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1

Laser-Assisted Etching of Silicon in Hydrofluoric Acid  

NASA Astrophysics Data System (ADS)

Laser-assisted wet etching (LAWE) has been considered for direct, non-lithographic creation of fine line patterns in microelectronics but not applied because of poor etch profiles. Two novel etching methods, laser-assisted aerosol jet etching (LAAJE) and laser-liquid film etching (LLFE), were investigated and developed in this study. The LAAJE process is not suitable for systems in which an electrochemical mechanism prevails while LLFE shows a profile improvement over LAWE technique. LLFE offers attractive possibilities for a high degree of anisotropic etching without causing radiation damage. Successful development of LAAJE and LLFE required a detailed understanding of the nature of laser-induced reactions and their effects on the properties of materials. In this study, silicon was etched with the 514.5 nm line from an argon-ion laser in the presence of an aqueous solution of hydrofluoric acid (HFA). A theoretical analysis of LAWE was performed and a 2-D mathematical model of LAWE was developed. The theoretical and mathematical results were confirmed by experimental results of the effects of laser fluence, exposure time, doping level, conductivity type, and etchant concentrations on etch rates of various n- and p- type silicon samples. Photovoltage and cathodic current measurements gave information that led to determination of the number of electrons consumed for hydrogen evolution and the quantum yield for silicon oxidation. From these measurements, the photocurrent doubling phenomenon was confirmed and an electrochemical mechanism of the reaction between silicon and HFA under illumination with photon energy larger than the band gap of Si was proposed. In this study, the results of direct patterning on n-Si(100) by the LLFE technique are presented. V-groove profiles with line widths of 20 to 50 mu m were obtained experimentally when the focused laser beam spot size was 1.5 mum. This orientation dependent etching results from the differential etch rate of the various crystallographic planes. The ratio of the etch rate in the < 100 > direction to the < 111> direction in Si, R(100)/R(111), was determined to be 1.94 in this study. The large etch profile of Si was due to the large hole diffusion length of Si and the small value of R(100)/R(111). For smaller etch geometries, and vertical profiles, III-V compounds with small values of hole diffusion length coupled with the use of short wavelength laser beam should be investigated.

Lim, Pean

2

In situ monitoring and universal modelling of sacrificial PSG etching using hydrofluoric acid  

Microsoft Academic Search

A video system has been designed to monitor in situ and accurately the etching of sacrificial phosphosilicate-glass (PSG) microchannels using hydrofluoric acid (HF). An universal model, which predicts accurately the etching length vs. time over a wide range of HF concentration (3-49 wt.%), has been identified. In addition to diffusion, this model is based on a first-and-second order chemical reaction

Jianqiang Liu; Yu-Chong Tai; Jiajing Lee; Kim-Cheok Pong; Yitshak Zohar; Chih-Ming Ho

1993-01-01

3

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

2012-08-01

4

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

PubMed Central

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.

2009-01-01

5

Chemical properties of oxidized silicon carbide surfaces upon etching in hydrofluoric acid.  

PubMed

Hydrogen termination of oxidized silicon in hydrofluoric acid results from an etching process that is now well understood and accepted. This surface has become a standard for studies of surface science and an important component in silicon device processing for microelectronics, energy, and sensor applications. The present work shows that HF etching of oxidized silicon carbide (SiC) leads to a very different surface termination, whether the surface is carbon or silicon terminated. Specifically, the silicon carbide surfaces are hydrophilic with hydroxyl termination, resulting from the inability of HF to remove the last oxygen layer at the oxide/SiC interface. The final surface chemistry and stability critically depend on the crystal face and surface stoichiometry. These surface properties affect the ability to chemically functionalize the surface and therefore impact how SiC can be used for biomedical applications. PMID:19919146

Dhar, Sarit; Seitz, Oliver; Halls, Mathew D; Choi, Sungho; Chabal, Yves J; Feldman, Leonard C

2009-11-25

6

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

PubMed

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis. PMID:21519648

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

2011-01-01

7

A selective etching phenomenon on {001} faceted anatase titanium dioxide single crystal surfaces by hydrofluoric acid.  

PubMed

A selective etching phenomenon on {001} faceted anatase TiO(2) single crystal surfaces by HF and associated etching mechanism are reported. Density functional theory (DFT) calculations reveal that HF stabilizes the grown {001} facets at low concentrations, but selectively destroys the grown {001} facets at high concentrations. PMID:21240390

Wang, Yun; Zhang, Haimin; Han, Yanhe; Liu, Porun; Yao, Xiangdong; Zhao, Huijun

2011-03-14

8

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

PubMed

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

Steinhauser, Henrique Caballero; Turssi, Cecilia Pedroso; Franca, Fabiana Mantovani Gomes; Amaral, Flavia Lucisano Botelho do; Basting, Roberta Tarkany

2014-04-01

9

Tuning the reflectivity of high-contrast gratings based on silicon and silica by means of wet etching with hydrofluoric acid  

NASA Astrophysics Data System (ADS)

We report on experimental etching techniques to trim the efficiency of high-contrast gratings based on silicon and silica. We show that the resonance wavelength and hence the reflectivity can be tuned by means of selectively etching the silica grating. In order to realize a well-defined adjustment of the grating profiles the etching rates of silica layers with hydrofluoric acid were determined. Coatings deposited by different techniques such as electron-beam evaporation, ion plating and thermal oxidation are compared and the influence of structuration on the etching is investigated, as well. This work basically helps to improve the maximum reflectivity that can be realized with these high-contrast reflectors and tune the resonance to a required wavelength.

Jacobitz, Tassilo; Kroker, Stefanie; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

2012-02-01

10

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 ?m deep hemispherical microcavity was obtained for a 60 min etching with magnetic agitation at room temperature.

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

2013-07-01

11

Study on hydrofluoric acid-based clad etching and chemical sensing characteristics of fiber Bragg gratings of different reflectivity fabricated under different UV exposure times  

NASA Astrophysics Data System (ADS)

An experimental study on hydrofluoric acid (HF)-based clad etching and chemical sensing characteristics of fiber Bragg gratings (FBG) of different reflectivity fabricated under different UV (255 nm) exposure times is presented. Two FBGs of reflectivity 11% and 93% were inscribed by phase mask-based exposition of the photosensitive fibers by a 5.5 kHz repetition rate of 255 nm UV pulses for 15 s and 10 min, respectively. These two FBGs, employed in an HF-based clad etching experiment, revealed a much higher etching rate of 2.03 ?m/min for the grating of reflectivity 11% as compared to 1.69 ?m/min for the grating of reflectivity 93%. The performance of these etched FBGs were also studied for refractive index sensing of the chemicals ethanol and ethylene glycol under different fiber etching times, hence of different residual cladding diameter. It was observed that the same refractive index sensitivity for both the chemicals could be achieved under smaller etching time, i.e., larger residual cladding diameter, for the FBG with lower reflectivity. This differentiating behavior of FBGs under etching and sensing may be linked to the different degree of densification in fused silica fiber cladding under different UV fluence exposures.

Kumar, Jitendra; Mahakud, Ramakant; Prakash, Om; Dixit, Sudhir Kumar

2013-05-01

12

Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method  

NASA Astrophysics Data System (ADS)

We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been observed from PSiNW samples etched using the optimum hydrofluoric acid (HF) concentration. The strongest photoluminescence (PL) signal has been measured from samples etched with 4.8 M of HF, beyond which a significant decreasing in PL emission intensity has been observed. A qualitative model is proposed for the formation of PSiNWs in the presence of Ag catalyst. This model affirms our observations in PL enhancement for samples etched using HF < 4.8 M and the eventual PL reduction for samples etched beyond 4.8 M of HF concentration. The enhancement in PL signals has been associated to the formation of PSiNWs and the quantum confinement effect in the Si nanocrystallites. Compared to PSiNWs without Si-Ox, the HF treated samples exhibited significant blue PL peak shift of 100 nm. This effect has been correlated to the formation of defect states in the surface oxide. PSiNWs fabricated using the electroless etching method can find useful applications in optical sensors and as anti-reflection layer in silicon-based solar cells.

Najar, A.; Slimane, A. B.; Hedhili, M. N.; Anjum, D.; Sougrat, R.; Ng, T. K.; Ooi, B. S.

2012-08-01

13

Geochemistry of Hydrofluoric Acid in Kaolinitic Soils  

SciTech Connect

This document explores the geochemical reactions likely to occur when hydrofluoric acid is spilled on Savannah River Site (SRS) soil. In particular, we evaluate the potential of environmental damage from a one-time release of concentrated hydrofluoric acid into a trench. According to interviews with personnel involved, sometime between 1955 and 1960 drums of 50-60 per cent hydrofluoric acid were disposed in a trench in the Central Shops area. The method of disposal suggests that most of the acid would have been released at the time of burial. No evidence of drum disposal or acidic pH values was found. Therefore, the Soil and Groundwater Closure Projects group requested that we evaluate potential risk by examining the major geochemical interactions expected between hydrofluoric acid and soil. The geochemical calculations in this report were done with The Geochemist's Workbench (Registered). This program uses an extended Debye-Huckel method for calculating activity coefficients. The conclusions of this report are accurate, but some of the intermediate steps may have higher uncertainty. Hydrofluoric acid disposed in a trench in the area would have reacted with soil kaolinite to neutralize the pH to a value of about 4.2. Based on conservative assumptions, this would have occurred within the top 500 cm of soil. This analysis considers only the reaction of the acid with kaolinite. Other processes such as dilution, dispersion, and clogging of permeability would contribute to neutralization of the acid within a shorter distance. When the acid solution reached the water table, dilution would have driven the solution to saturation with gibbsite. A resulting layer enriched in aluminum may be the only remnant of the acid disposal identifiable today. However, any such layer would be difficult to identify because of the normally high aluminum concentrations in the soil. Subtle textural evidence of shallow soil dissolution may be present, but 40 years of rainfall infiltration may well have erased such evidence.

DENHAM, MILES

2004-05-11

14

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

DOEpatents

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

Hankins, Matthew G. (Albuquerque, NM)

2009-10-06

15

X-ray photochemical wet etching of n-Si (100) in hydrofluoric solution  

SciTech Connect

Photochemical wet etching of n-type Si (100) was carried out in hydrofluoric acid (49 wt %) solution using high-flux synchrotron x-ray radiation. Under illumination of high-flux white x-ray beam, silicon is electropolished with an etching rate of about 1.5 nm/min. When illuminated with a monochromatic x-ray beam of relatively low flux, a porous silicon layer is formed instead. The open circuit potential increases under the white x-ray beam, in contrast to the results of visible or ultraviolet photoelectrochemistry. The authors attribute the electroless electropolishing of silicon to the enhanced band bending caused by the x-ray illumination.

Cho, I. H.; Kim, D. H.; Noh, D. Y. [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

2006-07-31

16

Hydrofluoric acid burns of the eye.  

PubMed

A case of hydrofluoric acid (HF) burns of the eye is reported and a review is presented of our investigation into the mechanism of HF toxicity in ocular tissues. A number of therapeutic procedures that have been successful in the treatment of HF skin burns were studied in the rabbit for use in the eye. Immediate single irrigation with water, normal saline or isotonic magnesium chloride solution is the most effective therapy for ocular HF burns. Extrapolation of other skin burn treatments to use in the eye is unacceptable due to the toxicity of these agents in normal eyes and the additive damage caused in burned eyes. PMID:6886845

McCulley, J P; Whiting, D W; Petitt, M G; Lauber, S E

1983-06-01

17

Purification of dilute hydrofluoric acid by commercial ion exchange resins  

Microsoft Academic Search

This paper describes the results from an experimental study of the purification of dilute hydrofluoric acid (5wt.%) by ion exchange. Hydrofluoric acid was prepared by dilution from technical grade concentrated HF; important amounts of metal impurities were found in the diluted acid, mainly Na, Fe, As, B, Ca, K, Mg, Mn, Mo, PO43?, and Ti. The semiconductor industry developed the

I. Fernández-Olmo; J. L. Fernández; A. Irabien

2007-01-01

18

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

PubMed

This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography-tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L(-1)), wide linear range (10 to 1,000 ng L(-1)), and high repeatability (1.9 to 8.2 %) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples. PMID:24748445

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

2014-06-01

19

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

1987-01-01

20

Mechanical integrity of polysilicon films exposed to hydrofluoric acid solutions  

Microsoft Academic Search

This paper presents the results from a comparative study of Young's modulus, residual stress, and membrane burst pressure of undoped LPCVD polysilicon films exposed to various concentrations of hydrofluoric acid (HF). Load deflection measurements on square membranes of polysilicon with residual tensile stress were used to obtain estimates of Young's modulus, residual stress and burst pressure. The polysilicon membranes were

James A. Walker; Kaigham J. Gabriel; Mehran Mehregany

1991-01-01

21

Mechanical integrity of polysilicon films exposed to hydrofluoric acid solutions  

Microsoft Academic Search

The results from a comparative study of Young's modulus, residual stress, and membrane burst pressure of undoped LPCVD polysilicon films exposed to various concentrations of hydrofluoric acid (HF) are presented. A reversal from compressive to tensile stress through a high-temperature anneal for large-grain polysilicon is an important (although ancillary) result of this study. As HF concentration is increased, residual stress

J. A. Walker; K. J. Gabriel; M. Mehregany

1990-01-01

22

Hydrofluoric Acid Corrosion Study of High-Alloy Materials  

Microsoft Academic Search

A corrosion study involving high-alloy materials and concentrated hydrofluoric acid (HF) was conducted in support of the Molten Salt Reactor Experiment Conversion Project (CP). The purpose of the test was to obtain a greater understanding of the corrosion rates of materials of construction currently used in the CP vs those of proposed replacement parts. Results of the study will help

P. E. Osborne; A. S. Icenhour; G. D. Del Cul

2002-01-01

23

Nature of niobium passivation in hydrofluoric-sulfuric acid baths  

SciTech Connect

The authors investigate the growth, dissolution, thickness, and phase behavior of niobium oxide passivating films on the surface of niobium during electrochemical polishing and oxidation of the metal in hydrofluoric and sulfuric acid solutions. The dependence of the film properties on the concentration of acids in the solution was determined in order to optimize process control conditions for passivation and polishing procedures. Laser interferometry and oscillography were used to examine the film.

Eidel'berg, M.I.; Sandulov, D.B.

1987-10-01

24

Mechanical integrity of polysilicon films exposed to hydrofluoric acid solutions  

Microsoft Academic Search

This paper presents the results from a comparative study of Young’s modulus, residual stress, and membrane burst pressure\\u000a of undoped LPCVD polysilicon films exposed to various concentrations of hydrofluoric acid (HF). Load deflection measurements\\u000a on square membranes of polysilicon with residual tensile stress were used to obtain estimates of Young’s modulus, residual\\u000a stress and burst pressure. The polysilicon membranes were

James A. Walker; Kaigham J. Gabriel; Mehran Mehregany

1991-01-01

25

Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1  

Microsoft Academic Search

The conversion of the uranium hexafluoride (UFâ) which is removed from the Molten Salt Reactor Experiment (MSRE), into a stable oxide for long-term storage will produce a significant amount of slightly contaminated, concentrated aqueous hydrofluoric acid (HF). Sin&the handling of this HF is complicated and dangerous, it was decided to transform it into a stable solid fluoride (e.g., CaFâ, AlFâ,

Osborne

2000-01-01

26

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

2011-03-01

27

Electrochemical investigation of copper deposition onto silicon from hydrofluoric acid and buffered hydrofluoric acid solutions  

NASA Astrophysics Data System (ADS)

For the fabrication of ULSI circuits, the silicon surface should be free of metallic and particulate contamination and be atomically smooth. Heavy metal contaminants have detrimental effects on the yield of microelectronic processing and reliability of solid state devices by increasing the junction leakage current, degrading the integrity of gate oxide and reducing the oxide breakdown voltage. It has been demonstrated that the contamination level for most metals has to be controlled below 10sp{10} atoms/cmsp2 for sub-quarter micron processing. Some transition and noble metal ions such as copper, silver and gold are known to deposit on silicon surfaces in acidic fluoride based solutions. Among them, copper has been the focus of most research due to the widespread use of copper in microelectronic industry. To investigate the mechanisms by which copper deposits on silicon surfaces in HF and BHF solutions, different electrochemical techniques were used, including dc polarization and ac impedance spectroscopy (EIS). The results of electrochemical measurements, in conjunction with various surface characterization techniques, such as TXRF, AFM and TEM, reveal the rates of reactions that occur at silicon/solution interface can be affected by many factors, such as silicon dopant type and doping levels, ionic strength of electrolytes, illumination conditions and the use of additives. For example, under darkness, the amount of copper deposition is nearly one order of magnitude less than that under illumination for p-type silicon in both HF and BHF solutions and n-type silicon in HF solutions. In BHF solutions, n-type silicon is very close to its flat band condition where illumination plays little role. The addition of copper ions in BHF solutions not only causes metal contamination, but also generates severe surface roughness due to the masking effect of copper on the anisotropic etching of silicon in BHF solutions. Local etching rate of 1nm/min was measured on the silicon sample prepared in 100 ppb Cusp{2+} BHF solutions. Some additives such as surfactants and hydrochloric acid can effectively reduce the reaction rates of silicon corrosion and copper deposition by either blocking the active reaction sites or form copper ion complexes.

Li, Guangming

28

Hydrofluoric acid-resistant composite window and method for its fabrication  

DOEpatents

A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

Ostenak, C.A.; Mackay, H.A.

1985-07-18

29

Process for the removal of arsenic in the manufacture of hydrofluoric acid  

US Patent & Trademark Office Database

There is disclosed a process wherein impurities are removed from hydrofluoric acid by converting the highly volatile arsenic compounds into a compound with a very high boiling point. The process comprises the following steps: input of distilled hydrofluoric acid, which contains arsenic, into a reactor and cooling down to a temperature below room temperature; oxidation of the arsenic contained in the hydrofluoric acid in the form of arsenic trifluoride with an oxidizing agent in the presence of a surplus of potassium ions coming from potassium bifluoride in order to obtain an arsenic complex which is both stable and of high boiling point; halting the cooling of the reaction mixture and continuation of the stirring for a period of from 1-24 hours, permitting the mixture to remain quiescent to permit deposition; and finally distilling of the hydrofluoric acid at a temperature below reflux conditions, whereupon the arsenic complex formed during the oxidation reaction is removed from the hydrofluoric acid.

1991-09-10

30

Use of hemodialysis after ingestion of a mixture of acids containing hydrofluoric acid.  

PubMed

Hydrofluoric acid (HF) is a highly toxic poison that can be rapidly fatal. Death usually results from the many systemic effects of dissociated fluoride ions, including hypocalcemia, hypomagnesemia, hyperkalemia, and direct cardiotoxicity. A patient is described who accidentally ingested a hydrofluoric acid-containing substance and who likely benefited from hemodialysis. His fluoride level post-dialysis was reduced by approximately 70% from a level drawn three hours prior to the initiation of hemodialysis. However, the single treatment did not reduce the fluoride level to normal. A review of the pathophysiology of hydrofluoric acid intoxication and the outcomes of prior exposures suggests that hemodialysis could play a vital role in the management of poisonings with fluoride-containing substances. However, the initial hemodialysis treatment should be prolonged beyond the standard four-hour session. PMID:22011695

Antar-Shultz, M; Rifkin, S I; McFarren, C

2011-11-01

31

The kinetics of leaching rock ilmenite with hydrofluoric acid  

NASA Astrophysics Data System (ADS)

As part of a U.S. Bureau of Mines program to develop a more continuous titanium metal process that exploits domestic resources, a study was made of the kinetics of hydrofluoric acid (HF) leaching of New York rock ilmenite. The effects of leach temperature, HF concentration, and particle size on leach rate were investigated. The data fit a shrinking core model with the rate controlled by the chemical reaction step. The rate of reaction is related to temperature by the Arrhenius relationship with the activation energy being 52.6 kJ/mol for titanium and 48.4 kJ/mol for iron. The rate is linearly dependent on the HF concentration and inversely proportional to the average starting diameter of the particle. Generalized rate expressions were developed for titanium and iron. Using 19.33M HF at 45°C, 99% of the titanium and 100% of the iron in New York rock ilmenite were leached in 40 minutes.

Hansen, Dennis A.; Traut, Davis E.

1989-05-01

32

Mechanical integrity of polysilicon films exposed to hydrofluoric acid solutions  

NASA Astrophysics Data System (ADS)

This paper presents the results from a comparative study of Young’s modulus, residual stress, and membrane burst pressure of undoped LPCVD polysilicon films exposed to various concentrations of hydrofluoric acid (HF). Load deflection measurements on square membranes of polysilicon with residual tensile stress were used to obtain estimates of Young’s modulus, residual stress and burst pressure. The polysilicon membranes were exposed to four different solutions of the 49% by weight reagent HF including 10:1 DI water and HF, 1:1 DI water the HF, commercial 10:1 buffered oxide etchant, or pure HF ( i.e. 49% by weight reagent). Two control groups were studied composed of membranes with no treatment and membranes exposed to DI water. Young’s modulus changed from an average of 190 GPa for the control groups to an average of 240 GPa for films exposed to pure HF. Residual stress values exhibited a less pronounced and opposite change, with an average of 42 MPa for the control groups and an average of 27 MPa for films exposed to pure HF. Similarly, burst pressure was seen to decrease with increasing HF concentration, ranging in value from an average of 96.5 kPa (14 psi) for the control groups to an average of 34.5 kPa (5 psi) for films exposed to pure HF. It was found that the change in the investigated mechanical properties of polysilicon was approximately equal for HF:DI solutions of HF concentration above 10%. Furthermore, for solutions of equal HF concentration, the addition of the buffering agent decreases the effect on membrane burst pressures significantly.

Walker, James A.; Gabriel, Kaigham J.; Mehregany, Mehran

1991-09-01

33

Hydrofluoric Acid Corrosion Study of High-Alloy Materials  

SciTech Connect

A corrosion study involving high-alloy materials and concentrated hydrofluoric acid (HF) was conducted in support of the Molten Salt Reactor Experiment Conversion Project (CP). The purpose of the test was to obtain a greater understanding of the corrosion rates of materials of construction currently used in the CP vs those of proposed replacement parts. Results of the study will help formulate a change-out schedule for CP parts. The CP will convert slightly less than 40 kg of {sup 233}U from a gas (UF{sub 6}) sorbed on sodium fluoride pellets to a more stable oxide (U{sub 3}O{sub 8}). One by-product of the conversion is the formation of concentrated HF. Six moles of highly corrosive HF are produced for each mole of UF{sub 6} converted. This acid is particularly corrosive to most metals, elastomers, and silica-containing materials. A common impurity found in {sup 233}U is {sup 232}U. This impurity isotope has several daughters that make the handling of the {sup 233}U difficult. Traps of {sup 233}U may have radiation fields of up to 400 R at contact, a situation that makes the process of changing valves or working on the CP more challenging. It is also for this reason that a comprehensive part change-out schedule must be established. Laboratory experiments involving the repeated transfer of HF through 1/2-in. metal tubing and valves have proven difficult due to the corrosivity of the HF upon contact with all wetted parts. Each batch of HF is approximately 1.5 L of 33 wt% HF and is transferred most often as a vapor under vacuum and at temperatures of up to 250 C. Materials used in the HF side of the CP include Hastelloy C-276 and Monel 400 tubing, Haynes 230 and alloy C-276 vessels, and alloy 400 valve bodies with Inconel (alloy 600) bellows. The chemical compositions of the metals discussed in this report are displayed in Table 1. Of particular concern are the almost 30 vendor-supplied UG valves that have the potential for exposure to HF. These valves have been proven to have a finite life due to failure, most often at the bellows flange ring. It was discovered that the entire bellows assembly was not all alloy 600 but that alloy 600 bellows had been welded to a stainless steel alloy 316 (SS-316) flange ring. A previous study documents and addresses this problem.1 The fabricators of the valves immediately corrected the problem and began fabricating all wetted parts of the bellows assembly from alloy 600. At the same time, the fabricators began to make alloy C-276 valve bodies and stem tips available for sale. This material is known to be superior to the alloy 400 valve bodies and stem tips of the standard UG valves that had already been installed in the CP. A decision was made to purchase alloy C-276 bodies and stem tips and to change out those alloy 400 components that had already been installed. Due to the enormity of this task (both in terms of time and money), it was desirable to determine the longevity of alloy C-276 vs alloy 400 components in a side-by-side comparison. Also of interest was the question of how long the new (all-alloy 600) bellows would last in comparison with the original alloy 600/SS-316 bellows. A basic HF corrosion test was proposed to compare corrosion rates of several high-alloy materials. Because much of the alloy 400 in the system had been gold plated, some gold-plated alloy 400 coupons were included. Due to time and funding limitations, actual CP variables such as temperature and pressure were not duplicated. Instead, a simple partial-immersion test at ambient temperature was conducted. The purpose of this test was to gain information on the rate of corrosion of different alloys in the CP and to attempt to derive some idea of their expected lifetimes in the operating environment.

Osborne, P.E.

2002-09-11

34

Detection of Hydrofluoric Acid by a SiO2 Sol-Gel Coating Fiber-Optic Probe Based on Reflection-Based Localized Surface Plasmon Resonance  

PubMed Central

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 SiO2 sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO2 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.

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

2011-01-01

35

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

PubMed

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

2011-01-01

36

Spinner For Etching Of Semiconductor Wafers  

NASA Technical Reports Server (NTRS)

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

Lombardi, Frank

1989-01-01

37

Trapping proton transfer intermediates in the disordered hydrogen-bonded network of cryogenic hydrofluoric acid solutions.  

PubMed

A molecular-level description of the structural and dynamical aspects that are responsible for the weak acid behaviour of dilute hydrofluoric acid solutions and their unusual increased acidity at near equimolar concentrations continues to elude us. We address this problem by reporting reflection-absorption infrared spectra (RAIRS) of cryogenic HF-H(2)O binary mixtures at various compositions prepared as nanoscopic films using molecular beam techniques. Optical constants for these cryogenic solutions [n(omega) and k(omega)] are obtained by iteratively solving Fresnel equations for stratified media. Modeling of the experimental RAIRS spectra allow for a quantitative interpretation of the complex interplay between multiple reflections, optical interference and absorption effects. The evolution of the strong absorption features in the intermediate 1000-3000 cm(-1) range with increasing HF concentration reveals the presence of various ionic dissociation intermediates that are trapped in the disordered H-bonded network of cryogenic hydrofluoric acid solutions. Our findings are discussed in light of the conventional interpretation of why hydrofluoric acid is a weak acid revealing molecular-level details of the mechanism for HF ionization that may be relevant to analogous elementary processes involved in the ionization of weak acids in aqueous solutions. PMID:18688521

Ayotte, Patrick; Plessis, Sylvain; Marchand, Patrick

2008-08-28

38

Corrosion Inhibition of Hydrochloric - Hydrofluoric Acid\\/Mutual Solvent Mixtures at Elevated Temperatures  

Microsoft Academic Search

The Western Co. has developed a corrosion inhibitor for HCl-HF\\/mutual solvent systems used in acid stimulation of wells. The use of hydrochloric-hydrofluoric acid mixtures for the matrix treatment of sandstone reservoirs has been a successful stimulation technique for over a decade. A more recent development has been the addition of mutual solvents, such as ethylene glycol monobutyl ether, to these

Robert Woodroof Jr; James Baker; Robert Jenkins Jr

1975-01-01

39

New Acid Etched Titanium Dental Implant Surface  

Microsoft Academic Search

SUMMARY The purpose of this investigation was to create an acid etched implant surface that results in a surface similar to that gained by using sandblasting combined with acid etching and to compare it with surfaces of commercially available screw-type implants. Titanium grade V discs were machined in preparation for acid etching. Tests were carried out using different acids and

Gintaras Juodzbalys; Marija Sapragoniene; Ann Wennerberg

40

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

PubMed Central

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

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

2013-01-01

41

Monitoring metal ion contamination onset in hydrofluoric acid using silicon-diamond and dual silicon sensing electrode assembly.  

PubMed

Potentiometric detection of trace levels of metallic contamination onset in hydrofluoric acid using a silicon-based sensor in conjunction with two non-contaminating reference electrode systems is presented in this paper. In the first case, conductive diamond was used as a non-contaminating reference electrode. Cyclic voltammetry and open-circuit potential experiments demonstrated the feasibility of using a conductive diamond film electrode as a quasi-reference electrode in the HF solution. In the second case, a dual silicon electrode system was used with one of the silicon-based electrodes protected with an anion permeable membrane behaving as the quasi-reference electrode. The dual silicon sensing electrode system possessed an additional operational advantage of being unaffected by the solution acidity. Though both sensing configurations were able to detect the metal ion contamination onsets at the parts-per-trillion to parts-per-billion levels, the dual silicon electrode design showed a greater compatibility for the on-line detection of metallic impurities in HF etching baths commonly used in semiconductor processing. PMID:11445955

Ponnuswamy, T; Chen, J J; Xu, F; Chyan, O

2001-06-01

42

Dissolution of plutonium oxide in nitric acid at high hydrofluoric acid concentrations  

SciTech Connect

The dissolution of plutonium dioxide in nitirc acid (HNO/sub 3/) at high hydrofluoric acid (HF) concentrations has been investigated. Dissolution rate curves were obtained using 12M HNO/sub 3/ and HF at concentrations varying from 0.05 to 1.0 molar. The dissolution rate increased with HF concentration up to 0.2M and then decreased at higher concentrations. There was very little plutonium dissolved at 0.7 and 1.0M HF because of the formation of insoluble PuF/sub 4/. Various oxidizing agents were added to 12M HNO/sub 3/-1M HF dissolvent to oxidize Pu(IV) to Pu(VI) and prevent the formation of PuF/sub 4/. Ceric (Ce(IV)) and silver (Ag(II)) ions were the most effective in dissolving PuO/sub 2/. Although these two oxidants greatly increased the dissolution rate, the rates were not as rapid as those obtained with 12M HNO/sub 3/-0.2M HF.

Kazanjian, A.R.; Stevens, J.R.

1984-06-15

43

FEM3 modeling of ammonia and hydrofluoric acid dispersion. [A phase-change submodel  

SciTech Connect

FEM3 is a three-dimensional computer model that was designed to simulate the atmospheric dispersion of heavier-than-air gas releases. Recently a phase-change submodel based on local thermodynamic equilibrium has been implemented to treat vapor-liquid transition of the dispersed material. A preliminary evaluation of the phase-change submodel was performed by using data obtained from two recently conducted series of field experiments, namely, the pressurized ammonia spills conducted by LLNL and the anhydrous hydrofluoric acid dispersion experiments conducted by Amoco Oil Company and LLNL. FEM3 results compare reasonably well with the good data available from one ammonia spill and two hydrofluoric acid spills and, in particular, the results obtained by using the phase-change submodel represent considerable improvements over those from all-vapor simulations. While the present phase-change submodel qualitatively handles the aerosol effects, including gravity flow and heat transfer between the vapor and droplets, it tends to over-estimate the rate of droplet evaporation. 16 refs., 12 figs., 7 tabs.

Chan, S.T.; Rodean, H.C.; Blewitt, D.N.

1987-07-01

44

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

Microsoft Academic Search

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 (HN0â) 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

Norby

1992-01-01

45

Corrosion of high-alloy materials in aqueous hydrofluoric acid environments  

SciTech Connect

A series of immersion tests for eight high-alloy materials was performed in a variety of hydrofluoric acid (HF) environments. Solution strengths of 0.05%, 1%, 10%, 24%, and 48% HF were examined at 24 C, 50 C, and 76 C. Coupons of each alloy were exposed fully immersed in solution and partially exposed in the aerated vapor above each solution. In addition, a limited number of U-bend tests were performed to examine susceptibility to stress corrosion cracking. Comparison of alloy performance (corrosion rate calculated from weight loss, metallographic evaluation of attack) indicated alloys C-22 (UNS N06022) and C-276 (UNS N10276) exhibited overall superior performance. Other alloys showed useful resistance for a limited range of conditions.

Pawel, S.J. (Oak Ridge Y-12 Plant, TN (United States). Development Div.)

1994-12-01

46

Study of the chemical behavior of hydrofluoric, nitric and sulfuric acids mixtures applied to niobium polishing  

Microsoft Academic Search

This paper describes the experimental work that has been conducted to develop new chemical polishing baths for surface treatments of niobium RF cavities. The role of the different chemicals is detailed and a wide range of composition is explored. The relationship between the niobium etching rate and the concentration of each mineral acid is put in evidence. Optimization of the

A. Aspart; C. Z Antoine

2004-01-01

47

Study of the chemical behavior of hydrofluoric, nitric and sulfuric acids mixtures applied to niobium polishing  

NASA Astrophysics Data System (ADS)

This paper describes the experimental work that has been conducted to develop new chemical polishing baths for surface treatments of niobium RF cavities. The role of the different chemicals is detailed and a wide range of composition is explored. The relationship between the niobium etching rate and the concentration of each mineral acid is put in evidence. Optimization of the bath composition was done in order to get in the same time safe and easy handle conditions, brilliant surface and low grain boundaries etching.

Aspart, A.; Antoine, C. Z.

2004-04-01

48

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

PubMed

Various applications of dental lasers on dental materials have been proposed for surface modifications. This study evaluated whether laser etching could be an alternative to hydrofluoric acid (HF) etching. One hundred and ten lithia-based all-ceramic specimens (Empress 2) (R: 4 mm, h: 4 mm) were prepared and divided into five groups (n = 22/group). The untreated specimens served as the control, while one of the experimental groups was treated with 9.5% HF for 30 seconds. Three remaining test groups were treated with different laser (Er:YAG laser wavelength:2940 nm, OpusDent) power settings: 300 mJ, 600 mJ and 900 mJ. Ten specimens in each group were luted to the other 10 specimens by a dual-curing cement (Variolink II), and shear-bond strength (SBS) tests were performed (Autograph, crosshead speed: 0.5 mm/minute). The results were statistically analyzed (Kruskal Wallis and Mann Whitney-U, alpha = .05). Mean SBS (MPa) were 31.9 +/- 4.0, 41.4 +/- 4.3, 42.8 +/- 6.2, 29.2 +/- 4.5 and 27.4 +/- 3.8 for the control and HF, 300, 600 and 900 mJ groups, respectively. SEM evaluations revealed different surface morphologies depending on the laser parameters. The differences between HF acid and 300 mJ, when compared with the control, 600 and 900 mJ groups, were significant (p < .05). The 300 mJ laser group exhibited the highest shear-bond strength values, indicating that laser etching could also be used for surface treatments. PMID:17427827

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

2007-01-01

49

Sulphuric acid etching of polyethylene surfaces  

Microsoft Academic Search

The sulphuric acid etching of polyethylene results in the formation of sulphonic groups, varying the surface properties. The\\u000a study of the groups formed during the etching has been carried out by means of frustrated multiple internal reflection infrared\\u000a spectroscopy (FMIR). Densities, thermal properties, superficial resistances and resistivities have been correlated with the\\u000a content of sulphonic groups and treatment time. Moreover,

C. Fonseca; J. M. Pereña; J. G. Fatou; A. Bello

1985-01-01

50

Regeneration of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal  

Microsoft Academic Search

A technique for selectively separating approximately 65 wt.% of the Si(IV) in coal has been developed. The technique first uses aqueous hydrofluoric acid (HF) to react with aluminosilicates and quartz to form fluoride complexed Al and Si species in solution. Aluminium cations, in the form of Al(NO3)3, are then added to the solution to complex fluoride as AlF2+ and hydrolyse

Karen M. Steel; John W. Patrick

2004-01-01

51

Silica optical fibre behaviour to chemical exposure to hydrofluoric acid vapours  

NASA Astrophysics Data System (ADS)

Reliability of standard single mode silica optical fibre and hermetic coated fibre has been investigated through chemical exposure to hydrofluoric acid (HF) vapours into a hermetic closed disposal for different durations. Dynamic fatigue tests were implemented using a two-point bending testing device. Three series of samples subject to HF attack for variable times were compared. Standard fibres tested immediately after exposure show a broader distribution of fibre strength accompanied by the drastic decrease of the failure stress. Drying treated standard fibres prior to testing has also led to a broader distribution and a slight decrease of failure stress by comparison to as-received fibres. Drying in oven prior to mechanical measurement makes handling difficult and results in brittle fibres that exhibit much lower strength and broader distribution of failure stress. Polymer reacts with hydrogen fluoride, which induces viscosity changes, but it returns to solid state after thermal treatment. This is consistent with SEM observations. Same experiments have been implemented on the hermetic coated fibre. No significant change in the Weibull distribution and the mean fibre strength was observed after 6 days of chemical exposure to HF vapours. By comparison to standard commercial fibre, the hermetic coated fibre appeared extremely durable in harsh chemical conditions.

Severin, Irina; Poulain, Marcel; El Abdi, Rochdi

2006-05-01

52

Possible hazardous effects of hydrofluoric acid and recommendations for treatment approach: a review.  

PubMed

Hydrofluoric acid (HF) is commonly used for conditioning the glass ceramics either prior to cementation or for intraoral repair in prosthetic and restorative dentistry. The present study offers a review of chemical properties of HF used, highlight the possible hazardous effects of this agent, and to recommend the treatment approach for potential risks. Available published information documented in PubMed, Medline, and Picarta literature databases was reviewed. Additional information was derived from scientific reports, medical and chemical textbooks, handbooks, product information, manufacturers' instructions, Internet web sites of the HF manufacturers. No report was found on the incidence of the hazardous effects of HF in dentistry. Reports from other fields presented incidences of acute and chronic symptoms in exposure to HF. While acute symptoms include skin or nail burns, chronic ones involve systemic toxicity, eye injuries, inhalation and ingestion-related symptoms that can be even fatal. HF can be harmful and particularly aggressive to soft tissues, but symptoms may not be apparent immediately after exposure. The hazardous effects are not based on the pH value, but on the toxicity of HF. Potential hazards of HF known from other applications than dentistry should be considered also in dental applications. Especially the clinicians, who often deal with adhesive cementation or repair of glass ceramics, should take necessary precautions for possible hazards of HF. PMID:22065247

Ozcan, Mutlu; Allahbeickaraghi, Arezo; Dündar, Mine

2012-02-01

53

NOVEL CHARACTERIZATION OF THE ELECTROPOLISHING OF NIOBIUM WITH SULFURIC AND HYDROFLUORIC ACID MIXTURES  

SciTech Connect

Niobium surfaces are commonly electropolished in an effort to obtain optimally smooth surfaces for high-field SRF cavity applications. We report the first use of controlled electrochemical analysis techniques to characterize electropolishing of Nb in a sulfuric and hydrofluoric acid electrolyte. Through the use of a reference electrode we are able to clearly distinguish the anode, cathode polarization potentials as well as the electrolyte voltage drop that sum to the applied power supply voltage. We then separate the temperature and HF concentration dependence of each. We also report the first use of Electrochemical Impedance Spectroscopy (EIS) on this system. EIS results are consistent with a presence of a compact salt film at the Nb/electrolyte interface that is responsible for the limiting current. Microscopic understanding of the basic Nb EP mechanism is expected to provide an appropriate foundation with which to optimize the preparation of high-field niobium cavity surfaces. The implication of EIS for monitoring Nb surface during electropolishing shows this technology could be potentially used as a source of on-line feedback.

Hui Tian; Charles Reece; Michael Kelley; Sean Corcoran

2008-02-12

54

Functionalization of graphene and few-layer graphene with aqueous solution of hydrofluoric acid  

NASA Astrophysics Data System (ADS)

In the present study, conditions suitable for efficient modification of graphene and few-layer graphene (FLG) films with aqueous solutions of hydrofluoric acid (HF) and for local protection of the graphene against such modification in isopropyl alcohol were identified. A combination of the two treatments gives one a key to nanodesign of graphene-based 2D devices. It was found that a few-minute treatment of graphene or FLG in HF aqueous solutions (?1 min for graphene and ?5 min for FLG films about 5 nm thick) leads to strong changes in the structural and electrical properties of graphene involving a step-like increase in resistivity (up to 1011 ?/?). Two types of materials were obtained after different times of treatment: (i) promising for electronic applications of the material due to a combination of high carrier mobility, high conductivity, and strong current modulation by gate voltage (up to four orders of magnitude); (ii) a material with insulating properties and graphene quantum dots embedded in an insulating matrix.

Nebogatikova, N. A.; Antonova, I. V.; Volodin, V. A.; Prinz, V. Ya.

2013-08-01

55

Improvement of 13C and 15N CPMAS NMR spectra of bulk soils, particle size fractions and organic material by treatment with 10% hydrofluoric acid  

Microsoft Academic Search

Summary The small organic matter content of mineral soils makes it difficult to obtain I3C and 15N nuclear magnetic resonance (NMR) spectra with acceptable signal-to-noise ratios. Subjecting such samples to hydrofluoric acid removes mineral matter and leads to a relative increase in organic material. The effect of treatment with 10% hydrofluoric acid on bulk chemical composition and resolution of solid-state

M. W. I. SCHMIDT; H. KNICKER; P. G. HATCHER; I. KOGEL-KNABNER

1997-01-01

56

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.

2010-08-01

57

Etching of nanostructures on soda-lime glass.  

PubMed

Nanostructures were created on the surface of optical glass using nanosphere lithography. The substrates were etched with vapor-phase hydrofluoric (HF) acid. The etching rate was studied and compared with existing results of wet and dry HF etching. An empirical etching rate formula is found for etching depth up to 300 nm. The subsequent artificial material layer demonstrated enhanced transmittance in optical wavelengths. PMID:24978727

Wang, Elmer; Zhao, Yang

2014-07-01

58

Influence of hydrofluoric acid on extraction of thorium using a commercially available extraction chromatographic resin.  

PubMed

The dependence of Th recovery on hydrofluoric acid (HF) concentration in nitric acid (HNO(3)) solutions (1-5 mol/dm(3)) containing 1x10(-6) mol/dm(3) of Th and various concentrations of HF and the elution behavior were studied using a commercially available UTEVA (for uranium and tetravalent actinide) resin column. Thorium recovery decreased with an increase in HF concentration in the sample solutions. The concentration of HF at which Th recovery started to decrease was approximately 1x10(-4) mol/dm(3) in 1 mol/dm(3) HNO(3) solution, approximately 1x10(-3) mol/dm(3) in 3 mol/dm(3) HNO(3) solution, and approximately 1x10(-2) mol/dm(3) in 5 mol/dm(3) HNO(3) solution. When Al(NO(3))(3) (0.2 mol/dm(3)) or Fe(NO(3))(3) (0.6 mol/dm(3)) was added as a masking agent for F(-) to the Th solution containing 1x10(-1) mol/dm(3) HF and 1 mol/dm(3) HNO(3), Th recovery improved from 1.4+/-0.3% to 95+/-5% or 93+/-3%. Effective extraction of Th using UTEVA resin was achieved by selecting the concentration of HNO(3) and/or adding masking agents such as Al(NO(3))(3) according to the concentration of HF in the sample solution. PMID:19327779

Shimada-Fujiwara, Asako; Hoshi, Akiko; Kameo, Yutaka; Nakashima, Mikio

2009-05-01

59

Acute health effects in a community after a release of hydrofluoric acid  

SciTech Connect

{approximately} 3,000 persons were evacuated from a Texas community after 24,036 kg (53,000 lb) of caustic hydrofluoric acid (HF) were released from a nearby petrochemical plant. Emergency room and hospital records of 939 persons who were seen at two area hospitals were reviewed. Most persons who presented at the emergency rooms were female (56%) or black (60%), and their mean age was 33.9 y. The most frequently reported symptoms were eye irritation (41.5%), burning throat (21%), headache (20.6%), and shortness of breath (19.4%). Physical examination results were normal for 49% of the cases; however, irritation of the eyes, nose, throat, skin, and lungs were noted on other exams. Decreased pulmonary function was demonstrated by pulmonary function tests (forced expiratory volume in the first second, less than 80% of predicted value, 42.3%); hypoxemia (pO2 less than 80 mm Hg, 17.4%) and hypocalcemia (less than 8.5 mg/dl, 16.3%) were also noted. Ninety-four (10%) of the cases were hospitalized, and more than 83% of all cases were discharged with a primary diagnosis of HF exposure. There are several reports of individuals who are acutely and chronically exposed to HF; however, we are unaware of other published reports that describe exposure of a community to HF. This incident represented a unique opportunity to study the immediate health impact on a community of residents who were exposed to a hazardous materials release. Results of this analysis suggest that (a) initial health problems should be followed up, (b) any long-term health effects of HF exposure must be assessed, and (c) the health impact on the population at risk should be determined.

Wing, J.S.; Brender, J.D.; Sanderson, L.M.; Perrotta, D.M.; Beauchamp, R.A. (Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control, Atlanta, GA (USA))

1991-05-01

60

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.

1993-04-01

61

Chemical analysis of acidic silicon etch solutions I. Titrimetric determination of HNO(3), HF, and H(2)SiF(6).  

PubMed

The chemical etching of silicon using HF-HNO(3) mixtures is a widely used process in the processing of silicon wafers for microelectronic or photovoltaic applications. The control of the etch bath composition is the necessary condition for an effective bath utilization, for the replenishment of the consumed acids, and to maintain a certain etch rate. The present paper describes two methods for the total analysis of the individual etch bath constituents HF, HNO(3), and H(2)SiF(6). Both methods start with an aqueous acid-base titration determining the total acid concentration and the concentration of H(2)SiF(6). The first method is an acid-base titration using a 0.1molL(-1) methanolic solution of cyclohexylamine (CHA) as non-aqueous titrant to determine the content of nitric acid. Then, the amount of hydrofluoric acid is calculated from the difference between the total acid and nitric acid content. The second method is based on the determination of the total fluoride concentration using a fluoride ion-selective electrode (F-ISE). The content of hydrofluoric acid is obtained from the difference between the total fluoride content and the amount of fluoride bound as H(2)SiF(6). The amount of nitric acid results finally calculated as difference to the total acid content. PMID:19073019

Henßge, Antje; Acker, Jörg

2007-09-15

62

Catalytic activity of noble metals for metal-assisted chemical etching of silicon  

NASA Astrophysics Data System (ADS)

Metal-assisted chemical etching of silicon is an electroless method that can produce porous silicon by immersing metal-modified silicon in a hydrofluoric acid solution without electrical bias. We have been studying the metal-assisted hydrofluoric acid etching of silicon using dissolved oxygen as an oxidizing agent. Three major factors control the etching reaction and the porous silicon structure: photoillumination during etching, oxidizing agents, and metal particles. In this study, the influence of noble metal particles, silver, gold, platinum, and rhodium, on this etching is investigated under dark conditions: the absence of photogenerated charges in the silicon. The silicon dissolution is localized under the particles, and nanopores are formed whose diameters resemble the size of the metal nanoparticles. The etching rate of the silicon and the catalytic activity of the metals for the cathodic reduction of oxygen in the hydrofluoric acid solution increase in the order of silver, gold, platinum, and rhodium.

Yae, Shinji; Morii, Yuma; Fukumuro, Naoki; Matsuda, Hitoshi

2012-06-01

63

Theory, experiment, and application of optical fiber etching.  

PubMed

Based on fiber Bragg grating (FBG), an online monitoring system for the etching process of optical fiber in a hydrofluoric (HF) acid solution has been designed. The variation curves of the wavelength shifts of FBGs with etching time at three different temperatures have been obtained and analyzed theoretically. The results show that the etching process of optical fiber in HF acid solution can be understood by the variation of the wavelength shift of FBG with etching time. Finally, required tapered fiber tips can be made by controlling the etching velocity and the pulling velocity of optical fiber from the etching solution. PMID:22907012

Yuan, Yinquan; Wang, Lina; Ding, Liyun; Wu, Chenhui

2012-08-20

64

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.

SABATINI, Camila

2013-01-01

65

Characterization of modified alumina as adsorbent for gas-solid chromatography. Modification of alumina with potassium fluoride-hydrofluoric acid mixed solution  

Microsoft Academic Search

The adsorption characteristics of alumina to hydrocarbons are varied by its impregnation with a mixed solution of potassium fluoride-hydrofluoric acid followed by thermal treatment. The adsorptive property of the alumina is decreased with the increase of concentration of potassium fluoride in the mixed solution and of the heating temperature. The surface layer of the modified alumina seems to consist of

Sadaaki Moriguchi; Shinsuke Takei

1974-01-01

66

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

PubMed Central

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

Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

2013-01-01

67

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

1998-01-01

68

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.

1992-03-03

69

Wide angle near-field optical probes by reverse tube etching  

Microsoft Academic Search

We present a simple modification of the tube etching process for the fabrication of fiber probes for near-field optical microscopy. It increases the taper angle of the probe by a factor of two. The novelty is that the fiber is immersed in hydrofluoric acid and chemically etched in an upside-down geometry. The tip formation occurs inside the micrometer tube cavity

S. Patanè; E. Cefalì; A. Arena; P. G. Gucciardi; M. Allegrini

2006-01-01

70

Precise elemental and isotopic analyses in silicate samples employing ICP-MS: application of hydrofluoric acid solution and analytical techniques.  

PubMed

In this review, a new classification of elements based on behavior in hydrofluoric acid (HF) solution is presented for the precise quantitative analysis of each element by inductively coupled plasma mass spectrometry (ICP-MS). The elements are divided into 7 groups: (1) "fluorophile" elements; (2) insoluble fluoride-forming elements; (3) "bromophile" or "iodophile" elements; (4) "oxophile" elements; (5) "aquaphile" elements; (6) bare cation elements; and (7) other elements. Especially, the importance of fluorophile and insoluble fluoride-forming elements in elemental analysis is described. Due to the elemental characteristics, these two groups of elements cannot be dissolved simultaneously in the same solution, and thus cannot be measured together. In addition, coprecipitation of the fluorophile elements with the insoluble fluorides occurs in some conditions and hinders accurate analysis. The peculiar conditions when the coprecipitation occurs are discussed, and the "Al-addition" and "Mg-addition" methods for overcoming these problems are described. In addition, some state-of-the-art analytical techniques in ICP-MS are shown, and future directions of the element analysis are presented. PMID:19822960

Makishima, Akio; Tanaka, Ryoji; Nakamura, Eizo

2009-10-01

71

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

2014-06-01

72

Wet etching mechanisms of ITO films in oxalic acid  

Microsoft Academic Search

This study examines how oxalic acid solutions affect indium tin oxide (ITO) etching. Experimental results show that the etching rate of ITO films increased linearly with the concentration of C2O42-. The open circuit potentials included in the potential–pH diagrams for indium and tin in aqueous oxalic acid systems helped determine that ITO films was dissolved by the formation of In(C2O4)2-

Tzu-Hsuan Tsai; Yung-Fu Wu

2006-01-01

73

Orthodontic bonding to acid- or laser-etched prebleached enamel  

PubMed Central

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

Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

2013-01-01

74

Microdroplet-etched highly birefringent low-loss fiber tapers.  

PubMed

We use hydrofluoric acid microdroplets to directly etch highly birefringent biconical fiber tapers from standard single-mode fibers. The fiber tapers have micrometer-sized cross sections, which are controlled by the etching condition. The characteristic teardrop cross section leads to a high group birefringence of B(G)?0.017 and insertion losses <0.7 dB over waist lengths of about 2.1 mm. PMID:22743468

Mikkelsen, Jared C; Poon, Joyce K S

2012-07-01

75

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.

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

2011-01-01

76

The Effect of Etching on Ti6A 14V Interfacial Chemistry and Adhesion to Evaporated Gold and a Commercial Adhesive  

Microsoft Academic Search

Titanium 6-aluminum 4-vandium alloys were etched for varying periods of time in aqueous solution of hydrofluoric acid and ammonium dihydrogen phosphate. Following etching, one-half of the specimens were covered with vacuum evaporated gold while the other half were bonded with a commercial adhesive. Gold adhesion to the alloys was evaluated by pressure sensitive tape peel tests and lap shear tests

W. L. Baun

1981-01-01

77

An X-ray photoelectron spectroscopy study of the HF etching of native oxides on Ge(111) and Ge(100) surfaces  

Microsoft Academic Search

An X-ray photoelectron spectroscopy (XPS) study of the removal of the native oxides from the Ge(111) and Ge(100) surfaces by hydrofluoric (HF) acid based etch treatments is presented. A cyclic HF etch, water rinse procedure which was repeated a number of times before loading the samples into the XPS chamber was found to be an effective surface oxide removal treatment.

Terri Deegan; Greg Hughes

1998-01-01

78

Lipoprotein lipase and hydrofluoric acid deactivate both bacterial lipoproteins and lipoteichoic acids, but platelet-activating factor-acetylhydrolase degrades only lipoteichoic acids.  

PubMed

To identify the Toll-like receptor 2 ligand critically involved in infections with gram-positive bacteria, lipoprotein lipase (LPL) or hydrogen peroxide (H(2)O(2)) is often used to selectively inactivate lipoproteins, and hydrofluoric acid (HF) or platelet-activating factor-acetylhydrolase (PAF-AH) is used to selectively inactivate lipoteichoic acid (LTA). However, the specificities of these chemical reactions are unknown. We investigated the reaction specificities by using two synthetic lipoproteins (Pam(3)CSK(4) and FSL-1) and LTAs from pneumococci and staphylococci. Changes in the structures of the two synthetic proteins and the LTAs were monitored by mass spectrometry, and biological activity changes were evaluated by measuring tumor necrosis factor alpha production by mouse macrophage cells (RAW 264.7) following stimulation. PAF-AH inactivated LTA without reducing the biological activities of Pam(3)CSK(4) and FSL-1. Mass spectroscopy confirmed that PAF-AH monodeacylated pneumococcal LTA but did not alter the structure of either Pam(3)CSK(4) or FSL-1. As expected, HF treatment reduced the biological activity of LTA by more than 80% and degraded LTA. HF treatment not only deacylated Pam(3)CSK(4) and FSL-1 but also reduced the activities of the lipoproteins by more than 60%. Treatment with LPL decreased the biological activities by more than 80%. LPL also removed an acyl chain from the LTA and reduced its activity. Our results indicate that treatment with 1% H(2)O(2) for 6 h at 37 degrees C inactivates Pam(3)CSK(4), FSL-1, and LTA by more than 80%. Although HF, LPL, and H(2)O(2) treatments degrade and inactivate both lipopeptides and LTA, PAF-AH selectively inactivated LTA with no effect on the biological and structural properties of the two lipopeptides. Also, the ability of PAF-AH to reduce the inflammatory activities of cell wall extracts from gram-positive bacteria suggests LTA to be essential in inflammatory responses to gram-positive bacteria. PMID:19553557

Seo, Ho Seong; Nahm, Moon H

2009-08-01

79

Water recovery from etching effluents for the purpose of rinsing stainless steel  

Microsoft Academic Search

The objective of the study was the choice of unit processes for a treatment train. The wastewater to be treated was the effluent from rinsing of stainless steel which had been etched in nitric acid and hydrofluoric acid. The proposed treatment train involved the following unit processes: electrodialysis (ED1) and cation exchange and electrodialysis (ED2). The ED1 provided removal efficiencies

Jacek Wisniewski; Stanislaw Suder

1995-01-01

80

Kinetics and modeling of wet etching of aluminum oxide by warm phosphoric acid  

Microsoft Academic Search

Aluminum oxide has been used widely in the microelectronic industry for dielectric films. Etching kinetics of vacuum sputtered aluminum oxide films by warm phosphoric acid is studied. The etch rate is found to be constant when the concentration and temperature of the etchant are fixed and the films being etched come from the same deposition batch. Etch rates obtained at

Bo Zhou; W. F. Ramirez

1996-01-01

81

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

PubMed

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

1970-07-01

82

Formation of wide and deep pores in silicon by electrochemical etching  

Microsoft Academic Search

Electrochemical etching of n-type silicon in hydrofluoric acid electrolyte is now well known as a technique for micro- or macroporous silicon formation. It is commonly admitted that the width of pores can extend over four orders of magnitude, from 2 nm to 20 ?m. In this study the feasibility of using this technique to form larger pores is demonstrated. The

P Kleimann; J Linnros; S Petersson

2000-01-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2001-10-01

84

Silicon vertical microstructure fabrication by catalytic etching  

NASA Astrophysics Data System (ADS)

This study presents an effective, simple and inexpensive process for forming micro-scale vertical structures on a (1?0?0) silicon wafer. Several modified etchants and micro-patterns including rectangular, snake-like, circular and comb patterns were employed to determine the optimum etching process. We found that an etchant solution consisting of 4.6 M hydrofluoric acid, 0.44 M hydrogen peroxide and isopropyl alcohol produces microstructures at an etching rate of 0.47 µm min-1 and surface roughness of 17.4 nm. All the patterns were transferred faithfully to the silicon substrate.

Huang, Mao-Jung; Yang, Chii-Rong; Chang, Chun-Ming; Chu, Nien-Nan; Shiao, Ming-Hua

2012-08-01

85

High aspect ratio submicron silicon pillars fabricated by photoassisted electrochemical etching and oxidation  

Microsoft Academic Search

A technique for fabricating submicron free-standing silicon pillars has been developed. The silicon pillars have a high packing density, and aspect ratios over 50:1 can easily be achieved. Photoassisted electrochemical etching in hydrofluoric acid is used to etch deep macropores in n-type silicon wafers which have been patterned by standard photolithography. The regular macropores can be used for fabricating photonic

H. W. Lau; G. J. Parker; R. Greef

1995-01-01

86

Acid-Etching of Caries-Like Lesions of Enamel: A Polarized Light Microscopic Study  

Microsoft Academic Search

The histopathologic effects of acid-etching on caries-like lesions of enamel were studied using polarized light techniques. The results indicated that surface losses and qualitative changes in the superficial portions of the etched surface zones were similar to those reported previously for sound enamel. The etched, intact surface zones appeared to be more porous, while still maintaining their integrities. The ability

M. J. Hicks; L. M. Silverstone

1984-01-01

87

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.

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

2009-01-01

88

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

89

MEMS Process Flow Insensitive to Timed ETCH Induced Anchor Perimeter Variation on SOI and Bulk Silicon Wafer Substrates  

Microsoft Academic Search

This paper describes a novel silicon on insulator (SOI) process flow with an electrically isolated mechanical substrate anchor perimeter insensitive to SiO2 sacrificial layer timed hydrofluoric acid etch variation. A novel low electrical resistance substrate connection is facilitated between the top SOI layer and silicon substrate using a polysilicon trench refill via process step. A process combining both the silicon

G. J. O'Brien; D. J. Monk

2007-01-01

90

Effects of fluoride treatment on phosphoric acid-etching in primary teeth: an AFM observation.  

PubMed

The aim of this study was to examine the effect of fluoride application on 37% phosphoric acid-etching by atomic force microscopy (AFM) in primary tooth samples based on a clinical protocol used in a pediatric dental hospital. Enamel samples were prepared from 36 exfoliated and non-carious primary teeth. Primary tooth samples were randomly assigned to one of the four groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. Group 1 received no fluoride application, Group 2 was pre-treated with fluoride and then received acid-etching 2 weeks later. One week separated the fluoride treatment and the acid-etching in Group 3, while Group 4 received acid-etching immediately after the fluoride treatment. The vestibular enamel surfaces of each primary tooth sample were scanned in air at a resolution of 512 x 512 pixels and a scan speed of 0.8 line/s. On the enamel surfaces of the primary teeth after APF pre-treatment, debris were observed although the teeth were smoother than they were prior to APF. As a result, it was concluded that APF treatment is responsible for decreased primary tooth surface roughness. The enamel surfaces etched for 20s showed that acid-etching was effective not only in removing scratches and debris, but also for evaluating enamel rod characteristics. Primary tooth enamel surfaces after etching showed minute structures caused by the decreased hydroxyapatite nanoparticle space, compared to those before etching. Also, acid-etching showed significantly increased roughness effects (p<0.0001, n=9). Finally, as more time elapsed after APF pre-treatment, the roughness was decreased to a lesser degree (p=0.005, n=9). We suggest that primary teeth etching 2 weeks after APF pre-treatment used clinically in pediatric hospitals may be effective to obtain properly etched enamel surfaces. PMID:20219379

Choi, Samjin; Rhee, Yeri; Park, Jeong-Hoon; Lee, Gi-Ja; Kim, Kyung-Sook; Park, Jae-Hong; Park, Young-Guk; Park, Hun-Kuk

2010-07-01

91

Microtomographic analysis of subsurface enamel and dentine following Er:YAG laser and acid etching.  

PubMed

The Er:YAG laser, with or without phosphoric acid, is used to promote enamel surface changes to increase restorative material retention. However, such irradiation might induce subsurface enamel damage. In the present study, X-ray microtomography was used to compare the subsurface enamel beneath laser and acid conditioned; laser-only etched and acid-only etched surfaces. Laser and acid conditioning increased the etching depth, but did not induce significant damage in the enamel subsurface. Analysis of the laser-only etched enamel subsurface revealed a small reduction in mineral concentration suggesting an increase in porosity, allowing greater penetration of acid and resulting in an increased acid-etch depth. PMID:11803892

Groth, E B; Mercer, C E; Anderson, P

2001-06-01

92

[Microretention of plastic filling materials on acid etched enamel].  

PubMed

In order to study the strength of the physical bond between composite materials and acid etched enamel, various commonly used composites were applied to the conditioned surface of extracted young permanent bicuspids. The specimens were stored in saline at 37 degrees C for one week and nine weeks and then subjected to tensile strength test. The following composites were tested: Restodent, Nuva Seal/Nuva Fil, Cosmic, Smile, Adaptic and Concise Enamel Bond. The latter was used in 4 different ways. The results of the study indicate that all the tested materials have a fairly good retention on the conditioned enamel. However, when using Concise Enamel Bond, care must be taken not to let the pure, liquid resin polymerize on the enamel before applying the composite, because this will give a poor bonding between the enamel and the filling. In addition to the tensile strength test, the materials were submitted to scanning electron microscop, to examine their penetration ability into conditioned enamel. The results of this study seem to indicate that the resin part of viscous composites (Cosmic and Concise pastes) was able to penetrate into the crevices of the etched enamel as well as the more fluid types (Restodent, Nuva Seal and diluted Concise). PMID:1060049

Raadal, M

1975-11-01

93

The Influence of Composition upon Surface Degradation and Stress Corrosion Cracking of the Ni-Cr-Mo Alloys in Wet Hydrofluoric Acid  

SciTech Connect

At concentrations below 60%, wet hydrofluoric acid (HF) is extremely corrosive to steels, stainless steels and reactive metals, such as titanium, zirconium, and tantalum. In fact, only a few metallic materials will withstand wet HF at temperatures above ambient. Among these are the nickel-copper (Ni-Cu) and nickel-chromium-molybdenum (Ni-Cr-Mo) alloys. Previous work has shown that, even with these materials, there are complicating factors. For example, under certain conditions, internal attack and stress corrosion cracking (SCC) are possible with the Ni-Cr-Mo alloys, and the Ni-Cu materials can suffer intergranular attack when exposed to wet HF vapors. The purpose of this work was to study further the response of the Ni-Cr-Mo alloys to HF, in particular their external corrosion rates, susceptibility to internal attack and susceptibility to HF-induced SCC, as a function of alloy composition. As a side experiment, one of the alloys was tested in two microstructural conditions, i.e. solution annealed (the usual condition for materials of this type) and long-range ordered (this being a means of strengthening the alloy in question). The study of external corrosion rates over wide ranges of concentration and temperature revealed a strong beneficial influence of molybdenum content. However, tungsten, which is used as a partial replacement for molybdenum in some Ni-Cr-Mo alloys, appears to render the alloys more prone to internal attack. With regard to HF-induced SCC of the Ni-Cr-Mo alloys, this study suggests that only certain alloys (i.e., those containing tungsten) exhibit classical SCC. It was also discovered that high external corrosion rates inhibit HF-induced SCC, presumably due to rapid progression of the external attack front. With regard to the effects of long-range ordering, these were only evident at the highest test temperatures, where the ordered structure exhibited much higher external corrosion rates than the annealed structure.

Crook, P; Meck, N S; Rebak, R B

2006-12-04

94

Formation of three-dimensional microstructures by electrochemical etching of silicon  

NASA Astrophysics Data System (ADS)

This letter describes the promising technique of micromachining using the properties of electrochemical etching of (100)-oriented n-type silicon in a hydrofluoric acid electrolyte. The technique is based on electropolishing of a wafer except for areas where vertical structures are needed and does not require a periodic pattern. Predefined steps of a few microns depth prior to the electrochemical etching define the shape and position of the structures. The three-dimensional microstructure width can be adjusted with the etching parameters, also enabling the formation of free-standing structures. The feasibility of this technique is demonstrated by forming high aspect ratio microneedles and tubes.

Kleimann, P.; Linnros, J.; Juhasz, R.

2001-09-01

95

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.

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

2014-01-01

96

Silicon x-ray monochromator surfaces by independent oxidation and etching steps  

NASA Astrophysics Data System (ADS)

X-ray monochromators should ideally possess a surface that does not distort a diffracted beam. Beam distortions have been observed at the APS for rough surfaces. Mechanical polishing leaves sub-surface damage. The standard method to remove this damage is to wet etch Si crystals in a mixture of nitric acid and hydrofluoric acid. During the etch an oxide is produced and removed in the same acid bath. X-ray diffraction from a bulk reflection that is largely unaffected by strain can be obtained by this method. However, the smoothness is degraded to produce an orange-peel morphology. For the present study we carried out the oxidation and etching steps independently. By first growing an oxide layer in a furnace and subsequently etching away the the oxide layer, we find that sub-surface damage can be removed and the surface quality can be improved over that found with only wet etching.

Macrander, Albert; MacArthur, Kimberley; Maj, Josef; Qian, Jun; Linnen, Dan; Khachatryan, Ruben; Wieczorek, Michael; Conley, Ray; Genis, Alan

2009-03-01

97

Nanoparticle-based etching of silicon surfaces  

DOEpatents

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)

2011-12-13

98

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

2008-01-01

99

Bone contact around osseointegrated implants: a histologic study of acid-etched and machined surfaces.  

PubMed

Current literature reports that surface acid etching can improve bone--implant contact (BIC). The aim of this study was to evaluate the differences of BIC between acid-etched (Osseotite) and machined surface implants. Six white New Zealand mature rabbits were used in the present investigation. Each rabbit received two implants, specially made with two surfaces on it (one acid-etched and one machined) into each tibia. A total of 24 implants were inserted. Two animals each were killed at 15, 30, and 60 days after implant placement. Histomorphometry of BIC was statistically evaluated. The acid-etched surfaces showed a greater bone contact percentage than the machined ones during the early phase of healing (15 days), which was not statistically significant. On the other hand, after 30 and 60 days, the differences of BIC between acid-etched and machined surfaces were statistically significant. The acid-etched surface appears to improve BIC at a later stage of healing. PMID:16700653

Celletti, Renato; Marinho, Vanessa C; Traini, Tonino; Orsini, Giovanna; Bracchetti, Guido; Perrotti, Vittoria; Piattelli, Adriano

2006-01-01

100

Etching of tungsten and tungsten silicide films by chlorine atoms  

SciTech Connect

Thin films of tungsten and tungsten silicide were etched both within and downstream from a Cl/sub 2/ plasma discharge at 200 mtorr pressure and temperatures below 150/sup 0/C. When samples were positioned downstream from the discharge, etching proceeded solely by chemical reaction of the film with chlorine atoms. Without a discharge, molecular chlorine did not etch tungsten or tungsten silicide. Downstream and in-plasma tungsten etch rates were approximately equal at 110/sup 0/C, but the chlorine atom etch rate dropped more rapidly than the in-plasma etch rate as temperature decreased. The chemical reaction between chlorine atoms and the tungsten film was proportional to the gas phase Cl atom mole fraction. A pretreatment consisting of either a dilute hydrofluoric acid dip or a short plasma etch cycle was necessary for atom etching of tungsten silicide films. The etch rate of tungsten silicde in Cl/sub 2/ plamsas were approximately an order of magnitude higher and less temperature sensitive than those in the downstream (atom) configuration.

Fischi, D.S. (Air Products and Chemicals, Inc., Applied Research and Development, Allentown, PA (US)); Rodriques, G.W. (Dept. of Chemical Engineering, Univ. of Wisconsin, Madison, WI (US)); Hess, D.W. (Dept. of Chemical Engineering, Univ. of California, Berkeley, CA (US))

1988-08-01

101

Dual-peak long-period fiber gratings with enhanced refractive index sensitivity by finely tailored mode dispersion that uses the light cladding etching technique  

NASA Astrophysics Data System (ADS)

We have experimentally investigated the mode dispersion property and refractive index sensitivity of dual-peak long-period fiber gratings (LPGs) that were sensitized by hydrofluoric acid (HF) etching. The nature of the coupled cladding modes close to the dispersion turning point makes the dual-peak LPGs ultrasensitive to cladding property, permitting a fine tailoring of the mode dispersion and index sensitivity by the light cladding etching method using HF acid of only 1% concentration. As an implementation of an optical biosensor, the etched device was used to detect the concentration of hemoglobin protein in a sugar solution, showing a sensitivity as high as 20 nm/1%.

Chen, Xianfeng; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

2007-02-01

102

Dual-peak long-period fiber gratings with enhanced refractive index sensitivity by finely tailored mode dispersion that uses the light cladding etching technique.  

PubMed

We have experimentally investigated the mode dispersion property and refractive index sensitivity of dual-peak long-period fiber gratings (LPGs) that were sensitized by hydrofluoric acid (HF) etching. The nature of the coupled cladding modes close to the dispersion turning point makes the dual-peak LPGs ultrasensitive to cladding property, permitting a fine tailoring of the mode dispersion and index sensitivity by the light cladding etching method using HF acid of only 1% concentration. As an implementation of an optical biosensor, the etched device was used to detect the concentration of hemoglobin protein in a sugar solution, showing a sensitivity as high as 20 nm/1%. PMID:17230235

Chen, Xianfeng; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

2007-02-01

103

Basic Biological SciencesThe Effect of Acid-etching on Caries-like Lesions Treated with Stannous Fluoride  

Microsoft Academic Search

The effect of acid-etching on SnF2-treated caries-like lesions was investigated. The results suggested that remineralization occurred, limited to the superficial portions of the lesions. In addition, we observed etching patterns which are comparable to those described for etched sound enamel.

M. J. Hicks; L. M. Silverstone

1983-01-01

104

A quantitative study of enamel acid etch patterns on surfaces used for retention of resin-bonded fixed prostheses.  

PubMed

This study investigated the quality of in vivo etch patterns on the bonding surfaces of 46 abutment teeth following acid etching with 37% phosphoric acid for 30 seconds. Two-stage putty and light bodied addition cured silicone impressions of the etched lingual surfaces were used to form replicas that were then viewed using the scanning electron microscope. Over 69% of the lingual bonding surface area of incisors, canine and premolars were unetched, 16% barely etched, 7% etched and less than 2% ideally etched. There was no significant difference in the quality of etch between different tooth types. There was a significantly greater proportion of poorly etched enamel towards the cervical margin in comparison with the occlusal half. This may have implications in retention of resin bonded bridges. PMID:16180638

Hobson, R S; Crotty, T; Thomason, J M; Jepson, N J A

2005-09-01

105

Effect of fluoride pretreatment on primary and permanent tooth surfaces by acid-etching.  

PubMed

This study observed the effect of fluoride application on a 37% phosphoric acid etching for 20 s of the enamel surfaces of primary and permanent teeth based on a clinical protocol employed in dental hospitals, through atomic force microscopy and scanning electron microscopy. Enamel samples were prepared from 84 exfoliated and noncarious teeth. Primary (groups 1-4) and permanent (groups 5-8) tooth samples were assigned randomly to one of eight groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) treatment. Groups 1 and 5 received no fluoride application. Groups 2-4 and 6-8 were pretreated with fluoride and received acid-etching 2 weeks later (groups 2 and 6), 1 week later (groups 3 and 7), and immediately (groups 4 and 8). The acid-etching process led to a significant increase in roughness (p<0.0001), and the APF treatment led to a decrease in primary and permanent tooth surface roughness (p<0.005). An acid-etching procedure 2 weeks after performing an APF pretreatment might be recommended to obtain the maximum enamel adhesion of a resin composite. PMID:21254111

Choi, Samjin; Cheong, Youjin; Lee, Gi-Ja; Park, Hun-Kuk

2010-01-01

106

Surface characterization of alkali- and heat-treated Ti with or without prior acid etching  

NASA Astrophysics Data System (ADS)

Titanium and its alloys are used as implant materials in dental and orthopaedic applications. The material affinities to host bone tissue greatly concern with the recovery period and good prognosis. To obtain a material surface having excellent affinity to bone, acid etching prior to alkali- and heat-treatment of Ti was conducted. The surface characteristics of the prepared sample indicated that the roughness as well as the wettability increased by pre-etching. Bone-like apatite was formed on pre-etched, alkali- and heat-treated Ti surface in simulated body fluid (SBF) within 3 days, while it takes 5 days on the solely alkali- and heat-treated surface. Osteoblastic cells showed better compatibility on the per-etched surface compared to the pure Ti surface or alkali- and heat-treated surface. Moreover, the pre-etched surface showed better pull-off tensile adhesion strength against the deposited apatite. Thus, acid etching prior to alkali- and heat-treatment would be a promising method for enhancing the affinity of Ti to host bone tissue.

An, Sang-Hyun; Matsumoto, Takuya; Miyajima, Hiroyuki; Sasaki, Jun-Ichi; Narayanan, Ramaswamy; Kim, Kyo-Han

2012-03-01

107

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

PubMed

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

2013-01-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

109

Water and acid recovery from the rinse after metal etching operations  

Microsoft Academic Search

The effluent from which water and acid were to be recovered came from the rinse after metal etching with hydrochloric acid. The effluent under study contained hydrochloric acid (24 eq H+\\/m3), iron salts (100 g Fetot\\/m3), small amounts of nickel salts (2.7 g Ni2+\\/m3) and chromium salts (0.6 g Cr3+), and had an electrolytic conductivity of 8.4 mS\\/cm. Water recovery

Jacek Wi?niewski; Gra?yna Wi?niewska

1999-01-01

110

Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid  

SciTech Connect

Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material.

Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

1999-04-02

111

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.

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

2012-01-01

112

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

PubMed

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and pretreated as follows: (1) 37% phosphoric acid; (2) Er:YAG laser (1.5 ml/min water spray, 100 mJ energy output, 10 Hz frequency, focal distance 17 mm); (3) Er:YAG laser + 37% phosphoric acid. The treated surfaces were isolated by double adhesive Sellotape and after insertion of a split Teflon matrix at an isolated site, sealant was applied. The specimens were thermocycled and stored at 37°C in distilled water for 72 h, then subjected to a tensile bond strength test (50 kgf at 0.5 mm/min). The mean tensile bond strengths (± SD, in megapascals) were: 18.51 ± 5.68 in group 1, 8.06 ± 2.69 in group 2, and 17.33 ± 5.04 in group 3. Data were submitted to analysis of variance and the Tukey test. No significant difference were found between groups 1 (37% phosphoric acid) and group 3 (Er:YAG laser + 37% phosphoric acid) but treatment with the Er:YAG laser alone (group 2) resulted in significantly lower tensile bond strength than seen in the other groups. In this setting, the Er:YAG laser prepared the enamel surface for sealing but did not eliminate the need for acid etching before sealant application. PMID:21336680

Shahabi, Sima; Bagheri, Hossein G; Ramazani, Kosar

2012-03-01

113

Fabrication of tapered single mode fiber by chemical etching and used as a chemical sensor based on evanescent field absorption  

NASA Astrophysics Data System (ADS)

Single mode tapered fiber (SMTF) has been fabricated with core diameter of 8 ?m and reduced cladding diameter up to 11 ?m by hydrofluoric acid (HF) etching technique. To obtain the required cladding diameter, the time of etching has been optimized by using different HF concentrations. The mechanism as well as kinetics path of etching reaction on standard optical fiber is discussed. This study is related to surface catalyzed dissociation of HF followed by direct reaction with adsorbate molecules and the surface silicon oxide molecules. The etched tapered fibers are then packaged on quartz substrate to use as sensor element. Finally, the etched fiber is used as an element within chemical sensor based on evanescent field absorption. In this experiment, a 419-ppm cobalt nitrate solution is used for sensing.

Gangopadhyay, Tarun K.; Halder, A.; Das, S.; Paul, M. C.; Pal, M.; Salza, M.; Gagliardi, G.

2010-12-01

114

The durability of adhesion to phosphoric acid etched, wet dentin substrates  

Microsoft Academic Search

Objective. The purpose of this study was to investigate the influence of remaining non-resin-impregnated, phosphoric acid demineralized dentin upon the long-term durability of specimens that were wet-bonded to bovine dentin substrates.Methods. Prepared bovine dentin samples were etched with 65% phosphoric acid then rinsed with water and kept wet during application of 5wt% 4-methacryloyloxyethyl trimellitate anhydride (4-META) in acetone primer. This

Gen Kato; Nobuo Nakabayashi

1998-01-01

115

Fiber post adhesion to radicular dentin: The use of acid etching prior to a one-step self-etching adhesive.  

PubMed

The aim of this study was to evaluate the bond strength of fiber posts luted with a one-step self-etching adhesive with the push-out test after phosphoric acid conditioning of the root dentin. Thirty-six single-rooted teeth were endodontically treated. Teeth were sectioned perpendicularly to the cementoenamel junction, and a 10-mm post space was prepared with a calibrated bur. Specimens were then divided into three groups according to the adhesive protocol: A, total-etch three steps; B, self-etch one step; and C, 32% phosphoric acid conditioning and self-etch one step. Fiber posts were luted with self-curing resin-based cement. Teeth were cut in 1-mm slices and pushed until failure with an Instron machine. Results were statistically analyzed with the ANOVA and Bonferroni tests (P < .05). Two additional specimens from each group were examined under the scanning electron microscope (SEM). The 32% phosphoric acid significantly influenced the push-out bond strength of fiber posts luted with self-etch adhesives (P < .05). SEM analysis showed a continuous hybrid layer with resin tags and lateral branches in groups A and C, while group B showed smear layer dissolution with poor infiltration of the tubules. PMID:22670257

Scotti, Nicola; Rota, Riccardo; Scansetti, Marco; Migliaretti, Giuseppe; Pasqualini, Damiano; Berutti, Elio

2012-01-01

116

Citric acid etching of cervical sclerotic dentin lesions: an AFM study.  

PubMed

Atomic force microscopy (AFM) has been used to determine microstructural changes, etching rates of peritubular dentin, and intertubular dentin recession during demineralization in dilute acidic solutions. These studies have not included many forms of altered dentin, including noncarious sclerotic root dentin associated with Cl V (abfraction) lesions. We sought to determine microstructural changes and recession rates during demineralization in citric acid (pH 2.5, 0.018M) for the transparent/sclerotic zone. Highly polished dentin disks were prepared from teeth with noncarious C1 V lesions (n = 3) and compared with normal root dentin (n = 3). Samples were etched at 5-s intervals for 1 min and at longer intervals up to 30 min. The depth changes in various portions of the dentin with respect to the reference layer were measured and changes in microstructure observed in solution in the wet cell of the AFM. In sclerotic dentin, most tubule lumens were occluded with crystalline deposits that etched more slowly than the other dentin components, but etching rates could not be determined due to their irregular geometry. The intertubular dentin recession quickly reached a plateau after a depth change of <1 microm for all dentin types, in agreement with prior work. Mixed linear regression models indicated an important difference between the etching of sclerotic intertubular dentin and that of non-sclerotic root dentin that became apparent after 600 s (p = 0.037). The sclerotic intertubular dentin underwent less depth change at the plateau (558 nm) compared to normal root dentin (744 nm). In addition, normal root dentin underwent significantly greater recession than coronal dentin (p = 0.002). The results of this study indicate that intertubular sclerotic dentin from Cl V lesions etches differently than normal root dentin, and this may help explain the difficulties in restoring such lesions with current bonding procedures. PMID:10602066

Marshall, G W; Chang, Y J; Saeki, K; Gansky, S A; Marshall, S J

2000-03-01

117

Biomechanical comparison of the sandblasted and acid-etched and the machined and acid-etched titanium surface for dental implants.  

PubMed

To make a direct biomechanical comparison between the sandblasted and acid-etched surface (SLA) and the machined and acid-etched surface (MA), a well-established animal model for implant removal torque testing was employed, using a split-mouth experimental design. All implants had an identical cylindrical solid-screw shape with the standard ITI thread configuration, without any macroscopic retentive structures. After 4, 8, and 12 weeks of bone healing, removal torque testing was performed to evaluate the interfacial shear strength of each surface type. Results showed that the SLA surface was more powerful in enhancing the interfacial shear strength of implants in comparison with the MA surface. Removal torque values of the SLA-surfaced implants were about 30% higher than those of the MA-surfaced implants (p = 0.002) except at 4 weeks, when the difference was at the threshold of statistical significance (p = 0.0519). The mean removal torque values for the SLA implants were 1.5074 Nm at 4 weeks, 1.8022 Nm at 8 weeks, and 1.7130 Nm at 12 weeks; and correspondingly, 1.1924 Nm, 1.3092 Nm, and 1.3226 Nm for the MA implants. It can be concluded that the SLA surface achieves a better bone anchorage than the MA surface, and that sandblasting before acid etching has a beneficial effect on the interfacial shear strength. As regards the bone-implant interfacial stiffness calculated from the torque-rotation curve, the SLA implants showed an overall more than 5% higher stiffness compared with the MA implants, although the difference did not reach the statistical significance level. PMID:11857440

Li, Dehua; Ferguson, Stephen J; Beutler, Thomas; Cochran, David L; Sittig, Caroline; Hirt, Hans Peter; Buser, Daniel

2002-05-01

118

Histological structures and acidic etching sensitivities of the enamels at the occlusal pit parts in the deciduous and permanent teeth  

Microsoft Academic Search

The purpose of this study is to compare the histological structures and acidic etching sensitivities of the enamels at the occlusal pit parts between the deciduous molars and permanent molars. They were observed by the polarizing and scanning electron microscopies. The enamel rods were less made slender by EDTA etching and the outlines of the apatite crystals, constituting the enamel

Masashi Takahashi; Jinhua Zheng; Kazuhisa Mori; Izumi Mataga; Kan Kobayashi

2006-01-01

119

Recovery of nitric acid from waste etching solution using solvent extraction.  

PubMed

A process was developed to recover nitric acid from the waste stream of wafer industry using solvent extraction technique. Tributyl phosphate (TBP) was selected among several extractants because of its better selectivity towards HNO(3), overall superiority in operation, favorable physical properties and economics. The waste solution containing 260 g/L CH(3)COOH, 460 g/L HNO(3), 113 g/L HF and 19.6g/L Si was used as feed solution for process optimization. In the pre-treatment stage >99% silicon and hydrofluoric acid was precipitated out as Na(2)SiF(6). Equilibrium conditions for HNO(3) recovery were optimized from the batch test results as: four stages of extraction at an organic:aqueous (O:A) ratio of 3, four stages of scrubbing at O:A ratio of 5 and five stages of stripping at an O:A ratio of 1.5. The extraction of HNO(3) was suppressed by the presence of acetic acid (HAc) in the feed solution. To examine the feasibility of the extraction system a continuous operation was carried out for 200 h using a multistage mixer-settler. The concentration of pure HNO(3) recovered was 235 g/L with a purity of 99.8%. PMID:18755545

Shin, Chang-Hoon; Kim, Ju-Yup; Kim, Jun-Young; Kim, Hyun-Sang; Lee, Hyang-Sook; Mohapatra, Debasish; Ahn, Jae-Woo; Ahn, Jong-Gwan; Bae, Wookeun

2009-04-30

120

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

2009-10-01

121

Single- and multi-scan femtosecond laser writing for selective chemical etching of cross section patternable glass micro-channels  

NASA Astrophysics Data System (ADS)

We report on the fabrication of three dimensional micro-fluidic channels in fused silica glass using a combination of femtosecond laser writing and hydrofluoric acid wet etching to flexibly create various cross-sectional profiles of highly uniform shape and smooth vertical walls. The laser power, polarization, focusing depth, scanning angle and scanning speed were systematically studied with single- and multi-scan configurations to assess optimum micro-channel formation including etch rate, surface roughness, and stress-induced crack formation. We introduce the formation of vertical access-ports that extend the buried channel formation to unlimited length without tapering or distortion of the channel cross-sectional shape.

Ho, Stephen; Herman, Peter R.; Aitchison, J. Stewart

2012-01-01

122

Anisotropic etching versus interaction of atomic steps: Scanning tunneling microscopy observations on HF\\/NH4F-treated Si(111)  

Microsoft Academic Search

After exsitu etching with various solutions of hydrofluoric acid (HF) and ammonium fluoride (NH4F) Si(111) samples are transferred into ultrahigh vacuum with an ultrafast load-lock and characterized by scanning tunneling microscopy (STM): Concentrated HF selectively removes any surface oxide and, thus chemically prepares the initially burried, isotropically rough Si\\/SiO2 interface while highly buffered HF (i.e., NH4F) attacks bulk silicon anisotropically.

G. J. Pietsch; M. Henzler

1993-01-01

123

Effects of laser and acid etching and air abrasion on mineral content of dentin  

Microsoft Academic Search

The aim of this study was to evaluate the mineral content of dentin prepared using an Er,Cr:YSGG laser at four different power\\u000a settings, acid etching, and air abrasion. The study teeth comprised 35 molars which were randomly divided into seven equal\\u000a groups. The occlusal third of the crowns were cut with a slow-speed diamond saw. The groups were as follows:

Meral Arslan Malkoc; Serife Tuba Ta?demir; A. Nilgun Ozturk; Bora Ozturk; Gizem Berk

2011-01-01

124

AFM characterization of bovine enamel and dentine after acid-etching  

Microsoft Academic Search

Teeth are constituted mainly of hydroxyapatite molecules (Ca10(PO4)6(OH)2), grouped in different microstructural arrangements, depending on the dental layer considered (enamel or dentine). In the present work, these dental microstructural arrangements were characterized by atomic force microscopy. Enamel and dentine samples were cut from freshly extracted bovine incisor teeth. After metallographic polishing, the dental surfaces were etched with lactic acid (113.8mmol\\/L,

Roberto Pizarro Sanches; Choyu Otani; Alvaro José Damião; Walter Miyakawa

2009-01-01

125

The efficacy of acid etching for removing contamination in layered dental restorations.  

PubMed

Contamination between incremental layers of a composite resin restoration can occur during surgical procedures. The present study sought to evaluate how two decontamination treatments affected the shear bond strength between layers of a saliva-contaminated composite resin surface. Forty disks of a nanohybrid composite resin were prepared and divided into four groups (n = 10). The surfaces of all specimens (except for samples in Group 1, the positive control) were contaminated with human saliva. For the negative control samples (Group 2), no decontamination was performed. For Group 3 samples, acid etching was performed and adhesive was applied. For Group 4, surfaces were roughened with a diamond bur prior to acid etching and adhesive application. The specimens were submitted to a shear bond strength test, and the data were analyzed using one-way ANOVA and Tukey tests (? = 0.05). No significant differences were detected between the mean shear bond strengths of samples in Groups 1, 3, and 4 (p < 0.05). Shear bond strength was significantly reduced in Group 2 samples (p < 0.05). Acid etching and the application of adhesive improved shear bond strength, producing values similar to those in the positive control group. PMID:23032239

Furuse, Adilson Yoshio; Pirolo, Rodrigo; Rodrigues, Luciana Koene Vieira; Pizzatto, Eduardo; Losso, Estela Maris; Mondelli, Jose

2012-01-01

126

SEM observations of Retzius lines and prism cross-striations in human dental enamel after different acid etching regimes  

Microsoft Academic Search

Objective and design: Sectioned and ground enamel surfaces need to be etched with acid in order for the enamel structure to be exposed for study in the SEM. In the present study Retzius lines and prism cross-striations were observed in variably ground specimens after etching with nitric acid of different concentrations (0.1, 1, 2.5 and 5%) and for different time

Chunfang Li; Steinar Risnes

2004-01-01

127

Note: electrochemical etching of silver tips in concentrated sulfuric acid.  

PubMed

Sharp metal tips have many uses, including in scanning probe microscopy. Silver is a particularly interesting metal for plasmonic enhancement, e.g., in tip-enhanced Raman spectroscopy, however few methods for the production of silver tips have been explored. A simple and reliable one step dc electrochemical method for the production of sharp silver tips in concentrated H2SO4 is presented. The optimal conditions are 10 V cell voltage and 99% sulfuric acid for tip radii below 100 nm. A LabView program was written to control the cut-off of the circuit to within a millisecond to avoid blunting the tips after drop-off. PMID:23464271

Hodgson, P A; Wang, Y; Mohammad, A Awez; Kruse, P

2013-02-01

128

Efficacy of self-etching primers containing carboxylic acid monomers on the adhesion between composite resin and dentin.  

PubMed

A study was conducted to examine the efficacy of carboxylic acid monomers as self-etching primers by measuring the tensile bond strengths between composite resin and dentin. Several kinds of carboxylic acid monomers, such as o-(N-methacryloyl amino)benzoic acid (o-MABA), m-(N-methacryloyl amino)benzoic acid (m-MABA), p-(N-methacryloyl amino)benzoic acid (p-MABA), 4-methacryloxy phthalic acid (4-MPA), 2-(N-methacryloyl amino) terephthalic acid (2-MATPA), and 5-(N-methacryloyl) amino)isophthalic acid (5-MAIPA), were prepared. 4-methacryloxyethyl trimellitic anhydride (4-META) was also used as a component of the self-etching primer. The DMSO solutions of these monomers were used as self-etching primers. The tensile bond strengths between composite resin and dentin were measured after 24 h immersion in water at 37 degrees C. When DMSO was used as a self-etching primer, the bond strengths were below 5 MPa. Among the monocarboxylic acid monomers, m-MABA gave the highest mean bond strength at 60 s application, and 5MAIPA gave the highest mean bond strength at 30 s application among the dicarboxylic acid monomers, although the differences among the values were not always significant. The smear layer was partially dissolved by treatment with the self-etching primer. PMID:9663978

Hayakawa, T; Kikutake, K; Nemoto, K

1998-03-01

129

Improvement of Removal Rate in Abrasive-Free Planarization of 4H-SiC Substrates Using Catalytic Platinum and Hydrofluoric Acid  

NASA Astrophysics Data System (ADS)

We used catalyst-referred etching, which is an abrasive-free planarization method, to produce an extremely smooth surface on a 4H-SiC substrate. However, the removal rate was lower than that obtained by chemical mechanical polishing, which is the planarization method generally used for SiC substrates. To improve the removal rate, we investigated its dependence on rotational velocity and processing pressure. We found that the removal rate increases in proportion to both rotational velocity and processing pressure. A lapped 4H-SiC substrate was planarized under conditions that achieved the highest removal rate of approximately 500 nm/h. A smooth surface with a root-mean square roughness of less than 0.1 nm was fabricated within 15 min. Because the surface, which was processed under conditions of high rotational velocity and high processing pressure, consisted of a step--terrace structure, it was well ordered up to the topmost surface.

Okamoto, Takeshi; Sano, Yasuhisa; Tachibana, Kazuma; Pho, Bui Van; Arima, Kenta; Inagaki, Kouji; Yagi, Keita; Murata, Junji; Sadakuni, Shun; Asano, Hiroya; Isohashi, Ai; Yamauchi, Kazuto

2012-04-01

130

Characterization of deep wet etching of fused silica glass for single cell and optical sensor deposition  

NASA Astrophysics Data System (ADS)

The development of a high-throughput single-cell metabolic rate monitoring system relies on the use of transparent substrate material for a single cell-trapping platform. The high optical transparency, high chemical resistance, improved surface quality and compatibility with the silicon micromachining process of fused silica make it very attractive and desirable for this application. In this paper, we report the results from the development and characterization of a hydrofluoric acid (HF) based deep wet-etch process on fused silica. The pin holes and notching defects of various single-coated masking layers during the etching are characterized and the most suitable masking materials are identified for different etch depths. The dependence of the average etch rate and surface roughness on the etch depth, impurity concentration and HF composition are also examined. The resulting undercut from the deep HF etch using various masking materials is also investigated. The developed and characterized process techniques have been successfully implemented in the fabrication of micro-well arrays for single cell trapping and sensor deposition. Up to 60 µm deep micro-wells have been etched in a fused silica substrate with over 90% process yield and repeatability. To our knowledge, such etch depth has never been achieved in a fused silica substrate by using a non-diluted HF etchant and a single-coated masking layer at room temperature.

Zhu, Haixin; Holl, Mark; Ray, Tathagata; Bhushan, Shivani; Meldrum, Deirdre R.

2009-06-01

131

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

132

Analysis methods for meso- and macroporous silicon etching baths.  

PubMed

: 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. PMID:22805742

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

2012-01-01

133

Analysis methods for meso- and macroporous silicon etching baths  

PubMed Central

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.

2012-01-01

134

Fabrication of highly ordered nanopillar arrays and defined etching of ALD-grown all-around platinum films  

NASA Astrophysics Data System (ADS)

Highly ordered arrays of silicon nanopillars are etched by means of induced-coupled-plasma reactive-ion etching (RIE). The sulfur hexafluoride/oxygen (SF6/O2)-based cryogenic process allows etching of nanopillars with an aspect ratio higher than 20:1 and diameters down to 30 nm. Diameters can be further reduced by a well-controllable oxidation process in O2-ambient and a subsequent etching in hydrofluoric acid. This approach effectively removes surface contaminations induced by former RIE, as shown by x-ray photoelectron spectroscopy. Atomic layer deposition (ALD) is used to establish an all-around Al2O3/Pt stack onto the vertically aligned nanorods. Two approaches are successfully applied to remove the resistant Pt coating from the nanopillar tips.

Bethge, O.; Pozzovivo, G.; Henkel, C.; Abermann, S.; Bertagnolli, E.

2012-08-01

135

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

PubMed

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

Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

2013-01-01

136

AFM characterization of bovine enamel and dentine after acid-etching.  

PubMed

Teeth are constituted mainly of hydroxyapatite molecules (Ca(10)(PO(4))(6)(OH)(2)), grouped in different microstructural arrangements, depending on the dental layer considered (enamel or dentine). In the present work, these dental microstructural arrangements were characterized by atomic force microscopy. Enamel and dentine samples were cut from freshly extracted bovine incisor teeth. After metallographic polishing, the dental surfaces were etched with lactic acid (113.8 mmol/L, pH 3.3). Three etching times were tested: 1, 3 and 5 min. Atomic force micrographs showed that 1 min of etching time was effective to remove the smear layer, polishing debris and scratches, and display the characteristics of interest for both enamel and dentine. Although the bovine dental enamel rod cross-section presented keyhole-like shape, its measured dimensions (8.8 microm of major axis and 3.7 microm of minor axis) exhibited an insignificant discrepancy from human prisms diameters. Bovine dentinal tubules displayed larger mean diameters (4.0 microm) and a lower density (approximately 17,100 tubules/mm(2)) than human dentine, suggesting that the use of bovine dentine as a substitute for human dentine in resin adhesion investigations should be reconsidered. Apatite nanoparticles presented a mean radius (22-23 nm) considerably smaller than that of human teeth. PMID:19138525

Sanches, Roberto Pizarro; Otani, Choyu; Damião, Alvaro José; Miyakawa, Walter

2009-06-01

137

Analysis of p-Si macropore etching using FFT-impedance spectroscopy  

PubMed Central

The dependence of the etch mechanism of lithographically seeded macropores in low-doped p-type silicon on water and hydrofluoric acid (HF) concentrations has been investigated. Using different HF concentrations (prepared from 48 and 73?wt.% HF) in organic electrolytes, the pore morphologies of etched samples have been related to in situ impedance spectra (IS) obtained by Fast Fourier Transform (FFT) technique. It will be shown that most of the data can be fitted with a simple equivalent circuit model. The model predicts that the HF concentration is responsible for the net silicon dissolution rate, while the dissolution rate selectivity at the pore tips and walls that ultimately enables pore etching depends on the water content. The ‘quality’ of the pores increases with decreasing water content in HF/organic electrolytes.

2012-01-01

138

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

USGS Publications Warehouse

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

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

1996-01-01

139

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

NASA Astrophysics Data System (ADS)

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

Gratz, Andrew J.; Fisler, Diana K.; Bohor, Bruce F.

1996-08-01

140

Etch Stop Process for Fabrication of Thin Diaphragms in Lithium Niobate  

NASA Astrophysics Data System (ADS)

In this paper, we present a novel process for the fabrication of thin diaphragms in lithium niobate (LiNbO3) wafers for various sensor applications. The process uses a thermal inversion layer as an etch stop. Thermal inversion is a process which forms a layer with a poling direction opposite to that of the bulk crystal. The thermal inversion layer can be used as an etch stop because the etch rate on the +Z face in hydrofluoric acid is much slower than that on the -Z face. The thickness of the thermal inversion layer determines the thickness of the final diaphragm; diaphragms with thicknesses of 6 and 30 ?m have been fabricated in Z-cut and 128°-Y-cut wafers, respectively.

Randles, Andrew B.; Esashi, Masayoshi; Tanaka, Shuji

2007-12-01

141

Limited evidence suggests no difference in orthodontic attachment failure rates with the acid-etch technique and self-etch primers.  

PubMed

Data sourcesThe Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, Chinese Biomedical Literature Database, the WHO International Clinical Trials Registry, and the National Institutes of Health Clinical Trials Registry were searched with no restrictions regarding language or date of publication.Study selectionRandomised controlled trials comparing different etching materials, or different etching techniques using the same etchants, for the bonding of fixed orthodontic brackets to incisors, canines and premolars in children and adults.Data extraction and synthesisStudy assessment, risk of bias assessment and data extraction were carried out independently by at least two reviewers. The primary outcome was bond failure rate.ResultsThirteen studies involving 417 patients with 7184 teeth/brackets were included. Two studies were considered to be at low risk of bias, 10 at high risk and one at unclear risk. Eleven studies compared the effects of self-etching primers (SEPs) with conventional etchants.Five of these studies (three of split-mouth design and two of parallel design) reported data at the participant level, with the remaining studies reporting at the tooth level, thereby ignoring clustering/the paired nature of the data.A meta-analysis of these five studies, with follow-up ranging from five to 37 months, provided low-quality evidence that was insufficient to determine whether or not there is a difference in bond failure rate between SEPs and conventional etchants (risk ratio 1.14; 95% confidence interval (CI) 0.75 to 1.73; 221 participants). The uncertainty in the CI includes both no effect and appreciable benefit and harm. Subgroup analysis did not show a difference between split-mouth and parallel studies.There were no data available to allow assessment of decalcification, participant satisfaction and cost-effectiveness. One study reported decalcification, but only at the tooth level.Two studies compared two different SEPs. Both studies reported bond failure rate, with one of the studies also reporting decalcification. However, as both studies reported outcomes only at the tooth level, there were no data available to evaluate the superiority of any of the SEPs over the others investigated with regards to any of the outcomes of this review. No eligible studies were found evaluating different etching materials (eg phosphoric acid, polyacrylic acid, maleic acid), concentrations or etching times.ConclusionsWe found low quality evidence that was insufficient to conclude whether or not there is a difference in bond failure rate between SEPs and conventional etching systems when bonding fixed orthodontic appliances over a five- to 37-month follow-up. Insufficient data were also available to allow any conclusions to be formed regarding the superiority of SEPs or conventional etching for the outcomes: decalcification, participant satisfaction and cost-effectiveness, or regarding the superiority of different etching materials, concentrations or etching times, or of any one SEP over another.Further well-designed RCTs on this topic are needed to provide more evidence in order to answer these clinical questions. PMID:24971857

Fleming, Padhraig S

2014-06-01

142

Effect of Lactic Acid Etching on Bonding Effectiveness of Orthodontic Bracket after Water Storage  

PubMed Central

Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (? = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets.

Alsulaimani, Fahad F.

2014-01-01

143

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

PubMed

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

Guo, Jian; Yu, Bingjun; Wang, Xiaodong; Qian, Linmao

2014-01-01

144

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.

2014-01-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

146

The Morphological Effect of the Acquired Pellicle on Acid-etched Enamel: A Scanning Electron Microscopy Analysis.  

PubMed

Purpose: The aim of this study was to determine the effect of the acquired pellicle on enamel etching. Materials and Methods: One-hundred teeth were sectioned in the buccal-lingual direction at the half crown. One-hundred half-crowns were polished with pumice powder and rotating brushes (group B) and one-hundred half-crowns were not polished on the buccal surface (group A). The samples were etched by 37% orthophosphoric acid gel for 30 seconds in a 2 mm diameter circular area at the middle upper section of the crown, rinsed with distilled water for 20 s, air dried for 20 s and observed by Scanning Electron Microscopy. Three independent operators determined the quality of enamel etching on a four-point scale using 200 images, which were computed by digital Image Analysis software. It analyses the grey values and converts them to three-dimensional graphics to value the surface extension. Analysis Of Variance test was used for comparisons between and within groups. Results: The mean of the operator values for the A samples is 2 ("Poorly defined etch") and for the B samples is 3 ("Defined etch"). The Image Analysis showed a significant difference (Analysis of Variance test) in the extension of the etched areas between groups A and B. The samples from group B had 11.7% more effectively etched enamel surfaces than the samples from group A. Conclusion: Acquired pellicle removal by dental prophylaxis is necessary before enamel etching because it improves the effectiveness of the etching procedure. PMID:24984652

Marchetti, Elena; Guida, Andrea; de Carolis, Carlo; Lomurno, Giuseppe; Eramo, Stefano

2014-06-01

147

Use of an electrochemically etched platinum microelectrode for ascorbic acid mapping in oranges.  

PubMed

A positionable platinum microelectrode fabricated by electrochemical etching was used to monitor the concentration of ascorbic acid in fruits and vegetables. Studies carried out with ascorbate oxidase confirmed the suitability of the amperometric sensor to measure selectively the ascorbic acid content. The results obtained with the proposed method for ascorbic acid determination in orange juices compared well with those found by iodimetry with coulometrically generated iodine. The standard deviation calculated by measuring limiting current values in voltammograms was found to be 3% (n = 150). The sensor allowed the evaluation of the spatial distribution of ascorbic acid concentration in oranges by in-situ measurements. Ascorbic acid concentration maps show that in a perpendicular cut the concentration is higher near the peel to the center of the fruit. In a parallel cut, the concentration increases with the distance to the stem. A correlation between the ripening stage and the ascorbic acid concentration was also observed from electrochemical measurements, the content being higher in mature fruits. PMID:16608233

Paixão, Thiago R L C; Lowinsohn, Denise; Bertotti, Mauro

2006-04-19

148

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

1996-01-01

149

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

PubMed Central

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

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

2014-01-01

150

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).  

PubMed

Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead, and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution (approximately 0.55 mol L(-1) HF, pH approximately 1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc support was used. The optimum experimental conditions, evaluated also in terms of the signal-to-noise ratio, were as follows: deposition potential -1100 mV vs. Ag/AgCl, KCl 3 mol L(-1), deposition time 3-10 min, electrode rotation 3000 rpm, SW scan from -1100 mV to +100 mV, SW pulse amplitude 25 mV, frequency 100 Hz, DeltaE(step) 8 mV, t(step) 100 ms, t(wait) 60 ms, t(delay) 2 ms, t(meas) 3 ms. Under these conditions the metal peak potentials were Cd -654 +/- 1 mV, Pb -458 +/- 1 mV, Cu -198 +/- 1 mV. The electrochemical behaviour was reversible for Pb, quasi-reversible for Cd, and kinetically controlled (possibly following chemical reaction) for Cu. The linearity of the response with concentration was verified up to approximately 4 microg L(-1) for Cd and Pb and approximately 20 microg L(-1) for Cu. The detection limits were 5.8 ng L(-1), 3.6 ng L(-1), and 4.3 ng L(-1) for Cd, Pb, and Cu, respectively, with t(d) = 5 min. The method was applied for determination of the metals in spicules of two specimens of marine sponges (Demosponges) from the Portofino natural reserve (Ligurian Sea, Italy, Petrosia ficiformis) and Terra Nova Bay (Ross Sea, Antarctica, Sphaerotylus antarcticus). The metal contents varied from tens of ng g(-1) to approximately 1 microg g(-1), depending on the metal considered and with significant differences between the two sponge species. PMID:18642105

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

2008-09-01

151

Effect of etching time and light source on the bond strength of metallic brackets to ceramic.  

PubMed

This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (?=0.05). Specimens etched for 20 s presented significantly lower bond strength (p<0.05) compared with those etched for 60 s. No significant differences (p>0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic. PMID:21915523

Gonçalves, Paulo Roberto Amaral; Moraes, Rafael Ratto de; Costa, Ana Rosa; Correr, Américo Bortolazzo; Nouer, Paulo Roberto Aranha; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

2011-01-01

152

Two-dimensional nanostructures on optical glass via nanosphere lithography and vapor HF etching  

NASA Astrophysics Data System (ADS)

It is desired to have artificial optical materials with controllable optical properties. One approach is to create composite materials with nanomachining and nanostructures. In this research, two-dimensional (2D) nanostructures were created on the surface of optical glass using nanosphere lithography. The effective refractive index of the artificial layer is smaller than the refractive index of the substrate and can be varied by changing the size of the nanoparticles and depth of etching. In comparison with conventional techniques, this approach is more efficient and cost-effective for the creation of large areas of thin surface layers as an artificial material. A uniform monolayer of 200 nm polystyrene nanospheres was deposited on soda-lime glass slides. Deposition was performed via a slide-coating technique to take advantage of capillary forces. The slides were etched with vapor-phase hydrofluoric acid (HF) to create 2D structures. Vapor-phase etching was selected in order to etch the substrate without disturbing the monolayer nanoparticle mask. The etching rate of nanostructures was studied. An atomic force microscope (AFM) was used to monitor the nanosphere monolayers and etching analysis. It was shown that the nanoparticle pattern was successfully transferred to the surface of the substrate. The resultant thin-layer of modified substrate serves as an artificial material with a desired refractive index which modifies the surface reflection and transmission properties. The substrate with the created artificial material layer demonstrated reduced reflectivity in optical wavelengths.

Wang, Elmer; Zhao, Yang

2013-09-01

153

Spectroscopic investigations of the stability of porous silicon structure obtained by etching Si(100) in aqueous ammonium fluoride solution  

NASA Astrophysics Data System (ADS)

The structure of porous silicon (por-Si) obtained by electrochemical etching of Si(100) single crystal wafers in an aqueous ammonium fluoride solution with isopropyl alcohol additions has been studied using X-ray reflection spectroscopy, X-ray photoelectron spectroscopy, and external X-ray quantum yield measurements. It is established that por-Si layers obtained by the nontraditional technology (not involving hydrofluoric acid) possess a partly amorphized structure and bear a stable surface oxide film with a thickness not exceeding 5 nm.

Filatova, E. O.; Lysenkov, K. M.; Sokolov, A. A.; Ovchinnikov, A. A.; Marchenko, D. E.; Kashkarov, V. M.; Nazarikov, I. V.

2010-02-01

154

[Optimization of implant surfaces: titanium plasma spray and acid-etched sandblasting -- current status].  

PubMed

The aim of this review was to update the concepts regarding the preparation of the surfaces of titanium implants, focusing on TPS (titanium plasma-sprayed implants) and SLA (sandblasted and acid etched implants). Texture was the most remarkable isolated feature, regarded as an osseointegration promoter. In a comprehensive review of the effects of implant surface topography on cell behavior, one can verify that there is bone apposition onto the implant surface regardless of its characteristics: polished or rough, made of titanium or ceramic. Roughness is not mandatory for bone apposition. However, it has been shown that roughness may play an important role in the percentage of bone apposition as well as in the velocity of apposition. In this review, a quite promising type of surface called SLA is pointed out, showing that either roughness or acid conditioning of the surfaces can significantly improve shear strength. Besides optimizing the procedure, these surface characteristics may, eventually, allow for an earlier loading of the implant and extend the indications for implants in low-density alveolar bone and in regenerated bone. PMID:11705201

Amarante, E S; de Lima, L A

2001-01-01

155

Three-Dimensional Microdrilling of Glass by Multiphoton Process and Chemical Etching  

NASA Astrophysics Data System (ADS)

We demonstrate the three-dimensional microdrilling of glass by the multiphoton process with nonresonant femtosecond laser pulses and by the subsequent chemical etching. We use photomachinable glass which is sensitive to cw UV light of a wavelength shorter than 320 nm. After the focused irradiation of nonresonant femtosecond laser pulses at 400 nm and subsequent heat treatment, crystallites of Li2O·SiO2, which are more soluble in dilute hydrofluoric acid than matrix glass, precipitate in the focused area of the laser within the glass sample. After etching the crystallites, three-dimensional holes are formed in the glass sample. We produce straight and Y-branched holes in the glass sample. This technique can be applied to the fields of microoptics, microelectronics and microchemicals.

Kondo, Yuki; Qiu, Jianrong; Mitsuyu, Tsuneo; Hirao, Kazuyuki; Yoko, Toshinobu

1999-10-01

156

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

PubMed Central

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

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

2013-01-01

157

Porous siliconformation and etching process for use in silicon micromachining  

DOEpatents

A reproducible process for uniformly etching silicon from a series of micromechanical structures used in electrical devices and the like includes providing a micromechanical structure having a silicon layer with defined areas for removal thereon and an electrochemical cell containing an aqueous hydrofluoric acid electrolyte. The micromechanical structure is submerged in the electrochemical cell and the defined areas of the silicon layer thereon are anodically biased by passing a current through the electrochemical cell for a time period sufficient to cause the defined areas of the silicon layer to become porous. The formation of the depth of the porous silicon is regulated by controlling the amount of current passing through the electrochemical cell. The micromechanical structure is then removed from the electrochemical cell and submerged in a hydroxide solution to remove the porous silicon. The process is subsequently repeated for each of the series of micromechanical structures to achieve a reproducibility better than 0.3%.

Guilinger, Terry R. (Albuquerque, NM); Kelly, Michael J. (Albuquerque, NM); Martin, Jr., Samuel B. (Albuquerque, NM); Stevenson, Joel O. (Albuquerque, NM); Tsao, Sylvia S. (Albuquerque, NM)

1991-01-01

158

Application of hydrophobic resin adhesives to acid-etched dentin with an alternative wet bonding technique.  

PubMed

Hydrophilic dentin adhesives are prone to water sorption that adversely affects the durability of resin-dentin bonds. This study examined the feasibility of bonding to dentin with hydrophobic resins via the adaptation of electron microscopy tissue processing techniques. Hydrophobic primers were prepared by diluting 2,2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl] pro- pane/triethyleneglycol dimethacrylate resins with known ethanol concentrations. They were applied to acid-etched moist dentin using an ethanol wet bonding technique that involved: (1) stepwise replacement of water with a series of increasing ethanol concentrations to prevent the demineralized collagen matrix from collapsing; (2) stepwise replacement of the ethanol with different concentrations of hydrophobic primers and subsequently with neat hydrophobic resin. Using the ethanol wet bonding technique, the experimental primer versions with 40, 50, and 75% resin exhibited tensile strengths which were not significantly different from commercially available hydrophilic three-step adhesives that were bonded with water wet bonding technique. The concept of ethanol wet bonding may be explained in terms of solubility parameter theory. This technique is sensitive to water contamination, as depicted by the lower tensile strength results from partial dehydration protocols. The technique has to be further improved by incorporating elements of dentin permeability reduction to avoid water from dentinal tubules contaminating water-free resin blends during bonding. PMID:17600324

Sadek, Fernanda T; Pashley, David H; Nishitani, Yoshihiro; Carrilho, Marcella R; Donnelly, Adam; Ferrari, Marco; Tay, Franklin R

2008-01-01

159

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

PubMed

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

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

2003-01-01

160

Investigations on the SR method growth, etching, birefringence, laser damage threshold and dielectric characterization of sodium acid phthalate single crystals  

Microsoft Academic Search

Optically good quality semi-organic single crystal of sodium acid phthalate (NaAP) was successfully grown by Sankaranarayanan-Ramasamy (SR) method. Transparent, colourless ?001? oriented unidirectional bulk single crystals of diameters 10 and 20mm and length maximum up to 75mm were grown by the SR method. The grown crystals were subjected to various characterization studies such as etching, birefringence, laser damage threshold, UV–vis

A. Senthil; P. Ramasamy; Sunil Verma

2011-01-01

161

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

PubMed

By combination of experiments and density functional theory calculations, we present a simple but effective "facet dependent binding and etching" strategy for non-enzymatic and non-aggregated colorimetric sensing of blood uric acid (UA), using unmodified Ag nanoprisms as the signal readout. In the absence of UA, the triangular Ag nanoprisms are etched alongside (110) facets by H2O2 and form round nanodiscs, and a more than 160nm surface plasmon resonance (SPR) blue shift is observed. Because of special affinity between UA and side facets of the Ag nanoprisms, pre-added UA can well protect the Ag nanoprisms from etching. Such protection effect can be used for well quantifying UA in the range of 10-3000nM, based on the inverse proportion of the SPR blue shift with the added analyte. Due to very thin plate morphology (5nm) and facet dependent binding/etching effects of the Ag nanoprisms, the sensing system has ultrahigh sensitivity. The detection limit is only 10nM, which is about 2 to 4 orders of magnitude lower than that of previous colorimetric sensing systems. In addition to accurate quantitation, the proposed strategy can conveniently discriminate the patient of hyperuricemia from normal person by naked eyes. So, the present simple, low-cost and visualized UA chemosensor has great potential in the applications for point-of-care diagnostics. PMID:24732599

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

2014-09-15

162

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic.  

PubMed

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (?=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic. PMID:22814690

Costa, Ana Rosa; Correr, Américo Bortolazzo; Puppin-Rontani, Regina Maria; Vedovello, Silvia Amélia; Valdrighi, Heloísa Cristina; Correr-Sobrinho, Lourenço; Vedovello Filho, Mário

2012-01-01

163

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

2011-10-01

164

Acid-etching andHydration Influence onDentin Roughness andWettability  

Microsoft Academic Search

Adhesion ofrestorative andprotective materials to dentin isanimportant requirement foroperative andpre- ventive dentistry. Wettability androughness aredentin sub- strate conditions thatarecritical toestablishing good adhesion. Thisstudy examined superficial anddeepdentin forvariations inwatercontact angle measurements and roughness forpolished, etched, dehydrated, andrehydrated states. Superficial anddeepdentin disks from6non-carious third molarswereprepared forAFM (Atomic Force Microscope) observation, roughness measurement, andcon- tactangle measurements following specific treatments: hydrated andpolished, etched (10%H3PO4),

J. I. Rosales; G. W. Marshall; S. J. Marshall; L. G. Watanabe; M. Toledanol; M. A. Cabrerizo

165

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.

2011-10-01

166

Scanning probe microscopy studies of PbS surfaces oxidized in air and etched in aqueous acid solutions  

NASA Astrophysics Data System (ADS)

Natural n-type PbS single crystals have been studied using AFM, STM and STS after long-term oxidation in air at ambient temperatures and extensive etching in aqueous acid solutions, in contrast to previous work devoted to initial corrosion of fresh surfaces. The exposure of PbS to atmosphere at high relative humidity for several days yields widespread loose oxidation products; the process is much slower at low humidity. Surface morphologies diverge after the treatment in 1 M perchloric and hydrochloric acid solutions at room temperature and become widely different at elevated temperatures, displaying commonly etch pits up to several micrometers in size and depth along with rather uniformly distributed 20-100 nm protrusions of PbS phase. The changes both in topography and semiconducting properties of PbS found by tunneling spectroscopy have been explained in terms of the non-uniform distribution of donor- and acceptor-type defects D +/D - in the metal depleted surface layer, which are generated by chemical reactions and, in turn, determine the rates of the PbS corrosion. In particular, the D - centers exhibit a self-catalyzing effect on the non-oxidative local dissolution of PbS in HCl media, resulting in the deep etch pits.

Mikhlin, Yuri L.; Romanchenko, Alexander S.; Shagaev, Alexander A.

2006-06-01

167

Influence of the anodic etching current density on the morphology of the porous SiC layer  

NASA Astrophysics Data System (ADS)

In this report, we fabricated a porous layer in amorphous SiC thin films by using constant-current anodic etching in an electrolyte of aqueous diluted hydrofluoric acid. The morphology of the porous amorphous SiC layer changed as the anodic current density changed: At low current density, the porous layer had a low pore density and consisted of small pores that branched downward. At moderate current density, the pore size and depth increased, and the pores grew perpendicular to the surface, creating a columnar pore structure. At high current density, the porous structure remained perpendicular, the pore size increased, and the pore depth decreased. We explained the changes in pore size and depth at high current density by the growth of a silicon oxide layer during etching at the tips of the pores.

Cao, Anh Tuan; Luong, Quynh Ngan Truc; Dao, Cao Tran

2014-03-01

168

In vivo use of a dual acid etch biopsy for the evaluation of lead profiles in human surface enamel.  

PubMed

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age-groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration of the first enamel biopsy layer was five times higher than in the second biopsy layer. A strong relation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratios was desirable and that a robust regression analysis approach was needed instead of classic least-squares regression analysis. However, the second biopsy provided more reliable lead estimates. In this study no increase in lead concentration in surface enamel could be demonstrated with age. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to preeruptive uptake. PMID:1913763

Cleymaet, R; Bottenberg, P; Retief, D H; Slop, D; Michotte, Y; Coomans, D

1991-01-01

169

The effect of phosphoric acid concentration on resin tag length and bond strength of a photo-cured resin to acid-etched enamel  

Microsoft Academic Search

Objectives: To determine the relationship between depth of penetration and tensile bond strength of a photo-cured resin to phosphoric acid etched enamel, and the efficacy of enamel etchants that are less aggressive than a concentration of 10% H3PO4.Methods: The tensile bond strength and length of tags produced by a photo-cured (20s) resin consisting of pre-polymerized TMPT\\/silica in 3% HNPM–TEGDMA on

M. J. Shinchi; K. Soma; N. Nakabayashi

2000-01-01

170

Acid-etching and Hydration Influence on Dentin Roughness and Wettability  

Microsoft Academic Search

Adhesion of restorative and protective materials to dentin is an important requirement for operative and preventive dentistry. Wettability and roughness are dentin substrate conditions that are critical to establishing good adhesion. This study examined superficial and deep dentin for variations in water contact angle measurements and roughness for polished, etched, dehydrated, and rehydrated states. Superficial and deep dentin disks from

J. I. Rosales; G. W. Marshall; S. J. Marshall; L. G. Watanabe; M. Toledano; M. A. Cabrerizo; R. Osorio

1999-01-01

171

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

NASA Astrophysics Data System (ADS)

The isotopic composition of six elements (Zn, Pd, Ag, Cd, Sn, and Te) was determined in three acid-etched residues of the Allende meteorite, using a specially developed high-efficiency procedure to separate and purify the nanogram amounts of these elements. Results showed no isotope dilution anomalies, similar to those found by Anders (1988) for Xe (Xe-HL) in these samples, for any of these elements, indicating that these residues are not being derived directly from the Xe-HL carriers.

Loss, R. D.; Rosman, K. J. R.; de Laeter, J. R.

1990-12-01

172

Etching kinetics of a self-etching primer.  

PubMed

Self-etching primers are thought to offer significant advantages over total-etch adhesive systems. The hypothesis tested in this study was that there was no difference in etching characteristics between a self-etching primer and a phosphoric acid solution at the same pH. Etching was assessed using atomic force microscopy (AFM) evaluation of site-specific changes in the height of the peritubular and intertubular dentin as a function of exposure time. Human dentin disks (n = 6/group), prepared with an acid-resistant glass reference layer, were etched with a self-etching primer and with 0.0134 M phosphoric acid (both pH approximately egual to 1.94). Depth changes relative to the reference layer were measured with the AFM after each etching interval, at 15 different locations, each in the peritubular and intertubular dentin. The total demineralization depth was measured in a scanning electron microscope. Peritubular dentin etching rate was linear while it could be measured (up to 15 s) and was greater for the self-etching primer (p < 0.0001). Intertubular dentin displayed a similar demineralization pattern with both acids, ultimately reaching a plateau in the majority of specimens. The self-etching primer attained a plateau after less recession than phosphoric acid (p < 0.0001). Dentin demineralization appears to be affected by other factors in addition to the pH of the etchant solutions. PMID:12182312

Oliveira, Sofia S A; Marshall, Sally J; Hilton, Joan F; Marshall, Grayson W

2002-10-01

173

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

PubMed

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

2014-01-01

174

The air-abrasion technique versus the conventional acid-etching technique: A quantification of surface enamel loss and a comparison of shear bond strength  

Microsoft Academic Search

The purpose of this study was to quantify the surface enamel loss that results when an air-abrasive technique is used and to compare the shear bond strength of different prebonding and bonding methods. Enamel loss was determined for 2 enamel-conditioning methods: acid etching with 37% phosphoric acid; and sandblasting with 50 ?m aluminum oxide particles under different conditions. A profilometer

Wendela L. van Waveren Hogervorst; Albert J. Feilzer; Birte Prahl-Andersen

2000-01-01

175

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

PubMed

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

2012-08-01

176

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

PubMed

This study evaluated the influence of etching periods on the surface/interface morphology and bond strength to glass ceramic with or without application of an unfilled resin after silane. Ceramic discs were divided into 12 groups, defined by etching time with 10% hydrofluoric acid: G1/G7--etching for 10 seconds, G2/G8--20 seconds; G3/G9--40 seconds; G4/G10--60 seconds; G5/G11--120 seconds and G6/G12--60 + 60 seconds. All the groups were silanated after etching and G7 - G12 received a layer of unfilled resin after silane. Microshear testing using resin cement was performed, with 12 resin cylinders tested per group. The data was submitted to two-way ANOVA and the Student-Newman-Keuls' test (p<0.05). Evaluation of the etching pattern and bonding interfaces was conducted by SEM. The bond strength means (MPa) were: 19.4 +/- 3.5, 22.3 +/- 5.1, 22.2 +/- 3.2, 17.8 +/- 2.1, 15.3 +/- 3.0 and 14.3 +/- 1.8 for G1-G6 and 17.4 +/- 4.8, 21.3 +/- 2.1, 21.1 +/- 2.3, 24.7 +/- 5.8, 20.4 +/- 2.2 and 18.5 +/- 4.6 for G7-G12. Poor etching was detected after 10 seconds of conditioning; whereas deep channels were extensively observed on surfaces etched for 120 and 60 + 60 seconds. Unfilled voids underlying the ceramic-cement interface were detected when only silane was applied. Full completion of the irregularities on G11 was detected using unfilled resin. When only silane was applied, the 60-second group and those etched for longer periods showed lower bond strengths. When both silane and unfilled resin were applied, all etching periods generally showed similar values. In conclusion, the etching period influenced the surface/interface topography and bond strength to ceramic. The application of unfilled resin was able to infiltrate all unfilled voids beneath the ceramic-cement interface, except on re-etched surfaces. PMID:20672726

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

2010-01-01

177

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.

Kukiattrakoon, Boonlert; Thammasitboon, Kewalin

2012-01-01

178

In vitro analysis of femtosecond laser as an alternative to acid etching for achieving suitable bond strength of brackets to human enamel.  

PubMed

This study aims to evaluate the effect of laser irradiation and orthophosphoric acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. Three groups (n?=?20) of extracted premolar teeth were randomly established depending on the laser treatment performed on the buccal surfaces: (1) no laser (control); (2) Er:YAG laser (2,940 nm, 0.8 W, 100 ?s/pulse, 10 Hz) and; (3) Ti:Sapphire laser (795 nm, 1 W, 120 fs/pulse, 1 kHz). Each group was divided into two subgroups according to whether 37 %-orthophosphoric acid etching was made after laser irradiation or not. Brackets were randomly luted with Transbond(TM) XT adhesive resin. After 72 h, a SBS test was developed in a universal testing machine (crosshead speed, 0.5 mm/min). Representative specimens from each experimental subgroup were examined by means of scanning electron microscopy. Cement residuals remaining on the premolar surfaces were assessed using the adhesive remnant index. ANOVA, post-hoc tests for intergroup comparisons, chi-square test and linear regression were run for data analyses (??=?0.05). After acid etching, SBS values did not differ regardless the laser treatment. When phosphoric acid was not applied, the SBS values of the femtosecond laser group were significantly higher than for the other groups. Femtosecond laser without acid seems to be the most suitable method to improve bond strengths at the bracket/enamel interface, thus avoiding the disadvantages inherent to acid etching. PMID:23483297

Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; Castillo-Oyagüe, R; García, A; Albaladejo, A

2014-05-01

179

Unintentional F doping of SrTiO3(001) etched in HF acid-structure and electronic properties  

SciTech Connect

We show that the HF acid etch commonly used to prepare SrTiO3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average {approx} 13% of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO2 terminated.

Chambers, Scott A.; Droubay, Timothy; Capan, Cigdem; Sun, Guangyuan

2012-02-01

180

Phosphoric acid and sodium fluoride: a novel etching combination on titanium.  

PubMed

We investigate whether a novel and inexpensive etching method, H3PO4 + NaF, on titanium could obtain both a lower hydrogen content and superior calcium phosphate deposition performance, while achieving similar surface roughness in comparison with the traditional etching method. Pure titanium samples were treated with different concentrations of H3PO4 + NaF at ambient temperature without auxiliary implementations (groups A, B and C), and were treated using the traditional method (group T). The samples were then maintained in simulated body fluid for 10 and 20 days. The surface morphology and chemistry, as well as the hydrogen content and distribution, were studied. The hydrogen content of the new groups are in the range of 31 (3.6)-86.9 (7.2) ppm, and that of group T is 287 (13.5) ppm. The amount of deposited calcium phosphates increases as the hydrogen content approaches 90 ppm; however, this trend does not apply as the hydrogen content exceeds 90 ppm. The surface roughnesses of groups A, B and C are in the range of 0.47 (0.01)-0.92 (0.05) µm. The new surface topography regularly transforms, and the surfaces with round pits exert a better effect on the deposition of calcium phosphates than the surfaces with sharp cusps. PMID:24704898

Jia, Fang; Zhou, Lei; Li, Shaobin; Lin, Xi; Wen, Binxue; Lai, Chunhua; Ding, Xianglong

2014-06-01

181

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.

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

2014-01-01

182

Sensing structure based on surface plasmonic resonance in single mode optical fibers chemically etched  

NASA Astrophysics Data System (ADS)

Many optical systems based on Surface Plasmon Resonance (SPR) have been developed for work as refractometers, chemical sensors or even for measure the thickness of metal and dielectric thin films. These kinds of systems are usually large, expensive and cannot be used for remote sensing. Optical fiber sensors based on SPR has been widely studied for the last 20 years with several configurations mostly using multimode optical fibers with large cores and plastic claddings. Sensors based on SPR present very high sensitivity to refractive index variations when compared to the traditional refractive index sensors. Here we propose a SPR sensor based in a single mode fiber. The fiber end is chemically etched by emersion in a 48% hydrofluoric acid solution, resulting a single mode fiber with the cladding removed in a small section. A resonance dip around 1580 nm was attained in good agreement with the simulation scenario that takes into account the real characteristics of the fiber.

Coelho, L.; Almeida, J. M.; Santos, J. L.; Ferreira, R. A. S.; André, P. S.; Viegas, D.

2013-05-01

183

Apparatus For Etching Or Depositing A Desired Profile Onto A Surface  

DOEpatents

An apparatus and method for modifying the surface of an object by contacting said surface with a liquid processing solution using the liquid applicator geometry and Marangoni effect (surface tension gradient-driven flow) to define and confine the dimensions of the wetted zone on said object surface. In particular, the method and apparatus involve contouring or figuring the surface of an object using an etchant solution as the wetting fluid and using real-time metrology (e.g. interferometry) to control the placement and dwell time of this wetted zone locally on the surface of said object, thereby removing material from the surface of the object in a controlled manner. One demonstrated manifestation is in the deterministic optical figuring of thin glasses by wet chemical etching using a buffered hydrofluoric acid solution and Marangoni effect.

Rushford, Michael C. (Livermore, CA); Britten, Jerald A. (Oakley, CA)

2004-05-25

184

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

PubMed

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

1994-12-01

185

Assessing Double Acid-Etched Implants Submitted to Orthodontic Forces and Used as Prosthetic Anchorages in Partially Edentulous Patients  

PubMed Central

Abstract: The use of implants as anchorage for orthodontic forces seems to be a good alternative in partially edentulous patients needing orthodontic treatment. This study is aimed at assessing the performance and behavior of microtextured surface endosseous implants obtained by means of a double acid etching against orthodontic forces, as well as their adequacy to be used first as anchorage and later as fixtures for the definitive prosthesis. Materials and Methods: A total of 93 double acid-etched surface parallel wall implants (Osseotite® Implants, Implant Innovations Inc., Palm Beach, Florida, USA) were inserted in 38 partially edentulous patients prior to orthodontic treatment This was carried out by following two-stage surgery protocols in the maxilla as well as in the mandible. After a healing period of six months for the maxilla and four months for the mandible, the implants were used as anchorage for sliding, compression and traction orthodontic forces between 100 to 200 g by means of Ni-TI springs. Bone level and Resonance Frequency Analysis (RFA) were measured before and after the introduction of the orthodontics forces. Results: After removal of the orthodontics appliances, all the implants remained stabile and served as support for prosthetic replacement of missing teeth. The bone level showed no variationeven when a positive difference 0.02 ± 0.38mm was noticed. The RFA scored a significant difference (p? 0.03) between the initial Implant Stability Quotient (ISQ) values (66) and the final ones (68). Conclusions: These findings showed that Osseotite implants were able to support the orthodontic forces applied during this investigation, maintaining osseointegration without significant variation in bone level. Therefore, they can be used to support dental prosthesis once they have been used as orthodontic anchorage under the cited conditions.

de Cravero Marta, Rugani; Carlos, Ibanez Juan

2008-01-01

186

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.

ZHANG, Ying; WANG, Yong

2014-01-01

187

Observation and Study of Dislocation Etch Pits in Molecular Beam Epitaxy Grown Gallium Nitride With the Use of Phosphoric Acid and Molten Potassium Hydroxide.  

National Technical Information Service (NTIS)

Defects continue to challenge the functionality and reliability gallium nitride (GaN)-based devices. GaN grown on sapphire by molecular beam epitaxy was investigated by wet etching in hot phosphoric acid (H3PO4) and molten potassium hydroxide (KOH). Hexag...

F. Semendy U. Lee

2007-01-01

188

Surface Roughness of Acid-Etched and Demineralized Bovine Enamel Measured by a Laser Speckle Method  

Microsoft Academic Search

Bovine enamel was exposed to buffered lactic acid in hydroxyethylcellulose, hydrochloric acid or orthophosphoric acid during different periods. The resulting surface roughness was determined by a laser speckle technique, by a mechanical profilometric instrument, and from SEM stereomicrographs by applying these techniques to the same samples. The methods are compared. The results correspond reasonably well. Exposure of the enamel to

R. A. J. Groenhuis; W. L. Jongebloed; J. J. ten Bosch

1980-01-01

189

Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching.  

PubMed

Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics. PMID:21711891

Timoshenko, Victor Yur'evich; Gonchar, Kirill Alexandrovich; Mirgorodskiy, Ivan Victorovich; Maslova, Natalia Evgen'evna; Nikulin, Valery Eduardovich; Mussabek, Gaukhar Kalizhanovna; Taurbaev, Yerzhan Toktarovich; Svanbayev, Eldos Abugalievich; Taurbaev, Toktar Iskataevich

2011-01-01

190

Effect of electroless etching parameters on the growth and reflection properties of silicon nanowires.  

PubMed

Vertically aligned silicon nanowire (Si NW) arrays have been fabricated over large areas using an electroless etching (EE) method, which involves etching of silicon wafers in a silver nitrate and hydrofluoric acid based solution. A detailed parametric study determining the relationship between nanowire morphology and time, temperature, solution concentration and starting wafer characteristics (doping type, resistivity, crystallographic orientation) is presented. The as-fabricated Si NW arrays were analyzed by field emission scanning electron microscope (FE-SEM) and a linear dependency of nanowire length to both temperature and time was obtained and the change in the growth rate of Si NWs at increased etching durations was shown. Furthermore, the effects of EE parameters on the optical reflectivity of the Si NWs were investigated in this study. Reflectivity measurements show that the 42.8% reflectivity of the starting silicon wafer drops to 1.3%, recorded for 10 µm long Si NW arrays. The remarkable decrease in optical reflectivity indicates that Si NWs have a great potential to be utilized in radial or coaxial p-n heterojunction solar cells that could provide orthogonal photon absorption and enhanced carrier collection. PMID:21389572

Ozdemir, Baris; Kulakci, Mustafa; Turan, Rasit; Unalan, Husnu Emrah

2011-04-15

191

Capillary electrophoresis coupled with electrochemiluminescence detection using porous etched joint.  

PubMed

A new setup to couple capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection is described in which the electrical connection of CE is achieved through a porous section at a distance of 7 mm from the CE capillary outlet. Because the porous capillary wall allowed the CE current to pass through and there was no electric field gradient beyond that section, the influence of CE high-voltage field on the ECL procedure was eliminated. The porous section formed by etching the capillary with hydrofluoric acid after only one side of the circumference of 2-3 mm of polyimide coating of the capillary was removed, while keeping the polyimide coating on the other part to protect the capillary from HF etching makes the capillary joint much more robust since only a part of the circumference of it is etched. A standard three-electrode configuration was used in experiments with Pt wire as a counter electrode, Ag/AgCl as a reference electrode, and a 300-microm diameter Pt disk as a working electrode. Compared with CE-ECL conventional decoupler designs, the present setup with a porous joint has no added dead volume created. Moreover, the dead volume can be increasingly decreased by shortening the distance ( approximately 100 microm) between the working electrode and the end of the separation capillary. The versatility in choice of capillaries and separation buffers within this design is the main advantage over the use of small i.d. capillary and low conductivity buffer in some CE-ECL systems. The performance of this setup is illustrated by the analyses of tripropylamine and proline. PMID:15228365

Yin, Xue-Bo; Qiu, Haibo; Sun, Xiuhua; Yan, Jilin; Liu, Jifeng; Wang, Erkang

2004-07-01

192

Chemical analysis of acidic silicon etch solutions II. Determination of HNO(3), HF, and H(2)SiF(6) by ion chromatography.  

PubMed

The processing of silicon in microelectronics and photovoltaics involves the isotropic chemical etching using HF-HNO(3) mixtures to clean the surface from contaminations, to remove the saw damage, as well as to polish or to texture the wafer surface. Key element of an effective etch process control is the knowledge of the actual etch bath composition in order to maintain a certain etch rate by replenishment of the consumed acids. The present paper describes a methods for the total analysis of the etch bath constituents HF, HNO(3), and H(2)SiF(6) by ion chromatography. First step is the measurement of the total fluoride and nitrate content in the analyte. In a second step, H(2)SiF(6) is precipitated as K(2)SiF(6). After careful filtration of the precipitate, the fluoride concentration in the filtrate is measured and the content of free HF is calculated therefrom. The K(2)SiF(6) is dissolved again and the fluoride content measured and recalculated as H(2)SiF(6). The results obtained with the presented method are discussed with respect to the results from two other, previously published methods, based on a titration using methanolic cyclohexylamine solution as titrant and based on a method using a fluoride ion selective electrode (F-ISE). An evaluation with respect to the needs for an industrial application is given. PMID:19071795

Acker, Jörg; Henßge, Antje

2007-06-15

193

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

PubMed

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

2013-01-01

194

Effects of acid-etching on the tensile properties of demineralized dentin matrix  

Microsoft Academic Search

Objectives. Little research has been done to evaluate the effects of acids commonly used in adhesive dentistry, on the tensile properties of the demineralized dentin matrix. The purpose of this study was to evaluate the effects of a number of acidic conditioners on the ultimate tensile strength (UTS) and modulus of elasticity (E) of human coronal dentin matrix.Methods. Small hour-glass

Yi Zhang; Kelli Agee; Jacques Nör; Ricardo Carvalho; Bhupinder Sachar; Carl Russell; David Pashley

1998-01-01

195

Creation of superhydrophobic stainless steel surfaces by acid treatments and hydrophobic film deposition.  

PubMed

In this work, we present a method to render stainless steel surfaces superhydrophobic while maintaining their corrosion resistance. Creation of surface roughness on 304 and 316 grade stainless steels was performed using a hydrofluoric acid bath. New insight into the etch process is developed through a detailed analysis of the chemical and physical changes that occur on the stainless steel surfaces. As a result of intergranular corrosion, along with metallic oxide and fluoride redeposition, surface roughness was generated on the nano- and microscales. Differences in alloy composition between 304 and 316 grades of stainless steel led to variations in etch rate and different levels of surface roughness for similar etch times. After fluorocarbon film deposition to lower the surface energy, etched samples of 304 and 316 stainless steel displayed maximum static water contact angles of 159.9 and 146.6°, respectively. However, etching in HF also caused both grades of stainless steel to be susceptible to corrosion. By passivating the HF-etched samples in a nitric acid bath, the corrosion resistant properties of stainless steels were recovered. When a three step process was used, consisting of etching, passivation and fluorocarbon deposition, 304 and 316 stainless steel samples exhibited maximum contact angles of 157.3 and 134.9°, respectively, while maintaining corrosion resistance. PMID:22913317

Li, Lester; Breedveld, Victor; Hess, Dennis W

2012-09-26

196

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.

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

2012-01-01

197

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.

2012-11-01

198

Comparative In Vitro Study of the Bond Strength of Composite to Enamel and Dentine Obtained with Laser Irradiation or Acid-etch  

Microsoft Academic Search

. The shear bond strength of composite resin on enamel and dentine was compared after acid-etch or irradiation by Er:YAG and\\u000a Nd:YAP lasers. Forty-eight extracted molars were selected. Dentine and enamel samples were prepared by buccal and lingual\\u000a surface sectioning to expose a plane enamel or dentine surface. Samples (n=12) were randomly assigned to eight groups. In groups 1 and

V. Armengol; A. Jean; P. Weiss; H. Hamel

1999-01-01

199

Effect of acid etching duration on tensile bond strength of composite resin bonded to erbium:yttrium–aluminium–garnet laser-prepared dentine. Preliminary study  

Microsoft Academic Search

The purpose of this study was to compare the tensile bond strength of composite resin bonded to erbium:yttrium–aluminium–garnet\\u000a (Er:YAG) laser-prepared dentine after different durations of acid etching. The occlusal third of 68 human third molars was\\u000a removed in order to expose the dentine surface. The teeth were randomly divided into five groups: group B (control group),\\u000a prepared with bur and

M. Chousterman; D. Heysselaer; S. M. Dridi; F. Bayet; B. Misset; L. Lamard; A. Peremans; C. Nyssen-Behets; S. Nammour

2010-01-01

200

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

Microsoft Academic Search

This study evaluated the effect of cavity preparation using air abrasion or carbide bur on bond strength to enamel treated\\u000a with a self-etching primer (Tyrian SPE) or a phosphoric acid etchant. Twenty-four molars were divided into three groups: high-speed; standard handpiece (ST air abrasion) or supersonic handpiece (SP air abrasion) of the same air-abrasive system. The enamel surfaces were treated

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

2007-01-01

201

The effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of double acid-etched implants  

PubMed Central

Purpose One of the most frequent complications related to dental implants is peri-implantitis, and the characteristics of implant surfaces are closely related to the progression and resolution of inflammation. Therefore, a technical modality that can effectively detoxify the implant surface without modification to the surface is needed. The purpose of this study was to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on the microstructural changes in double acid-etched implant surfaces according to the laser energy and the application duration. Methods The implant surface was irradiated using an Er:YAG laser with different application energy levels (100 mJ/pulse, 140 mJ/pulse, and 180 mJ/pulse) and time periods (1 minute, 1.5 minutes, and 2 minutes). We then examined the change in surface roughness value and microstructure. Results In a scanning electron microscopy evaluation, the double acid-etched implant surface was not altered by Er:YAG laser irradiation under the condition of 100 mJ/pulse at 10 Hz for any of the irradiation times. However, we investigated the reduced sharpness of the specific ridge microstructure that resulted under the 140 mJ/pulse and 180 mJ/pulse conditions. The reduction in sharpness became more severe as laser energy and application duration increased. In the roughness measurement, the double acid-etched implants showed a low roughness value on the valley area before the laser irradiation. Under all experimental conditions, Er:YAG laser irradiation led to a minor decrease in surface roughness, which was not statistically significant. Conclusions The recommended application settings for Er:YAG laser irradiation on double acid-etched implant surface is less than a 100 mJ/pulse at 10 Hz, and for less than two minutes in order to detoxify the implant surface without causing surface modification.

Kim, Ji-Hyun; Herr, Yeek; Chung, Jong-Hyuk; Shin, Seung-Il

2011-01-01

202

Sandblasted-acid-etched titanium surface influences in vitro the biological behavior of SaOS-2 human osteoblast-like cells.  

PubMed

Osseointegrated dental implants have been successfully used over the past several years, allowing functional replacement of missing teeth. Surface properties of titanium dental implants influence bone cell response. Implant topography appears to modulate cell growth and differentiation of osteoblasts thus affecting the bone healing process. Optimal roughness and superficial morphology are still controversial and need to be clearly defined. In the present study we evaluated in vitro the biological behavior of SaOS-2 cells, a human osteoblast-like cell line, cultured on two different titanium surfaces, smooth and sandblasted-acid-etched, by investigating cell morphology, adhesion, proliferation, expression of some bone differentiation markers and extracellular matrix components. Results showed that the surface topography may influence in vitro the phenotypical expression of human osteoblast-like cells. In particular the tested sandblasted-acid-etched titanium surface induced a significantly increased Co I deposition and ?2-?1 receptor expression as compared to the relatively smooth surface, promoting a probable tendency of SaOS-2 cells to shift toward a mature osteoblastic phenotype. It is therefore likely that specific surface properties of sandblasted-acid-etched titanium implants may modulate the biological behavior of osteoblasts during bone tissue healing. PMID:21422669

Ramaglia, Luca; Postiglione, Loredana; Di Spigna, Gaetano; Capece, Gabriele; Salzano, Salvatore; Rossi, Guido

2011-01-01

203

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

PubMed Central

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

Saks?, H; Jakobsen, T; Saks?, M; Baas, J; Jakobsen, SS; Soballe, K

2013-01-01

204

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.

2013-08-01

205

Effect of adhesive hydrophilicity and curing-time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin  

PubMed Central

Objective This study examined the ability of five comonomer blends (R1-R5) of methacrylate-based experimental dental adhesives solvated with 10 mass% ethanol, at reducing the permeability of acid-etched dentin. The resins were light-cured for 20, 40 or 60 s. The acid-etched dentin was saturated with water or 100% ethanol. Method Human unerupted third molars were converted into crown segments by removing the occlusal enamel and roots. The resulting crown segments were attached to plastic plates connected to a fluid-filled system for quantifying fluid flow across smear layer-covered dentin, acid-etched dentin and resin-bonded dentin. The degree of conversion of the resins was measured using Fourier transform infrared spectroscopy. Result Application of the most hydrophobic comonomer blend (R1) to water-saturated dentin produced the smallest reductions in dentin permeability (31.9, 44.1 and 61.1% after light-curing for 20, 40 or 60 s respectively). Application of the same blend to ethanol-saturated dentin reduced permeability of 74.1, 78.4 and 81.2%, respectively (p<0.05). Although more hydrophilic resins produced larger reductions in permeability, the same trend of significantly greater reductions in ethanol-saturated dentin over that of water-saturated dentin remained. This result can be explained by the higher solubility of resins in ethanol vs. water. Significance The largest reductions in permeability produced by resins were equivalent but not superior, to those produced by smear layers. Resin sealing of dentin remains a technique-sensitive step in bonding etch-and-rinse adhesives to dentin.

Cadenaro, Milena; Breschi, Lorenzo; Rueggeberg, Frederick A.; Agee, Kelli; Di Lenarda, Roberto; Carrilho, Marcela; Tay, Franklin R.; Pashley, David H.

2009-01-01

206

Nanoscopic tip sensors fabricated by gas phase etching of optical glass fibers  

NASA Astrophysics Data System (ADS)

Silica-based fiber tips are used in a variety of spectroscopic, micro- or nano-scopic optical sensor applications and photonic micro-devices. The miniaturization of optical sensor systems and the technical implementation using optical fibers can provide new sensor designs with improved properties and functionality for new applications. The selective-etching of specifically doped silica fibers is a promising method in order to form complex photonic micro structures at the end or within fibers such as tips and cavities in various shapes useful for the all-fiber sensor and imaging applications. In the present study, we investigated the preparation of geometrically predefined, nanoscaled fiber tips by taking advantage of the dopant concentration profiles of highly doped step-index fibers. For this purpose, a gas phase etching process using hydrofluoric acid (HF) vapor was applied. The shaping of the fiber tips was based on very different etching rates as a result of the doping characteristics of specific optical fibers. Technological studies on the influence of the etching gas atmosphere on the temporal tip shaping and the final geometry were performed using undoped and doped silica fibers. The influence of the doping characteristics was investigated in phosphorus-, germanium-, fluorine- and boron-doped glass fibers. Narrow exposed as well as protected internal fiber tips in various shapes and tip radiuses down to less than 15 nm were achieved and characterized geometrically and topologically. For investigations into surface plasmon resonance effects, the fiber tips were coated with nanometer-sized silver layers by means of vapour deposition and finally subjected to an annealing treatment.

Bierlich, Jörg; Kobelke, Jens; Brand, David; Kirsch, Konstantin; Dellith, Jan; Bartelt, Hartmut

2012-12-01

207

Large area fabrication of vertical silicon nanowire arrays by silver-assisted single-step chemical etching and their formation kinetics  

NASA Astrophysics Data System (ADS)

Vertically aligned silicon nanowire (SiNW) arrays have been fabricated over a large area using a silver-assisted single-step electroless wet chemical etching (EWCE) method, which involves the etching of silicon wafers in aqueous hydrofluoric acid (HF) and silver nitrate (AgNO3) solution. A comprehensive systematic investigation on the influence of different parameters, such as the etching time (up to 15 h), solution temperature (10–80?°C), AgNO3 (5–200 mM) and HF (2–22 M) concentrations, and properties of the multi-crystalline silicon (mc-Si) wafers, is presented to establish a relationship of these parameters with the SiNW morphology. A linear dependence of the NW length on the etch time is obtained even at higher temperature (10–50?°C). The activation energy for the formation of SiNWs on Si(100) has been found to be equal to ?0.51 eV . It has been shown for the first time that the surface area of the Si wafer exposed to the etching solution is an important parameter in determining the etching kinetics in the single-step process. Our results establish that single-step EWCE offers a wide range of parameters by means of which high quality vertical SiNWs can be produced in a very simple and controlled manner. A mechanism for explaining the influence of various parameters on the evolution of the NW structure is discussed. Furthermore, the SiNW arrays have extremely low reflectance (as low as <3% for Si(100) NWs and <12% for mc-Si NWs) compared to ?35% for the polished surface in the 350–1000 nm wavelength range. The remarkably low reflection surface of SiNW arrays has great potential for use as an effective light absorber material in novel photovoltaic architectures, and other optoelectronic and photonic devices.

Srivastava, Sanjay K.; Kumar, Dinesh; Schmitt, S. W.; Sood, K. N.; Christiansen, S. H.; Singh, P. K.

2014-05-01

208

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

PubMed

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

2014-01-01

209

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

PubMed Central

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.

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

2014-01-01

210

FEM3 Modeling of Ammonia and Hydrofluoric Acid Dispersion.  

National Technical Information Service (NTIS)

FEM3 is a three-dimensional computer model that was designed to simulate the atmospheric dispersion of heavier-than-air gas releases. Recently a phase-change submodel based on local thermodynamic equilibrium has been implemented to treat vapor-liquid tran...

D. N. Blewitt H. C. Rodean S. T. Chan

1987-01-01

211

Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid.  

National Technical Information Service (NTIS)

The report 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 restric...

T. M. Swager

2004-01-01

212

Biomechanical evaluation of the interfacial strength of a chemically modified sandblasted and acid-etched titanium surface.  

PubMed

The functional capacity of osseointegrated dental implants to bear load is largely dependent on the quality of the interface between the bone and implant. Sandblasted and acid-etched (SLA) surfaces have been previously shown to enhance bone apposition. In this study, the SLA has been compared with a chemically modified SLA (modSLA) surface. The increased wettability of the modSLA surface in a protein solution was verified by dynamic contact angle analysis. Using a well-established animal model with a split-mouth experimental design, implant removal torque testing was performed to determine the biomechanical properties of the bone-implant interface. All implants had an identical cylindrical shape with a standard thread configuration. Removal torque testing was performed after 2, 4, and 8 weeks of bone healing (n = 9 animals per healing period, three implants per surface type per animal) to evaluate the interfacial shear strength of each surface type. Results showed that the modSLA surface was more effective in enhancing the interfacial shear strength of implants in comparison with the conventional SLA surface during early stages of bone healing. Removal torque values of the modSLA-surfaced implants were 8-21% higher than those of the SLA implants (p = 0.003). The mean removal torque values for the modSLA implants were 1.485 N m at 2 weeks, 1.709 N m at 4 weeks, and 1.345 N m at 8 weeks; and correspondingly, 1.231 N m, 1.585 N m, and 1.143 N m for the SLA implants. The bone-implant interfacial stiffness calculated from the torque-rotation curve was on average 9-14% higher for the modSLA implants when compared with the SLA implants (p = 0.038). It can be concluded that the modSLA surface achieves a better bone anchorage during early stages of bone healing than the SLA surface; chemical modification of the standard SLA surface likely enhances bone apposition and this has a beneficial effect on the interfacial shear strength. PMID:16637025

Ferguson, S J; Broggini, N; Wieland, M; de Wild, M; Rupp, F; Geis-Gerstorfer, J; Cochran, D L; Buser, D

2006-08-01

213

Microstructure of CdTe thin films after mixed nitric and phosphoric acids etching and (HgTe, CuTe)-graphite pasting  

Microsoft Academic Search

We report on our investigation of the microstructure and composition of the surface of CdTe films after mixed nitric and phosphoric (NP) acids etching, (HgTe, CuTe)-graphite pasting, and thermal annealing. We find that after this process, a thin layer of CdxHg1?xTe forms between the CdTe and Te-rich layers, giving a structure of CdTe\\/CdxHg1?xTe\\/Te. High-resolution electron microscopy reveals that the CdxHg1?xTe

Yanfa Yan; K. M. Jones; X. Wu; M. M. Al-Jassim

2005-01-01

214

Continuous-flow Mass Production of Silicon Nanowires via Substrate-Enhanced Metal-Catalyzed Electroless Etching of Silicon with Dissolved Oxygen as an Oxidant  

NASA Astrophysics Data System (ADS)

Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods.

Hu, Ya; Peng, Kui-Qing; Liu, Lin; Qiao, Zhen; Huang, Xing; Wu, Xiao-Ling; Meng, Xiang-Min; Lee, Shuit-Tong

2014-01-01

215

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

Microsoft Academic Search

The formation of a superficial layer of tiny flakes has been observed on teeth prepared by Erbium lasers. It has been suggested\\u000a that removing this layer (mechanically or chemically) may increase the bond strength of the resin composite. The purpose of\\u000a this study is to evaluate the effect of various etching times on bond strength of resin composite to enamel

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

2010-01-01

216

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

PubMed

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

2010-05-01

217

Acidizing: A well completion reference  

SciTech Connect

Acidizing removes near-wellbore formation damage by dissolving or bypassing drilling mud, completion fluid or other restrictions. These treatments include matrix pump rate jobs, washes and chemical injection. Matrix stimulation techniques are performed without fracturing reservoir rock. Acid is used to remove drilling, completion, workover or production damage. Solvents and surfactants like crude, condensate, diesel or mutual solvents are used to change pore fluid or formation wettability characteristics. Washes remove scale and other dispersible or soluble material from formations, perforations and casing. The purpose of the above methods is to improve well productivity by removing or mitigating formation damage. Hydrofluoric (HF) acid dissolves clay and fine particles in sandstones. Hydrochloric (HCl) acid etches wormholes that bypass damage in carbonates. Products are subdivided into groups that have similar function and performance. Where applicable, groups have been subdivided to reflect significant differences in additive chemical nature to emphasize uniqueness in the product lines of each company. Products and additives are grouped in 28 categories: water-base completion fluids; water-base polymers; friction reducers; fluid loss; diverting agents; polymer plugs; acid inhibitors; acid retarders; emulsifiers; clay stabilizers; surfactants; non-emulsifiers; fines suspender; anti-sludge agent; foamers; scale inhibitors; iron (Fe) control; oxygen scavenger; mutual solvents; corrosion inhibitors; paraffin control; miscellaneous products; acid systems; retarded acid system; mud acid plus surfactants; mud acid plus alcohol; SGMA; and retarded HF.

NONE

1997-11-01

218

Effect of acid and laser etching on shear bond strength of conventional and resin-modified glass-ionomer cements to composite resin.  

PubMed

Success in sandwich technique procedures can be achieved through an acceptable bond between the materials. The aim of this study was to compare the effect of 35% phosphoric acid and Er,Cr:YSGG laser on shear bond strength of conventional glass-ionomer cement (GIC) and resin-modified glass-ionomer cement (RMGIC) to composite resin in sandwich technique. Sixty-six specimens were prepared from each type of glass-ionomer cements and divided into three treatment groups as follows: without pretreatment, acid etching by 35% phosphoric acid for 15 s, and 1-W Er,Cr:YSGG laser treatment for 15 s with a 600-?m-diameter tip aligned perpendicular to the target area at a distance of 1 mm from the surface. Energy density of laser irradiation was 17.7 J/cm(2). Two specimens in each group were prepared for evaluation under a scanning electron microscope (SEM) after surface treatment and the remainder underwent bonding procedure with a bonding agent and composite resin. Then the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Two-factor analysis of variance and post-hoc Tukey test showed that the cement type, surface treatment method, and the interaction of these two factors significantly affect the shear bond strength between glass-ionomer cements and composite resin (p < 0.05). Surface treatment with phosphoric acid or Er,Cr:YSGG laser increased the shear bond strength of GIC to composite resin; however, in RMGIC only laser etching resulted in significantly higher bond strength. These findings were supported by SEM results. The fracture mode was evaluated under a stereomicroscope at ×20. PMID:21234634

Navimipour, Elmira Jafari; Oskoee, Siavash Savadi; Oskoee, Parnian Alizadeh; Bahari, Mahmoud; Rikhtegaran, Sahand; Ghojazadeh, Morteza

2012-03-01

219

Morphological Study on Porous Silicon Carbide Membrane Fabricated by Double-Step Electrochemical Etching  

NASA Astrophysics Data System (ADS)

The structure of porous silicon carbide membranes that peeled off spontaneously during electrochemical etching was studied. They were fabricated from n-type 6H SiC(0001) wafers by a double-step electrochemical etching process in a hydrofluoric electrolyte. Nanoporous membranes were obtained after double-step etching with current densities of 10--20 and 60--100 mA/cm2 in the first and second steps, respectively. Microporous membranes were also fabricated after double-step etching with current densities of 100 and 200 mA/cm2. It was found that the pore diameter is influenced by the etching current in step 1, and that a higher current is required in step 2 when the current in step 1 is increased. During the etching processes in steps 1 and 2, vertical nanopore and lateral crack formations proceed, respectively. The influx pathway of hydrofluoric solution, expansion of generated gases, and transfer limitation of positive holes to the pore surface are the key factors in the peeling-off mechanism of the membrane.

Omiya, Takuma; Tanaka, Akira; Shimomura, Masaru

2012-07-01

220

Metallurgical factors influencing the corrosion of aluminum, Al-Cu, and Al-Si alloy thin films in dilute hydrofluoric solution  

Microsoft Academic Search

The corrosion behavior of sputter-deposited Al, Al-Cu, and Al-Si alloy thin films in dilute hydrofluoric (HF) acid solution\\u000a was investigated. These materials maintain a thin aluminum oxide film in dilute HF solutions and, consequently, are susceptible\\u000a to localized corrosion. Pit densities increase for the alloys with Cu and, to a lesser extent, Si additions. Open circuit\\u000a potentials (OCP) are more

J. R. Scully; D. E. Peebles; A. D. Romig; D. R. Frear; C. R. Hills

1992-01-01

221

Process for etching mixed metal oxides  

DOEpatents

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

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

1994-10-18

222

Process for etching mixed metal oxides  

DOEpatents

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

Ashby, Carol I. H. (Edgewood, NM); Ginley, David S. (Evergreen, CO)

1994-01-01

223

Etch Pits on Calcite Cleavage Faces  

Microsoft Academic Search

THIS communication describes some of the effects observed on calcite cleavage faces after etching with dilute acid. Puchegger1 has reported etch pits which formed a rib-like pattern on either side of scratch marks made on calcite. More striking features are described here.

H. Watts

1959-01-01

224

Effects of machined/turned, TiO2-blasted and sandblasted/acid-etched titanium oral implant surfaces on nerve conduction: a study on isolated rat sciatic nerves.  

PubMed

The purpose of this study was to explore the clinical relevance of the effects of machined/turned, TiO(2)-blasted and sandblasted/acid-etched titanium oral implant surfaces on nerve conduction. Isolated rat sciatic nerves were placed between two suction electrodes in a pyrex bath containing a tyrode solution. Evoked compound action potentials (cAPs) of the nerves were recorded before and after contact with the implants. The mandibular incisors of randomly selected animals were extracted and changes in cAP amplitudes were used as controls. The differences in final cAP values of Astra Tech implants and rat natural teeth were insignificant (P < 0.05), whereas the differences between other groups were significant (P < 0.05). Machined/turned-surface implants did not cause any change in cAPs. A slight decrease in cAPs was observed for TiO(2)-blasted and sandblasted/acid-etched implants, and the natural teeth. The reductions of cAPs in latter groups were not 50% after an application time of 300 min. The cAP changes of nerves contacting TiO(2)-blasted and sandblasted/acid-etched oral implants fall within physiologic limits in vitro. Machined/turned, TiO(2)-blasted, and sandblasted/acid-etched titanium implant surfaces do not lead to irreversible neurotoxic effects. PMID:14598405

Onur, Mehmet A; Cehreli, Murat Cavit; Ta?, Zeynep; Sahin, Saime

2003-11-15

225

Rapid formation of AgnX(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction  

NASA Astrophysics Data System (ADS)

This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation.This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation. Electronic supplementary information (ESI) available: Detailed experimental procedures, additional SEM images, XRD pattern. See DOI: 10.1039/c4nr00364k

Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

2014-05-01

226

Effective Light Absorptive Layer Using Mezo-Porous Silicon by Electrochemical Etching  

NASA Astrophysics Data System (ADS)

Porous silicon (PS), an excellent light diffuser, can be used as an antireflective layer that does not need to be coated with other antireflection coating (ARC) materials. PS layers were obtained by electrochemical etching (ECE) anodization of silicon wafers in hydrofluoric acid/ethanol/deionized (DI) water solution (HF/EtOH/H2O). This technique selectively removes Si atoms from the sample surface, forming a PS layer with adjustable optical, electrical, and mechanical properties. A PS layer with optimal antireflection characteristics was obtained for a charge density (Q) of 5.2 C/cm2. The weighted reflectance was reduced from 24 to 4% in the wavelength range from 400 to 1000 nm. The weighted reflectance with optimized PS layers is much less than that with a commercial SiNX ARC on a potassium hydroxide (KOH) pretextured multicrystalline silicon (mc-Si) surface. Therefore, it can be successfully used as an alternative way for the preparation of a PS antireflective layer for a silicon solar cell.

Kwon, Jae?Hong; Lee, Soo?Hong; Ju, Byeong?Kwon

2006-04-01

227

Rapid formation of AgnX(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction.  

PubMed

This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation. PMID:24744113

Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

2014-06-01

228

Effect of dehiscences to the bone response of implants with an Acid-etched surface: an experimental study in miniature pigs.  

PubMed

Spontaneous early exposure of submerged implants during the healing phase as a factor for early crestal bone loss around the implants is still being controversially discussed. The aim of this study was to examine the potential impact of dehiscences on the osseointegration process of acid-etched dental implants with a shortened healing period in the maxilla. Five animals received a total of 15 titanium implants 8 weeks postextraction. Eight of these implants were placed in the maxilla to osseointegrate within a shortened healing period of 3 months, whereas the remaining implants were inserted in the lower jaw and served as controls with a regular healing time. Polyfluorochrome sequential labeling with xylenol orange, calcein green, and alizarin complexone was performed 2, 5, and 8 weeks after implant placement. After 12 weeks of unloaded and submerged healing, the animals were killed and the implants removed en bloc. After the processing of the undecalcified PMMA-embedded samples, thin ground sections (40-60 µm) were made. The histomorphometric determination of the bone-to-implant contact (BIC) was calculated using light microscopy. The peri-implant bone apposition rate and the direction of bone growth were determined with the fluorescence microscope. For statistical evaluation, the Mann-Whitney U test, Wilcoxon signed ranks test, and Friedman test were chosen. During the healing period, nonartificial dehiscences were observed at 9 implants. The average BIC was 54.19% (14.51%-68.97%). There were significantly lower BIC rates detected for the cervical part of the implants compared with the middle part. An influence of dehiscences on the osseointegration could not be proven. There were no significant differences between the BIC values of the upper and lower jaw. During the observation period from the third to the eighth week after implantation, the average new bone formation rate was 2.32 µm/d (1.76-2.82 µm/d). During this period, the amount of new bone growth decreased insignificantly. Based on the sequence of the polyfluorochrome labeling, an implantopetal (53.03%) as well as an implantofugal bone growth (46.97%) have been observed. It could be assumed that the acid-etched implants offered a prerequisite to osseointegrate under a shortened healing period. The observed dehiscences seemed not to have compromised the rate of osseointegration. PMID:20557147

Ruehe, Baerbel; Heberer, Susanne; Bayreuther, Katja; Nelson, Katja

2011-01-01

229

Spectrometric analysis of process etching solutions of the photovoltaic industry--determination of HNO3, HF, and H2SiF6 using high-resolution continuum source absorption spectrometry of diatomic molecules and atoms.  

PubMed

The surface of raw multicrystalline silicon wafers is treated with HF-HNO(3) mixtures in order to remove the saw damage and to obtain a well-like structured surface of low reflectivity, the so-called texture. The industrial production of solar cells requires a consistent level of texturization for tens of thousands of wafers. Therefore, knowing the actual composition of the etch bath is a key element in process control in order to maintain a certain etch rate through replenishment of the consumed acids. The present paper describes a novel approach to quantify nitric acid (HNO(3)), hydrofluoric acid (HF), and hexafluosilicic acid (H(2)SiF(6)) using a high-resolution continuum source graphite furnace absorption spectrometer. The concentrations of Si (via Si atom absorption at the wavelength 251.611 nm, m(0),(Si)=130 pg), of nitrate (via molecular absorption of NO at the wavelength 214.803 nm, [Formula: see text] ), and of total fluoride (via molecular absorption of AlF at the wavelength 227.46 nm, m(0,F)=13 pg) were measured against aqueous standard solutions. The concentrations of H(2)SiF(6) and HNO(3) are directly obtained from the measurements. The HF concentration is calculated from the difference between the total fluoride content, and the amount of fluoride bound as H(2)SiF(6). H(2)SiF(6) and HNO(3) can be determined with a relative uncertainty of less than 5% and recoveries of 97-103% and 96-105%, respectively. With regards to HF, acceptable results in terms of recovery and uncertainty are obtained for HF concentrations that are typical for the photovoltaic industry. The presented procedure has the unique advantage that the concentration of both, acids and metal impurities in etch solutions, can be routinely determined by a single analytical instrument. PMID:22608457

Bücker, Stefan; Acker, Jörg

2012-05-30

230

Interface shear strength of titanium implants with a sandblasted and acid-etched surface: a biomechanical study in the maxilla of miniature pigs.  

PubMed

The purpose of the present study was to evaluate the interface shear strength of unloaded titanium implants with a sandblasted and acid-etched (SLA) surface in the maxilla of miniature pigs. The two best documented surfaces in implant dentistry, the machined and the titanium plasma-sprayed (TPS) surfaces served as controls. After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the interface shear strength of each implant type. The results revealed statistically significant differences between the machined and the two rough titanium surfaces (p <.00001). The machined surface demonstrated mean removal torque values (RTV) between 0.13 and 0.26 Nm, whereas the RTV of the two rough surfaces ranged between 1.14 and 1.56 Nm. At 4 weeks of healing, the SLA implants yielded a higher mean RTV than the TPS implants (1.39 vs. 1. 14 Nm) without reaching statistical significance. At 8 and 12 weeks of healing, the two rough surfaces showed similar mean RTVs. The implant position also had a significant influence on removal torques for each implant type primarily owing to differences in density in the periimplant bone structure. It can be concluded that the interface shear strength of titanium implants is significantly influenced by their surface characteristics, since the machined titanium surface demonstrated significantly lower RTV in the maxilla of miniature pigs compared with the TPS and SLA surfaces. PMID:10397960

Buser, D; Nydegger, T; Oxland, T; Cochran, D L; Schenk, R K; Hirt, H P; Snétivy, D; Nolte, L P

1999-05-01

231

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

PubMed Central

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

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

2011-01-01

232

An analysis of the shear strength of the bond between enamel and porcelain laminate veneers with different etching systems: acid and Er,Cr:YSGG laser separately and combined  

Microsoft Academic Search

Conditioning of the enamel surface is now an accepted and widely applied technique used to improve retention in porcelain\\u000a laminate veneer restorations. The aim of this study was to evaluate strength of the bond between porcelain laminate veneers\\u000a and tooth surfaces etched with acid and laser, separately and together. The teeth studied comprised 60 incisors extracted\\u000a for periodontal reasons. These

Berivan Dundar; Kahraman Gündüz Guzel

233

Er:YAG laser radiation etching of enamel  

NASA Astrophysics Data System (ADS)

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

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

1996-12-01

234

Impact of Citric Acid Etching on Biocompatibility and Osseous Organisation of a Natural Bovine Bone Mineral: Preliminary Results of an In-Vitro\\/In-Vivo Study  

Microsoft Academic Search

\\u000a Within the last years it was shown that etching of biomaterials can improve hydrophilicity and cell proliferation which in\\u000a turn may accelerate the osseointegration of implants. The aim of the present study was to evaluate the influence of superficial\\u000a etching of a xenogenous bone mineral on cell proliferation and bone regeneration. A granular bone substitute material [BSM]\\u000a (Cerabone® [CB], botiss

D. Rothamel; F. Schwarz; M. Herten; K. Berndsen; T. Fienitz; L. Ritter; T. Dreiseidler; J. Zöller

235

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.

1991-01-01

236

Bone-added osteotome sinus floor elevation with simultaneous placement of non-submerged sand blasted with large grit and acid etched implants: a 5-year radiographic evaluation  

PubMed Central

Purpose Implant survival rates using a bone-added osteotome sinus floor elevation (BAOSFE) procedure with simultaneous placement of a non-submerged sand blasted with large grit and acid etched (SLA) implant are well documented at sites where native bone height is less than 5 mm. This study evaluated the clinical results of non-submerged SLA Straumann implants placed at the time of the BAOSFE procedure at sites where native bone height was less than 4 mm. Changes in graft height after the BAOSFE procedure were also assessed using radiographs for 5 years after the implant procedure. Methods The BAOSFE procedure was performed on 4 patients with atrophic posterior maxillas with simultaneous placement of 7 non-submerged SLA implants. At least 7 standardized radiographs were obtained from each patient as follows: before surgery, immediately after implant placement, 6 months after surgery, every year for the next 3 years, and after more than 5 years had passed. Clinical and radiographic examinations were performed at every visit. Radiographic changes in graft height were calculated with respect to the implant's known length and the original sinus height. Results All implants were stable functionally, as well as clinically and radiographically, during the follow-up. Most of the radiographic reduction in the grafted bone height occurred in the first 2 years; reduction after 2 years was slight. Conclusions The simultaneous placement of non-submerged SLA implants using the BAOSFE procedure is a feasible treatment option for patients with severe atrophic posterior maxillas. However, the grafted bone height is reduced during the healing period, and patients must be selected with care.

Jung, Jee-Hee; Choi, Seong-Ho; Cho, Kyoo-Sung

2010-01-01

237

Influence of asymmetric etching on ion track shapes in polycarbonate  

NASA Astrophysics Data System (ADS)

By combining low-energy ion irradiation with asymmetric etching, conical nanopores of controlled geometry can be etched in polycarbonate (PC). Cone bases vary from 0.5 to 1 ?m. Top diameters down to 17 nm are reached. When etching from one side, the pH on the other side (bathed in neutral or acidic buffer) was monitored. Etching temperature ranged from 65 °C to 80 °C. Pore shape characterization was achieved by electro replication combined with SEM observation. The tip shape depended on whether an acidic buffer was used or not on the stopped side.

Clochard, M.-C.; Wade, T. L.; Wegrowe, J.-E.; Balanzat, E.

2007-12-01

238

Titrimetric determination of silicon dissolved in concentrated HF-HNO3-etching solutions.  

PubMed

The wet chemical etching of silicon by concentrated HF-HNO(3) mixtures in solar and semiconductor wafer fabrication requires the strict control of the etching conditions. Surface morphology and etch rates are mainly affected by the amount of dissolved silicon, that is continuously enriched in the etching solution with each etching run. A fast and robust method for the titrimetric determination of the total dissolved silicon content out of the concentrated etching solution is presented. This method is based on the difference between the two equivalence points of the total amount of acid and the hydrolysis of the hexafluorosilicic anion. This approach allows a silicon determination directly from the etching process in spite of the presence of dissolved nitric oxides in the etching solution. The influences of different acid mixing ratios and of the etching solution density depending on the silicon content is considered and discussed in detail. PMID:18970360

Henssge, Antje; Acker, Jörg; Müller, Constanze

2006-01-15

239

New look at sandstone acidizing  

Microsoft Academic Search

The acid mutual solvent (AMS) technique is a 3-step process which involves a preflush, a mixed HF-HCl stage, and an afterflush employing the mutual solvent. The preflush is normally regular hydrochloric acid (15% HCl). This step is designed to serve as a buffer between formation water and hydrofluoric acid. Normally an adequate preflush is 50 gal of regular acid per

Gidley

1973-01-01

240

Plasma atomic layer etching  

Microsoft Academic Search

Summary form only given. The thinning of the dielectric in the metal (and non-metal) gate stacks and the need to resolve etching on an atomic layer basis present large technological challenges. Conventional plasma processes which utilize reactive ion etching typically do not have sufficient controllability to achieve atomic layer resolution and to avoid damage. To ensure atomic-level control it is

A. Agarwal; M. J. Kushner

2006-01-01

241

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.

2006-03-01

242

In vivo Remineralization of Etched Human and Rat Enamel  

Microsoft Academic Search

A method is described for observation of in vivo reminerahzation after acid etching of human and rat teeth under standardized conditions. Surface morphology was studied on SEM pictures (× 300–10,000). Three types of etch patterns were encountered varying from tooth to tooth and from surface to surface. In general, two different reminerahzation patterns were found in human enamel characterized by

P. Gängler; I. Hoyer

1984-01-01

243

Incinerator ash dissolution model for the system: Plutonium, nitric acid and hydrofluoric acid  

SciTech Connect

This research accomplished two goals. The first was to develop a computer program to simulate a cascade dissolver system. This program would be used to predict the bulk rate of dissolution in incinerator ash. The other goal was to verify the model in a single-stage dissolver system using Dy/sub 2/O/sub 3/. PuO/sub 2/ (and all of the species in the incinerator ash) was assumed to exist as spherical particles. A model was used to calculate the bulk rate of plutonium oxide dissolution using fluoride as a catalyst. Once the bulk rate of PuO/sub 2/ dissolution and the dissolution rate of all soluble species were calculated, mass and energy balances were written. A computer program simulating the cascade dissolver system was then developed. Tests were conducted on a single-stage dissolver. A simulated incinerator ash mixture was made and added to the dissolver. CaF/sub 2/ was added to the mixture as a catalyst. A 9M HNO/sub 3/ solution was pumped into the dissolver system. Samples of the dissolver effluent were analyzed for dissolved and F concentrations. The computer program proved satisfactory in predicting the F concentrations in the dissolver effluent. The experimental sparge air flow rate was predicted to within 5.5%. The experimental percentage of solids dissolved (51.34%) compared favorably to the percentage of incinerator ash dissolved (47%) in previous work. No general conclusions on model verification could be reached. 56 refs., 11 figs., 24 tabs.

Brown, E V

1988-06-01

244

Separation of Metal Ions by Anion Exchange in Mixtures of Hydrochloric Acid and Hydrofluoric Acid.  

National Technical Information Service (NTIS)

Distribution coefficients were determined for the adsorption of more than 40 elements on anion-exchange resins from mixtures of HCl (0.1 to 12M) and HF (0.1-8M). Two resins, Dowex 1 x 10, 200 to 400 mesh and Dowex 1 x 4, 100 to 200 mesh, were used. Distri...

J. P. Faris

1978-01-01

245

Etching of enamel for direct bonding with a thulium fiber laser  

Microsoft Academic Search

Background: Laser etching of enamel for direct bonding can decrease the risk of surface enamel loss and demineralization which are the adverse effects of acid etching technique. However, in excess of +5.5°C can cause irreversible pulpal responses. In this study, a 1940- nm Thulium Fiber Laser in CW mode was used for laser etching. Aim: Determination of the suitable Laser

Ayse S. Kabas Sarp; Murat Gülsoy

2011-01-01

246

Dry Etching for Micromachining Applications  

Microsoft Academic Search

\\u000a Dry etching processes provide the tools to machine precision high-aspect-ratio structures that form the basic building blocks\\u000a of microelectromechanical systems. Dry etching processes consist of (1) purely chemical (spontaneous gas phase etching), (2)\\u000a purely physical (ion beam etching or ion milling), and (3) a combination of both methods (reactive ion or plasma etching)\\u000a for the controlled removal of desired substrate

Srinivas Tadigadapa; Franz Lärmer

247

Plasma etching in semiconductor fabrication  

SciTech Connect

The contents of this book are: Introduction; Plasma Excitation and Reactor Design; Silicon and Silicon Dioxide Etching in Plasmas; Aluminium Etching in Chlorinated Plasmas; The Plasma Etching of III/V Compound Semiconductors; Operating Frequency and the Plasma; Probe Characteristics and Plasma Measurements of an Electrotech Planar Plasma Etcher; The RF Voltage/Current Characteristics and Related DC Negative Bias Properties of an Electrotech Flat Bed Planar Plasma Etcher; and Methods of Reducing the Etch Rate of Positive Photoresist Masks During Plasma Etching.

Morgan, R.A.

1985-01-01

248

Machine for electrochemical etch stop  

NASA Astrophysics Data System (ADS)

The configurations of electrochemical silicon etch-stop are discussed in this paper. An electrochemical etching machine with software and hardware, which can control the etching process of silicon very well, is designed and fabricated bas don the theory of electrochemical etching. Accurate etching temperature is obtained by modified integral algorithm of PID presented in temperature control in software. With an algorithm presented in control of etch-stop, the tech-stop point can be detected according to the characteristics of p- n junction current-time in electrochemical etching. The machine with hardware including S/H, controller and actuator can adapt to all wet etching configurations such as poly- electrode electrochemical etch-stop.

Zhou, Kun; Lan, Mujie; Chen, Weiping; Wang, Donghong

2001-09-01

249

Effect of Ethylene diamine tetra acetic acid and sodium hypochlorite solution conditioning on microtensile bond strength of one-step self-etch adhesives  

PubMed Central

Background: Attempts to improve bond strength of self-etch adhesives can enhance the durability of composite restorations. Aims: The aim of the present study was to evaluate the effect of collagen and smear layer removal with sodium hypochlorite solution (NaOCl) and EDTA on micro-tensile bond strength (?TBS) of self-etch adhesives to dentin. Settings and Design: It was an in-vitro study. Materials and Methods: Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers’ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5°C and 55°C, the samples were sectioned and tested for ?TBS. Statistical Analysis: Data were analyzed by two-way ANOVA and Tukey-HSD test. Results: The highest ?TBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. ?TBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups. Conclusions: Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased ?TBS.

Kasraei, Shahin; Azarsina, Mohadese; Khamverdi, Zahra

2013-01-01

250

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.

1986-01-01

251

Etching fission tracks in zircons  

USGS Publications Warehouse

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

Naeser, C. W.

1969-01-01

252

Valutazione del Trattamento Superficiale Sulle Prestazioni Meccaniche a Fatica di Impianti in Titanio Plasma-Sprayed e Titanio Sabbiato e Mordenzato (Evaluation of Surface Treatment on Mechanical Fatigue Performance of Titanium Plasma-Sprayed and Sandblasted Large-Grid and Acid-Etched Titanium Dental Implants).  

National Technical Information Service (NTIS)

This study describes the mechanical fatigue performance of two different commercial dental implant groups. Titanium Plasma-Sprayed (TPS) and Sandblasted Large-grid and Acid-etched (SLA) dental implants were tested and the apical end of each implant was ve...

R. Bedini G. De Angelis G. Di Cintio R. Lelapi M. Tallarico U. Romeo

2001-01-01

253

Flame etching enhances the sensitivity of carbon-fiber microelectrodes.  

PubMed

Small sensors are useful for in vivo measurements and probing small spaces. In this paper, we compare two methods of fabrication of small, cylindrical carbon-fiber microelectrodes: flame-etching and electrochemical etching. With both methods, microelectrodes can be fabricated with tip diameters of 1 to 3 microm. Electrodes were tested with fast-scan cyclic voltammetry. Flame etching resulted in electrodes that have larger S/N ratios and higher currents per unit area for 1 microM dopamine than normal carbon-fiber microelectrodes or electrochemically etched electrodes. Therefore, the increased sensitivity is not just a property of size. The flame-etched surfaces had nanometer-scale surface features that were not observed on the other electrodes and exhibited increased sensitivity for other electroactive compounds found in the brain, including ascorbic acid, DOPAC, and serotonin. Faster kinetics and a faster response to a step change in dopamine were also observed, when the applied waveform was -0.4 to 1.0 V and back at 400 V/s. The sensitivity of the flame-etched electrodes was enhanced by overoxidizing the surface. The flame-etched electrodes were used to detect dopamine release in anesthetized rats after a single stimulation pulse. The small flame-etched electrodes will facilitate measurements of low concentrations in discrete brain regions or small organisms. PMID:18416534

Strand, Andrew M; Venton, B Jill

2008-05-15

254

Total etch technique and cavity isolation.  

PubMed

In the total etch technique for chemically adhesive composite restorations, the phosphoric acid penetrates only 10 microns or less into the vital dentin with the dentinal tubules being filled with the odontoblast processes. The acid is completely removed by subsequent air-water jet spray washing. The tubule apertures are perfectly sealed by the protective bonding agent layer with the resin tags adhering to the tubule walls and the resin-impregnated dentin surface. Isolation of the cavity from moisture contamination is required for only less than a few seconds after drying the etched cavity until the bonding agent coating and after this coating until the composite resin placement. Such a short time for isolation is quite easy even without a rubber dam when a trained assistant is cooperating. PMID:1389356

Fusayama, T

1992-01-01

255

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

2005-01-01

256

Containment of nitric acid solutions of Plutonium-238  

NASA Astrophysics Data System (ADS)

The corrosion of various metals that could be used to contain nitric acid solutions of Pu-238 has been studied. Tantalum and tantalum/2.5% tungsten resisted the test solvent better than 304L stainless steel and several INCONEL alloys. The solvent used to imitate nitric acid solutions of Pu-238 contained 70% nitric acid, hydrofluoric acid, and ammonium hexanitratocerate.

Reimus, M. A. H.; Silver, G. L.; Pansoy-Hjelvik, L.; Ramsey, K. B.

1999-01-01

257

Chemical etching of crystal and thin film cadmium telluride  

NASA Astrophysics Data System (ADS)

Single crystal p-CdTe and thin film p-CdTe, made by an air annealing of electrodeposited n-CdTe, were subjected to chemical etching by bromine in methanol (BM) and by potassium dichromate-sulphuric acid (KD). XPS and SIMS gave both qualitative and quantitative information on the effects. Etch rates were determined. For the concentrations examined, KD etched more rapidly than BM etched, and gave much deeper Cd depletion regions. In films which had been BM etched and washed, Br was present throughout the film. After KD etching, a very small amount of Cr was still present in films. The results indicate that the etchants travel along grain boundaries. Both etches left surfaces rich in Te 0. In addition, BM produced CdBr 2 and TeBr 4, both removable by washing. Varying the concentration of BM did not increase the maximum depletion depth of 2 nm. Diluting KD reduced the Cd depletion region. Conditions to give a desired Cd depletion depth were established.

Danaher, W. J.; Lyons, L. E.; Marychurch, M.; Morris, G. C.

1986-12-01

258

Selective Etching of Semiconductor Glassivation  

NASA Technical Reports Server (NTRS)

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

Casper, N.

1982-01-01

259

Atomic layer etching of germanium  

Microsoft Academic Search

Atomic layer etching of Ge has been investigated experimentally based on the surface chemistry that Cl can adsorb on the clean Ge surface at room temperature and desorb thermally as GeCl2 at high temperatures. The ideal etching rate of one monolayer per cycle has been achieved. The critical Cl2 dosage for the saturated etching rate was about 7.2×106 L. Increase

Keiji Ikeda; Shigeru Imai; Masakiyo Matsumura

1997-01-01

260

Absorption of ammonia on tantalum hydroxide synthesized by a hydrofluoric acid method  

Microsoft Academic Search

Ammonia is strongly absorbed on tantalum hydroxide prepared by ammonia neutralization of TaF7\\u000a 2? or TaF6\\u000a ? complexes. FTIR analysis of tantalum hydroxide shows a characteristic peak around 1,400 cm?1, attributed to NH4\\u000a +. TG and FTIR analyses show that the NH4\\u000a + decomposes at about 500 °C. The correct chemical formula of tantalum hydroxide prepared by ammonia neutralization of TaF7\\u000a 2?

Deming Zhao; Heng Jiang; Hong Gong; Tingting Su

2011-01-01

261

RATES OF DISSOLUTION AND PASSIVATION OF HAFNIUM-FREE ZIRCONIUM IN HYDROFLUORIC ACID  

Microsoft Academic Search

The dissolution reaction of Zr in HF is: Zr + 4H\\/sup +\\/ yields and ; under the conditions of the experiments is much faster than that of Tl, and is a ; linear friction of the HF concentration (up to N - 0.5): V - 2000 N mmâcm\\/; sub -2\\/min⁻¹. A black hydride film is formed on Zr during its

M. E. Straumanis; W. J. James; A. S. Neiman

1959-01-01

262

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

PubMed

The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (± 1 SD) for groups 1-4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs. PMID:21300729

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

2012-04-01

263

Inorganic acid emission factors of semiconductor manufacturing processes.  

PubMed

A huge amount of inorganic acids can be produced and emitted with waste gases from integrated circuit manufacturing processes such as cleaning and etching. Emission of inorganic acids from selected semiconductor factories was measured in this study. The sampling of the inorganic acids was based on the porous metal denuders, and samples were then analyzed by ion chromatography. The amount of chemical usage was adopted from the data that were reported to the Environmental Protection Bureau in Hsin-chu County according to the Taiwan Environmental Protection Agency regulation. The emission factor is defined as the emission rate (kg/month) divided by the amount of chemical usage (L/month). Emission factors of three inorganic acids (i.e., hydrofluoric acid [HF], hydrochloric acid [HCl], and sulfuric acid [H2SO4]) were estimated by the same method. The emission factors of HF and HCl were determined to be 0.0075 kg/L (coefficient of variation [CV] = 60.7%, n = 80) and 0.0096 kg/L (CV = 68.2%, n = 91), respectively. Linear regression equations are proposed to fit the data with correlation coefficient square (R2) = 0.82 and 0.9, respectively. The emission factor of H2SO4, which is in the droplet form, was determined to be 0.0016 kg/L (CV = 99.2%, n = 107), and its R2 was 0.84. The emission profiles of gaseous inorganic acids show that HF is the dominant chemical in most of the fabricators. PMID:14977323

Chein, HungMin; Chen, Tzu Ming; Aggarwal, Shankar Gopala; Tsai, Chuen-Jinn; Huang, Chun-Chao

2004-02-01

264

Superhydrophobic properties of ultrathin rf-sputtered Teflon films coated etched aluminum surfaces  

Microsoft Academic Search

Superhydrophobicity has been demonstrated on ultrathin rf-sputtered Teflon coated etched aluminum surfaces. The etching of aluminum surfaces has been performed using dilute hydrochloric acid. An optimized etching time of 2.5 min is found to be essential, before Teflon coating, to obtain a highest water contact angle of 164±3° with a lowest contact angle hysteresis of 2.5±1.5°, with the water drops simply

D. K. Sarkar; M. Farzaneh; R. W. Paynter

2008-01-01

265

Individualized Learning Package about Etching.  

ERIC Educational Resources Information Center

An individualized learning package provides step-by-step instruction in the fundamentals of the etching process. Thirteen specific behavioral objectives are listed. A pretest, consisting of matching 15 etching terms with their definitions, is provided along with an answer key. The remainder of the learning package teaches the 13 steps of the…

Sauer, Michael J.

266

GaAs pillar array-based light emitting diodes fabricated by metal-assisted chemical etching  

NASA Astrophysics Data System (ADS)

We demonstrate GaAs pillar array-based light emitting diodes (LEDs) with axial p-i-n junctions fabricated using a room-temperature metal-assisted chemical etching (MacEtch) method. Variations in vertical etch rates for all three doping types of GaAs are investigated as a function of etching temperature, oxidant/acid concentration ratio, and dilution of the etching solution. Control over nanopillar morphologies is demonstrated, simply through modification of the etching conditions. Optical emission enhancement from the MacEtched p-i-n GaAs nanopillar LED is observed, relative to the non-etched planar counterpart, through room-temperature photoluminescence and electroluminescence characterization.

Mohseni, Parsian K.; Hyun Kim, Seung; Zhao, Xiang; Balasundaram, Karthik; Dong Kim, Jeong; Pan, Lei; Rogers, John A.; Coleman, James J.; Li, Xiuling

2013-08-01

267

Regenereringsmetoder vid Blandsyrabetning (Recycling Techniques for Mixed Acid Pickling).  

National Technical Information Service (NTIS)

Stainless steel pickling is carried out with several pickling treatments. for the final pickling, a mixture of nitric acid and hydrofluoric acid known as mixed acid is used. This project has been accomplished in order to elucidate the state of the art of ...

O. Ekengren J. Tolf

1994-01-01

268

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.

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

2012-01-01

269

Comparison of wet and dry chrome etching with the CORE2564  

Microsoft Academic Search

Chrome masks have traditionally been wet etched in an acidic solution of cerric ammonium nitrate. The etchant is commonly sprayed on the mask while the mask is slowly rotated, using an APT-914 or equivalent processor. While this process is well-understood, relatively trouble- free and inexpensive, the isotropic nature of wet etching results in an undercut of the chrome relative to

Peter D. Buck; Brian J. Grenon

1994-01-01

270

Submicron patterned metal hole etching  

DOEpatents

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)

2000-01-01

271

Effect of etching on the electrical and magnetic properties of writer shield material  

NASA Astrophysics Data System (ADS)

Magnetron sputtered permalloy films are treated by wet chemical etchings with acid etchant as well as fluorine based reactive ion etch (RIE). Upon these treatments, the resistivity and coercivity of the permalloy film increase is within 10 %. No significant increase observed with prolonged etching time. The effective magnetization change of the permalloy films are within 5 % post the treatments. Atomic force microscope (AFM) and transmission electron microscope (TEM) are used to study the surface and interface evolution of permalloy film upon etching. The small impact on the electrical and magnetic properties of permalloy films can be correlated with the surface oxide protecting layer formation during the etch. Consequently, sputtered NiFe is a safe material to expose to these etching processes for write pole shield application.

Han, Hongmei; Li, Yang; Su, Wencheng; Chen, Lifan; Zhang, Jinqiu

2013-11-01

272

Wet Etching of TiO2-Based Precursor Amorphous Films for Transparent Electrodes  

NASA Astrophysics Data System (ADS)

We investigated wet etching of Nb-doped anatase TiO2 (TNO) transparent conducting thin films and their precursors in an amorphous phase deposited by rf sputtering on glass substrates. The polycrystalline TNO films showed a very low etching rate of less than 0.06 nm/min in concentrated sulfuric acid (H2SO4) even at elevated temperatures up to 95 °C. In contrast, H2SO4 etched the precursor films at a rate of 1.4 nm/min at 95 °C. The etching rate of the amorphous films followed the Arrhenius equation, leading us to conjecture that a much higher etching rate of ˜230 nm/min can be achieved at 170 °C. These results indicate that wet-etching of precursor amorphous films prior to crystallization represents a practical and low-cost lithographic technique for patterning TiO2-based transparent electrodes.

Ohkubo, Junpei; Hirose, Yasushi; Sakai, Enju; Nakao, Shoichiro; Hitosugi, Taro; Hasegawa, Tetsuya

2011-01-01

273

Photosensitive etch protection coating for silicon wet-etch applications  

NASA Astrophysics Data System (ADS)

A spin-on polymeric material has been developed to replace the silicon nitride mask used in the MEMS industry for silicon wet-etch processing. Built-in photosensitivity eliminates the need for additional photoresists in the system. The process consists of applying an organosilane-based primer layer onto a silicon wafer, followed by spin coating the photosensitive layer. After a soft bake, the coating is imaged by exposing it to ultraviolet light. After a post-exposure bake, the coating is developed by a solvent. After a final bake, the prepared wafer is then etched in a hot concentrated alkaline solution to complete the pattern transfer. The polymer-coated area remains protected with insignificant and controllable undercut after extended hours of wet etching. Etch protection performance was characterized as a ratio of undercut (u) to etch depth (h). The polymeric mask allows silicon substrates to be etched anisotropically in the same way as silicon nitride masks although more undercut occurs when KOH or NaOH are used as etchants. With use of tetramethylammonium hydroxide (TMAH) as an etchant, a consistent 1-2% undercut ratio (u/h×100%) was obtained. The effects of various parameters such as use of different etchants and the effects of etchant concentration and delayed processing on undercut ratio are investigated.

Dalvi-Malhotra, J.; Zhong, X. F.; Planje, C.

2008-03-01

274

Neutron Dosimetry Using Electrochemical Etching.  

National Technical Information Service (NTIS)

Registration of alpha -tracks and fast-neutron-induced recoils tracks by the electrochemical etching technique as applied to sensitive polymer foils (e.g., polycarbonate) provides a simple, sensitive and inexpensive means of fast neutron personnel dosimet...

S. J. Su G. B. Stillwagon K. Z. Morgan

1977-01-01

275

Method of Etching Zirconium Diboride.  

National Technical Information Service (NTIS)

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon. This invention relates in general to a method of etching zirconium diboride, zircon...

L. S. Heath B. Kwiatkowski

1988-01-01

276

Etching Of Semiconductor Wafer Edges  

DOEpatents

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)

2003-12-09

277

Etch rates for micromachining processing  

Microsoft Academic Search

The etch rates for 317 combinations of 16 materials (single-crystal silicon, doped, and undoped polysilicon, several types of silicon dioxide, stoichiometric and silicon-rich silicon nitride, aluminum, tungsten, titanium, Ti\\/W alloy, and two brands of positive photoresist) used in the fabrication of microelectromechanical systems and integrated circuits in 28 wet, plasma, and plasmaless-gas-phase etches (several HF solutions, H3PO4, HNO3 +H2O+NH4F, KOH,

Kirt R. Williams; Richard S. Muller

1996-01-01

278

Northern Arabia Etched Terrain  

NASA Technical Reports Server (NTRS)

(Released 23 May 2002) The Science Many places on Mars display scabby, eroded landscapes that commonly are referred to as etched terrain. These places have a ragged, tortured look that reveals a geologic history of intense deposition and erosion. This THEMIS image shows such a place. Here a 10 km diameter crater is superposed on the floor of a 40 km diameter crater, most of which is outside of the image but apparent in the MOLA context image. The rugged crater rim material intermingles with low, flat-topped mesas and layers with irregular outlines along with dune-like ridges on many of the flat surfaces. The horizontal layers that occur throughout the scene at different elevations are evidence of repeated episodes of deposition. The apparent ease with which these deposits have been eroded, most likely by wind, suggests that they are composed of poorly consolidated material. Air-fall sediments are the likely candidate for this material rather than lava flows. The dune-like ridges are probably inactive granule ripples produced from the interaction of wind and erosional debris. The large interior crater displays features that are the result of deposition and subsequent erosion. Its raised rim is barely discernable due to burial while piles and blocks of slumped material along the interior circumference attest to the action of erosion. Some of the blocks retain the same texture as the surrounding undisrupted surface. It appears as if the crater had been buried long enough for the overlying material to be eroded into the texture seen today. Then at some point this overburden foundered and collapsed into the crater. Continuing erosion has caused the upper layer to retreat back from what was probably the original rim of the crater, producing the noncircular appearance seen today. The length of time represented by this sequence of events as well as the conditions necessary to produce them are unknown. The Story Have you ever seen an ink etching, where the artistic cross-hatching of lines creates the image of a town or a landscape? Click on the large THEMIS image above, and you'll see why this scabby, eroded landscape is known as etched terrain. Etched terrain is found in lots of areas of Mars. These places have a ragged, tortured look that reveals a geologic history where material has been deposited and eroded away with great intensity over time. Much of the terrain looks like peeling, layered-on paint. In a sense, that's what it's all about. Deposits of dust and dirt settled down from the air in layer after uneven layer, while the wind kept eroding it away. Dune-like ridges also mark the surface in tiny ripples. Unlike the loose sand dunes we're familiar with on Earth, these ridges are probably harder and more stationary, They are produced by long-term interactions between the sculpting, knife-like action of the Martian wind and the deposited materials of dust and 'dirt' on the surface. What we can also see in this image is a six-mile-wide crater. If you look at the context image to the right, you can see that it is actually a crater within a crater. The larger crater is about 24 miles wide in diameter. (Students! How many times bigger is the larger crater than the one that lies inside of it? If you look at the context image, you can get a really good sense of what 'four times bigger' really means.) What's interesting about this crater is that it doesn't have typical features known to many craters: it isn't nice-and-neatly round and its raised rim is barely noticeable. That's because there's been a whole lot of depositing and eroding going on here too. After the impact crater formed, it was probably entirely buried by deposits over time. In fact, it was probably buried long enough for the overlying material to be eroded into the texture seen today. At some point, the load on top foundered and collapsed into the crater. Around the inside circumference of the crater, you can see piles of slumped material (material that has slid downslope). Some of these blocks of material have the same textur

2002-01-01

279

Method of etching zirconium diboride  

SciTech Connect

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon. This invention relates in general to a method of etching, zirconium diboride(ZrB/sub 2/) and, in particular, to a method of dry etching a thin film of ZrB/sub 2/ that has been deposited onto a substrate and patterned using photolithography. U.S. patent application S.N. 156, 124, filed 16 February, 1988, of Linda S. Heath for Method of Etching Titanium Diboride and assigned to a common assignee and with which this application is copending describes and claims a method of etching titanium diboride with a dry etch. Zirconium diboride, like titanium diboride, TiB/sub 2/, has become of interest in laboratory research because of its resistance to change or degradation at high temperatures. By adjusting the process parameters, one is able to attain etch rates of 67 to 140 A/min for ZrB/sub 2/. This is useful for patterning ZrB/sub 2/ as a diffusion barrier or a Schottky contact to semiconductors. The ZrB/sub 2/ film may be on a GaAs substrate.

Heath, L.S.; Kwiatkowski, B.

1988-03-31

280

Lucian Freud: The Painter's Etchings  

NSDL National Science Digital Library

Diving into this web exhibition created by MoMA on the work of artist Lucian Freud without considering the title ("The Painter's Etchings") or reading the introductory texts can be a bit disorientating. One might ask, "Why are there so many oil paintings in a show of etchings?" The first sentence of the introduction makes it clear: "Lucian Freud is a painter who also makes etchings." The purpose of the exhibition is to present Freud's etchings alongside his paintings and drawings, in order to see the relationships between the works. For example, Freud's daughter, Bella, has been a frequent sitter for her father since the 1980s. In the show, there are 5 etchings and a painting of Bella, dating from 1981 to 1995. Each of these images of Bella can be selected and compared to the others. There is also audio for several of Freud's sitters, such as a short recording of art critic Martin Gayford, who posed for both a painting and an etching in the exhibition, comparing these experiences.

2008-01-01

281

Etching mechanism and morphology evolution in dry etching  

NASA Astrophysics Data System (ADS)

III-V compound semiconductors (GaAs(100), GaP(100), InP(100), and GaN(0001)) and an insulator (amorphous SiO2) were etched, then their morphological dependencies on etch conditions were studied. All of them were etched in Cl 2/H2/Ar plasmas. Low energy electron enhanced etching (LE4) technique was mostly used to prevent surface and subsurface damage that may interfere with surface roughness. This technique exploits electrons from a DC plasma positive column instead of ion bombardment for the chemical reaction enhancement on sample surfaces. However, the effects of ion bombardment were also studied. The selection of bombarding species (electrons or ions) and energy of the bombarding species were controlled by biasing potentials for samples. In any case, the bias potential to sample surfaces was kept within a range of low energy during bombardment to prevent etch-induced damage which may affect the morphological evolution. The x-ray Triple Axis Diffractometer (TAD) was used to monitor structural damage after etching; energy dispersive x-ray spectroscopy (EDX), for chemical impurities or etch product residues. However, no structural damage nor residue was detected within the experimental conditions. Scanning electron microscopy (SEM) was used to observe surface morphologies; then, height variations over the surfaces were obtained using atomic force microscopy (AFM). The AFM data quantified statistical behavior (i.e. rms height variation, skewness, auto-covariance function, structure factor) of the surfaces. Such statistical behavior was linked with atomic mechanisms through scaling theory. This methodology revealed that quenched noise and thermochemical properties, which are highly dependent on temperature, govern surface morphologies for GaAs(100), GaP(100), and Inp(100). Although the nature of quenched noise is not well understood, this study shows that ridges in the mum range act as quenched noise. The quenched noise originates in nonuniform thermochemical properties on the surface and chemically stubborn, thus slowly etching, spots become ridges of {111} facets running along <110> directions. Electron or ion bombardment mitigates the effects of quenched noise and, in turn, makes the etch rate faster with smaller spatial exponents. Especially, ion bombardment turned out to be more effective than electron bombardment to remove quenched noise. Quenched noise, thermochemical properties, and physical bombardment are inter-related as described above. Therefore, proper temperature (to control thermochemical effects) and bias potential to the sample surface (to control bombardment species and energies) are required to manage quenched noise and, in turn, control the final morphologies. (Abstract shortened by UMI.)

Lee, Sang Ho

282

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.

1999-02-04

283

Dry Ice Etches Terrain  

NASA Technical Reports Server (NTRS)

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

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

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

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

2007-01-01

284

The effects of etching on the surface of plasticized poly(vinylidene fluoride)  

Microsoft Academic Search

Poly(vinylidene fluoride) (PVDF) plasticized with 10% dibutyl sebacate undergoes chemical etching with fuming nitric acid, resulting in the removal of amorphous chain segments from the surface layer; there is little or no chemical modification of the remaining material.

D Glennon; T. G Nevell; J Tsibouklis; R. J Ewen

1998-01-01

285

Composites - Reviewing of Types, Pulp Protection Etching, and Pin Technique - Placement and Finishing.  

National Technical Information Service (NTIS)

The video discusses various composite filling materials. Photomicrographs show the desirability of pupal protection. Advantages of enamel acid etching are presented. The use of pins is seen and the techniques of finishing the restoration are demonstrated.

1994-01-01

286

Transparentization of Tunnel-Etched Al Foil by Anodic Oxidation  

NASA Astrophysics Data System (ADS)

The transparentization of etched Al foil was achieved by anodic oxidation in acid solution. The anodization under a low-voltage condition in chromic acid electrolyte contributed to a decrease in the amount of residual Al and generated a transparent porous material in the visible-wavelength region. The obtained transparent porous foil can be used for the preparation of several functional optical devices that require a transparent porous substrate with a large surface area.

Mizuki, Issei; Kondo, Toshiaki; Nishio, Kazuyuki; Masuda, Hideki

2009-02-01

287

Reactive ion etching of fluorine containing photoresist  

NASA Astrophysics Data System (ADS)

Photoresist are commonly used in semiconductor processing as soft masks for pattern transfer into multilayer stacks using reactive ion etching. The etch performance of the photoresist during such a process is an important consideration during resist selection. Since resist composition strongly influences it's etch performance, understanding the correlation is important for resist development as well as etch optimization. In this paper, blanket etch rate of photoresist used in ArF lithography were examined as a function of polymer structure and atomic content. In particular, the impact of Fluorine content on blanket etch rate was studied. Etch results for a diverse sample of development and commercial resists were first fitted with the Ohnishi parameter [2] and ring parameter [3] models. The Ohnishi model correlates the carbon, hydrogen and oxygen atomic content of the resist to blanket etch rate whereas the ring parameter model is based on the cyclic carbon content. Since some of the evaluated resists contained fluorine which significantly influences the etch performance, both models were found to be inadequate in assessing its impact. Thus we introduce a modified Ohnishi parameter model to help examine the relative contributions due to resist fluorine content. With the new empirical model, good fits were obtained for etch rates of a fluorine containing resists. The model also enabled analysis of the etch process to determine the relative influence of oxygen versus fluorine content in the resist on etch rate. Finally, the model was utilized to design newer etch resistant materials and the improved etch performance was verified.

Patel, Kaushal S.; Pham, Victor; Li, Wenjie; Khojasteh, Mahmoud; Varanasi, Pushkara Rao

2006-03-01

288

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.

2010-03-17

289

Top-Down Nanomanufacturing: Etching Process  

NSDL National Science Digital Library

This overview of nanotechnology is presented by the NaMCATE project. According to the introductory page,"in the top-down nano-manufacturing process flow, etch processes permanently transfer a mask pattern to a substrate or clean the surface of remaining materials for subsequent processing steps." In this module, methods of etching and steps in etch process are presented. Additionally, the module provides three learning activities titled Chemical Etching, Physical (Sputter) Etch, and Electrochemical Deposition and Chemical Etching. Lastly, a performance assessment and two powerpoint presentations are included.Users must create a free login in order to access materials. 10/7/11 -AHT

2011-09-22

290

Etching conditions for resin-modified glass ionomer cement for orthodontic brackets.  

PubMed

This study reports the tensile bond strength of orthodontic eyelets (RMO, Inc, Denver, Colo) bonded to human extracted teeth with a resin-modified glass ionomer cement (RMGIC) (Fuji Ortho LC, GC America, Alsip, Ill) and various acid etchants (Etch-37 and All-Etch, Bisco, Schaumburg, Ill; Ultra Etch, 3M Unitek, St Paul, Minn) for enamel preparation before bonding. The enamel etch conditions were as follows: 37% phosphoric acid with silica; 37% phosphoric acid, silica-free; 10% phosphoric acid, silica-free; 10% polyacrylic acid; and unetched enamel. Bond strength was measured by pulling in tension on the eyelet with a 0.018-in steel wire perpendicular to the enamel surface with a testing machine (Instron model 1125, Canton, Mass) at a speed of 2 mm/min. A light-cured resin cement (Transbond XT, 3M Unitek, Monrovia, Calif) applied to enamel etched with 37% phosphoric acid containing silica served as a control. Each group included 30 specimens. The Weibull distribution (m) was used for statistical analysis with a 90% CI. The different etchants used with RMGIC did not affect tensile bond strength. The resin cement group had the highest tensile strength. Significantly lower bond strengths were observed when glass ionomer cement was used to bond orthodontic attachments to nonetched teeth. However, unlike resin cement, RMGIC can bond effectively to etched teeth in a moist environment without an additional bonding agent. PMID:12045770

Valente, Rudolfo M; De Rijk, Waldemar G; Drummond, James L; Evans, Carla A

2002-05-01

291

Etched fiber optic strain sensor  

NASA Astrophysics Data System (ADS)

Based on the effects of mode-volume mismatch and lateral bending, a new type of optical fiber intensity sensors are presented. These sensors do not require the use of external structures to impose perturbations on fibers. Instead, the topological structures are formed directly onto the fiber cladding. The geometry of the features is defined by thermal engraving and the structures are formed by chemical etching. The etched fiber sensing elements have been fabricated with asymmetric structures and tested as strain sensors. It has been shown in experiment that the responses of the optical fiber strain gauges are linear, repeatable, have a high cyclic endurance and temperature stability and no measurable hysteresis. The etched fiberoptic sensing array embedded in composites and the principle and technology of array sensing signal processing in artificial neural network are also described.

Yang, Jianliang; Xiang, Qing; Yu, Guohua; Huang, Dexiu; Zhao, Yuelong

1996-09-01

292

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

2005-01-01

293

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

PubMed Central

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

2012-01-01

294

Etch defects in YBa 2Cu 3O 7-? single crystals grown from flux  

NASA Astrophysics Data System (ADS)

The crystallographic defects in (001), (100)/(010) and (011) faces of YBa 2Cu 3O 7-? (YBCO) single crystals, revealed by chemical etching with acetic acid, as well as mixed solutions of acetic acid, nitric acid and methanol, have been studied. We have found clear evidence for growth hillocks and steps on these etched faces. Three types of etch pits are observed: Type I is a square pyramid with growth steps along the <100> and <010> directions; type II is an octagonal pattern of the above square truncated along the <110> direction; and type III is a shallow ellipse with long and short axes in the <100>/<010> and <001> direction, respectively. Due to their spiral growth features types I and II are designated screw dislocation etch pits and type III is thought to be of Hopper-like morphology, on the basis of the growth mechnism. Clustering and tangling of dislocation etch pits have also been observed. The etching rate is anisotropic with different speeds in the four principal directions being Va<110>> Va<100>/<010>> Vc<001>> Vi<111>. The density of the dislocation etch pits is of the order of 10 6 cm -2 (001) and 10 5 cm -2 in the (100)/(010) surfaces.

Lin, C. T.; Liang, W. Y.

1994-05-01

295

Digital Electrochemical Etching of Compound Semiconductors.  

National Technical Information Service (NTIS)

The principles for an electrochemical digital etching method for compound semiconductors are described and initial results reported. The method is designed to allow atomic level control over the etching process, resulting in the removal of a bilayer of th...

Q. P. Lei J. L. Stickney

1992-01-01

296

Hydrogen peroxide etching proves useful for germanium  

NASA Technical Reports Server (NTRS)

Influence of process variations in the etching of germanium with hydrogen peroxide has been studied, along with damage effects due to radiation. The work advances the knowledge of the etching process for germanium.

Dayal, Y.; Kampwirth, R.; Primak, W.

1968-01-01

297

ION BEAM ETCHING EFFECTS IN BIOLOGICAL MICROANALYSIS  

EPA Science Inventory

Oxygen ion beam sputter etching used in SIMS has been shown to produce morphologic effects which have similarities and differences in comparison to rf plasma etching of biological specimens. Sputter yield variations resulting from structural microheterogeneity are illustrated (e....

298

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.

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

299

Thermodynamic study of photomask plasma etching  

Microsoft Academic Search

Photomask plasma etch reactions were studied using Gibbs energy minimization method. The equilibrium compositions were analyzed at practical photomask plasma etch conditions of temperatures, pressures, and reactant inputs. The thermodynamic calculations were based on common gaseous systems used in photomask plasma etching such as Cl2-O2-He, SF6-O2-He, and CF4-O2-He, as well as alternative gases. For Cr etch, the thermodynamically calculated results

Banqiu Wu

2004-01-01

300

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.

1986-01-01

301

Semiconductor etching by hyperthermal neutral beams  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

302

Atomic layer controlled digital etching of silicon  

Microsoft Academic Search

The mechanisms of atomic layer controlled digital etching are examined with particular reference to the digital etching of silicon with fluorine. The experiments included repeated reaction cycles of fluorine atom adsorption on a cooled Si surface followed by Ar(+) ion (20 eV) irradiation inducing fluorine\\/Si reactions. With an increase in Ar(+) irradiation time, the digital etch rate increases and reaches

Hiroyuki Sakaue; Seiji Iseda; Kazushi Asami; Jirou Yamamoto; Masataka Hirose; Yasuhiro Horiike

1990-01-01

303

Correlation between the grain orientation dependence of color etching and chemical etching.  

PubMed

A gray cast iron specimen was investigated by color and chemical etching with optical and atomic force microscopy, and the effect of grain orientation on the effectiveness of etching was examined. It was proven that the grain orientation dependence of chemical and color etching is just the opposite, and that the specimen surface after color etching is not uniformly smooth. Explanation for the layer structure of the color etched iron specimen is given. PMID:23149222

Bonyár, Attila; Szabó, Peter J

2012-12-01

304

Anisotropic etching and electrochemical etch-stop properties of silicon in TMAH:IPA:pyrazine solutions  

Microsoft Academic Search

Anisotropic etching and electrochemical etch-stop properties of single-crystal silicon in tetramethylammonium hydroxide (TMAH):\\u000a isopropyl alcohol (IPA) solutions containing pyrazine were investigated. With the addition of IPA to TMAH solution, an improvement\\u000a in flatness on the etching front and a reduction in undercutting were observed, but the etch rate on (100) silicon decreased.\\u000a However, the (100) silicon etch rate is improved

Gwiy-Sang Chung

2001-01-01

305

A New Method for High-Rate Deep Dry Etching of Silicate Glass with Variable ETCH Profile  

Microsoft Academic Search

Compared to the deep reactive ion etching (DRIE) of silicon, the etching of silicate glasses by plasma processing is much more critical. Especially high etch rates as well as highly selective etching are challenging issues in this respect. The following paper reports on a dry etching method offering not only selective and high rate etching but a high flexibility for

A. Bertz; R. Fendler; R. Schuberth; W. Hentsch; T. Gessner

2007-01-01

306

Effect of grain orientation on chemical etching.  

PubMed

The effect of grain orientation on the effectiveness of pre-etching before color etching was investigated by the help of electron back scattering diffraction and atomic force microscopy in case of cast iron. Strong correlation was found between the angle between the specimen normal and the [001] orientation of the ferrite grains and the depth of the etching. If the angle between the specimen normal and the [001] direction of the ferritic grain is small, then the speed of the etching is low, but the lateral variation of the etching speed within the grain is larger. PMID:22030301

Szabó, Peter J; Bonyár, Attila

2012-02-01

307

Dry etching of polydimethylsiloxane using microwave plasma  

NASA Astrophysics Data System (ADS)

This paper presents a new polydimethylsiloxane (PDMS) dry-etching method that uses microwave plasma. The applicability of the method for fabricating microstructures and removing residual PDMS is also verified. The etch rate of PDMS was dominantly influenced by the gas flux ratio of CF4/O2 and the microwave power. While the PDMS etch rate increased as the flux ratio of CF4 was increased, the etch rate decreased as the flux ratio of O2 was increased. The maximum etch rate of 4.31 µm min-1 was achieved when mixing oxygen (O2) and tetrafluoromethane (CF4) at a 1:2 ratio at 800 W power. The PDMS etch rate almost linearly increased with the microwave power. The ratio of the vertical etch rate to the lateral etch rate was in a range of 1.14-1.64 and varied with the gas fluxes. In consideration of potential applications of the proposed PDMS etching method, array-type PDMS microwells and network-type microprotrusion structures were fabricated. The contact angle was dramatically increased from 104° (non-etched PDMS surface) to 148° (etched PDMS surface) and the surface was thereby modified to be superhydrophobic. In addition, a thin PDMS skin that blocked holes and PDMS residues affixed in nickel microstructures was successively removed.

Hwang, Sung Jin; Oh, Dong Joon; Jung, Phill Gu; Lee, Sang Min; Go, Jeung Sang; Kim, Joon-Ho; Hwang, Kyu-Youn; Ko, Jong Soo

2009-09-01

308

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

PubMed

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

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

2013-11-01

309

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

DOEpatents

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

Kampwirth, Robert T. (Darien, IL); Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

1981-01-01

310

Reversal of Compromised Bonding to Oxidized Etched Dentin  

Microsoft Academic Search

The mechanism responsible for hydrogenperoxide- or sodium-hypochlorite-induced reductions in dentin bond strength is unknown. This in vitro study tested the hypothesis that these oxidizing agents were responsible by attempting to reverse the effect with sodium ascorbate, a reducing agent. Human dentin was treated with these oxidants before or after being acid-etched and with or without post-treatment with sodium ascorbate. They

S. C. N. Lai; Y. F. Mak; G. S. P. Cheung; R. Osorio; M. Toledano; R. M. Carvalho; F. R. Tay; D. H. Pashley

2001-01-01

311

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

2010-11-01

312

Photovoltaic properties of a novel stain etched porous silicon and its application in photosensitive devices  

Microsoft Academic Search

Photovoltaic (PV) properties of porous silicon (PS) produced by a novel stain (chemical) etch solution based on fluoroboric (HBF4) acids are described for the first time. Sandwich structure devices in which semi-transparent continuous gold electrodes are deposited on stain-etched PS have been observed to show high efficiency in photocurrent under visible light exposure. Additionally, palladium (Pd) metallization of the nanoporous

B. Ünal; A. N. Parbukov; S. C. Bayliss

2001-01-01

313

A Wafer-Scale Etching Technique for High Aspect Ratio Implantable MEMS Structures.  

PubMed

Microsystem technology is well suited to batch fabricate microelectrode arrays, such as the Utah electrode array (UEA), intended for recording and stimulating neural tissue. Fabrication of the UEA is primarily based on the use of dicing and wet etching to achieve high aspect ratio (15:1) penetrating electrodes. An important step in the array fabrication is the etching of electrodes to produce needle-shape electrodes with sharp tips. Traditional etching processes are performed on a single array, and the etching conditions are not optimized. As a result, the process leads to variable geometries of electrodes within an array. Furthermore, the process is not only time consuming but also labor-intensive. This report presents a wafer-scale etching method for the UEA. The method offers several advantages, such as substantial reduction in the processing time, higher throughput and lower cost. More importantly, the method increases the geometrical uniformity from electrode to electrode within an array (1.5 ± 0.5 % non-uniformity), and from array to array within a wafer (2 ± 0.3 % non-uniformity). Also, the etching rate of silicon columns, produced by dicing, are studied as a function of temperature, etching time and stirring rate in a nitric acid rich HF-HNO(3) solution. These parameters were found to be related to the etching rates over the ranges studied and more-importantly affect the uniformity of the etched silicon columns. An optimum etching condition was established to achieve uniform shape electrode arrays on wafer-scale. PMID:20706618

Bhandari, R; Negi, S; Rieth, L; Solzbacher, F

2010-07-01

314

Metal-assisted electrochemical etching of silicon.  

PubMed

In this paper the metal-assisted electrochemical etching of silicon is introduced. By electrochemical measurement and sequent simulation, it is revealed that the potential of the valence band maximum at the silicon/metal interface is more negative than that of the silicon/electrolyte interface. Accordingly, holes injected from the back contact are driven preferentially to the silicon/metal interface. Consequently, silicon below metal is electrochemically etched much faster than a naked silicon surface without metal coverage. Metals such as Ag and Cu have been utilized to catalyze the electrochemical etching. Feature sizes as small as 30 nm can be achieved by metal-assisted electrochemical etching. Meanwhile, the metal-assisted electrochemical etching method enables convenient control over the etching direction of non-(100) substrates, and facilitates the fabrication of orientation-modulated silicon nanostructures. PMID:20972316

Huang, Z P; Geyer, N; Liu, L F; Li, M Y; Zhong, P

2010-11-19

315

A practical approach to reactive ion etching  

NASA Astrophysics Data System (ADS)

In this paper, general aspects of the reactive ion etching (RIE) technique will be described, such as anisotropy, loading effect, lag effect, RIE chemistries and micro-masking, followed by a brief overview of etching dielectrics (SiOx, SiNx) and crystalline Si. The second section of the paper is dedicated to etching III–V compound semiconductors where, based on RIE results of GaN material, a simple and practical thermodynamic approach is exposed, explaining the criteria for selecting the best chemistry for etching a specific material and explaining the GaN etching results. Finally, a comprehensive study of etching InP-based materials using various chemistries will be discussed, as well as their various photonic applications.

Karouta, Fouad

2014-06-01

316

Laser-driven fusion etching process  

DOEpatents

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

Ashby, Carol I. H. (Edgewood, NM); Brannon, Paul J. (Albuquerque, NM); Gerardo, James B. (Albuquerque, NM)

1989-01-01

317

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.

2014-03-01

318

Study of Excimer Laser Electrochemical Etching Silicon  

Microsoft Academic Search

To further understand the behavior of laser-induced electrochemical etching process, the experiments of micromachining silicon by laser-induced electrochemical etching were carried out. 248nm excimer laser as light source is adopted in this work with the power of 109W\\/cm2 for the first time and KOH solution is used as electrolyte. Based on the experiment results, the surface images and etching rate

Liangcai. Xiongl; Tielin. Shil; Zirong Tang

2007-01-01

319

Thermodynamic study of photomask plasma etching  

NASA Astrophysics Data System (ADS)

Photomask plasma etch reactions were studied using Gibbs energy minimization method. The equilibrium compositions were analyzed at practical photomask plasma etch conditions of temperatures, pressures, and reactant inputs. The thermodynamic calculations were based on common gaseous systems used in photomask plasma etching such as Cl2-O2-He, SF6-O2-He, and CF4-O2-He, as well as alternative gases. For Cr etch, the thermodynamically calculated results showed that volatile CrO2Cl2 was the moderate equilibrium composition in the predetermined system only when the temperature was higher than 400 C, indicating that temperatures of heavy particles in practical plasma conditions might be higher than this temperature. The effects of assistant chemicals on equilibrium compositions were investigated. For MoSi etch, the thermodynamic calculation showed that the main volatile etch products were MoF6 and SiF4. The comparison of MoSi etch using SF6 and CF4 was made and gaseous input condition for obtaining all volatile products was found, which would be helpful for defectivity and passivation controls. The calculation also showed that the addition of oxygen in SF6 and CF4 systems could increase the equilibrium composition of atomic fluorine, resulting in the etch rate increase. This result agreed with previous hypothesis on the oxygen effects on etch rate. For quartz etch, the calculation showed that the main volatile etch product was SiF4. For Ta or TaN absorber EUV mask etch, the volatile Ta-containing product was found to be TaCl5.

Wu, Banqiu

2004-10-01

320

Method of sputter etching a surface  

DOEpatents

A surface is textured by co-sputter etching with a target and a seed material with the surface 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, C.H. Jr.

1982-02-26

321

Hydrogen Bubbles and Formation of Nanoporous Silicon during Electrochemical Etching  

Microsoft Academic Search

Many nanoporous Si structures, including those formed by common electrochemical etching procedures, produce a uniformly etch nanoporous surface. If the electrochemical etch rate is slowed down, details of the etch process can be explored and process parameters may be varied to test hypotheses and obtain controlled nanoporous and defect structures. For example, after electrochemical etching of a heavily n-doped (R

Laxmikant V. Saraf; Donald R. Baer; Zheming Wang; James S. Young; Mark H. Engelhard; Suntharampillai Thevuthasan

2005-01-01

322

Selective Etching of Silicon for Selective Area Epitaxial Growth.  

National Technical Information Service (NTIS)

Process conditions are described for selectively etching silicon by wet and dry etching techniques. High etch rates are achieved and a selectivity (etch rate of silicon/etch rate of masking material) as high as 600 is obtained when thermal oxide is used a...

D. J. Advena J. H. Dinan

1996-01-01

323

Method for dry etching of transition metals  

DOEpatents

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

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

1998-09-29

324

Method for dry etching of transition metals  

DOEpatents

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

Ashby, Carol I. H. (Edgewood, NM); Baca, Albert G. (Albuquerque, NM); Esherick, Peter (Albuquerque, NM); Parmeter, John E. (Albuquerque, NM); Rieger, Dennis J. (Tijeras, NM); Shul, Randy J. (Albuquerque, NM)

1998-01-01

325

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

2010-08-01

326

Advanced plasma etch technologies for nanopatterning  

NASA Astrophysics Data System (ADS)

Advances in patterning techniques have enabled the extension of immersion lithography from 65/45nm through 14/10nm device technologies. A key to this increase in patterning capability has been innovation in the subsequent dry plasma etch processing steps. Multiple exposure techniques such as litho-etch-litho-etch, sidewall image transfer, line/cut mask and self-aligned structures have been implemented to solution required device scaling. Advances in dry plasma etch process control, across wafer uniformity and etch selectivity to both masking materials and have enabled adoption of vertical devices and thin film scaling for increased device performance at a given pitch. Plasma etch processes such as trilayer etches, aggressive CD shrink techniques, and the extension of resist trim processes have increased the attainable device dimensions at a given imaging capability. Precise control of the plasma etch parameters affecting across design variation, defectivity, profile stability within wafer, within lot, and across tools have been successfully implemented to provide manufacturable patterning technology solutions. IBM has addressed these patterning challenges through an integrated Total Patterning Solutions team to provide seamless and synergistic patterning processes to device and integration internal customers. This paper will discuss these challenges and the innovative plasma etch solutions pioneered by IBM and our alliance partners.

Wise, Rich

2012-03-01

327

Advanced plasma etch technologies for nanopatterning  

NASA Astrophysics Data System (ADS)

Advances in patterning techniques have enabled the extension of immersion lithography from 65/45 nm through 14/10 nm device technologies. A key to this increase in patterning capability has been innovation in the subsequent dry plasma etch processing steps. Multiple exposure techniques, such as litho-etch-litho-etch, sidewall image transfer, line/cut mask, and self-aligned structures, have been implemented to solution required device scaling. Advances in dry plasma etch process control across wafer uniformity and etch selectivity to both masking materials have enabled adoption of vertical devices and thin film scaling for increased device performance at a given pitch. Plasma etch processes, such as trilayer etches, aggressive critical dimension shrink techniques, and the extension of resist trim processes, have increased the attainable device dimensions at a given imaging capability. Precise control of the plasma etch parameters affecting across-design variation, defectivity, profile stability within wafer, within lot, and across tools has been successfully implemented to provide manufacturable patterning technology solutions. IBM has addressed these patterning challenges through an integrated total patterning solutions team to provide seamless and synergistic patterning processes to device and integration internal customers. We will discuss these challenges and the innovative plasma etch solutions pioneered by IBM and our alliance partners.

Wise, Rich

2013-10-01

328

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

2012-11-01

329

Tungsten etching mechanisms in CF4\\/O2 reactive ion etching plasmas  

Microsoft Academic Search

Insitu x-ray photoelectron spectroscopy (XPS), etch rate measurements, and optical emission spectroscopy have been used to examine the etching characteristics of tungsten in CF4\\/O2 reactive ion etching plasmas. It is found that the etch rate maximum of tungsten occurs at a proportion of oxygen in excess of that required to produce the maximum gas phase fluorine atom concentration, and this

Tim D. Bestwick; Gottlieb S. Oehrlein

1989-01-01

330

Etching radical controlled gas chopped deep reactive ion etching  

DOEpatents

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

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

331

Electrochemical etching of titanium-alloy castings  

SciTech Connect

This study was conducted to determine whether a potentiostatic electrochemical method could be used to etch selectively either the dendrites or the interdendritic material from Ti cast structures and thereby reveal their microstructures. Cast binary titanium alloys containing Mo, Ta, Nb, Al, and Cr and one multicomponent alloy containing Al, Ta, Nb, and Mo were polarized in sulfuric, oxalic, and fluosilicic acids and in a potassium hydroxide solution. Potentiostatic anodic polarization curves were obtained for each alloy. Results showed that the electrode potential for passivation was nearly the same for all alloys in a given acid, although the current density at the passivation potential varied from alloy to alloy. Generally for most alloying elements, the current density at the passivation potential decreased as the concentration of the alloying element increased, but not linearly. In the alkaline solution only the Ti-15% Cr alloy underwent significant dissolution, which occurred in the transpassive potential region. We were able to develop the dendritic structure with only the Ti-15% Mo, Ti-15% Ta, and Ti-15% Cr alloys. Possible reasons for our inability to delineate the dendritic structure in other alloys are discussed.

Griess, J.C.; David, S.A.; Gray, R.J.; Houck, C.W.

1983-10-01

332

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

SciTech Connect

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

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

2008-01-09

333

Influence of Applied Potentials on Anisotropic Etching of Silicon Described Using Kinematic Wave Etch Model  

Microsoft Academic Search

Anisotropic etch rates of silicon in KOH solutions were studied as a function of an externally applied potential. A combination of three micromachined samples consisting of predry-etched wagon-wheel patterns and masked trench offset patterns was used to measure the etch rates at a large number of crystal orientations simultaneously. The measured data was described in terms of microscopic properties, including

Q. D. Nguyen; M. Elwenspoek

2007-01-01

334

Influence of Etching Potential on Convex Corner Anisotropic Etching in TMAH Solution  

Microsoft Academic Search

Anisotropic etching with tetramethylammonium hydroxide (TMAH) water solutions is a simple and CMOS-compatible way to obtain geometrical patterns in single-crystal silicon wafers. The fabrication of trenches and other features is although limited by the need to compensate convex corners which tend to be etched very fast. Such compensation produces footings at the bottom edge of the etched walls, yielding a

Alvise Bagolini; Alessandro Faes; Massimiliano Decarli

2010-01-01

335

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.

2013-07-01

336

Modeling and optimization of the chemical etching process in niobium cavities  

SciTech Connect

Niobium cavity is an important component of the integrated NC/SC high-power linacs. Over the years researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells and buffered chemical polishing produce good results. The objective of this paper is to study the effect of chemical etching on the surface quality and to optimize this process. Chemical etching of the inner surface of the cavity is achieved by circulating acid through it. As the acid interacts with the surface, it eliminates imperfections and improves surface quality. During etching, a pipe with baffles is inserted within the cavity to direct the flow along the surfaces. A finite element computational fluid dynamics model is developed for the etching process. The problem is modeled as a two-dimensional, axisymmetric, steady state fluid flow problem. This model is used to evaluate the current etching process. An alternative design with an expanding baffle is proposed. The new design is optimized to improve the chemical etching process. (authors)

Subramanian, S.; Xue, Q.; Trabia, M.; Chen, Y.; Schill, R. Jr. [Howard R. Hughes College of Engineering, University of Nevada, Las Vegas, NV 89154-4027 (United States)

2002-07-01

337

Gallium nitride nanowires by maskless hot phosphoric wet etching  

NASA Astrophysics Data System (ADS)

We demonstrate gallium nitride (GaN) nanowires formation by controlling the selective and anisotropic etching of N-polar GaN in hot phosphoric acid. Nanowires of ~109/cm,2 total height of ~400 nm, and diameters of 170-200 nm were obtained. These nanowires have both non-polar {1100}/ {1120} and semi-polar {1011} facets. X-Ray Diffraction characterization shows that screw dislocations are primarily responsible for preferential etching to create nanowires. Indium gallium nitride multi-quantum wells (MQWs) grown on these GaN nanowires showed a blue shift in peak emission wavelength of photoluminescence spectra, and full width at half maximum decreased relative to MQWs grown on planar N-polar GaN, respectively.

Bharrat, D.; Hosalli, A. M.; Van Den Broeck, D. M.; Samberg, J. P.; Bedair, S. M.; El-Masry, N. A.

2013-08-01

338

Deep ultraviolet enhanced wet chemical etching of gallium nitride  

NASA Astrophysics Data System (ADS)

We report a study of the ultraviolet (UV) irradiation effects on the wet chemical etching of unintentionally doped n-type gallium nitride (GaN) layers grown on sapphire substrates. When illuminated with a 253.7 nm mercury line source, etching of GaN is found to take place in aqueous phosphorus acid (H3PO4) and potassium hydroxide (KOH) solutions of pH values ranging from -1 to 2 and 11 to 15, respectively. Formation of gallium oxide is observed on GaN when illuminated in dilute H3PO4 and KOH solutions. These results are attributed to a two-step reaction process upon which the UV irradiation is shown to enhance the oxidative dissolution of GaN.

Peng, L.-H.; Chuang, C.-W.; Ho, J.-K.; Huang, C.-N.; Chen, C.-Y.

1998-02-01

339

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

PubMed

Herein, we investigate the behaviour of the surface recombination of light-induced charge carriers during the etching of Si in alkaline (KOH) and acidic etching solutions of HF/HNO(3)/CH(3)COOH (HNA) or HF/HNO(3)/H(3)PO(4) (HNP) at different concentration ratios of HF and HNO(3) by means of photoluminescence (PL) measurements. The surface recombination velocity is strongly reduced during the first stages of etching in HF/HNO(3)-containing solutions pointing to a interface well passivated by the etching process, where a positive surface charge is induced by hole injection from NO-related surface species into the Si near-surface region (back surface field effect). This injected charge leads to a change in band bending by about 150 mV that repulses the light-induced charge carriers from the surface and therefore enhances the photoluminescence intensity, since non-radiative surface recombination is reduced. PMID:22761060

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

2012-08-27

340

Wet Etching of Heat Treated Atomic Layer Chemical Vapor Deposited Zirconium Oxide in HF Based Solutions  

NASA Astrophysics Data System (ADS)

Alternative materials are being considered to replace silicon dioxide as gate dielectric material. Of these, the oxides of hafnium and zirconium show the most promise. However, integrating these new high-k materials into the existing complementary metal-oxide-semiconductor (CMOS) process remains a challenge. One particular area of concern is the wet etching of heat treated high-k dielectrics. In this paper, work done on the wet etching of heat treated atomic layer chemical vapor deposited (ALCVD) zirconium oxide in HF based solutions is presented. It was found that heat treated material, while refractory to wet etching at room temperature, is more amenable to etching at higher temperatures when methane sulfonic acid is added to dilute HF solutions. Selectivity over SiO2 is still a concern.

Balasubramanian, Sriram; Raghavan, Srini

2008-06-01

341

Selective enamel etching: effect on marginal adaptation of self-etch LED-cured bond systems in aged Class I composite restorations.  

PubMed

The aim of this study was to evaluate the influence of previous enamel etch and light emitting diode (LED) curing on gap formation of self-etch adhesive systems in Class I composite restorations after thermomechanical aging (TMA). Thus, on 192 human molars, a box-shaped Class I cavity was prepared maintaining enamel margins. Self-etch adhesives (Clearfil SE and Clearfil S3) were used to restore the preparation with a microhybrid composite. Before application of the adhesives, half of the teeth were enamel etched for 15 seconds with 37% phosphoric acid; the other half were not etched. For the photoactivation of the adhesives and composite, three light-curing units (LCUs) were used: one polywave (Ultra-Lume LED 5, UL) and two single-peak (FlashLite 1401, FL and Radii-cal, RD) LEDs. After this, epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to TMA. New replicas were made from the aged specimens for marginal adaptation analysis by scanning electron microscopy. Data were submitted to Kruskal-Wallis and Wilcoxon tests (?=0.05). Before TMA, when enamel was etched before the application of S3, no gap formation was observed; however, there were gaps at the interface for the other tested conditions, with a statistical difference (p?0.05). After TMA, the selective enamel etching previous to the S3 application, regardless of the LCU, promoted higher marginal adaptation compared to the other tested groups (p?0.05). Prior to TMA, higher marginal integrity was observed, in comparison with specimens after TMA (p?0.05). With regard to Clearfil SE and Clearfil Tri-S cured with FL, no differences of gap formation were found between before and after aging (5.3 ± 3.8 and 7.4 ± 7.5, respectively), especially when the Clearfil Tri-S was used in the conventional protocol. When cured with RD or UL and not etched, Clearfil Tri-S presented the higher gap formation. In conclusion, additional enamel etching promoted better marginal integrity for Clearfil Tri-S, showing it to be an efficient technique for Class I composite restorations. The two-step self-etch adhesive was not influenced by selective enamel etching or by the LED-curing unit. PMID:22313271

Souza-Junior, E J; Prieto, L T; Araújo, C T P; Paulillo, L A M S

2012-01-01

342

Polishing and etching langasite and quartz crystals  

Microsoft Academic Search

Langasite is a promising new piezoelectric material which is similar to quartz in its acoustic behavior. Little was known until recently about the methods needed to mechanically polish and chemically polish\\/etch this material. The results of polishing and etching experiments are described. Conventional quartz polishing methods, with polishing agents such as a rare earth slurry or ruby powder, did not

Sally Laffey; Mary Hendrickson; John R. Vig

1994-01-01

343

Note: electrochemical etching of sharp iridium tips.  

PubMed

We describe an etching procedure for the production of sharp iridium tips with apex radii of 15-70 nm, as determined by scanning electron microscopy, field ion microscopy, and field emission measurements. A coarse electrochemical etch followed by zone electropolishing is performed in a relatively harmless calcium chloride solution with high success rate. PMID:22129021

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

2011-11-01

344

Plasma etching for advanced polymer optical devices  

Microsoft Academic Search

Plasma etching is a common microfabrication technique which can be applied to polymers as well as glasses, metals, and semiconductors. The fabrication of low loss and reliable polymer optical devices commonly makes use of advanced microfabrication processing techniques similar in nature to those utilized in standard semiconductor fabrication technology. Among these techniques, plasma\\/reactive ion etching is commonly used in the

Donald S. Bitting

2003-01-01

345

Radiation resistance of track etched membranes  

Microsoft Academic Search

Track etched membranes (TEMs) obtained by irradiation of polymer films with heavy ions and subsequent etching of latent tracks can be applied in many fields and among others in biomedicine as well. It is important to know radiation resistance of TEMs because of wide use of radiation sterilization in the case of biomedical devices.Tensile properties of TEMs made of PET

M Buczkowski; B Sartowska; D Wawszczak; W Starosta

2001-01-01

346

Large area etching for porous semiconductors  

Microsoft Academic Search

While electrochemical etching of small samples in the 1 cm region is relatively easy, this is not true for large areas, i.e. standard wafer sizes up to 300 mm. The paper outlines the specific demands and difficulties in some detail, discusses large area etching strategies and systems, in particular for very deep macropores, and presents and discusses various results from

J. Carstensen; M. Christophersen; S. Lölkes; E. Ossei-Wusu; J. Bahr; S. Langa; G. Popkirov; H. Föll

2005-01-01

347

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

348

Chemical Etching of Group III - V Semiconductors  

NASA Astrophysics Data System (ADS)

Chemical etching is basically a process used to selectively remove controlled amounts of material from the original substrate. The etch depth can be designed to be just tens of angstroms or up to a few hundred angstroms. The etching process is one of the important stages in the fabrication of micro electronics devices. Errors at this stage will severely impair performance of these devices. Due to the present diadvantages of dry etching, wet chemical etching will still be useful for some time. it is infact one of the standard technique for the processing of Integral Circuits (Ics). This article reviews the chemical etchants used for the reatment of GaAs and others III - V. Semiconductors, the factors involved in their mechanism and the many potential pitfalls, arwillan detects associated with them. The article should present an understandable account for the non-specialist reaser yet it does offer a useful material and information for the specialists readers an well.

Kadhim, Najah J.; Laurie, Stuart H.; Mukherjee, D.

1998-07-01

349

Focused-Ion-Beam-Induced Gas Etching  

NASA Astrophysics Data System (ADS)

Focused ion beam (FIB)-assisted gas etching has several advantages over physical sputtering in many applications. Advantages include etch rate enhancements of one to two orders of magnitude, dramatically reduced redeposition of etched material on sidewalls in high-aspect-ratio structures, etch selectivity, and reduced implantation of the primary ion species in the sample. Applications which benefit from focused ion beam (FIB) gas etching include photomask and X-ray mask defect repair, integrated circuit modification for failure analysis, and sample preparation for scanning electron microscope and transmission electron microscope analysis. This paper describes a simple phenomenological model which takes into account the ion beam and scanning parameters, gas flux, and basic material constants. Approximate formulas are given in terms of these parameters and compared to experimental results.

Harriott, Lloyd

1994-12-01

350

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

2009-10-01

351

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

352

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.

2002-04-08

353

Galvanic etch stop for Si in KOH  

NASA Astrophysics Data System (ADS)

Etch stops and etch-stopping techniques are essential 'tools' for 2D and 3D MEMS devices. Until now, use of a galvanic etch stop (ES) for micromachining in alkaline solutions was usually prohibited due to the large Au:Si area needed and/or high oxygen content required to achieve the ES. We report a new galvanic ES which requires a Au:exposed silicon area ratio of only ~1. Thus for the first time a practical galvanic ES for KOH has been achieved. The ES works by adding small amounts of sodium hypochlorite, NaOCl, to KOH solutions. Essentially the NaOCl increases the oxygen content in the KOH etchant. The dependancy of the galvanic ES on KOH concentration and temperature is investigated. Also, we report on the effects of the added NaOCl on etch rates. SEM images are used to examine the galvanically etch-stopped membranes and their surface morphology. For 33% KOH solutions the galvanic etch stop worked well, producing membranes with uniform thickness ~6 µm (i.e. slightly greater than the deposited epilayer). For 20% KOH solutions, the galvanic etch stop still worked, but the resulting membranes were a little thicker (~10 µm).

Connolly, E. J.; French, P. J.; Xia, X. H.; Kelly, J. J.

2004-08-01

354

Dynamics of ion-assisted etching  

NASA Astrophysics Data System (ADS)

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

Sebel, Petrus Gerardus Maria

355

Electrical, optical and surface properties of P 2S 5\\/(NH 4) 2S x+ Se-treated doped-channel field-effect transistors with double etch-stop layers  

Microsoft Academic Search

This work describes doped-channel field-effect transistors (DCFETs), featuring both low–high doped-channels and double AlAs etch-stop layers used in a selective etch recessed-gate process. A developed highly selective wet etching process is applied as a gate-recess technique to fabricate DCFETs. Selective wet etching using citric acid\\/H2O2\\/NH4OH\\/H2O solutions in conjunction with double thin AlAs etch-stop layers is a reasonably simple, safe, and

Y. S. Lin; Y. T. Lin; Y. W. Huang

2011-01-01

356

Electroless epitaxial etching for semiconductor applications  

DOEpatents

A method for fabricating thin-film single-crystal silicon on insulator substrates using electroless etching for achieving efficient etch stopping on epitaxial silicon substrates. Microelectric circuits and devices are prepared on epitaxial silicon wafers in a standard fabrication facility. The wafers are bonded to a holding substrate. The silicon bulk is removed using electroless etching leaving the circuit contained within the epitaxial layer remaining on the holding substrate. A photolithographic operation is then performed to define streets and wire bond pad areas for electrical access to the circuit.

McCarthy, Anthony M. (Menlo Park, CA)

2002-01-01

357

Dry etching method for compound semiconductors  

DOEpatents

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

Shul, Randy J. (Albuquerque, NM); Constantine, Christopher (Safety Harbor, FL)

1997-01-01

358

Dry etching method for compound semiconductors  

DOEpatents

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.

1997-04-29

359

Method of sputter etching a surface  

DOEpatents

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)

1984-01-01

360

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 ...

361

PECVD silicon carbide as a chemically resistant material for micromachined transducers  

Microsoft Academic Search

Plasma enhanced chemical vapor deposited (PECVD) amorphous hydrogenated silicon carbide is a material with many potential applications for micromachined transducers. Specifically, its resistance to etching in a broad range of media such as sulfuric acid\\/peroxide, hydrofluoric acid and potassium hydroxide make it an excellent choice for use as an encapsulating material for media compatible transducers. This etch resistance also makes

Anthony F. Flannery; Nicholas J. Mourlas; Christopher W. Storment; Stan Tsai; Samantha H. Tan; John Heck; Dave Monk; Thomas Kim; Bishnu Gogoi; Gregory T. A. Kovacs

1998-01-01

362

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

DOEpatents

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

Ashby, Carol I. H. (Edgewood, NM); Myers, David R. (Albuquerque, NM)

1992-01-01

363

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.

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

2014-01-01

364

Ioninduced chlorination of titanium leading to enhanced etching  

Microsoft Academic Search

The ion-induced chemical etching of titanium with chlorine has been studied. Quartz crystal microbalance studies show that the ion beam etch rate of Ti is enhanced upon addition of molecular chlorine, whereas molecular chlorine does not etch Ti in the absence of ion stimulation. This is very similar to the etching behavior of silicon in the presence of argon stimulation

W. L. O’Brien; T. N. Rhodin; L. C. Rathbun

1988-01-01

365

Method for anisotropic etching in the manufacture of semiconductor devices  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

366

Comparative study on dry etching of polycrystalline diamond thin films  

Microsoft Academic Search

The reactive ion etching (RIE) technique was used to etch polycrystalline diamond thin films. In this study we investigate the influence of process parameters (total pressure, rf power, gas composition) of standard capacitively coupled plasma RIE system on the etching rate of diamond films. The surface morphology of etched diamond films was characterized by Scanning Electron Microscopy and the chemical

Tibor Izak; Alexander Kromka; Oleg Babchenko; Martin Ledinsky; Karel Hruska; Elisseos Verveniotis

367

Method for anisotropic etching in the manufacture of semiconductor devices  

DOEpatents

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) [Seabrook, TX; Cross, Jon B. (Santa Fe, NM) [Santa Fe, NM

1993-01-01

368

Polycarbonate microfilters by nuclear tracking and chemical etching (track-etching) technique: Preparation and characterization  

Microsoft Academic Search

Track-etched polycarbonate (PC) microfilters were successfully prepared by tracking with fission frag- ments in the Thai Research Reactor-1\\/Modification-1 nu- clear reactor and chemical etching with sodium hydroxide aqueous solutions. The porosity of the as-prepared microfil- ters can be controlled by varying the exposure time in the nuclear reactor and the average pore diameter by varying the etching conditions. In the

Pornphan Makphon; Wichian Ratanatongchai; Somporn Chongkum; Supawan Tantayanon; Pitt Supaphol

2006-01-01

369

Thermal Neutron Dosimetry Using Electrochemical Etching.  

National Technical Information Service (NTIS)

This study demonstrates the feasibility of using high LET particle radiators to determine the thermal neutron dose by reaction particle registration in low background polycarbonate foils using electrochemical etching. When used in conjunction with the alr...

S. J. Su M. E. Sanders K. Z. Morgan

1979-01-01

370

Epoxy bond and stop etch fabrication method  

DOEpatents

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)

2000-01-01

371

Directional Etching of Silicon by Silver Nanostructures  

NASA Astrophysics Data System (ADS)

We report directional etching of nanostructures (nanochannels and nanotrenches) into the Si(100) substrates in aqueous HF and H2O2 solution by lithographically defined Ag patterns (nanoparticles, nanorods, and nanorings). The Effect of Ag/Si interface oxide on the directional etching has been studied by etching Ag/SiOx/Si samples of known interface oxide thickness. Based on high resolution transmission electron microscopy (HRTEM) imaging and TEM-energy dispersive X-ray (EDX) spectra of the Ag/Si interfaces, we propose that maintenance of the sub-nanometer oxide at the Ag/Si interfaces and Ag--Si interaction are the key factors which regulate the directional etching of Si.

Sharma, Pradeep

2011-02-01

372

Electrochemical Etching of Titanium-Alloy Castings.  

National Technical Information Service (NTIS)

This study was conducted to determine whether a potentiostatic electrochemical method could be used to etch selectively either the dendrites or the interdendritic material from Ti cast structures and thereby reveal their microstructures. Cast binary titan...

J. C. Griess S. A. David R. J. Gray C. W. Houck

1983-01-01

373

Investigations of Wafer Scale Etching with Xenon Difluoride  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

374

A Demonstration of Broadband RF Sensing: Empirical Polysilicon Etch Rate Estimation in a Lam 9400 Etch Tool  

Microsoft Academic Search

The sensitivity of a novel broad frequency band ( to ) RF sensing system to plasma etching process conditions is demonstrated. This is accomplished by using the sensing system to estimate polysilicon etch rate in a Lam 9400 etch tool. A designed experiment varying physical and chemical reactive ion etching regimes was performed with five repetitions at each experimental point.

Craig Garvin; J. W. Grizzle

375

Plasma etching: Yesterday, today, and tomorrow  

SciTech Connect

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

Donnelly, Vincent M.; Kornblit, Avinoam [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)] [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)

2013-09-15

376

Hybrid etching process and its application in thermopile infrared sensor  

Microsoft Academic Search

This paper presents a hybrid silicon etching processing technique for removing the entire bulk silicon to release microstructure. The proposed method that combines a back-side wet anisotropic pre-etching and a front-side XeF2 dry isotropic post-etching differs from previous works in silicon micromachining. Wet anisotropic pre-etching enhances the low-cost of the proposed method while the XeF2 dry post-etching avoids the stiction

Dehui Xu; Bin Xiong; Yuelin Wang; Yinglei Ma

2010-01-01

377

Performance of a New One-step Multi-mode Adhesive on Etched vs Non-etched Enamel on Bond Strength and Interfacial Morphology.  

PubMed

Purpose: To compare microtensile bond strength (?TBS) and interfacial morphology of a new one-step multimode adhesive with a two-step self-etching adhesive and two etch-and-rinse adhesives systems on enamel. Materials and Methods: Thirty human third molars were sectioned to obtain two enamel fragments. For ?TBS, 48 enamel surfaces were ground using 600-grit SiC paper and randomly assigned into 6 groups (n = 8): nonetched Scotchbond Universal [SBU]; etched SBU [SBU-et]; non-etched Clearfil SE Bond [CSE]; etched CSE [CSE-et]; Scotchbond Multi-Purpose [SBMP]; Excite [EX]. The etched specimens were conditioned with 37% phosphoric acid for 30 s, each adhesive system was applied according to manufacturers' instructions, and composite resin blocks (Filtek Supreme Plus, 3M ESPE) were incrementally built up. Specimens were sectioned into beams with a cross-sectional area of 0.8-mm2 and tested under tension (1 mm/min). The data were analyzed with oneway ANOVA and Fisher's PLSD (? = 0.05). For interface analysis, two samples from each group were embedded in epoxy resin, polished, and then observed using scanning electron microscopy (SEM). Results: The ?TBS values (in MPa) and the standard deviations were: SBU = 27.4 (8.5); SBU-et = 33.6 (9.3); CSE = 28.5 (8.3); CSE-et = 34.2 (9.0); SBMP = 30.4 (11.0); EX = 23.3 (8.2). CSE-et and SBU-et presented the highest bond strength values, followed by SBMP, CSE, and SBU which did not differ significantly from each other. EX showed the statistically significantly lowest bond strength values. SEM images of interfaces from etched samples showed long adhesive-resin tags penetrating into demineralized enamel. Conclusions: Preliminary etching of enamel significantly increased bond strength for the new one-step multimode adhesive SBU and two-step self-etching adhesive CSE. PMID:24847489

de Goes, Mario Fernando; Shinohara, Mirela Sanae; Freitas, Marcela Santiago

2014-06-01

378

Influence of etching with erbium, chromium:yttrium-scandium-gallium-garnet laser on microleakage of class V restoration.  

PubMed

The aim of this in vitro study was to evaluate some parameters of dental etching when irradiated with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. One-hundred sound human third molars were selected and randomly distributed into ten groups (n = 10). The class V cavities of group 1 (control) were prepared with a bur and etched with 37% phosphoric acid, while groups G2 to G10, were prepared with laser (5 W, 88.46 J/cm(2), 90/70% air/water) and etched with the following powers: G3 and G4, 0.25 W; G5 and G6, 0.5 W; G7 and G8, 0.75 W; G9 and G10, 1 W. Group G2 received no laser etching. Prior to restoration, G2, G4, G6, G8 and G10 received acid etching. After restoration, all samples were submitted to a microleakage test. According to statistical analysis (Kruskal-Wallis and Dunn's tests), G10 presented the lowest microleakage values (P<0.05). The other groups showed no differences between them. Etching with Er,Cr:YSGG laser (1 W) followed by phosphoric acid was effective in reducing the microleakage of class V restorations. PMID:19011950

Marotti, Juliana; Geraldo-Martins, Vinícius Rangel; Bello-Silva, Marina Stella; de Paula Eduardo, Carlos; Apel, Christian; Gutknecht, Norbert

2010-05-01

379

Effect of MTAD on the shear bond strength of self-etch adhesives to dentin  

PubMed Central

Background: As the use of different irrigants to eliminate residual debris and smear layer in the field of endodontic is unavoidable, by considering the effect of irrigants on the bond strength of resin composite restorations, this study was designed to evaluate the effect of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) on the shear bond strength of two self-etch adhesives, Clearfil SE Bond and Adper Prompt L- Pop to dentin. Materials and Methods: The crowns of 80 extracted premolars were transversally sectioned to expose dentin. Flat dentin surfaces were wet abraded with 320-grit abrasive paper and randomly assigned to eight groups according to two self-etch adhesive and four dentin surface treatments: direct application over smear layer (no treatment), etching with 35% phosphoric acid for 15s, 1 min 5.25% NaOCl/1 min MTAD and 20min 1.3% NaOCl/5min MTAD. Shear bond strength was tested 24 h after storage in distilled water at 37°C in incubator. Data were analyzed using one-way ANOVA followed by duncan post-hoc (?=0.05). Results: Phosphoric acid etching prior to SE Bond application significantly decreased the shear bond strength to dentin (P<0.05). Application of MTAD clinical protocol (20min 1.3% NaOCl/5min MTAD) did not significantly decrease the shear bond strength of self-etch adhesives to dentin (P=0.745) Conclusions: Based on the results of present investigation, it seems that the use of clinical protocol of 1.3% NaOCl as a root canal irrigant and a 5-min application of MTAD as a final rinse to remove the smear layer has no adverse effect on the shear bond strength of self-etch adhesives to dentin.

Mortazavi, Vajihesadat; Khademi, Abbasali; Khosravi, Kazem; Fathi, Mohammadhossein; Ebrahimi-Chaharom, Mohammadesmaeil; Shahnaseri, Shirin; Khalighinejad, Navid; Badrian, Hamid

2012-01-01

380

Cycle of two-step etching process using ICP for diamond MEMS applications  

Microsoft Academic Search

Inductively coupled plasma (ICP) etching was performed to etch diamonds, and a new diamond etching technique was established in order to obtain the high selective etching rate of diamond with respect to the silicon oxide etching mask and the smooth etched surface. Scanning electron microscope (SEM) observations and energy dispersive X-ray (EDX) characterizations of the etched diamond surfaces show that

Takatoshi Yamada; Hiromichi Yoshikawa; Hiroshi Uetsuka; Somu Kumaragurubaran; Norio Tokuda; Shin-ichi Shikata

2007-01-01

381

Electron emission from discontinuous gold-carbon compound film on etched porous aluminum oxide  

NASA Astrophysics Data System (ADS)

An electron emitter composed of discontinuous gold-carbon compound conducting film on etched porous aluminum oxide (PAO) layer is proposed in this letter. The PAO layer is located between two 30 ?m spaced cathode and grid electrode, and is etched in diluted phosphoric acid to introduce roughness on the soda lime glass surface and enhance discontinuity of the conducting film. Electron emission with good uniformity and stability is reproducibly obtained. The electron emission efficiency is higher than 2% at an anode voltage of 3 kV.

Wang, Zengmei; Li, Dejie; Yao, Baolun; Wang, Jian

2006-08-01

382

Precise Depth Control of Silicon Etching Using Chlorine Atomic Layer Etching  

Microsoft Academic Search

In this study, the atomic layer etching (ALE) of Si was carried out using Cl2 adsorption followed by Ar+ ion beam irradiation with a low energy Ar+ ion beam generated by an inductively coupled plasma ion gun. A saturated silicon etch rate due to chlorine ALE could be obtained when the Ar+ ion acceleration voltage of the ion gun was

Sang-Duk Park; Kyung-Suk Min; Byoung-Young Yoon; Do-Haing Lee; Geun-Young Yeom

2005-01-01

383

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

NASA Astrophysics Data System (ADS)

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

Yongliang, Li; Qiuxia, Xu

2010-03-01

384

Ultrahigh-Aspect-Ratio Contact Hole Etching  

NASA Astrophysics Data System (ADS)

An ultrasmall, 60nm-diameter, 2um-deep contact hole pattern of BPSG film was successfully fabricated using a poly-Si mask and a magnetically enhanced reactive-ion-etching system. Significantly weaker dependence of etch rate on aspect ratio(AR) was obtained up to AR=30, showing that the energetic ions (and/or neutralized molecules) with a sufficient flux for etching reaction are supplied onto the hole bottom even in such a extremely fine feature. On the other hand, neutral supply of polymer precursors onto the hole bottom (Si substrate) is not sufficient for polymerization in holes with aspect ratios greater than 10, where several energetic particles reach the hole bottoms and contribute to the etching reaction with Si substrates. For features with dimensions below 100nm, processing of vertical profiles is extremely difficult, and problems in the form of bowing at the sidewalls of the holes can occur. The shape of the etched feature and the occurrence of etch stops were shown to be in a trade-off relationship. However, vertical profiles were successfully obtained with diameters greater than 100nm without etch stops. It is possible that ion flux is significantly influenced (reduced) when ions pass through the poly-Si mask, rather than through the BPSG hole. The bowing is associated with bending of the incident ion trajectories, where the first stage of the trajectory change occurs at the mask, and subsequent multiple scattering of ions at the sidewall of the hole can occur. Other factors include sidewall protection by redeposited Si that was sputtered from the poly-Si mask and/or the deposited fluorocarbon polymers, and the effects of ion flux and energy bombarding these deposited materials. In the future, it will be necessary to clarify the details of the mechanisms of these phenomena and to establish technologies to control them. note number.

Ikegami, Naokatsu

1997-10-01

385

Reactive ion etching of tantalum pentoxide  

SciTech Connect

Etching experiments were performed using a parallel plate, RF reactive ion etching (RIE) system (ANELVA DEM-451M) with a 13.56 MHz RF power supply. The 250 mm diameter electrodes with cathode coupled configuration are separated by 89 mm. The wafers are mounted on the water-cooled cathode during etching. The following fluorocarbon gases were used as etch gases: CF/sub 4/, CF/sub 4//H/sub 2/ (partial pressure ratio of CF/sub 4//H/sub 2/ = 80/20) and CF/sub 4//O/sub 2/ (partial pressure ratio of CF/sub 4//O/sub 2/ = 95/5). The system pressure during etching was controlled to between 10 mTorr and 100 mTorr. Ta/sub 2/O/sub 5/ films were fabricated using an RF magnetron sputtering system. The Ta/sub 2/O/sub 5/ target, which was 10 cm in diameter and 5 mm thick, was used in the sputtering experiments. The sputtering gas consisted of mixtures of argon and oxygen (partial pressure ratio of Ar/O/sub 2/ = 80/20). The wafers were patterned using Shipley AZ 1350 positive photoresist. Thickness measurements were performed with a Taylor-Hobson surface profilimeter. Etch rates for Ta/sub 2/O/sub 5/, SiO/sub 2/, single-crystalline silicon (<100> oriented, p-type and 1.2 to 1.8 ohm-cm) and Shipley AZ 1350 positive photoresist, and individual etch rate ratios were studied.

Seki, S.; Tsujiyama, B.; Unagami, T.

1983-12-01

386

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

PubMed

Irradiation of enamel with laser energy changes the physical and chemical characteristics of the enamel surface, and these alterations hold promise for the conditioning of enamel for bonding procedures. This laboratory study examined the influence of laser irradiation of enamel at 2 different power settings with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system (Millennium System, Biolase Technology, Inc; San Clemente, Calif) on the shear bond strength of orthodontic appliances and compared these with that of acid-etching. The prepared surfaces of 40 noncarious, intact, extracted premolars were exposed to laser energy: 20 teeth at 2-W setting (5.6 J/cm(2)) and 20 teeth at 1-W setting (2.7 J/cm(2)) of the commercial laser unit. Twenty teeth were etched with 37% orthophosphoric acid. Brackets were bonded with an orthodontic no-mix adhesive, and shear bond strength was determined with a universal testing machine. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Etched and restored surfaces of an acid-etched tooth and a 2-W laser-irradiated tooth were examined with scanning electron microscopy (SEM). Laser treatment under 2 W resulted in bond strengths of 7.11 +/- 4.56 megapascals (MPa), which was not significantly different from that of acid etching (8.23 +/- 2.30 MPa). Laser irradiation at 1 W resulted in bond strengths of 5.64 +/- 3.19 MPa, which was significantly different from that of acid etching (P <.05). However, large SD and coefficient of variation values of both laser groups made reliability of this method as an enamel conditioner questionable. Scanning electron microscopy studies of the restored irradiated surfaces showed good surface characteristics, whereas the lased surface was still more irregular than the restored acid-etched sample. Although laser devices are effectively used in some other areas of dentistry, enamel conditioning with an Er,Cr:YSGG laser cannot be considered a successful alternative to the conventional methods of increasing bond strengths to enamel. PMID:12490877

U?ümez, Serdar; Orhan, Metin; U?ümez, Aslihan

2002-12-01

387

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

NASA Astrophysics Data System (ADS)

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

Sugano, Koji; Tabata, Osamu

2001-09-01

388

A room temperature etching route to tungsten oxide hydrate nanoplates with expanded surface area  

Microsoft Academic Search

Tungsten oxide hydrate nanoplates with expanded surface area have been synthesized through the acid treatment of tungstate?aluminum keggin nanocomposite. According to powder X-ray diffraction and W LIII-edge X-ray absorption spectroscopic analyses, X-ray amorphous nanocomposite is changed into crystalline WO3·2H2O upon the acidic etching of alumina component. Nitrogen adsorption?desorption isotherm and field emission-scanning electron microscopy measurements clearly demonstrated that the surface

Ah Reum Han; Seong-Ju Hwang; Hyun Jung; Jin-Ho Choy

2008-01-01

389

Mechanism for environmental etch of acrylic melamine-based automotive clearcoats: Identification of degradation products  

Microsoft Academic Search

This paper focuses on defining the reaction mechanism involved in the environmental etch of acrylic melamine-based automotive\\u000a clearcoats via an identification of reaction products. This has been accomplished through a comparative study of products\\u000a formed on acid treatment of neat crosslinkers, and those formed following laboratory acid treatment and field exposure of\\u000a acrylic melamine clearcoat systems. Bulk elemental, X-ray photoelectron

P. J. Schmitz; J. W. Holubka; Li-Feng Xu

2000-01-01

390

High Rate Deep Si Etching using Capacitively Coupled Plasma  

NASA Astrophysics Data System (ADS)

High rate deep Si etching using SF6/O2 gas chemistry by Magnetically-Enhanced Reactive Ion Etch (MERIE) system using a Dipole-Ring Magnet (DRM) is studied. It is capable of etching holes 40 ?m in diameter in a Si substrate at etch rates as high as 50 ?m/min. It was found that the Si etch reaction is dominated by the density of fluorine radicals, which is realized at high frequency and pressure. In holes with higher aspect ratios, it was found that the Si etch rate at the bottom of holes is determined not only by the supply of fluorine radicals, but is also influenced by an etch-inhibiting effect related to the sidewall of the hole. Using an 8 ?m square mask, holes with straight sidewalls were etched to a depth of 60 ?m at an etch rate of 24 ?m/min.

Sakai, Itsuko; Sakurai, Noriko; Ohiwa, Tokuhisa

391

Patterning enhancement techniques by reactive ion etch  

NASA Astrophysics Data System (ADS)

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

Honda, Masanobu; Yatsuda, Koichi

2012-03-01

392

Microleakage of resin-modified glass ionomer restorations with selective enamel etching.  

PubMed

SUMMARY Aim : Bonding of resin-modified glass ionomers to enamel is an important quality, especially when saliva contamination is inevitable. This study evaluated if microleakage of a resin-modified glass ionomer improves with selective enamel etching, with or without saliva contamination. Methods : Class V cavities with the occlusal margin in enamel and the gingival margin on the root were prepared in extracted human permanent teeth and filled with a resin-modified glass ionomer using an acidic primer according to the manufacturer's recommendation or with an additional selective enamel etching step. Preparations were contaminated with saliva before primer application or before restoration placement (n=10). Restored teeth were thermocycled between 5°C and 55°C for 1000 cycles, stained with basic fuchsin, and sectioned. Microleakage distance was measured and analyzed with analysis of variance followed by Duncan post hoc test at a significance level of 0.05. Results : Enamel microleakage was highest when saliva contamination occurred before the placement of resin-modified glass ionomer. Microleakage distances were significantly reduced in the selective etching groups regardless of saliva contamination. However, selective etching of enamel increased microleakage in cementum. The increase in cementum leakage was significantly higher when saliva contamination occurred before restoration placement. Conclusion : Selective etching reduces enamel microleakage of a resin-modified glass ionomer even with saliva contamination, but it may increase microleakage at the cementum. The severity of microleakage is affected by the timing of saliva contamination. PMID:24967989

Ludlow, Sw; Farmer, Sn; Donaldson, Me; Tantbirojn, D; Versluis, A

2014-01-01

393

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

PubMed Central

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.

2014-01-01

394

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

2014-02-01

395

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

PubMed

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

2012-05-01

396

Plasma etch method for extreme ultraviolet lithography photomask  

SciTech Connect

Studies on extreme ultraviolet mask etch were carried out by using the Gibbs energy minimization method to select plasma etch chemistries and to determine product volatility when etching absorber material to ensure a clean process and chamber operation. A self-mask method and corresponding etch conditions were proposed and experimentally examined using the antireflective portion of an absorber layer as a hard mask for the bulk absorber layer beneath. This approach overcame the intrinsic soft mask disadvantage of large etch critical dimension (CD) bias and low pattern transfer fidelity, producing significantly reduced etch CD bias (2 nm) and high pattern transfer fidelity.

Wu Banqiu; Kumar, Ajay [Applied Materials, Inc., 974 E. Arques Ave., M/S 81505, Sunnyvale, California 94085 (United States)

2007-02-05

397

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

2013-04-01

398

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

2013-09-01

399

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.

2014-01-01

400

Long germanium nanowires prepared by electrochemical etching.  

PubMed

Germanium (Ge) nanowires have been produced by electrochemical etching of single-crystalline n-type Ge [100] in a HCl-containing aqueous electrolyte. Macropores could be etched at various etching currents after an optimized procedure for homogeneous pore nucleation was used. Because of the narrow band gap of Ge (0.66 eV), the leakage current through pore walls is much higher than that, for example, in Si, leading to a constant dissolution of the pore walls. At sufficiently high current densities, it is then possible to form nanowires with diameters determined by the width of the space charge region, ranging from roughly 50 to 500 nm, and a length of several hundred micrometers. The role of the space charge region for stabilizing pore formation and in the formation of nanowires will be discussed. PMID:16834454

Fang, C; Föll, H; Carstensen, J

2006-07-01

401

Single beam determination of porosity and etch rate in situ during etching of porous silicon  

NASA Astrophysics Data System (ADS)

A laser reflection method has been developed and tested for analyzing the etching of porous silicon (PS) films. It allows in situ measurement and analysis of the time dependency of the etch rate, the thickness, the average porosity, the porosity profile, and the interface roughness. The interaction of an infrared laser beam with a layered system consisting of a PS layer and a substrate during etching results in interferences in the reflected beam which is analyzed by the short-time Fourier transform. This method is used for analysis of samples prepared with etching solutions containing different concentrations of HF and glycerol and at different current densities and temperatures. Variations in the etch rate and porosity during etching are observed, which are important effects to account for when optical elements in PS are made. The method enables feedback control of the etching so that PS films with a well-controlled porosity are obtainable. By using different beam diameters it is possible to probe interface roughness at different length scales. Obtained porosity, thickness, and roughness values are in agreement with values measured with standard methods.

Foss, S. E.; Kan, P. Y. Y.; Finstad, T. G.

2005-06-01

402

ICP cryogenic dry etching for shallow and deep etching in silicon  

NASA Astrophysics Data System (ADS)

We achieved to etch nano- and deep structures in silicon using ICP-cryogenic dry etching process. We etched nanopores and nanocantilevers with an etch rate of 13 nm/min, nanopillars with an etch rate of 2.8 ?m/min - 4.0 ?m/min, membrane and cantilever structures with an etch rate of 4 ?m/min and 3 ?m/min, respectively. Nanopores and nanocantilevers are interesting structures for Bionanoelectronics. Nanopillars can be used as substrates/templates for the MOCVD growth of GaN nanoLEDs. They are the basic constituents of a nanoparticle balance and also of a thermoelectric generator. For the joining of the silicon wafers of the thermoelectric generator the low temperature joining technique can be used. Cantilevers can be used for sensing, e.g. as tactile cantilevers. They can be used also as resonator for mass sensing even in the subnanogram region. The actuation of the resonator can be done by using piezoelectric thin films on the cantilevers. The mass detection depends on the resonance frequency shift caused by loaded mass on the cantilevers. Such cantilevers are robust and easy to produce. The deep etching in silicon was done by using a photoresist mask and creating perpendicular and smooth sidewalls.

Sökmen, Ü.; Balke, M.; Stranz, A.; Fündling, S.; Peiner, E.; Wehmann, H.-H.; Waag, A.

2009-05-01

403

Thinned fiber Bragg gratings as high sensitivity refractive index sensor  

Microsoft Academic Search

In this work, the numerical and experimental analysis on the use of thinned fiber Bragg gratings as refractive index sensors have been carried out. Wet chemical etching in a buffered hydrofluoric acid solution was used for sensor fabrication. Experimental characterization for an almost full etched cladding sensor is presented demonstrating good agreement with numerical results and resolutions of ?10-5 and

A. Iadicicco; A. Cusano; A. Cutolo; R. Bernini; M. Giordano

2004-01-01

404

Study of plasma - surface interactions: chemical dry etching and high-density plasma etching  

NASA Astrophysics Data System (ADS)

We report results of the characterization of the plasma - surface interactions of silicon and silicon dioxide in fluorocarbon discharges using real-time ellipsometry and post-plasma multi-technique surface analysis for chemical dry etching (CDE) and high-density plasma etching (HDPE). We show that changes of the gas composition in CDE causes major changes in silicon surface chemistry and etching behaviour. For low-pressure HDPE we investigate the influence of power deposition into the discharge and bias voltage and bias power at the wafer on the surface chemical changes of silicon and 0963-0252/5/2/012/img1.

Oehrlein, G. S.; Matsuo, P. J.; Doemling, M. F.; Rueger, N. R.; Kastenmeier, B. E. E.; Schaepkens, M.; Standaert, Th; Beulens, J. J.

1996-05-01

405

Optical Bends and Rings Fabricated by Preferential Etching.  

National Technical Information Service (NTIS)

Preferential etching techniques have been applied to the fabrication of optical bends and rings. Nearly perfect smooth waveguide walls formed by crystalline planes can still be obtained in the curved section. Application of such preferentially etched opti...

C. C. Tseng D. Botez S. Wang

1975-01-01

406

Sidewall Passivation by Oxidation During Refractory-Metal Plasma Etching.  

National Technical Information Service (NTIS)

Sidewalls in a pattern of a refractory metal on a substrate are passivated during plasma etching by introducing water vapor into the etching chamber. This process obtains nearly vertical sidewalls. In one exemplified embodiment, a pattern of tungsten on a...

J. Kosakowski W. Chu K. W. Foster C. R. Marrian M. C. Peckerar

1995-01-01

407

Reactive Ion Etching of Si Substrate using Three-Dimensional Aluminum Masks  

NASA Astrophysics Data System (ADS)

Three-dimensional micro fabrication process is one of the most important processes for micro-electro-mechanical systems field, optical device and many advance applications. This paper describes reactive ion etching of silicon substrates using three-dimensional aluminum masks. Aluminum masks were fabricated by photolithography, anodization and chemical etching. A 150 nm thick aluminum film was deposited on titanium-coated silicon substrates. Subsequently, square masks were patterned on the aluminum film by photolithography. After anodizing the aluminum film in 2 vol% sulfuric acid, an anodic oxide film was formed at the photoresist/aluminum film interface in addition to the open surface regions. After the anodic oxide film was removed by chemical etching in 20 vol% phosphoric acid, the resulting aluminum film surface showed convex features. Silicon substrates were fabricated using these aluminum masks. By controlling the gas mass flow and pressure, an etching rate of 32-94 nm/min and selectivity of 8.4-218 were achieved. Thus, this process proved to be effecitve method for fabricated three-dimensional microstructures on silicon substrates.

Katsumata, Nobuyuki; Ishida, Masafumi

408

Excimer laser induced etching of InP  

Microsoft Academic Search

We report 193 nm ArF excimer laser induced etching of InP in Cl2. Etching occurs by desorption of an In-chloride layer, as evidenced by an etch rate which increases linearly with laser repetition rate and is nearly pressure independent between 2 and 50 mTorr Cl2. At substrate temperatures near 150 °C, the etch rate increases above a ‘‘threshold’’ fluence of

V. M. Donnelly; T. R. Hayes

1990-01-01

409

Atomic layer in situ etching and MBE regrowth  

Microsoft Academic Search

We report on atomic layer precise etching in MBE with AsBr3 as the etching species. Selective etching of SiO2 masked GaAs (100) substrates allows in situ preparation of extremely sharp V-grooves with almost perfect planar {110} side facets. By MBE regrowth of V-grooves we can prepare buried layers and completely embedded wires. The electrical properties of etched interfaces in modulation

K. Eberl; M. Lipinski; H. Schuler

1999-01-01

410

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

2006-01-01

411

Anisotropic Etching, Silicon Crystal Orientation, and MEMS  

NSDL National Science Digital Library

The goal of this interactive Learning Invention Lab from MATEC is to help students understand how crystal orientation affects etch profiles in silicon. There are several diagrams and hands-on activities for students to do. Visit MATEC.org homepage for more information.

Lopez, Fabian

2012-12-31

412

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)

1997-01-01

413

Dry etching of III-V nitrides  

SciTech Connect

The chemical inertness and high bond strengths of the III-V nitrides lead to slower plasma etching rates than for more conventional III-V semiconductors under the same conditions. High ion density conditions (>3{times}l0{sup 9}cm{sup {minus}3}) such as those obtained in ECR or magnetron reactors produce etch rates up to an order of magnitude higher than for RIE, where the ion densities are in the 10{sup 9}cm{sup {minus}3} range. We have developed smooth anisotropic dry etches for GaN, InN, AlN and their alloys based on Cl{sub 2}/CH{sub 4}/H{sub 2}/Ar, BCl{sub 3}/Ar, Cl{sub 2}/H{sub 2}, Cl{sub 2}/SF{sub 6}, HBr/H{sub 2} and HI/H{sub 2} plasma chemistries achieving etch rates up to {approximately}4,000{angstrom}/min at moderate dc bias voltages ({le}-150V). Ion-induced damage in the nitrides appears to be less apparent than in other III-V`s. One of the key remaining issues is the achievement of high selectivities for removal of one layer from another.

Pearton, S.J. [Florida Univ., Gainesville, FL (United States); Shul, R.J. [Sandia National Labs., Albuquerque, NM (United States); McLane, G.F. [Army Research Laboratory, Ft. Monmouth, NJ (United States); Constantine, C. [Plasma Therm IP, St. Petersburg, FL (United States)

1995-12-01

414

Energy Gaps in Etched Graphene Nanoribbons  

Microsoft Academic Search

Transport measurements on an etched graphene nanoribbon are presented. It is shown that two distinct voltage scales can be experimentally extracted that characterize the parameter region of suppressed conductance at low charge density in the ribbon. One of them is related to the charging energy of localized states, the other to the strength of the disorder potential. The lever arms

C. Stampfer; J. Güttinger; S. Hellmüller; F. Molitor; K. Ensslin; T. Ihn

2009-01-01

415

Optimization of TMAH etching for MEMS  

NASA Astrophysics Data System (ADS)

Tetra-methyl ammonium hydroxide (TMAH) is an anisotropic silicon etchant that is gaining considerable use in silicon sensor micromachining due to its excellent compatibility with CMOS processing, selectivity, anisotropy and relatively low toxicity, as compared to the more used KOH and EDP etchants. In this paper, the influence of temperature and concentration of the TMAH solution together with oxidizer additions is studied in order to optimize the anisotropic silicon etching for MEMS fabrication. In particular this optimized etchant formulation has been employed at ITC-Irst in the development of a basic fabrication process for piezoresistive pressure sensors based on a silicon membrane and four resistors connected in a Weatherstone bridge configuration. The active element of the sensor, i.e. the thin silicon membrane, is formed by etching anisotropically from the backside of the wafer. Both process and etching have to be tuned and matched in order to obtain an optimum fabrication sequence. Some improvements such as higher etch rate and better surface finish have been obtained by the addition of ammonium peroxidsulfate as oxidizing agent under different conditions. This simplifies both the post processing and the tech set-up. The process parameters and the thermo-electro-mechanical characteristics of the pressure sensors were tested and are compared with the analytical and numerical simulations.

Brida, Sebastiano; Ferrario, Lorenza; Guarnieri, Vittorio; Giacomozzi, Flavio; Margesin, Benno; Paranjape, Makarand; Verzellesi, Giovanni; Zen, Mario

1999-03-01

416

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

2013-03-01

417

Recipes for Plasma Atomic Layer Etching  

Microsoft Academic Search

Summary form only given. The development of robust processes for gate plasma etching to produce desired profiles and sidewall angles is critical to future technological nodes. The gradual decrease in equivalent gate oxide thickness at future technology nodes (les 100 nm node) has necessitated process control at the atomic level. To insure this level of control, it is desirable to

A. Agarwal; M. J. Kushner

2007-01-01

418

Energetic Atoms Would Etch Photoresists Anisotropically  

NASA Technical Reports Server (NTRS)

Directed beams of single oxygen atoms having kinetic energies between 1 and 5 eV used in anisotropic etching of oxygen-labile photoresist patterns on silicon wafers. Key step in manufacturing integrated circuits on semiconductor wafers. Damage to semiconductor material under photoresist layer reduced or eliminated. Method incorporated into lithographic processes for fabrication of integrated circuits.

Koontz, Steven; Cross, Jon

1993-01-01

419

New phase formation in titanium aluminide during chemical etching  

SciTech Connect

A chemical etching technique is widely used for metallographic observation. Because this technique is based on a local corrosion phenomenon on a sample, the etching mechanism, particularly for two-phase alloys, can be understood by electrochemical consideration. This paper describes formation of a new phase in a Ti-45Al (at.%) titanium aluminide during chemical etching, and the experimental results are discussed electrochemically.

Takasaki, Akito; Ojima, Kozo; Taneda, Youji (National Defense Academy, Kanagawa (Japan). Dept. of Mathematics and Physics)

1994-05-01

420

New phase formation in titanium aluminide during chemical etching  

Microsoft Academic Search

A chemical etching technique is widely used for metallographic observation. Because this technique is based on a local corrosion phenomenon on a sample, the etching mechanism, particularly for two-phase alloys, can be understood by electrochemical consideration. This paper describes formation of a new phase in a Ti-45Al (at.%) titanium aluminide during chemical etching, and the experimental results are discussed electrochemically.

Akito Takasaki; Kozo Ojima; Youji Taneda

1994-01-01

421

Electrochemical etching of gold within nanoshaved self-assembled monolayers.  

PubMed

Wet etching of metal substrates with patterned self-assembled monolayers (SAMs) is an inexpensive and convenient method to produce metal nanostructures. For this method to be relevant to the fabrication of high precision plasmonic structures, the kinetics of nanoscale etching process, particularly in the lateral direction, must be elucidated and controlled. We herein describe an in situ atomic force microscopy (AFM) study to characterize the etching process within patterned SAMs with nanometer resolution and in real time. The in situ study was enabled by several unique elements, including single crystalline substrates to minimize the variability of facet-dependent etch rate, high-resolution nanoshaved SAM patterns, electrochemical-potential-controlled etching, and AFM kymographs to improve temporal resolution. Our approach has successfully quantified the extent of both lateral etching and vertical etching at different potentials. Our study reveals the presence of an induction period prior to the onset of significant lateral etching, which would be difficult to observe with the limited time resolution and sample-to-sample variation of ex situ studies. By increasing the vertical etch rate during this induction period with higher potentials, gold was etched up to 40 nm in the vertical direction with minimal lateral etching. High-resolution etching was also demonstrated on single crystal gold microplates, which are high quality gold thin films suitable for plasmonics studies. PMID:23713449

Shao, Jingru; Josephs, Eric A; Lee, Cheetar; Lopez, Adriana; Ye, Tao

2013-06-25

422

CR-39 track etching and blow-up method  

DOEpatents

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)

1987-01-01

423

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

2011-01-01

424

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

1993-01-01

425

Etching of tungsten and tungsten silicide films by chlorine atoms  

Microsoft Academic Search

Thin films of tungsten and tungsten silicide were etched both within and downstream from a Clâ plasma discharge at 200 mtorr pressure and temperatures below 150°C. When samples were positioned downstream from the discharge, etching proceeded solely by chemical reaction of the film with chlorine atoms. Without a discharge, molecular chlorine did not etch tungsten or tungsten silicide. Downstream and

D. S. Fischi; G. W. Rodriques; D. W. Hess

1988-01-01