreys & Cromwell Avenues, Stockton, San Joaquin County, CA


Etching properties and electrical characterization of surfaces of silicon-on-insulator substrates in presence of halogens  

SciTech Connect

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.

Abbadie, A.; Hamaide, G.; Chaupin, M.; Brunier, F. [SOITEC, Parc Technologique des Fontaines, 38920 Crolles cedex (France); Mariolle, D.; Martinez, E. [CEA, LETI, MINATEC, F38054 Grenoble (France); Maehliss, J. [Goethe University, Institute of Inorganic and Analytical Chemistry, 60438 Frankfurt (Germany)



Effects of etching time on the bottom surface morphology of ultrathin porous alumina membranes for use as masks  

NASA Astrophysics Data System (ADS)

We investigated the effect of etching time on the bottom surface morphologies of ultrathin porous alumina membranes (UT-PAMs) anodized in oxalic and phosphoric acid. The morphology of the bottom surface clearly changed and a unique surface undulation was observed during the etching process. Such an undulation regarding the bottom surface is attributed to the different etching rates between the dome-shaped barrier layer and the hexagonal cell walls. The results suggest that the bottom morphology of UT-PAMs formed after the barrier layer is opened significantly affects the contact area of the bottom side with the substrate. During the initial stage of the opening process for the barrier layer, the porous section will contact the substrate rather than the walls. However, as the etching time increases, the height of the porous section becomes considerably lower than that of the walls, which means that the walls will contact the substrate with a gap between the pores and the substrate. Based on our experimental results, we propose a possible schematic diagram describing the effects of UT-PAMs with differently-shaped bottom surfaces on the shapes of fabricated nanodots when the UT-PAMs are used as masks.

Yang, Sun A.; Choi, Yong Chan; Bu, Sang Don



Deposition Step in MEMS Time Multiplexed Etch  

NASA Astrophysics Data System (ADS)

The deposition step of the Bosch process is examined by first forming standard trenches using a Plasma-Therm DSE-II and then depositing on those for an extended time. The deposition profiles at the bottom and sidewalls of trenches provide useful insights into the physical processes driving deposition process. SEMs reveal a dense film at the top and bottom of the trench as expected; however, it has an isolated fiber structure (like blades of grass) along sidewalls. This sidewall ``film'' structure is independent of the reactor used to deposit, is not caused by the original sidewall scallops, and is not affected by an air break between trench formation and deposition. It is critically dependent upon the ion flux and energy. Our model shows that neutral flux alone cannot form such a deposit inside trenches. This indicates that the deposition step can be highly ion-enhanced and suggests that one reduce the ion flux during Bosch deposition steps to limit the deposition rate at the bottom of the trench/via and thereby increase the etch rate as well as prevent feature closing.

Overzet, Lawrence; Saraf, Iqbal; Goeckner, Matthew



Structural investigation of electrochemically etched silicon  

SciTech Connect

Small-angle neutron scattering, (SANS) measurements of four electrochemically etched, porous (PS) samples have been performed over a wide wavevector transfer (Q) range. The intermediate to high Q results can be modeled with a non-particulate, random phase model. Correlation length scales on the order of 1 to 2 nm thought to characterize the PS skeleton have been deduced from the SANS data. The microstructural anisotropy was studied by tilting two of the samples with respect to the neutron beam. These samples exhibited an asymmetric scattering pattern at intermediate Q(0.1 {le} Q {le} 0.6 nm{sup {minus}1} in this condition. Photoluminescence spectra from all four samples have been recorded as well. A correlation appears to exist between the SANS and photoluminescence measurements. An x-ray diffraction measurement of one sample demonstrates that the PS layer retains the silicon lattice structure. Significant peak broadening is observed and is interpreted as a quasi-particle size effect. The PS particle size calculated from the x-ray diffraction measurement is equal to the correlation length obtained in the SANS measurement.

Heuser, B.J. [Missouri Univ., Columbia, MO (United States). Research Reactor Facility; Spooner, S. [Oak Ridge National Lab., TN (United States); Glinka, C.J. [National Inst. of Standards and Technology (IMSE), Gaithersburg, MD (United States). Reactor Radiation Div.; Gilliam, D.L. [Lincoln Univ., Jefferson City, MO (United States). Dept. of Physics; Winslow, N.A.; Boley, M.S. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)



Nanometer-sized etching of magnetic tunnel junction stack for magnetic random access memory  

NASA Astrophysics Data System (ADS)

High-density plasma reactive ion etching of MTJ stack was investigated in an inductively coupled plasma of Cl 2/Ar and Cl 2/O 2/Ar gas mixes. Thin TiN hard mask was employed and the etching proceeded at ambient temperature. The effect of etch gas on the etch profiles of MTJ stack was examined by varying the gas concentration. In addition, the effects of etch parameters on the etch profiles and magnetic properties of MTJ stacks were investigated. The highly anisotropic etching of MTJ stack arrays with 200×200 and 100×100 nm 2 dimensions was successfully achieved.

Hyun Park, Ik; Ryun Min, Su; Hyun Park, Wang; Ho Shin, Kyung; Chung, Chee Won



Chemical Etching of Zinc Oxide for Thin-Film Silicon Solar Cells  

PubMed Central

Abstract Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided. PMID:22162035

Hüpkes, Jürgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke



Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector  

NASA Astrophysics Data System (ADS)

Experimental measurements of the etching solution temperature dependence of bulk etch rate using two independent methods revealed a few interesting properties. It is found that while the track saturation length is independent of etching temperature, the etching time needed to reach saturation is strongly temperature-dependent. It is demonstrated that there is systematic simple inverse relation between track saturation time, and etching solution temperature. In addition, and although, the relation between the bulk etch rate and etching solution temperature can be reasonably described by a modified form of the Arrhenius equation, better fits can be obtained by another equation suggested in this work.

Azooz, A. A.; Al-Jubbori, M. A.



Bonding of self-adhesive resin cements to enamel using different surface treatments: bond strength and etching pattern evaluations.  


This study evaluated the shear bond strengths and etching patterns of seven self-adhesive resin cements to human enamel specimens which were subjected to one of the following surface treatments: (1) Polishing with #600 polishing paper; (2) Phosphoric acid; (3) G-Bond one-step adhesive; or (4) Phosphoric acid and G-Bond. After surface treatment, the human incisor specimens were bonded to a resin composite using a self-adhesive resin cement [Maxcem (MA), RelyX Unicem (UN), Breeze (BR), BisCem (BI), seT (SE), Clearfil SA Luting (CL)] or a conventional resin cement [ResiCem (RE)]. Representative morphology formed with self-adhesive resin cements showed areas of etched enamel intermingled with areas of featureless enamel. In conclusion, etching efficacy influenced the bonding effectiveness of self-adhesive resin cements to unground enamel, and that a combined use of phosphoric acid and G-Bond for pretreatment of human enamel surfaces improved the bond strength of self-adhesive resin cements. PMID:20668359

Lin, Jie; Shinya, Akikazu; Gomi, Harunori; Shinya, Akiyoshi



Dry etching of CuCrO 2 thin films  

Microsoft Academic Search

Highly conducting films of p-type CuCrO2 are attractive as hole-injectors in oxide-based light emitters. In this paper, we report on the development of dry etch patterning of CuCrO2 thin films. The only plasma chemistry that provided some chemical enhancement was Cl2\\/Ar under inductively coupled plasma conditions. Etch rates of ?500Åmin?1 were obtained at chuck voltages around ?300V and moderate source

W. T. Lim; P. W. Sadik; D. P. Norton; S. J. Pearton; F. Ren



Focused, Nanoscale Electron-Beam-Induced Deposition and Etching  

Microsoft Academic Search

Focused electron-beam-induced (FEB-induced) deposition and etching are versatile, direct-write nanofabrication schemes that allow for selective deposition or removal of a variety of materials. Fundamentally, these processes are governed by an electron-induced reaction with a precursor vapor, which may either result in decomposition to a solid deposit or formation of a volatile etch by-product. The ability to induce such localized reactions

S. J. Randolph; J. D. Fowlkes; P. D. Rack



Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene  

Microsoft Academic Search

We demonstrate anisotropic etching of single-layer graphene by thermally-activated nickel nanoparticles. Using this technique, we obtain sub-10nm nanoribbons and other graphene nanostructures with edges aligned along a single crystallographic direction. We observe a new catalytic channeling behavior, whereby etched cuts do not intersect, resulting in continuously connected geometries. Raman spectroscopy and electronic measurements show that the quality of the graphene

Leonardo C. Campos; Vitor R. Manfrinato; Javier D. Sanchez-Yamagishi; Jing Kong; Pablo Jarillo-Herrero



The low-temperature conductivity of etched quantum wires  

Microsoft Academic Search

Low-temperature transport measurements made on nearly depleted n+ GaAs quantum wires fabricated by molecular beam epitaxy and reactive ion etching are described. In such wires, damage generated by the etching process introduces traps at the wire edges and increases the effective depletion regions there. Exposure of the wires to low-level visible light at low temperatures causes conductance increases whereas the

A. R. Long; M. Rahman; I. K. MacDonald; M. Kinsler; S. P. Beaumont; C. D. W. Wilkinson; C. R. Stanley



Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation  

NASA Technical Reports Server (NTRS)

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.

Kane, R. D.; Petrovic, J. J.; Ebert, L. J.



Reaction of magnesium diboride with H/sub 2/O, H/sub 2/O/sub 2/, and acids  

SciTech Connect

The authors study the stability of magnesium diboride in air, over steam, and in certain aggressive media. The magnesium diboride used was obtained by synthesis from the elements, with a particle size of 205 The stability of magnesium diboride in air and over steam was estimated from the change in weight. The chemical stability of magnesium diboride in mineral acids at different concentrations and in water was determined. Hydrofluoric acid and hydrogen peroxide completely decompose magnesium diboride. The kinetics of the decomposition of MgB/sub 2/ in aqueous solutions of acids were also calculated.

Lyashenko, V.I.; Kosolapova, T.Y.; Serebryakova, T.I.



Micropatterning on cylindrical surfaces via electrochemical etching using laser masking  

NASA Astrophysics Data System (ADS)

This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces.

Cho, Chull Hee; Shin, Hong Shik; Chu, Chong Nam



Recouping etch rates in pulsed inductively coupled plasmas  

SciTech Connect

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.

Agarwal, Ankur; Stout, Phillip J.; Banna, Samer; Rauf, Shahid; Collins, Ken [Applied Materials Inc., 974 E. Arques Avenue, M/S 81312, Sunnyvale, California 94085 (United States)



Vapor etching of nuclear tracks in dielectric materials  


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.

Musket, Ronald G. (Danville, CA); Porter, John D. (Berkeley, CA); Yoshiyama, James M. (Fremont, CA); Contolini, Robert J. (Lake Oswego, OR)



Level Set Approach to Anisotropic Wet Etching of Silicon  

PubMed Central

In this paper a methodology for the three dimensional (3D) modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon symmetry properties, by means of the interpolation technique using experimentally obtained values for the etching rates along thirteen principal and high index directions in KOH solutions. The resulting level set equations are solved using an open source implementation of the sparse field method (ITK library, developed in medical image processing community), extended for the case of non-convex Hamiltonians. Simulation results for some interesting initial 3D shapes, as well as some more practical examples illustrating anisotropic etching simulation in the presence of masks (simple square aperture mask, convex corner undercutting and convex corner compensation, formation of suspended structures) are shown also. The obtained results show that level set method can be used as an effective tool for wet etching process modeling, and that is a viable alternative to the Cellular Automata method which now prevails in the simulations of the wet etching process. PMID:22399916

Radjenovic, Branislav; Radmilovic-Radjenovic, Marija; Mitric, Miodrag



Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Hong Liu, and Zhong Lin Wang*,  

E-print Network

Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Wafer Hong Liu, and Zhong Lin Wang-step, hydrofluoric acid-free hydrothermal etching method that not only produces bismuth nano/micrometer-sized spheres Bismuth is a semimetal with unusual electronic properties that results from its highly anisotropic Fermi

Wang, Zhong L.


Silicon-aluminum oxynitride composite films deposited by reactive ion beam sputtering  

Microsoft Academic Search

Amorphous Silicon-Aluminum Oxynitride (SIALON) films were deposited by a reactive ion beam sputtering (IBS) method with neutralizer. The properties for insulating films were examined for these SIALON films. Auger analysis shows that the deposited SIALON films have uniform composition of atoms in the depth. The etching rate of the films by hydrofluoric acid 30 nm\\/min under the deposition condition above

Sohichi OGAWA; Yoshihiko SUZUKI; Masaaki Yoshitake; Kazuki Natsukawa



Aluminum Nitride Thin Films on Titanium for Piezoelectric MEMS Applications Seth Boeshore, Emily Parker, Vanni Lughi, Noel C. MacDonald  

E-print Network

Parker, Vanni Lughi, Noel C. MacDonald University of California, Santa Barbara Highly­textured aluminum piezoelectric MEMS. Titanium is a new and attractive platform for MEMS because of its corrosion resistance were then released by an isotropic wet etch in dilute hydrofluoric acid, and finally the top contact

MacDonald, Noel C.


Epitaxial Ag templates on Si(001) for bicrystal CoCrTa media Wei Yang and David N. Lambeth  

E-print Network

that geometrically a 4 4 mesh of Ag unit cells fits very well onto a 3 3 mesh of Si unit cells, with a mismatchEpitaxial Ag templates on Si(001) for bicrystal CoCrTa media Wei Yang and David N. Lambeth on hydrofluoric acid-etched Si 001 single crystal substrates and employed as templates for the epitaxial growth

Laughlin, David E.


Unicrystal Coalloy media on Si,,110... and David N. Lambeth  

E-print Network

on epitaxial Cr/Ag templates sput- ter deposited on hydrofluoric acid HF -etched Si 110 sub- strates dependence of rotational hysteresis.5 While single crystal MgO 110 substrates were also used to grow unicrys with the 4-to-3 lattice match at the Ag 001 /Si 001 interface as reported in our previous work on bicrystal

Laughlin, David E.


Hydroxyapatite Effect on Photopolymerization of Self-etching Adhesives with Different Aggressiveness  

PubMed Central

Objective To understand the correlation of the acidic monomer/hydroxyapatite (HAp) reaction with the photopolymerization behavior of self-etching adhesives with different aggressiveness. Methods Two commercial self-etching adhesives the strong Adper Prompt L-Pop (APLP, pH~0.8) and the mild Adper Easy Bond (AEB, pH~2.5) were used. HAp powders were incorporated into both adhesives to acquire solutions with concentrations of 0, 1, 3, 5, 7 wt%. The attenuated total reflectance Fourier transform infrared (ATR/FT-IR) technique was employed to collect the in-situ spectra during light-curing, from which the degree of conversion (DC) and polymerization rate (PR) were calculated. The pH of each tested solution was also measured. Results Without HAp incorporation, the DC and PR of the strong APLP (7.8% and 0.12%/s, respectively) were much lower than those of the mild AEB (85.5% and 5.7%/s, respectively). The DC and PR of APLP displayed an apparent increasing trend with the HAp content. For example, the DC increased from 7.8% to 58.4% and the PR increased from 0.12 to 3.8%/s when the HAp content increased from 0 to 7 wt%. In contrast, the DC and PR of AEB were much less affected by the HAp content. The observations were correlated well with the spectral and pH changes, which indicated that APLP underwent a higher extent of chemical reaction with HAp than AEB. Conclusions The results disclosed the important role of the acidic monomer/HAp chemical reaction in improving the photopolymerization of the strong (low-pH) self-etching adhesives such as APLP. The phenomenon of polymerization improvement strongly depended on the adhesive aggressiveness. PMID:22445789

Zhang, Ying; Wang, Yong




EPA Science Inventory

Each year, several million gallons of acid solutions are used by the Department of Defense (DoD) and its support contractors in various metal finishing operations such as stripping, etching, activation, passivation and pickling. Over time, these acids become contaminated with met...


Electron-Beam-Induced Cl2 Etching of GaAs  

Microsoft Academic Search

Electron-beam (EB)-induced Cl2 etching of GaAs is performed for the first time. Etching occurs only in the area exposed to both the Cl2 molecules and the EB. The etching rate is equal to that of a Cl2 gas phase etching. The morphologies of the etched surfaces are slightly rough, but the photoluminescence intensity of the processed sample does not change

Mototaka Taneya; Yoshimasa Sugimoto; Hiroshi Hidaka; Kenzo Akita



Tantalum carbide etch characterization in inductively coupled Ar\\/Clâ\\/HBr plasmas  

Microsoft Academic Search

The etching properties of tantalum carbide (TaC) in inductively coupled Ar\\/HBr\\/Clâ plasmas are investigated in this article. Both etching experiments on patterned and blanket wafers and an integrated plasma equipment-feature scale computational model are utilized in this investigation. Results show that TaC etching is adequately described by the classical reactive ion etching mechanism, whereby etching occurs due to the synergistic

H. Kawai; S. Rauf; E. Luckowski; P. L. G. Ventzek



Nanometer-sized etching of magnetic tunnel junction stack for magnetic random access memory  

Microsoft Academic Search

High-density plasma reactive ion etching of MTJ stack was investigated in an inductively coupled plasma of Cl2\\/Ar and Cl2\\/O2\\/Ar gas mixes. Thin TiN hard mask was employed and the etching proceeded at ambient temperature. The effect of etch gas on the etch profiles of MTJ stack was examined by varying the gas concentration. In addition, the effects of etch parameters

Ik Hyun Park; Su Ryun Min; Wang Hyun Park; Kyung Ho Shin; Chee Won Chung



Proposal of quasi thermal equilibrium model for etching phenomenon by gases: Example of the etching of 4H-SiC by H2  

NASA Astrophysics Data System (ADS)

We propose a new approach to derive the formula for the etching rate of condensed matter with a gaseous etchant, based on the model in which the chemical etching proceeds under nearly thermal equilibrium conditions. The model, called the quasi thermal equilibrium model, is applicable for the case that the reaction time is much shorter than the passage time of carrier gases over substrates. We have derived the formula giving the etching rates as functions of temperature, gas flow rate, and pressure for three cases: (1) a carrier gas acts as an etching gas, (2) a carrier gas is inactive and an etching gas is added, and (3) a carrier gas is active and an etching gas is added. We applied the model to the etching of 4H-SiC by H2 and showed that the quasi thermal equilibrium model proposed can successfully reproduce the experimental results of the temperature, gas flow rate, and pressure dependences of the etching rate.

Ishida, Yuuki; Yoshida, Sadafumi



A challenge to the conventional wisdom that simultaneous etching and resin infiltration always occurs in self-etch adhesives  

Microsoft Academic Search

This study provided morphological evidence that discrepancies between the depth of demineralisation and the depth of resin infiltration can occur in some mild self-etch adhesives. Sound dentine specimens derived from extracted human third molars were bonded with 5 one-step and 5 two-step self-etch adhesives. One millimeter thick slabs containing the resin–dentine interfaces were immersed in 50wt% aqueous ammoniacal silver nitrate

Ricardo M. Carvalho; Stefano Chersoni; Roland Frankenberger; David H. Pashley; Carlo Prati; Franklin R. Tay



Cl2/Ar based inductively coupled plasma etching of GaN/AlGaN structure  

NASA Astrophysics Data System (ADS)

Cl2/Ar based inductively coupled plasma etching of GaN/AlGaN is investigated using photoresist mask in a restricted domain of pressure < 10mTorr and RF power <100W, for selective mesa etching. The etch characteristics and rootmean- square surface roughness are studied as a function of process parameters viz. process pressure, Cl2 percentage in total flow rate ratio, and RF bias at a constant ICP power, to achieve moderately high GaN etch rate with anisotropic profiles and smooth surface morphology. The etch rate and resultant rms roughness of etched surface increased with pressure mainly due to dominant reactant limited etch regime. The etch rate also increased with increasing Cl2 % as a result of increased chlorine radicals that enhances chemical etching. The etch rate and rms roughness showed strong dependence on RF power with former increasing and later decreasing with applied RF power up to 80W. The process etch yield variation with applied RF bias is also reported. Negligible etch selectivity was observed between GaN and AlGaN up to 25% aluminum concentration with etch rate ~120nm/min. The studied etch parameters resulted in highly anisotropic mesa structures with Ga rich etched surface.

Rawal, D. S.; Arora, Henika; Agarwal, V. R.; Kapoor, Ashok; Vinayak, Seema; Sehgal, B. K.; Muralidharan, R.; Saha, Dipankar; Malik, H. K.



Surfactant-enhanced control of track-etch pore morphology  

NASA Astrophysics Data System (ADS)

The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few nanometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than the pore entrance. After a more prolonged etching the bottle-like (or "cigar-like") pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters.

Apel, P. Yu; Blonskaya, I. V.; Didyk, A. Yu; Dmitriev, S. N.; Orelovitch, O. L.; Root, D.; Samoilova, L. I.; Vutsadakis, V. A.



Pulsed high-density plasmas for advanced dry etching processes  

SciTech Connect

Plasma etching processes at the 22 nm technology node and below will have to satisfy multiple stringent scaling requirements of microelectronics fabrication. To satisfy these requirements simultaneously, significant improvements in controlling key plasma parameters are essential. Pulsed plasmas exhibit considerable potential to meet the majority of the scaling challenges, while leveraging the broad expertise developed over the years in conventional continuous wave plasma processing. Comprehending the underlying physics and etching mechanisms in pulsed plasma operation is, however, a complex undertaking; hence the full potential of this strategy has not yet been realized. In this review paper, we first address the general potential of pulsed plasmas for plasma etching processes followed by the dynamics of pulsed plasmas in conventional high-density plasma reactors. The authors reviewed more than 30 years of academic research on pulsed plasmas for microelectronics processing, primarily for silicon and conductor etch applications, highlighting the potential benefits to date and challenges in extending the technology for mass-production. Schemes such as source pulsing, bias pulsing, synchronous pulsing, and others in conventional high-density plasma reactors used in the semiconductor industry have demonstrated greater flexibility in controlling critical plasma parameters such as ion and radical densities, ion energies, and electron temperature. Specifically, plasma pulsing allows for independent control of ion flux and neutral radicals flux to the wafer, which is key to eliminating several feature profile distortions at the nanometer scale. However, such flexibility might also introduce some difficulty in developing new etching processes based on pulsed plasmas. Therefore, the main characteristics of continuous wave plasmas and different pulsing schemes are compared to provide guidelines for implementing different schemes in advanced plasma etching processes based on results from a particularly challenging etch process in an industrial reactor.

Banna, Samer; Agarwal, Ankur; Cunge, Gilles; Darnon, Maxime; Pargon, Erwine; Joubert, Olivier [Applied Materials Inc., 974 E. Arques Avenue, M/S 81312, Sunnyvale, California 94085 (United States); CNRS-LTM, 17 rue des Martyrs, 38054 Grenoble Cedex (France)



Dry etching resistance of resist base polymer and its improvement  

NASA Astrophysics Data System (ADS)

The etching rates of resist base polymers with several molecular weights were measured against fluorocarbon or chlorine plasma. The rate showed a minimum value at the weight-average molecular weight of approximately 10,000, and increased to a saturated value for higher molecular weights. For poly(p-hydroxystyrene) (PHS) protected with tert- butoxycarbonyl (BOC) or acetal (ACT) group, the rate became larger with increasing the protection ratio and the rate of BOC-protected PHS was lower than that of ACT-protected PHS. It was also found that the rate was significantly influenced by the prebake and increased as the temperature became higher. The etching rate of the resin with gradual cooling after the prebake was slower than that with quick cooling. These results may indicate that the dry etching resistance is independent of the density of resin film and influenced by the stability of arrangements of polymer molecules. The reduction of etching rate by the deep UV cure method has been tried. The rate decreased with the deep UV cure under N2 gas flow, while increased in the presence of O2 such as dry air. The films after deep UV cure under N2 and a dry air was scarcely dissolved in any organic solvents and this implies that the polymers are crosslinking. The absorbance band of carbonyl appeared in FT-IR spectra for the case under dry air may suggest that oxygen atoms in the polymer structure influence the dry etching resistance. We have tried deep UV cure under N2 gas flow for KrF chemically amplified PHS based resists and obtained the same level of etching rates as novolak resin. For ArF resists, the combination of the incorporation of acryl unit into the base polymer and deep UV cure under N2 gas flow may be an effective method for improving the dray etching resistance.

Kishimura, Shinji; Kimura, Yoshika; Sakai, Junjiro; Tsujita, Kouichirou; Matsui, Yasuji



Photonic crystal membrane reflectors by magnetic field-guided metal-assisted chemical etching  

SciTech Connect

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.

Balasundaram, Karthik; Mohseni, Parsian K.; Li, Xiuling, E-mail:, E-mail: [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Shuai, Yi-Chen; Zhao, Deyin; Zhou, Weidong, E-mail:, E-mail: [Department of Electrical Engineering, NanoFAB Center, University of Texas at Arlington, Arlington, Texas 76019 (United States)] [Department of Electrical Engineering, NanoFAB Center, University of Texas at Arlington, Arlington, Texas 76019 (United States)



A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces.  


A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy. PMID:21145675

Uli, Norjaidi; Kuppuswamy, R; Amran, Mohd Firdaus Che



Effect of Potential Field on Ion Deflection and Shape Evolution of Trenches during Plasma-Assisted Etching  

E-print Network

- rectionality in motion, etch both the sidewalls as well as the bottom of the feature. We call this "chemical-Assisted Etching Demetre J. Economou*'1 and Richard C. Alkire* Department of Chemical Engineering, University-assisted etching as compared to chemical etching. However, sidewall etching can occur even in the absence

Economou, Demetre J.


Innovative, Inexpensive Etching Technique Developed for Polymer Electro- Optical Structures  

NASA Technical Reports Server (NTRS)

Electro-optic, polymer-based integrated optic devices for high-speed communication and computing applications offer potentially significant advantages over conventional inorganic electro-optic crystals. One key area of integrated optical technology--primary processing and fabrication--may particularly benefit from the use of polymer materials. However, as efforts concentrate on the miniaturization of electro-integrated circuit pattern geometries, the ability to etch fine features and smoothly sloped sidewalls is essential to make polymers useful for electro-integrated circuit applications. There are many existing processes available to etch polymer materials, but they all yield nearly vertical sidewalls. Vertical sidewalls are too difficult to reliably cover with a metal layer, and incomplete metalization degrades microwave performance, particularly at high frequency. However, obtaining a very sloped sidewall greatly improves the deposition of metal on the sidewall, leading to low-loss characteristics, which are essential to integrating these devices in highspeed electro-optic modulators. The NASA Lewis Research Center has developed in-house an inexpensive etching technique that uses a photolithography method followed by a simple, wet chemical etching process to etch through polymer layers. In addition to being simpler and inexpensive, this process can be used to fabricate smoothly sloped sidewalls by using a commercial none rodible mask: Spin-On-Glass. A commercial transparent material, Spin-On-Glass, uses processes and equipment similar to that for photoresist techniques.

Nguyen, Hung D.



Etching Effects During the Chemical Vapor Deposition of (100) Diamond  

SciTech Connect

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.

Battaile, C.C.; Srolovitz, D.J.; Oleinik, I.I.; Pettifor, D.G.; Sutton, A.P.; Harris, S.J.; Butler, J.E.



Galvanic corrosion induced degredation of tensile properties in micromachined polycrystalline silicon  

NASA Astrophysics Data System (ADS)

Immersion of polycrystalline silicon in hydrofluoric acid-based solutions is often utilized in microsystem fabrication to liberate mechanical structures. The authors demonstrate, using microfabricated tensile specimens, that such etching can cause a catastrophic reduction in tensile strength and elastic modulus in silicon galvanically coupled to a metallic layer, such as commonly used gold. Galvanically corroded silicon exhibits grain-boundary attack leading to intergranular fracture and/or generalized material removal. The severity of damage and corresponding losses in strength and modulus depend on etch duration and etch chemistry. In contrast, without a metallic layer, uncorroded silicon fails transgranularly and independent of etch duration or chemistry.

Miller, David C.; Boyce, Brad L.; Gall, Ken; Stoldt, Conrad R.



Effects of Etching Time and NaOH Concentration on the Production of Alumina Nanowires Using Porous Anodic Alumina Template  

NASA Astrophysics Data System (ADS)

In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific.

Sadeghpour-Motlagh, M.; Mokhtari-Zonouzi, K.; Aghajani, H.; Kakroudi, M. Ghassemi



The effect of substrate temperature on the etching properties and the etched surfaces of magnetic tunnel junction materials in a CH3OH inductively coupled plasma system  

NASA Astrophysics Data System (ADS)

The etching characteristics of the magnetic films (PtMn, CoFe) and hard mask materials (W, Ta) forming a magnetic tunnel junction (MTJ) stack in a CH3OH inductively coupled plasma (ICP) system were investigated. We examined the etch rates of the metal films as a function of substrate temperature, and assessed the microstructures of the etched surfaces using high resolution transmission electron microscopy (HR-TEM). We also analyzed the surface states using X-ray photoelectron spectroscopy (XPS) and TEM electron energy loss spectroscopy (TEM-EELS). The PtMn and CoFe etch rates increased as the temperature increased, whereas the etch rates of W and Ta decreased slightly. Therefore the etch selectivity increased linearly with increasing substrate temperature. The CH3OH plasma formed nonvolatile etching byproducts with the magnetic films and hard mask metals. In the case of PtMn and CoFe, the surface composition of the etching byproducts changed with increasing temperature; the relative concentration of pure metal compared with metal oxide or carbide increased as the substrate temperature rose. The etch rate was determined by the sputtering yield of the materials formed on the etched surface; accordingly the etch rates of those magnetic films would increase due to the higher sputtering yield of pure metal.

Lee, Minsuk; Lee, Won-Jong



Alumina etch masks for fabrication of high-aspect-ratio silicon micropillars and nanopillars.  


We introduce using sputtered aluminum oxide (alumina) as a resilient etch mask for fluorinated silicon reactive ion etches. Achieving selectivity of 5000:1 for cryogenic silicon etching and 68:1 for SF(6)/C(4)F(8) silicon etching, we employ this mask for fabrication of high-aspect-ratio silicon micropillars and nanopillars. Nanopillars with diameters ranging from below 50 nm up to several hundred nanometers are etched to heights greater than 2 microm. Micropillars of 5, 10, 20, and 50 microm diameters are etched to heights of over 150 microm with aspect ratios greater than 25. Processing and characterization of the sputtered alumina is also discussed. PMID:19487807

Henry, M D; Walavalkar, S; Homyk, A; Scherer, A



Evolution of the crystallographic planes of cone-shaped patterned sapphire substrate treated by wet etching  

NASA Astrophysics Data System (ADS)

A series of wet etching experiments were performed to investigate the evolution of crystallographic planes of cone-shaped patterned sapphire substrate. During the etching process, three kinds of etching zones were found. Two etching zones appeared first and vanished with increasing etching time. The other one exposed later and expanded gradually. Finally, the cone-shaped pattern with an arcuate slope transformed to a hexagonal pyramid. The calculated orientation of the crystallographic planes in the two etching zones was {1 1¯ 0 3} and {4 3¯1¯ 27}, which were different from the previous reports.

Yang, Dechao; Liang, Hongwei; Qiu, Yu; Shen, Rensheng; Liu, Yang; Xia, Xiaochuan; Song, Shiwei; Zhang, Kexiong; Yu, Zhennan; Zhang, Yuantao; Du, Guotong



pH-controlled selective etching of Al2O3 over ZnO.  


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

Sun, Kaige G; Li, Yuanyuan V; Saint John, David B; Jackson, Thomas N



Influence of endodontic irrigants on bond strength of a self-etching adhesive.  


The aim of this in vitro study was to evaluate the bond strength of a self-etching adhesive system to dentine irrigated with sodium hypochlorite (NaOCl), chlorhexidine solution (CX) and ethylene diamine tetra acetic acid (EDTA) by microtensile testing. Sixty human third molars were sectioned 3 mm below the occlusal level and then randomly divided into six groups: G1(control), without irrigant solution; G2, 1% NaOCl; G3, 1% NaOCl followed by the application of 17% EDTA; G4, 2% CX; G5, 2% CX followed by the application of 17% EDTA and G6, 17% EDTA. The specimens received the self-etching adhesive system were restored with composite resin, then sectioned and trimmed to obtain four hourglass-shaped slabs from each tooth. The specimens were submitted to the microtensile test in a Universal Testing Machine at a crosshead speed of 0.5 mm min(-1) until fracture. The results were submitted to statistical analysis by anova /Newman-Keuls. The means and standard deviations (MPa) were: G1, 26.88 (±3.81); G2, 19.08 (±3.89); G3, 18.16 (±2.21); G4, 18.14 (±4.32); G5, 34.30 (±3.32); G6, 13.61 (±1.21). It was concluded that the application of 2% CX followed by the application of 17% EDTA resulted in increasing the bond strength of the self-etching adhesive system to dentine, when compared with the results obtained for the other tested groups. PMID:21418411

Farina, Ana P; Cecchin, Doglas; Barbizam, João V B; Carlini-Júnior, Bruno



Method and apparatus for spatially uniform electropolishing and electrolytic etching  


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.

Mayer, S.T.; Contolini, R.J.; Bernhardt, A.F.



Method and apparatus for spatially uniform electropolishing and electrolytic etching  


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.

Mayer, Steven T. (Piedmont, CA); Contolini, Robert J. (Pleasanton, CA); Bernhardt, Anthony F. (Berkeley, CA)



Study of etching rate uniformity in SRF cavities  

SciTech Connect

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.

Janardan Upadhyay, Svetozar Popovic, Leposova Vuskovic, H. Phillips, Anne-Marie Valente



Characteristics of silicon etching by silicon chloride ions  

SciTech Connect

Plasmas generated from halogen-containing gases, such as Cl{sub 2} or HBr, have been widely used in gate etching processes for semiconductor chip manufacturing. Such plasmas may contain silicon halide ions formed by the ionization of etching products that enter the plasma. In this study, to illustrate Si etching by such silicon halide ions, the sputtering yield of Si by SiCl{sub x}{sup +} (with x = 1 or 3) ions has been obtained as a function of the incident ion energy by using a mass-selected ion beam injection system. It has been found that, at sufficiently low energy, the incidence of SiCl{sup +} ions leads to the deposition of Si which may affect profile control in microelectronic device fabrication processes.

Ito, Tomoko; Karahashi, Kazuhiro; Hamaguchi, Satoshi [Center for Atomic and Molecular Technologies, Osaka University, 2-1 Yamadaoka, Suita-shi, Osaka 565-0871 (Japan); Kang, Song-Yun [TEL Technology Center Tsukuba, Tokyo Electron Ltd., 17 Miyukigaoka Tsukuba-shi, Ibaraki 305-0841 (Japan)



Dissolution kinetics and etch pit studies of potassium aluminium sulphate  

NASA Astrophysics Data System (ADS)

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.

van der Hoek, B.; Van Enckevort, W. J. P.; Van Der Linden, W. H.



Room-temperature photoenhanced wet etching of GaN  

NASA Astrophysics Data System (ADS)

Laser-enhanced, room-temperature wet etching of GaN using either dilute HCl:H2O (1:10) or 45% KOH:H2O(1:3) is reported. Etch rates of a few hundred Å/min (HCl) and up to a few thousand Å/min (KOH) have been measured for unintentionally doped n-type films of thickness (1-2 ?m) grown by MOCVD on a sapphire substrate. The etching is thought to take place photoelectrochemically with holes and electrons generated by incident illumination from 4.5 mW of HeCd laser power enhancing the oxidation and reduction reactions in an electrochemical cell.

Minsky, M. S.; White, M.; Hu, E. L.



Method of plasma etching Ga-based compound semiconductors  


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.

Qiu, Weibin; Goddard, Lynford L.



Method of plasma etching GA-based compound semiconductors  


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.

Qiu, Weibin; Goddard, Lynford L.



Tensile bond strength of sealants following Er:YAG laser etching compared to acid etching in permanent teeth  

Microsoft Academic Search

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of\\u000a a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The\\u000a enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and

Sima Shahabi; Hossein G. Bagheri; Kosar Ramazani


The mechanism of galvanic/metal-assisted etching of silicon  

NASA Astrophysics Data System (ADS)

Metal-assisted etching is initiated by hole injection from an oxidant catalyzed by a metal nanoparticle or film on a Si surface. It is shown that the electronic structure of the metal/Si interface, i.e., band bending, is not conducive to diffusion of the injected hole away from the metal in the case of Ag or away from the metal/Si interface in the cases of Au, Pd, and Pt. Since holes do not diffuse away from the metals, the electric field resulting from charging of the metal after hole injection must instead be the cause of metal-assisted etching.

Kolasinski, Kurt W.



A Reactive-Ion Etch for Patterning Piezoelectric Thin Film  

NASA Technical Reports Server (NTRS)

Reactive-ion etching (RIE) under conditions described below has been found to be a suitable means for patterning piezoelectric thin films made from such materials as PbZr(1-x)Ti(x)O3 or Ba(x)Sr(1.x)TiO3. In the original application for which this particular RIE process was developed, PbZr(1-x)Ti(x)O3 films 0.5 microns thick are to be sandwiched between Pt electrode layers 0.1 microns thick and Ir electrode layers 0.1 microns thick to form piezoelectric capacitor structures. Such structures are typical of piezoelectric actuators in advanced microelectromechanical systems now under development or planned to be developed in the near future. RIE of PbZr(1-x)Ti(x)O3 is usually considered to involve two major subprocesses: an ion-assisted- etching reaction, and a sputtering subprocess that removes reactive byproducts. RIE is favored over other etching techniques because it offers a potential for a high degree of anisotropy, high-resolution pattern definition, and good process control. However, conventional RIE is not ideal for patterning PbZr(1-x)Ti(x)O3 films at a thickness as great as that in the original intended application. In order to realize the potential benefits mentioned above, it is necessary to optimize process conditions . in particular, the composition of the etching gas and the values of such other process parameters as radio-frequency power, gas pressure, gas-flow rate, and duration of the process. Guidelines for determining optimum conditions can be obtained from experimental determination of etch rates as functions of these parameters. Etch-gas mixtures of BCl3 and Cl2, some also including Ar, have been found to offer a high degree of selectivity as needed for patterning of PbZr(1-x)Ti(x)O3 films on top of Ir electrode layers in thin-film capacitor structures. The selectivity is characterized by a ratio of approx.10:1 (rate of etching PbZr(1-x)Ti(x)O3 divided by rate of etching Ir and IrO(x)). At the time of reporting the information for this article, several experiments on RIE in BCl3 and Cl2 (and sometimes Ar) had demonstrated the 10:1 selectivity ratio, and further experiments to enhance understanding and obtain further guidance for optimizing process conditions were planned.

Yang, Eui-Hyeok; Wild, Larry



Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene  

Microsoft Academic Search

We demonstrate anisotropic etching of single-layer graphene by\\u000athermally-activated nickel nanoparticles. Using this technique, we obtain\\u000asub-10nm nanoribbons and other graphene nanostructures with edges aligned along\\u000aa single crystallographic direction. We observe a new catalytic channeling\\u000abehavior, whereby etched cuts do not intersect, resulting in continuously\\u000aconnected geometries. Raman spectroscopy and electronic measurements show that\\u000athe quality of the graphene

Leonardo C. Campos; Vitor R. Manfrinato; Javier D. Sanchez-Yamagishi; Jing Kong; Pablo Jarillo-Herrero




Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey



Modeling aluminum etch chemistry in high density plasmas  

SciTech Connect

The authors have assembled a chemical reaction mechanism that describes the BCl{sub 3}/Cl{sub 2}/Ar plasma etch of Al metallization layers. The reaction set for gas-phase and surface processes was derived either from literature data or estimated from data on related systems. A well-mixed reactor model was used to develop the mechanism and test it against experimental measurements of plasma species and etch-rates in processing reactors. Finally, use of reduced chemistry mechanisms are demonstrated in 2-D simulations for a complex reactor geometry.

Meeks, E. [Sandia National Labs., Livermore, CA (United States); Ho, P.; Buss, R. [Sandia National Labs., Albuquerque, NM (United States)



The mechanism of galvanic/metal-assisted etching of silicon  

PubMed Central

Metal-assisted etching is initiated by hole injection from an oxidant catalyzed by a metal nanoparticle or film on a Si surface. It is shown that the electronic structure of the metal/Si interface, i.e., band bending, is not conducive to diffusion of the injected hole away from the metal in the case of Ag or away from the metal/Si interface in the cases of Au, Pd, and Pt. Since holes do not diffuse away from the metals, the electric field resulting from charging of the metal after hole injection must instead be the cause of metal-assisted etching.



Plasma & reactive ion etching to prepare ohmic contacts  


A method of making a low-resistance electrical contact between a metal and a layer of p-type CdTe surface by plasma etching and reactive ion etching comprising: a) placing a CdS/CdTe layer into a chamber and evacuating said chamber; b) backfilling the chamber with Argon or a reactive gas to a pressure sufficient for plasma ignition; and c) generating plasma ignition by energizing a cathode which is connected to a power supply to enable the plasma to interact argon ions alone or in the presence of a radio-frequency DC self-bias voltage with the p-CdTe surface.

Gessert, Timothy A. (Conifer, CO)



Gate-controlled ultraviolet photo-etching of graphene edges  

SciTech Connect

The chemical reactivity of graphene under ultraviolet (UV) light irradiation is investigated under positive and negative gate electric fields. Graphene edges are selectively etched when negative gate voltages are applied while the reactivity is significantly suppressed for positive gate voltages. Oxygen adsorption onto graphene is significantly affected by the Fermi level of the final state achieved during previous electrical measurements. UV irradiation after negative-to-positive gate sweeps causes predominant oxygen desorption while UV irradiation after gate sweeps in the opposite direction causes etching of graphene edges.

Mitoma, Nobuhiko; Nouchi, Ryo [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, Sakai, Osaka 599-8570 (Japan)] [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, Sakai, Osaka 599-8570 (Japan)



Electrochemical etching of the semiconductor lead tin telluride  

NASA Technical Reports Server (NTRS)

Convective currents during the Bridgman growth of a compound semiconductor lead to temperature fluctuations at the solid-liquid interface. These temperature fluctuations in turn lead to microscopic compositional variations in the solid. Electrochemical principles have been applied to develop three etches which delineate the variations in the compound semiconductor, lead tin telluride, and allow optical studies of the growth kinetics of this material. Use of these etches has shown periodic lines during the initial growth, with indications of oscillatory instabilities developing in later stages of growth, and, finally, complete breakdown of the interface.

Barber, P. G.; Crouch, R. K.



Self-assembled TiO(2) nanotube arrays by anodization of titanium in diethylene glycol: approach to extended pore widening.  


We report on the formation of titanium dioxide nanotube arrays having the largest known pore size, approximately 350 nm diameter. The nanotube arrays are synthesized by Ti foil anodization in a diethylene glycol electrolyte containing low (0.5-2%) concentrations of hydrofluoric acid. The large pore size nanotube arrays are achieved with extended anodization durations of approximately 120 h, with the anodization duration showing a more significant effect on pore diameter than the anodization voltage. It appears that the combined effects of hydrofluoric acid content and anodization duration determine the lateral etching rate of the nanotubes, leading to the larger pore size nanotubes. PMID:20038179

Yoriya, Sorachon; Grimes, Craig A



Fabrication of high aspect ratio silicon nanostructure arrays by metal-assisted etching  

E-print Network

The goal of this research was to explore and understand the mechanisms involved in the fabrication of silicon nanostructures using metal-assisted etching. We developed a method utilizing metal-assisted etching in conjunction ...

Chang, Shih-wei, Ph.D. Massachusetts Institute of Technology



Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2 as a reaction gas  

PubMed Central

The synchrotron radiation (SR) stimulated etching of silicon elastomer polydimethylsiloxane (PDMS) using XeF2 as an etching gas has been demonstrated. An etching system with differential pumps and two parabolic focusing mirrors was constructed to perform the etching. The PDMS was found to be effectively etched by the SR irradiation under the XeF2 gas flow, and the etching process was area-selective and anisotropic. An extremely high etching rate of 40–50?µm (10?min)?1 was easily obtained at an XeF2 gas pressure of 0.2–0.4?torr. This suggests that SR etching using XeF2 gas provides a new microfabrication technology for thick PDMS membranes, which can open new applications such as the formation of three-dimensional microfluidic circuits. PMID:20029113

Chiang, Tsung-Yi; Makimura, Tetsuya; He, Tingchao; Torii, Shuichi; Yoshida, Tomoko; Tero, Ryugo; Wang, Changshun; Urisu, Tsuneo



Characterization and modeling of plasma etch pattern dependencies in integrated circuits  

E-print Network

A quantitative model capturing pattern dependent effects in plasma etching of integrated circuits (ICs) is presented. Plasma etching is a key process for pattern formation in IC manufacturing. Unfortunately, pattern dependent ...

Abrokwah, Kwaku O



Box 13: Silicon Micro/Nano-Fabrication Using Proton Beam Writing and Electrochemical Etching  

NASA Astrophysics Data System (ADS)

The fabrication of 3D structures in silicon is at the heart of many state-of-the-art technologies. Conventional etching technologies require multiple processing steps to fabricate free-standing multilevel structures [1, 2]. The two main wet chemistry procedures are chemical etching in KOH, which is unfortunately isotropic with very slow etching of <111> planes, and electrochemical etching in HF [3]. The electrochemical etching rate is proportional to the flux of holes to the silicon/electrolyte interface, i.e., the applied current density, so it is easy to control and anisotropic. Etching Si in HF at low current densities produces porous silicon, which can be selectively removed by KOH. The low cost and easy implementation of electrochemical etching has made it an attractive alternative to dry etching.

Blackwood, Daniel J.; Teo, Ee Jin


Plasma Etching for Sub45-nm TaN Metal Gates on High-k Dielectrics  

Microsoft Academic Search

Etching of TaN gates on high-k dielectrics (HfO2 or HfAlO) is investigated using HBr\\/Cl2 chemistry in a decoupled plasma source (DPS). The patterning sequence includes 248-nm lithography, plasma photoresist trimming, etching of a SiN-SiO2 hard mask, and photoresist stripping, followed by TaN etching. TaN etching is studied by design of experiment (DOE) with four variables using a linear model with

Vladimir N. Bliznetsov; Lakshmi Kanta Bera; Haw Yun Soo; N. Balasubramanian; Rakesh Kumar; Guo-Qiang Lo; Won Jong Yoo; Chih Hung Tung; Linn Linn



Vertical and Smooth Etching of InP by Cl2\\/Xe Inductively Coupled Plasma  

Microsoft Academic Search

We have demonstrated anisotropic and smooth etching of InP by an inductively coupled plasma (ICP) using Cl2\\/Xe at high substrate temperatures. We investigated the etching characteristics by varying the substrate temperature, gas pressure, Cl2 flow rate and rf power. Vertical and smooth dry etching of InP was achieved under a low dc bias of -80 V. The ICP etching process

Akihiro Matsutani; Hideo Ohtsuki; Fumio Koyama; Kenichi Iga



Selective electrochemical etching of p-CdTe (for photovoltaic cells)  

Microsoft Academic Search

The electrochemical etching of p-CdTe is investigated. This etching is based on a method used previously for the selective etching of n-type Cd-chalcogenide semiconductors. It is shown that the electrochemical etching creates a dense pattern of submicron pits, and increases the reverse bias photocurrent of a Schottky barrier device, made up of single crystal p-CdTe and a polysulfide electrolyte typically

R. Tenne



Chemical etching and organometallic chemical vapor deposition on varied geometries of GaAs  

NASA Technical Reports Server (NTRS)

Results of micron-spaced geometries produced by wet chemical etching and subsequent OMCVD growth on various GaAs surfaces are presented. The polar lattice increases the complexity of the process. The slow-etch planes defined by anisotropic etching are not always the same as the growth facets produced during MOCVD deposition, especially for deposition on higher-order planes produced by the hex groove etching.

Bailey, Sheila G.; Landis, Geoffrey A.; Wilt, David M.



High-rate laser-direct-write dry etching of titanium  

Microsoft Academic Search

Titanium surfaces can be etched spatially selective in a chlorine atmosphere under 488rnm cw Ar+-laser irradiation focused to 3rwm with well-controlled etch depth and high etch rate. By scanning the substrate, patterns can be generated by laser direct writing with high scan speed. The dependence of the etch rate on various parameters, such as laser power, scan speed and chlorine

O. Lehmann; M. Stuke



Wet anisotropic etching for fluidic 1D nanochannels  

Microsoft Academic Search

In this paper a method is proposed to fabricate channels for fluidic applications with a depth in the nanometer range. Channels with smooth and straight sidewalls are constructed with the help of micromachining technology by etching shallow trenches into langle110rangle silicon using native oxide as a mask material and OPD resist developer as the etchant. Sub-50 nm deep fluidic channels

Jeroen Haneveld; Henri Jansen; Erwin Berenschot; Niels Tas; Miko Elwenspoek



Deep NLD Plasma Etching of Fused Silica and Borosilicate Glass  

E-print Network

Deep NLD Plasma Etching of Fused Silica and Borosilicate Glass Mohammed J. Ahamed, Doruk Senkal process for Fused Silica (FS) and Borosilicate Glass (BSG) using magnetic Neutral Loop Discharge (NLD-elastic dissipation, high electrical resistance, and low optical loss. Borosilicate glass is a preferred material

Tang, William C


Understanding the Etched Hourglass Nebula - MyCn 18  

NASA Astrophysics Data System (ADS)

The Etched Hourglass Nebula is typical of many wasp-waisted PNe. Here we consider optical and infra-red imagery and spectroscopy with a view to understanding the structure of the nebula in terms of its ionisation along different directions, the origins of the extreme bipolar shaping and the effect of the off-centre central star.

Lloyd, M.; Matsuura, M.; Redman, M. P.; Jones, D.


Understanding the Etched Hourglass Nebula - MyCn 18  

Microsoft Academic Search

The Etched Hourglass Nebula is typical of many wasp-waisted PNe. Here we consider optical and infra-red imagery and spectroscopy with a view to understanding the structure of the nebula in terms of its ionisation along different directions, the origins of the extreme bipolar shaping and the effect of the off-centre central star.

M. Lloyd



Electron Beam Biasing of Substrates during Plasma Etching [1  

Microsoft Academic Search

Electron beam biasing of substrates is being studied as an alternative to the usual method of using a capacitively coupled, rf-powered wafer chuck. The advantage of biasing with an electron beam is that the electrons which arrive at the wafer do so with an anisotropic velocity distribution similar to the plasma sheath-accelerated ions. This becomes important when etching large aspect

A. K. Quick; N. Hershkowitz



Particle behaviour in an electron cyclotron resonance plasma etch tool  

Microsoft Academic Search

Sources of particles in a closed-coupled electron cyclotron resonance plasma source used for polysilicon etch included flaking of a residual film deposited on chamber surfaces and shedding of material from the electrostatic wafer chuck. A large, episodic increase in the number of particles added to a wafer in a clean system is observed more frequently for a plasma-on than for

M. G. Blain; G. D. Tipton; W. M. Holber; G. S. Selwyn; P. L. Westerfield; K. L. Maxwell



Passivation mechanisms in cryogenic SF6\\/O2 etching process  

Microsoft Academic Search

Passivation mechanisms of Si trenches involved in SF6\\/O2 cryogenic plasma etching were investigated in order to better control the process and avoid defects. Trench sidewalls and profiles were ex situ characterized geometrically by SEM and chemically by spatially resolved XPS experiments. These measurements reveal that the passivating layer is removed during the increase of the wafer chuck temperature leading to

R. Dussart; M. Boufnichel; G. Marcos; P. Lefaucheux; A. Basillais; R. Benoit; T. Tillocher; X. Mellhaoui; H. Estrade-Szwarckopf; P. Ranson



FEA Thermal Investigation of Wafer Thinning by Plasma Etching  

Microsoft Academic Search

In this work, finite element analysis (FEA) was used to predict transient heating and temperature distribution on the wafer surface during plasma etching process as backgrind (BG) tape degradation after plasma stress relief was observed. The wafer surface temperature during plasma process was measured using temperature indicator strips and used as input temperature for FEA analysis. Parametric studies were performed

Foo Lam Wong; Radimin; M. Teo; C. Lee



Experimental investigation of anisotropy in isotropic silicon etching  

NASA Astrophysics Data System (ADS)

Isotropic etching of silicon in HF-based solutions exhibits some level of anisotropy. We study this anisotropy in detail by etching silicon via circular mask openings for wafers of different orientations. The in-plane shape of the cavities is analyzed with high precision as a function of the etching time and opening size. Fourier expansion of the cavity shape is used to analyze different anisotropy components in relation to the crystal symmetry. It is found that the anisotropy pattern is in agreement with the crystal symmetry with a precision better than 0.4%. The relative anisotropy does not depend on the etching time and increases with the reduction of the opening size. For radii of mask holes a > 4 µm all the Fourier coefficients demonstrate a universal behavior increasing in absolute value linearly with a-1/3. The smaller holes exhibit saturation of these coefficients. The maximal anisotropy is about 9% for both (1 0 0) and (1 1 0) wafers but only 1.5% for (1 1 1).

Svetovoy, V. B.; Berenschot, J. W.; Elwenspoek, M. C.



Cryo-Etched Black Silicon for Use as Optical Black  

NASA Technical Reports Server (NTRS)

Stray light reflected from the surface of imaging spectrometer components in particular, the spectrometer slit degrade the image quality. A technique has been developed for rapid, uniform, and cost-effective black silicon formation based on inductively coupled plasma (ICP) etching at cryogenic temperatures. Recent measurements show less than 1-percent total reflectance from 350 2,500 nm of doped black silicon formed in this way, making it an excellent option for texturing of component surfaces for reduction of stray light. Oxygen combines with SF6 + Si etch byproducts to form a passivation layer atop the Si when the etch is performed at cryogenic temperatures. Excess flow of oxygen results in micromasking and the formation of black silicon. The process is repeatable and reliable, and provides control over etch depth and sidewall profile. Density of the needles can be controlled to some extent. Regions to be textured can be patterned lithographically. Adhesion is not an issue as the nanotips are part of the underlying substrate. This is in contrast to surface growth/deposition techniques such as carbon nanotubes (CNTs). The black Si surface is compatible with wet processing, including processing with solvents, the textured surface is completely inorganic, and it does not outgas. In radiometry applications, optical absorbers are often constructed using gold black or CNTs. This black silicon technology is an improvement for these types of applications.

Yee, Karl Y.; White, Victor E.; Mouroulis, Pantazis; Eastwood, Michael L.



Clean unzipping by steam etching to synthesize graphene nanoribbons  

NASA Astrophysics Data System (ADS)

A simple, clean method of steam etching carbon nanotubes is reported for the synthesis of graphene nanoribbons. The chemical mechanism of carbon nanotube unzipping is also discussed. As an anode catalyst, as-prepared graphene nanoribbons combined with Pt exhibit quite a high catalytic activity for ethanol electro-oxidation in fuel cells.

Zhuang, Naifeng; Liu, Chunchen; Jia, Lina; Wei, Lin; Cai, Jindi; Guo, Yonglang; Zhang, Yongfan; Hu, Xiaolin; Chen, Jianzhong; Chen, Xiaodong; Tang, Yuxin



Bulk Micromachining of Si by Metal-assisted Chemical Etching.  


Bulk micromachining of Si is demonstrated by the well-known metal-assisted chemical etching (MaCE). Si microstructures, having lateral dimension from 5 ?m up to millimeters, are successfully sculpted deeply into Si substrate, as deep as >100 ?m. The key ingredient of this success is found to be the optimizations of catalyst metal type and its morphology. Combining the respective advantages of Ag and Au in the MaCE as a Ag/Au bilayer configuration leads to quite stable etch reaction upon a prolonged etch duration up to >5 h. Further, the permeable nature of the optimized Ag/Au bilayer metal catalyst enables the etching of pattern features having very large lateral dimension. Problems such as the generation of micro/nanostructures and chemical attacks on the top of pattern surface are successfully overcome by process optimizations such as post-partum sonication treatment and etchant formulation control. The method can also be successful to vertical micromachining of Si substrate having other crystal orientations than Si(100), such as Si(110) and Si(111). The simple, easy, and low-cost nature of present approach may be a great help in bulk micromachining of Si for various applications such as microelectromechanical system (MEMS), micro total analysis system (?TAS), and so forth. PMID:24820931

Kim, Sang-Mi; Khang, Dahl-Young



Photonic jet to improve the lateral resolution of laser etching  

NASA Astrophysics Data System (ADS)

The techniques applying laser beams or optical systems are limited by the diffraction limit of the optical heads used. We demonstrate theoretically and experimentally that the use of the photonic jet allows an improvement in the optical resolution to achieve smaller etching without reducing the wavelength of the source. The potential of the photonic jet using a nanosecond pulsed near-infrared laser for micro-fabrication is also demonstrated. These lasers are the most common type of laser used in industrial processes because of their price and the fact that well-packaged sources are available. Their typical spatial resolution in laser etching is limited by the spot size of their focus point at around 25-70 ?m. This is the reason why a photonic jet, a high spatial concentration onto a half-wavelength spot of a beam that emerges in the vicinity of a dielectric microsphere, is of great interest. In our experiments, micro-scale glass (ns = 1.5) and BaTiO3 spheres (ns = 1.9) have been used to achieve photonic jets. The etching process has been tested on two substrates: silicon wafers, which have a significant absorption at 1064 nm, and glass plates, which have a lower absorption at this wavelength. The smallest marking achieved on silicon has an average diameter of 1.3 ?m and despite the low absorption, micrometric etchings have also been achieved on glass using larger microspheres.

Abdurrochman, Andri; Lecler, Sylvain; Fontaine, Joël.; Mermet, Frédéric; Meyrueis, Patrick; Tumbelaka, Bernard Y.; Montgomery, Paul



Advances in Deep Anisotropic Silicon Etch Processing for Mems  

NASA Astrophysics Data System (ADS)

This paper presents the latest developments in high rate deep silicon etching for MEMS applications. Since its introduction by STS over 5 years ago, the Advanced Silicon Etch (ASE®) process has provided the MEMS community with a method of fabricating high aspect ratio structures in silicon, with accurate critical dimension control, and a high degree of anisotropy. High selectivity to photoresist (up to 170:1) has also enabled replacement of hard masks, and in turn, this has simplified process flows for MEMS manufacturers. The ASE® technology uses non-toxic, fluorine-based chemistry, operates at room temperature, and has been shown to be production worthy for the volume manufacture of MEMS devices such as inertial sensors. As the MEMS industry matures, it places ever more demands on the processes and there is a growing requirement to achieve the same degree of anisotropy and critical dimension control, but at much higher etch-rates. An exhaustive series of trials to increase etch rates have successfully shown a nominal rate increase by a factor of >2. These results are presented in this paper.

Ashraf, H.; Bhardwaj, J. K.; Hall, S.; Hopkins, J.; Hynes, A. M.; Johnston, I.; McAuley, S.; Nicholls, G.; Atabo, L.; Ryan, M. E.; Watcham, S.



Particle reduction and control in plasma etching equipment  

Microsoft Academic Search

Particles within plasma etching equipment stick to the wafer and cause defects, resulting in large scale integrated circuit (LSI) yield reduction. We observed the behavior of particles resuspended in a vacuum chamber using a laser light scattering method. Investigating the influences of gases, static electricity, and plasma on particle resuspension, we found out that particles are not only suspended by

Tsuyoshi Moriya; Hiroyuki Nakayama; Hiroshi Nagaike; Yoshiyuki Kobayashi; Manabu Shimada; Kikuo Okuyama



Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking  


A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

Steeves, Arthur F. (Schenectady, NY); Stewart, James C. (Loudonville, NY)



Investigations of the isotropic etch of an ICP source for silicon microlens mold fabrication  

NASA Astrophysics Data System (ADS)

This work investigates the isotropic etching properties of an inductively coupled plasma (ICP) etcher for masked and maskless etching steps in reference to fabrication of a silicon microlens mold. Using the described method a wide range of lens geometries and lens arrays with 100% fill factor can be achieved. The silicon etching is performed with a continuous SF6 based ICP. Analysis of the etching profile was done by SEM inspection and by optical interferometric measurements. For the masked etching step a consistent picture of the profile evolution is obtained, including a relation between the etching depth, the radius of curvature of the profile, the etching time and the size of the mask opening. For the maskless etching step, the optimal etch is purely isotropic. Within the tested process parameter range the maskless etching showed a non-isotropic behavior, which results in lens aberrations, crystal orientation dependence, poor uniformity and roughness. Generally a trade-off between the individual etching behaviors is found, but useful etching recipes can be found for a range of different lens geometries.

Pontoppidan Larsen, Kristian; Ravnkilde, Jan T.; Hansen, Ole



The Applications of Plasma Diagnostic and Simulation in the Development of 300mm Etch Tool  

Microsoft Academic Search

Plasma uniformity and reactant delivery in plasma etch chamber have become challenging issues as wafer size increased to 300mm. In order to design a process chamber capable of performing uniform etch across large area wafer substrate in an inductive-coupled high density plasma etch chamber, the generation and transport of charged and neutral species in the chamber need to be understood

Tom Q. Ni; Wenli Z. Collison; Michael S. Barnes



Chlorine Etching For In-Situ Low-Temperature Silicon Surface Cleaning For Epitaxy Applications  

E-print Network

Chlorine Etching For In-Situ Low-Temperature Silicon Surface Cleaning For Epitaxy Applications K. H. inverse temperature is shown in Figure 1. #12;Figure 1 Etch rate of silicon surface versus inverse is used to clean silicon surfaces of impurities by etching a thin layer from the surface prior to silicon


Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas  

NASA Astrophysics Data System (ADS)

Cl2, Br2, HBr, Br2/Cl2, and HBr/Cl2 feed gases diluted in Ar (50%-50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br2/Ar and HBr/Cl2/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF2, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy 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. Photo-assisted etching in Cl2/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to ?110? cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M.; Economou, Demetre J.



Ion drag effects in inductively coupled plasmas for etching Wenli Z. Collisona)  

E-print Network

Ion drag effects in inductively coupled plasmas for etching Wenli Z. Collisona) and Mark J of the plasma. In this letter, we discuss the parameter space for inductively coupled plasma etching reactors for plasma equipment. The reactor in this study is an induc- tively coupled plasma ICP etching tool.6

Kushner, Mark


Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking  


A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking is described. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

Not Available



Etching characteristics of ZnO thin films in chlorine-containing inductively coupled plasmas  

E-print Network

Etching characteristics of ZnO thin films in chlorine-containing inductively coupled plasmas S 21 October 2005 Abstract This study examined the plasma etching characteristics of ZnO thin films and low cost [7]. From a manufacturing viewpoint, TCO films including ZnO need to be easily etched

Boo, Jin-Hyo


21 CFR 179.43 - Carbon dioxide laser for etching food.  

...2014-04-01 2014-04-01 false Carbon dioxide laser for etching food. 179.43 Section 179...Radiation Sources § 179.43 Carbon dioxide laser for etching food. Carbon dioxide laser light may be safely used for etching...



Consideration of correlativity between litho and etching shape  

NASA Astrophysics Data System (ADS)

We developed an effective method for evaluating the correlation of shape of Litho and Etching pattern. The purpose of this method, makes the relations of the shape after that is the etching pattern an index in wafer same as a pattern shape on wafer made by a lithography process. Therefore, this method measures the characteristic of the shape of the wafer pattern by the lithography process and can predict the hotspot pattern shape by the etching process. The method adopts a metrology management system based on DBM (Design Based Metrology). This is the high accurate contouring created by an edge detection algorithm used wafer CD-SEM. Currently, as semiconductor manufacture moves towards even smaller feature size, this necessitates more aggressive optical proximity correction (OPC) to drive the super-resolution technology (RET). In other words, there is a trade-off between highly precise RET and lithography management, and this has a big impact on the semiconductor market that centers on the semiconductor business. 2-dimensional shape of wafer quantification is important as optimal solution over these problems. Although 1-dimensional shape measurement has been performed by the conventional technique, 2-dimensional shape management is needed in the mass production line under the influence of RET. We developed the technique of analyzing distribution of shape edge performance as the shape management technique. In this study, we conducted experiments for correlation method of the pattern (Measurement Based Contouring) as two-dimensional litho and etch evaluation technique. That is, observation of the identical position of a litho and etch was considered. It is possible to analyze variability of the edge of the same position with high precision.

Matsuoka, Ryoichi; Mito, Hiroaki; Shinoda, Shinichi; Toyoda, Yasutaka



Characteristics of reactive ion etching lag in HBr/O2 plasma etching of silicon trench for nanoscale device  

NASA Astrophysics Data System (ADS)

In this study, we investigated the etching parameter dependence of the reactive ion etch (RIE) lag of nanometer silicon trenches using HBr/O2 plasma in an inductively coupled plasma etcher. As the O2 flow rate, pressure, and source power decreased and the substrate temperature increased, the RIE lag improved. The RIE lag dependence on the O2 flow rate correlated with surface oxidation which gives rise to charging up of positive ions and reduction in silicon etching rate. Increased oxidation, rate resulted in severer RIE lag. These were verified by actinometrical optical emission spectroscopy measurements. On the other hand, the decrease in substrate temperature worsened the RIE lag owing to the remaining etching by-products deposited on the substrate. When the pressure and source power decreased, the RIE lag improved owing to the increase in average ion energy. As the bias power increased, the RIE lag improved, but for excessively high power, the RIE lag deteriorated, as the positive ions could not reach the bottom of the trench due to charging. However, the RIE lag improved at high bias powers when the RF power was pulse-modulated. There was almost no frequency dependence of the RIE lag, but the RIE lag improved when the duty ratio was reduced. The improvement of the RIE lag in the pulsed plasma is thought to be due to the relaxation of the charging up of positive ions by the negative ions generated during the power-off period.

Park, Wanjae; Lee, WooHyun; Kim, Wan-Soo; Kim, Hyuk; Whang, Ki-Woong



X-ray photoelectron spectroscopy study of chemically-etched Nd-Ce-Cu-O surfaces  

NASA Technical Reports Server (NTRS)

Acetic acid, Br2, and HCl solutions are investigated for removing insulating species from Nd(1.85)Ce(0.15)CuO(4-delta) (NCCO) thin film surfaces. X-ray photoelectron spectroscopy (XPS) shows that the HCl etch is most effective, yielding O 1s spectra comparable to those obtained from samples cleaned in vacuum and a clear Fermi edge in the valence band region. Reduction and oxidation reversibly induces and eliminates, respectively, Fermi level states for undoped samples, but has no clearly observable effect on the XPS spectra for doped samples. Reactivity to air is much less for NCCO compared to hole superconductors, which is attributed to the lack of reactive alkaline earth elements in NCCO.

Vasquez, R. P.; Gupta, A.; Kussmaul, A.



Highly Selective GaAs/Al0.2Ga0.8As Wet Etch Process for the Gate Recess of Low-Voltage-Power Pseudomorphic High-Electron-Mobility Transistor  

NASA Astrophysics Data System (ADS)

A selective wet etch process for the gate recess of the GaAs power pseudomorphic high-electron-mobility transistors (pHEMT’s) was developed. The power pHEMT’s used in this study were epitaxially grown power Al0.2Ga0.8As/In0.2Ga0.8As pHEMT’s with a 250 Å GaAs cap layer and a 300 Å Al0.2Ga0.8As electron-donating layer. The electron-donating layer was used as the etch-stop layer for the gate recess. A selectivity of 3400:1 was achieved for GaAs/Al0.2Ga0.8As layers using citric acid/tripotassium citrate/hydrogen peroxide etching solutions in this study. This is the highest selectivity for GaAs/AlxGa1-xAs selective etching reported so far. The pHEMT’s processed using this selective etching demonstrated good device power performance, and the wet recess process did not cause any contamination or damage to the device. The test data indicates that this selective etch process can be of practical use for forming the gate recess of the power pHEMT’s with good device performance and excellent electrical uniformity.

Chang, Huang-Choung; Chang, Edward Y.; Chung, Chao-Cheng; Kuo, C. T.



Selective etching of InP and InGaAsP over AlInAs using CH4/H2 reactive ion etching  

NASA Astrophysics Data System (ADS)

Selective etching of InP and InGaAsP over AlInAs was obtained using CH4/H2 reactive ion etching without the addition of a fluorine containing gas. By tuning the methane-to-hydrogen ratio, pressure, and power, sputter desorption of the reacted AlInAs etch products can be inhibited, thus enabling AlInAs to be used as an etch stop layer. The use of a fluorine free mixture enables dielectrics such as silicon dioxide or nitride to be used as the masking material.

Arnot, H. E. G.; Glew, R. W.; Schiavini, G.; Rigby, L. J.; Piccirillo, A.



Study of dry etching for GaN and InGaN-based laser structure using inductively coupled plasma reactive ion etching  

Microsoft Academic Search

Dry etching of undoped, n-GaN, p-GaN and InGaN laser structure was investigated by inductively coupled plasmas reactive ion etching (ICP-RIE) using Ni mask. As Cl2\\/Ar gas flow rates were fixed at 10\\/25sccm, the etched surface roughness has the lowest value of 0.2nm at constant ICP\\/bias power=300\\/100W and 5mTorr chamber pressure for undoped GaN. The highest etching rate of 12,000Å\\/min for

Chih-Chiang Kao; H. W Huang; J. Y Tsai; C. C Yu; C. F Lin; H. C Kuo; S. C Wang



High-performance photonic crystal membrane reflectors by magnetically guided metal-assisted chemical etching  

NASA Astrophysics Data System (ADS)

Based on Fano resonance principles in photonic crystals, high performance broadband reflectors can be realized with 100% reflection. Applying an innovative magnetic field guided metal-assisted chemical etching (MacEtch) process, we report here high performance membrane reflectors on SOI with controlled sidewall etching and high reflection around 1550 nm. This work represents the first demonstration of magnetically guided MacEtch (h-MacEtch) of periodic arrays of discrete nanoholes of sub-micron dimensions. Such an innovative process can lead to facile formation of large area 2D and 3D nanoscale-structures, for high performance photonic crystal membrane reflectors, filters, and metamaterials.

Shuai, Yichen; Balasundaram, Karthik; Mohseni, Parsian K.; Zhao, Deyin; Yang, Hongjun; Li, Xiuling; Zhou, Weidong



Plasma etching of cavities into diamond anvils for experiments at high pressures and high temperatures  

SciTech Connect

We describe a method for precisely etching small cavities into the culets of diamond anvils for the purpose of providing thermal insulation for samples in experiments at high pressures and high temperatures. The cavities were fabricated using highly directional oxygen plasma to reactively etch into the diamond surface. The lateral extent of the etch was precisely controlled to micron accuracy by etching the diamond through a lithographically fabricated tungsten mask. The performance of the etched cavities in high-temperature experiments in which the samples were either laser heated or electrically heated is discussed.

Weir, S.T.; Cynn, H.; Falabella, S.; Evans, W.J.; Aracne-Ruddle, C.; Farber, D.; Vohra, Y.K. (LLNL); (UAB)



Chemical etching solutions for creating micromechanical retention in resin-bonded retainers.  


This study introduced three chemical etching solutions capable of producing micromechanical retention in nickel-chromium and nickel-chromium-beryllium alloys used for resin-bonded retainers. The effectiveness of the chemical etching solutions was evaluated with tensile strength tests and photographs at various magnifications with a scanning electron microscope. Chemical etching with the CG-Etch solution produced suitable and uniform microretention whereas the other solutions were not effective on all metal alloys. Significant differences (p < 0.05) relating to tensile bond strengths were noted. The CG-Etch solution gave the highest mean bond strength compared with solutions II, III, and control groups. PMID:8164175

Conceição, E N; de Goes, M F; Consani, S



High-Density Plasma Etching of Group-III Nitride Films for Device Application  

SciTech Connect

As III-V nitride device structures become more complicated and design rules shrink, well-controlled etch processes are necessary. Due to limited wet chemical etch results for the group-III nitrides, a significant amount of effort has been devoted to the development of dry etch processing. Dry etch development was initially focused on mesa structures where high etch rates, anisotropic profiles, smooth sidewalls, and equi-rate etching of dissimilar materials were required. For example, commercially available LEDs and laser facets for GaN-based laser diodes have been patterned using reactive ion etching (RIE). With the recent interest in high power, high temperature electronic devices, etch characteristics may also require smooth surface morphology, low plasma-induced damage, and selective etching of one layer over another. The principal criteria for any plasma etch process is its utility in the fabrication of a device. In this study, we will report plasma etch results for the group-III nitrides and their application to device structures.

Baca, A.G.; Crawford, M.H.; Han, J.; Lester, L.F.; Pearton, S.J.; Ren, F.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.



Etching of low-k materials in high density fluorocarbon plasma  

NASA Astrophysics Data System (ADS)

Low dielectric constant materials (low-k) are used as interlevel dielectrics in integrated circuits. This paper concerns the etching process of these materials in high density plasma with the aim to provide some insights concerning the etch mechanisms. Materials studied are methylsilsesquioxane (MSQ) polymers, either dense (SiOC) or containing 40% of porosity (porous SiOC). Amorphous hydrogenated silicon carbide (SiC) material, used as hard mask and/or etch stop layer, is also investigated. Etch is performed in an inductively coupled reactor using fluorocarbon gases, which have proven to be very successful in the etch of conventional SiO{2}. First, etching with hexafluoroethane (C{2}F{6}) is performed. Although etch rates are high, etch selectivities with respect to SiC are weak. So, oxygen, argon, and hydrogen are added to C{2}F{6} with the aim of improving selectivities. The best selectivity is obtained for the C{2}F{6}/H{2} (10% 90%) mixture. To understand etch rate and selectivity variations, plasma analyses by optical emission spectroscopy are correlated to surface analysis using X-Ray Photoelectron Spectroscopy (XPS). In general, atomic fluorine concentration in the plasma explains the etch rate, while the presence of a fluorocarbon layer on the surface is well correlated to the selectivity. To ensure that the etch process does not affect materials properties, and particularly their dielectric constant, bulk analysis by Fourier Transformed Infra-Red spectroscopy and images by Scanning Electron Microscopy have also been carried out.

Eon, D.; Raballand, V.; Cartry, G.; Peignon-Fernandez, M.-C.; Cardinaud, Ch.



Ultraviolet photoenhanced wet etching of GaN in K2S2O8 solution  

NASA Astrophysics Data System (ADS)

The mechanism of the UV photoenhanced wet etching of GaN is determined. The UV photoenhanced wet etching does not require an electrical contact to be made to the sample, and nitrides deposited on insulating substrates (such as sapphire) can be etched, unlike photoelectrochemical (PEC) wet etching. The present technique relies on adding an appropriate oxidizing agent, in this case, peroxydisulfate (S2O82-), to KOH solutions. In a similar mechanism to PEC wet etching, the regions of low defect density are preferentially etched, leaving regions of high electron recombination such as threading dislocations relatively intact. The threading dislocations may be physically broken off, either by stirring or by a postetch sonication of the sample in KOH solution. Smoothly etched surfaces can be obtained under the proper conditions. A noble metal mask acts in a catalytic manner, yielding etch rates approximately one order of magnitude greater than those observed using inert masks. The essential role of the free radicals, originating from the peroxydisulfate ion, in the etching reaction is confirmed. The etching reaction is more rapid for more heavily n-type doped samples, and insulating C-doped layers act as an etch stop layer.

Bardwell, J. A.; Webb, J. B.; Tang, H.; Fraser, J.; Moisa, S.



Improvement of polycrystalline silicon wafer solar cell efficiency by forming nanoscale pyramids on wafer surface using a self-mask etching technique  

PubMed Central

The creation of nanostructures on polycrystalline silicon wafer surface to reduce the solar reflection can enhance the solar absorption and thus increase the solar-electricity conversion efficiency of solar cells. The self-masking reactive ion etching (RIE) was studied to directly fabricate nanostructures on silicon surface without using a masking process for antireflection purpose. Reactive gases comprising chlorine (Cl2), sulfur hexafluoride (SF6), and oxygen (O2) were activated by radio-frequency plasma in an RIE system at a typical pressure of 120–130 mTorr to fabricate the nanoscale pyramids. Poly-Si wafers were etched directly without masking for 6–10?min to create surface nanostructures by varying the compositions of SF6, Cl2, and O2 gas mixtures in the etching process. The wafers were then treated with acid (KOH:H2O?=?1:1) for 1?min to remove the damage layer (100?nm) induced by dry etching. The damage layer significantly reduced the solar cell efficiencies by affecting the electrical properties of the surface layer. The light reflectivity from the surface after acid treatment could be significantly reduced to <10% for the wavelengths between 500 and 900?nm. The effects of RIE and surface treatment conditions on the surface nanostructures and the optical performance as well as the efficiencies of solar cells will be presented and discussed. The authors have successfully fabricated large-area (156?×?156 mm2) subwavelength antireflection structure on poly-Si substrates, which could improve the solar cell efficiency reproducibly up to 16.27%, higher than 15.56% using wet etching. PMID:23847751

Lin, Hsin-Han; Chen, Wen-Hwa; Hong, Franklin C.-N.



Enhanced electromagnetic loss of polybenzoxazole copolymerized with etched multiwalled carbon nanotube via direct Friedel-Crafts acylation  

NASA Astrophysics Data System (ADS)

Etched multiwalled carbon nanotube (EMCNT) was prepared via an in situ reaction between Si and MCNT induced by the reaction between Na and I2. Subsequently, EMCNTs was subjected to a copolymerization reaction with 4,6-diaminoresorcinol salt (DAR·2HCl) and terephthalic acid (TA) in polyphosphoric acid (PPA) by Friedel-Crafts acylation reaction without any acid treatment or modification. The structure and morphology of the as-prepared poly(p-phenylene benzobisoxazole) (PBO)/EMCNT nanocomposites were characterized by x-ray diffraction (XRD), Raman spectra, and transmission electron microscopy (TEM). The scanning electronic microscope (SEM) images indicated that the EMCNTs can disperse in PBO matrix uniformly without agglomeration. And the electromagnetic properties of the obtained PBO/EMCNT nanocomposites characterized by vector network analyzer (VNA) showed that the introduced PBO/EMCNT composites exhibited a greater enhancement in dielectric loss and magnetic loss than PBO.

Chen, Yong; Qian, Jun; Teng, Xin; Zhang, Kan; Zhuang, Qixin; Han, Zhewen



Energy band engineering for photoelectrochemical etching of GaN/InGaN heterostructures  

NASA Astrophysics Data System (ADS)

Photoelectrochemical (PEC) etching is a rapid and inexpensive means of etching GaN, InGaN, and related materials for micro-electro-mechanical systems (MEMS) applications. In this work, we show that bandgap engineering of GaN/InGaN heterostructures can be used to exert substantial control over PEC etching and achieve strain-free cantilevers. A single, 200-nm thick layer InGaN was selectively etched using bandgap-selective PEC etch. We show that the use of highly doped guard layers to confine photogenerated holes uniformly across the InGaN layer enables a uniform, fast, and effective PEC etch. This approach enables complete uniform etching using PEC and could enable many optical and MEMS devices.

Ramesh, Prashanth; Krishnamoorthy, Sriram; Rajan, Siddharth; Washington, Gregory N.



The effect of erbium, chromium:yttrium–scandium–gallium–garnet laser etching on marginal integrity of a resin-based fissure sealant in primary teeth  

Microsoft Academic Search

The aim of this in vitro study was to evaluate the effect of erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG)\\u000a laser pretreatment alone, or associated with acid etching, on the quality of marginal integrity (microleakage and marginal\\u000a gap) of a resin-based fissure sealant in primary teeth. Fifty sound primary molar teeth were randomly assigned to one of five\\u000a study groups, pretreated as follows: (1)

Elif Sungurtekin; Nurhan Özta?



Characteristics of the electrochemical etching of TiNi shape memory alloy in a LiCl-ethanol solution  

NASA Astrophysics Data System (ADS)

This paper presents the characteristics of the electrochemical etching of a TiNi shape memory alloy sheet in a non-aqueous electrolyte solution of LiCl-ethanol. It emerged that the etch rate, etch factor (etched depth/under-cut) and cross-sectional profile of the etched grooves were varied by the width of mask opening. The etch rate peaks with the opening width of 20-30 µm and the etched profile was U-shaped in the narrow opening grooves; in contrast, the etched profile became W-shaped in the wide opening grooves due to the electrolytic current becoming concentrated at the edge of the grooves. When electrochemical etching was carried out with a uniform mask pattern of 20 µm opening, the etching proceeded uniformly from the beginning of the etching in a 1 M solution. In contrast, the SMA surface was etched non-uniformly as etch-holes at low applied voltage in a 0.1 M solution. The etch rate and etch factor changed nonlinearly due to saturation during etching.

Mineta, Takashi; Makino, Eiji



Random and Uniform Reactive Ion Etching Texturing of Si  

SciTech Connect

The performance of a solar cell is critically dependent on absorption of incident photons and their conversion into electrical current. This report describes research efforts that have been directed toward the use of nanoscale surface texturing techniques to enhance light absorption in Si. This effort has been divided into two approaches. The first is to use plasma-etching to produce random texturization on multicrystalline Si cells for terrestrial use, since multicrystalline Si cannot be economically textured in any other way. The second approach is to use interference lithography and plasma-etching to produce gettering structures on Si cells for use in space, so that long-wavelength light can be absorbed close to the junction and make the cells more resistant to cosmic radiation damage.

Zaidi, S.H.



Bias-assisted KOH etching of macroporous silicon membranes  

NASA Astrophysics Data System (ADS)

This paper presents an improved technique to fabricate porous membranes from macroporous silicon as a starting material. A crucial step in the fabrication process is the dissolution of silicon from the backside of the porous wafer by aqueous potassium hydroxide to open up the pores. We improved this step by biasing the silicon wafer electrically against the KOH. By monitoring the current-time characteristics a good control of the process is achieved and the yield is improved. Also, the etching can be stopped instantaneously and automatically by short-circuiting Si and KOH. Moreover, the bias-assisted etching allows for the controlled fabrication of silicon dioxide tube arrays when the silicon pore walls are oxidized and inverted pores are released.

Mathwig, K.; Geilhufe, M.; Müller, F.; Gösele, U.



Mesoporous hollow sphere titanium dioxide photocatalysts through hydrothermal silica etching.  


Robust, monodisperse, mesoporous titanium dioxide (TiO?) submicrometer hollow spheres were synthesized through a single step hydrothermal silica etching reaction under mild conditions. Efficient silica (SiO?) removal was achieved without the use of toxic reagents, and a unique controllable silica redeposition mechanism was identified, imparting the hollow spheres with excellent structural integrity. The parameters of the hydrothermal reaction affecting the etching process, including pH, temperature, and silica concentration, were systematically investigated and optimized for the production of silica-templated hollow structures. The resulting processing conditions yielded TiO? hollow spheres with a surface area of ?300 m² g?¹ and anatase phase crystallization, which exhibited high adsorption capacity for methylene blue dye and good photocatalytic activity without requiring high-temperature calcination. PMID:23110421

Leshuk, Tim; Linley, Stuart; Baxter, George; Gu, Frank



Backscattered deposition in Ar sputter etch of silicon dioxide  

NASA Astrophysics Data System (ADS)

Detailed mechanisms of sputter etch of silicon dioxide in argon plasma are studied using a novel test structure. We have found that a significant amount of the sputtered material (up to 50% of the sputter flux) returns, as an isotropic backscattered flux to the wafer. This backscattered flux results in significant deposition that cannot be accounted for by redeposition, i.e., line-of-sight deposition of the sputtered material, alone. A profile simulator is used to demonstrate a new physical model for the Ar sputter-etch process, based on the interaction of three simultaneous processes: (1) sputtering, (2) direct (i.e., line-of-sight) redeposition of sputtered material, and (3) isotropic deposition of sputtered material backscattered from the gas phase. Simulated profiles show good agreement with experimental results on the test structure and a common device structure.

Chang, C. Y.; McVittie, J. P.; Saraswat, K. C.; Lin, K. K.



Reactive Ion Etching of Transition-Metal Alloys  

NASA Astrophysics Data System (ADS)

For production of advanced spin-electronic devices, such as a magnetic random access memory with the higher-density memory cell, a reactive ion etching (RIE) process of transition metal alloys is the indispensable component of development, while no transition-metal compounds with the relatively high vapor pressure have been founded so far. Here, we show the RIE process of a NiFe thin film by using CH4:O2:NH3 discharge. The RIE process was designed by ab initio calculations, and the present result is the first successful demonstration of the chemical effect in the RIE process for transition-metal alloys. The relative etching ratio of NiFe against Ti as the metal mask was decreased by substituting CH4 with CHF3.

Akinaga, Hiro; Takano, Fumiyoshi; Matsumoto, Shigeno; Diño, Wilson A. T.