Sample records for hydrofluoric acid etching

  1. Etching with Hydrofluoric Acid

    E-print Network

    Yoo, S. J. Ben

    . "Real" Resist Adhesion Problems during HF Etching In contrast to the large-scale resist peeling oxide) etching of the substrate with HF before resist coating results in a very poor and non-reproducible resist adhesion, which can be restored with a The etched profile reveals if either the resist adhesion

  2. Focus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid

    E-print Network

    Wilcock, William

    Focus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid Hydrofluoric acid (HF eye damage. HF vapors can seriously damage the lungs. Pulmonary edema (flooding of the lungs characterized by weight loss, brittle bones, anemia, and general ill health. Safe use If possible, avoid working

  3. Preliminary investigation of a novel retentive system for hydrofluoric acid etch-resistant dental ceramics

    Microsoft Academic Search

    D. J. Wood; N. L. Bubb; B. J. Millar; S. M. Dunne

    1997-01-01

    Statement of problem. A potential limitation to clinical use of In-Ceram and In-Ceram Spinell dental ceramics has been the inability to etch fit surfaces.Purpose. This study investigated a novel retentive system for In-Ceram and In-Ceram Spinell ceramics.Material and methods. The system, Bateman etch retention system, relies on incorporation of plastic chips on the surface of a specimen. The plastic chips

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

    PubMed Central

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

    2014-01-01

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

  5. Safety Slide 1 Hydrofluoric (HF) Acid Hazards http://www.emsworld.com/web/online/Education/Hydrofluoric-Acid-/5$12949

    E-print Network

    Cohen, Robert E.

    Safety Slide 1 ­ Hydrofluoric (HF) Acid Hazards http://www.emsworld.com/web/online/Education/Hydrofluoric-Acid-/5$12949 HF is less dissociated than most acids and deeply penetrates the skin. Symptoms of exposure://www.oseh.umich.edu/guidelines/hashp.shtml http://ehs.mit.edu/site/content/hydrofluoric-acid 1 Used for etching of Si or SiO2 Si + 4HNO3 SiO2 + 2

  6. DEPARTMENT OF CHEMICAL ENGINEERING Name of SOP Manual Hydrofluoric Acid (HF) Etching of Glass

    E-print Network

    Thompson, Michael

    , 2007 Definitions Terms None acronyms RMM ­ Risk Management Manual JHSC - Joint Health and Safety Committee EOHSS - Environmental & Occupational Health & Support Services OHSA ­ Occupational Health to the acid cabinet. 3. Approx. 1 mL of mineral oil will be poured into the solution of HF to contain HF

  7. 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)

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

    2013-05-01

    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.

  8. 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)

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

    2012-08-01

    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.

  9. The research on conformal acid etching process of glass ceramic

    NASA Astrophysics Data System (ADS)

    Wang, Kepeng; Guo, Peiji

    2014-08-01

    A series of experiments have been done to explore the effect of different conditions on the hydrofluoric acid etching. The hydrofluoric acid was used to etch the glass ceramic called "ZERODUR", which is invented by SCHOTT in Germany. The glass ceramic was processed into cylindrical samples. The hydrofluoric acid etching was done in a plastic beaker. The concentration of hydrofluoric acid and the etching time were changed to measure the changes of geometric tolerance and I observed the surface using a microscope in order to find an appropriate condition of hydrofluoric acid etching.

  10. Corrosion Behavior of Nickel Alloys in Wet Hydrofluoric Acid

    SciTech Connect

    Rebak, R B

    2004-02-06

    Hydrofluoric acid is a water solution of hydrogen fluoride (HF). Hydrofluoric acid is used widely in diverse types of industrial applications; traditionally, it is used in pickling solutions in the metal industry, in the fabrication of chlorofluorocarbon compounds, as an alkylation agent for gasoline and as an etching agent in the industry of glass. In recent years, hydrofluoric acid has extensively been used in the manufacture of semiconductors and microelectronics during the wet chemical cleaning of silicon wafers. Hydrofluoric acid can be considered a reducing acid and although it is chemically classified as weaker than, for example, sulfuric or hydrochloric acids, it is extremely corrosive. This acid is also particularly toxic and poses greater health hazard than most other acids. The corrosion behavior of metals in hydrofluoric acid has not been as systematic studied in the laboratory as for other common inorganic acids. This is largely because tests using hydrofluoric acid cannot be run in standard equipment and because of the toxic nature of this acid. Moreover, short-term weight loss laboratory corrosion tests in hydrofluoric acid can be frustrating since the results are not as highly reproducible as in the case of other acids such as sulfuric or hydrochloric. One of the reasons is because hydrofluoric acid commonly attacks the coupons used for testing in a non-uniform manner. That is, the corrosive power of this acid is not aimed to uniform thinning but mostly to localized penetration below the skin of the metal in the form of thin cracks, voids, pits, trenches and sometimes intergranular attack. Figure 1 shows the cross section of a coupon of Alloy 600 (N06600) exposed for 336 h to the vapor phase of a solution of 20% HF at 93 C. In cases where internal penetration occurs such as in Figure 1, it may not be recommended to use corrosion rates based on weight loss for material selection.

  11. Geochemistry of Hydrofluoric Acid in Kaolinitic Soils

    SciTech Connect

    DENHAM, MILES

    2004-05-11

    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.

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

    SciTech Connect

    Hankins, Matthew G. (Albuquerque, NM)

    2009-10-06

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

  13. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  14. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  15. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  16. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  17. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  18. Systemic and topical effects of intradermal hydrofluoric acid

    Microsoft Academic Search

    Massimo Gallerani; Vincenzo Bettoli; Luana Peron; Roberto Manfredini

    1998-01-01

    A 35-year-old man attempted suicide by subcutaneous self-administration of hydrofluoric acid (5 cc of a domestic rust removal solution containing 7% hydrofluoric acid). A burn 9 × 7 cm in diameter immediately appeared at the injection site (left forearm and fold of the elbow). In the emergency department, the burn was copiously washed with isotonic solution and treated with cutaneous

  19. Rationale of the treatment of hydrofluoric acid burns

    Microsoft Academic Search

    Shirley A. Carney; M. Hall; J. C. Lawrence; C. R. Ricketts

    1974-01-01

    Carney, Shirley A., Hall, M., Lawrence, J. C., and Ricketts, C. R. (1974).British Journal of Industrial Medicine,31, 317-321. Rationale of the treatment of hydrofluoric acid burns. On contact with skin hydrofluoric acid yields hydrogen and fluoride ions, which exhaust the tissue's buffering capacity. Fluoride was found to be toxic to skin cells, as judged by the accumulation of 3-phosphoglycerate (3-PG),

  20. Hypocalcemia, hypomagnesemia, and hypokalemia following hydrofluoric acid chemical injury.

    PubMed

    Dalamaga, Maria; Karmaniolas, Konstantinos; Nikolaidou, Athina; Papadavid, Evangelia

    2008-01-01

    Dermal exposure to hydrofluoric acid could potentially result in severe serum calcium and magnesium depletion induced by binding with fluoride anion. This report describes the case of a 48-year-old man who developed hypocalcemia and hypomagnesemia accompanied by hypokalemia-an interesting finding-following a chemical injury with exposure to 70% hydrofluoric acid. Successful treatment included administration of calcium gluconate and magnesium both intravenously and topically. PMID:18388571

  1. Burns caused by dilute hydrofluoric acid in the bleach.

    PubMed

    Fujimoto, Kazuhisa; Yasuhara, Naoaki; Kawarada, Harumichi; Kosaka, Sachiko; Kawana, Seiji

    2002-04-01

    Two male cleaning workers aged 62 (patient 1) and 28-(patient 2) presented with red, swollen, aching hands and fingers. At the first interview, the fingers of the right hand of both patients were swollen from the proximal interphalangeal joint to the tip of the finger. The fingers were red and intensely painful. The bleach that both patients used contained 9.5% hydrofluoric acid, and therefore we diagnosed their symptoms as those of burns caused by this agent. We subcutaneously injected 8.5% calcium gluconate into the affected fingers and dressed them with gauze soaked in cooled 0.025% benzethonium chloride. The patients did not use gloves at work, neither of them knew that the cleaning fluid contained dilute hydrofluoric acid, and they were unaware of the danger of this agent. They had not received proper education about the care and handling of poisons and deleterious substances such as hydrofluoric acid. The doctors who had examined the patients in the emergency ward overlooked the possibility of hydrofluoric acid burns, although they suspected chemical burns and confirmed the trade name of the cleaning agent. In addition, although the patients presented with intense pain, no white areas of coagulation and blistering, or surrounding erythemas, which are characteristic symptoms of such burns, were evident. The component of the cleaning agent was described on the container label in very small print. Had the words "poison" and "hydrogen fluoride" been printed in large characters, the examining doctors in the emergency ward would probably not have overlooked the presence of hydrofluoric acid, and the patients would perhaps have been more careful when using it. Hydrofluoric acid can be easily obtained by anyone through the Internet, although general consumers could not obtain industrial quantities. Therefore, the number of burn patients who are not familiar with hydrofluoric acid may increase in the future. PMID:12068331

  2. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  3. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  4. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  5. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  6. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  7. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  8. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  9. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  10. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  11. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  12. Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1

    Microsoft Academic Search

    Osborne

    2000-01-01

    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,

  13. Hydrofluoric acid-resistant composite window and method for its fabrication

    DOEpatents

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

    1985-07-18

    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.

  14. Comparative effectiveness of topical treatments for hydrofluoric acid burns.

    PubMed

    Bracken, W M; Cuppage, F; McLaury, R L; Kirwin, C; Klaassen, C D

    1985-10-01

    Hydrofluoric acid (HF) burns are characterized by progressive tissue necrosis and severe pain. Numerous topical treatments have been proposed, yet few have been studied experimentally. The present study was designed to examine the comparative efficacy of recommended treatments. Hair on the hind legs of rats was removed and 48 hours later 70% HF was applied. Calcium gluconate, Zephiran (benzalkonium chloride), A + D Ointment, aloe gel, and magnesium ointment were applied topically and burn development was monitored. Calcium gluconate significantly reduced burn size as early as one hour after application. Significant protection continued for seven days after the single application. The other treatments were not effective in decreasing or delaying HF burn development. The results indicated that calcium gluconate ointment was the most effective topical treatment for HF burns. PMID:4067676

  15. Treatment of hydrofluoric acid exposure to the eye

    PubMed Central

    Atley, Katherine; Ridyard, Edward

    2015-01-01

    AIM To review the current evidence of the treatment of hydrofluoric acid (HF) exposure to the human cornea. METHODS A comprehensive manual search of the literature was conducted through the Ovid interface to assess the mechanism and efficacy of each irrigator through a variety of clinical cases and experimental studies. RESULTS Ocular exposure to HF is extremely damaging to the eye and swift recognition and decontamination with an appropriate agent forms the basis of treatment. Although there are various decontamination solutions that have efficacy against the corrosive action of HF, irrigation with Hexafluorine proved to be the most safe and effective treatment for the eye. CONCLUSION In conclusion emergency departments could benefit from the availability of Hexafluorine for the treatment of HF ocular burns in patients. PMID:25709926

  16. Hydrofluoric acid treatment for improved performance of a nanofiltration membrane

    Microsoft Academic Search

    M. P. González Muñoz; R. Navarro; I. Saucedo; M. Avila; P. Prádanos; L. Palacio; F. Martínez; A. Martín; A. Hernández

    2006-01-01

    A method is proposed to improve the performance of a commercial nanofiltration membrane by treatment of the membrane with a hydrofluoric (HF) solution. A DS5DL (Osmonics) membrane, immersed for 14 days in HF (1% w\\/v), showed better solution permeability without deterioration of its potential for rejection of impurities. Such a prepared membrane was used for the purification of industrial phosphoric

  17. Effect of phosphoric and hydrofluoric acid on the structure and permeation of a nanofiltration membrane

    Microsoft Academic Search

    M. P. González; I. Saucedo; R. Navarro; P. Prádanos; L. Palacio; F. Martínez; A. Martín; A. Hernández

    2006-01-01

    The changes have been analyzed by studying the permeability of industrial phosphoric acid aqueous solutions through a nanofiltration membrane caused by treatment with phosphoric and hydrofluoric acid solutions. The retention of phosphoric acid together with its cationic impurities were also analyzed and attributed to a complex process of active layer modification. This process was studied in terms of both pore

  18. Fatal unintentional occupational poisonings by hydrofluoric acid in the U.S

    Microsoft Academic Search

    David W. Blodgett; Anthony J. Suruda; Barbara Insley Crouch

    2001-01-01

    Background Case reports have identified hydrofluoric acid (HF) as causing fatal work injury, and HF has both local and systemic toxicity. Surveillance for HF-related mortality is problematic because of the lack of unique coding for this acid in hospital records and vital statistics. Methods We identified HF-related fatal work injuries investigated by the Occupational Safety and Health Administration (OSHA) for

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

    PubMed Central

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

    2011-01-01

    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. PMID:22319388

  20. Hydrofluoric Acid Corrosion Testing on Unplated and Electroless Gold-Plated Samples

    SciTech Connect

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

    2000-08-01

    The Molten Salt Reactor Experiment (MSRE) remediation requires that almost 40 kg of uranium hexafluoride (UF6) be converted to uranium oxide (UO). In the process of this conversion, six moles of hydrofluoric acid (HP) are produced for each mole of UF6 converted.

  1. A Comparison of Calcium Gluconate and Zephiran for the Treatment of Dermal Hydrofluoric Acid Exposure

    Microsoft Academic Search

    Joshua G. Alters

    Hydrofluoric acid (HF), an aqueous form of hydrogen fluoride (Lewis 1993), typically emits a colorless irritating gas at room temperature (Hance, Solomon, Salmon, Fall, & Cass 1997). This highly corrosive, commonly used inorganic compound readily attacks materials such as concrete, glass, natural rubber, and metal alloys containing silica (EPA Chemical Profile 1987). The Occupational Safety and Health Administration (OSHA) has

  2. Spinner For Etching Of Semiconductor Wafers

    NASA Technical Reports Server (NTRS)

    Lombardi, Frank

    1989-01-01

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

  3. Preparation of luminescent silicon nanoparticles by photothermal aerosol synthesis followed by acid etching

    Microsoft Academic Search

    X. Li; Y. He; S. S. Talukdar; M. T. Swihart

    2004-01-01

    CO2 laser-induced pyrolysis of silane (photothermal aerosol synthesis) was used to produce Si nanoparticles. Particles with an average diameter as small as 5?nm were prepared directly from silane in the gas phase. Etching these particles with mixtures of hydrofluoric acid (HF) and nitric acid (HNO3) is shown to be an effective method to reduce the size of the particles produced

  4. [Hydrofluoric acid burns of the hands in the home environment: correct therapeutic approach].

    PubMed

    Nicoletti, Giovanni; Pellegatta, Tommaso

    2014-01-01

    The broad market penetration of products with components used primarily in the industrial sector requires the precise knowledge of their mechanism of action in order to perform a correct therapeutic approach. The article reports on three cases of domestic hydrofluoric acid burn that came to our Plastic Surgery Unit over the last three years. The treatment options are discussed in detail with emphasis on the importance of a constant update about such emerging diseases. PMID:24665624

  5. DFT study of the energetic and noncovalent interactions between imidazolium ionic liquids and hydrofluoric acid.

    PubMed

    Velarde, Marco V; Gallo, Marco; Alonso, P A; Miranda, A D; Dominguez, J M

    2015-04-16

    In this work, we evaluated the energetic interactions between imidazolium ionic liquids (ILs) and hydrofluoric acid, as well as the cation-anion interactions in ILs. We used DFT calculations that include dispersion corrections employing the PBE and M06 functionals. We tested 22 ILs, including [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][CH3COO], obtaining interaction energies in the range of -27 to -13 kcal/mol with the PBE functional. The NCI (noncovalent interaction) index developed by Yang and collaborators ( J. Am. Chem. Soc. 2010 , 132 , 6498 - 6506 ; J. Chem. Theory Comput. 2011 , 7 , 625 - 632 ) also was used for mapping the key noncovalent interactions (hydrogen bonds, van der Waals, and steric repulsions) between the anions and cations of ILs and also for interactions of ILs with hydrofluoric acid (HF). The results obtained show that the anions have a stronger effect with respect to cations in their capacity for interacting with hydrofluoric acid, and the strongest interaction energies occur in systems where the key noncovalent interactions are mainly hydrogen bonds. The [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][BF4] ionic liquids displayed the weakest cation-anion interactions. PMID:25803741

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

    PubMed Central

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

    2013-01-01

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

  7. Properties of LaAlO Film after Waterless Process Using Organic Solvent Containing Anhydrous Hydrofluoric Acid

    NASA Astrophysics Data System (ADS)

    Honjo, Masatomo; Komatsu, Naoyoshi; Masuzumi, Takuro; Aoki, Hidemitsu; Watanabe, Daisuke; Kimura, Chiharu; Sugino, Takashi

    2010-04-01

    Lanthanum (La)-based oxide films have been studied as high-k (high dielectric constant) gate dielectrics. However, moisture absorption is a serious problem for oxide films containing La. We have attempted to use waterless solutions instead of water-based solutions to remove high-k films to suppress the moisture absorption of the lanthanum aluminate (LaAlO) film. We report the effect of an anhydrous hydrofluoric acid (AHF) and isopropyl alcohol (IPA) mixed solution as an etching solution and hydrofluoro-ether (HFE) as a rising solution on the properties of LaAlO films. We have succeeded in suppressing the moisture absorption of LaAlO films by using waterless solutions for a front end of line (FEOL) process. In addition, the selectivity (LaAlO/SiO2), the etching ratio of LaAlO to SiO2, was improved using this process. It is considered that this technology will be useful for the next-generation devices with lanthanum-based oxide films.

  8. Hydrofluoric Acid (HF) Instructions The CEPSR Clean Room supplies one pound bottles of aqueous HF; their concentration may

    E-print Network

    Kim, Philip

    Hydrofluoric Acid (HF) Instructions The CEPSR Clean Room supplies one pound bottles of aqueous HF solution that resembles water; it is one of the strongest inorganic acids. Exposure to this acid can be no immediate pain or discomfort. HF differs from other acids because the fluoride ion readily penetrates

  9. Hydrofluoric acid releases in 17 states and the acute health effects associated, 1993-2001.

    PubMed

    Horton, D Kevin; Berkowitz, Zahava; Kaye, Wendy E

    2004-05-01

    Hydrofluoric (HF) acid is 1 of the strongest and most corrosive acids known. Human exposure commonly occurs from occupational releases and can result in severe injuries and death. Data from the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance (HSEES) system were used to conduct a descriptive analysis on the acute health effects of HF acid exposure. Of the total HSEES events (n = 49,106), HF acid releases occurred in 0.3% of events (n = 134). HF acid events were 2 times more likely to involve injuries when compared with other acid events and 3 times more likely when compared with nonacid events. Employees such as those in trucking services, petroleum refining, and chemical manufacturing need to understand the dangers of HF acid and should have the appropriate personal protective equipment available to prevent exposure. PMID:15167399

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

    SciTech Connect

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

    1984-06-15

    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.

  11. Topical treatment of experimental hydrofluoric acid skin burns by 2.5% calcium gluconate.

    PubMed

    Roblin, Isabelle; Urban, Martine; Flicoteau, Domitille; Martin, Chantel; Pradeau, Dominique

    2006-01-01

    Topical therapy with 2.5% calcium gluconate gel is considered as the "first-aid" treatment of accidental hydrofluoric acid skin burns. The efficacy of three different gel formulations varying in the amount and/or nature of their gelling and moisturizing agents was experimentally evaluated. Thirty male Wistar-Han rats (250 g) were exposed to 60 mul of 40% hydrofluoric acid for 2 minutes on two spots (4 cm) of skin under pentobarbital anesthesia. One lesion was massaged with 1 g of gel (10 rats/type of gel) at 3 minutes; 30 minutes; 1 hour; 1 hour, 30 minutes; 2 hours; 3 hours; and 4 hours after injury. During the next 3 days, rats received a single daily application of gel. The other lesion for each rat remained untreated (control). From day 1 after injury to the end of the study (day 17), gel therapy reduced the number of extensive (-66%), severe (-44%), and moderate (-34%) lesions (P < .0001). It reduced (P < .001) the median Area Under the Curve day 0-17 of burn injury from 34.0 (25th to 75th percentile: 18.2-44.5; untreated lesions) to 17.7 (7.0-26.7); overall, there was three cases of treatment failure. At day 17, full wound recovery was obtained in 14 cases by gel therapy compared with 6 in the absence of treatment. The efficacy of the three gel formulations was comparable for all evaluated parameters. Repeated applications of a 2.5% calcium gluconate gel is an efficient treatment of experimental 40% hydrofluoric acid skin burn; few differences were observed between evaluated gel formulations. PMID:17091088

  12. The Mechanism of Electropolishing of Niobium in Hydrofluoric-Sulfuric Acid Electrolyte

    SciTech Connect

    Tian, Hui; Corcoran, Sean; Reece, Charles; Kelley, Michael

    2008-07-01

    Niobium surfaces are commonly electropolished in an effort to obtain optimal smoothness for high-field superconducting radio-frequency cavity applications. We report the 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 and cathode polarization potentials as well as the electrolyte voltage drop, which together sum to the applied power supply voltage. We then identify the temperature and HF concentration dependence of each potential. We also report the use of electrochemical impedance spectroscopy (EIS) on this system. EIS results are consistent with the compact salt film mechanism for niobium electropolishing (EP) in this electrolyte and are not consistent with either the porous salt film or the absorbate-acceptor mechanism. Microscopic understanding of the basic Nb EP mechanism is expected to provide an appro

  13. Corrosion of high-alloy materials in aqueous hydrofluoric acid environments

    SciTech Connect

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

    1994-12-01

    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.

  14. [Acid etching of prefabricated porcelain veneers].

    PubMed

    Fernández Bodereau, E

    1989-01-01

    The aim of the present work is to study on standard porcelain teeth the acid concentration to produce the micromechanic retention with the cemented resin and then to enamel. Teeth were beater-up following the described technique, the application of two different types of etch solutions: hydrochloric acid and fluorhidric acid, in a lack of application time between 10 to 20 minutes. With the purpose of determine the type of etch solution that produce the best amount of micropores in standed porcelain laminates veneers we can conclude that: to the internal etched of the standard porcelain laminates veneer, the utilization of fluorhidric acid is the most convenient, also is necessary the previons stand blaster with aluminum oxide of 25 um to increase the retentive capacity over the etch surface. PMID:2520349

  15. MECHANISM OF INHIBITING EFFECT OF HYDROFLUORIC ACID IN FUMING NITRIC ACID ON LIQUID-PHASE CORROSION OF ALUMINUM AND STEEL ALLOYS

    Microsoft Academic Search

    D. M. Mason; J. B. Rittenhouse

    1958-01-01

    The inhibiting effect of hydrofluoric acid in fuming nitric acid on the ; liquid-phase corrosion of aluminum alloys and iron alloys is found to be ; dependent primarily on the formation of a tenacious insolable fluoride compound ; of aluminum or iron, respectively, on the surface of the metal. This mechanism ; is discussed in relation to: (1) solubility data

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

    Microsoft Academic Search

    Karen M. Steel; John W. Patrick

    2004-01-01

    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

  17. 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

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

    1997-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  19. The effects of hydrofluoric acid addition on the hydrothermal synthesis of templated uranium sulfates.

    PubMed

    Doran, Michael B; Cockbain, Ben E; Norquist, Alexander J; O'Hare, Dermot

    2004-11-21

    The effect of employing hydrofluoric acid as a mineraliser in the formation of organically templated uranium sulfate materials has been studied. Variable amounts of HF((aq)) were added to a series of reaction gels in which all other reactant concentrations were invariant, resulting in the formation of three different phases, depending upon the fluoride concentration. Two of these phases are novel; [N(2)C(4)H(14)][UO(2)(H(2)O)(SO(4))(2)] is a new templated uranium sulfate, containing anionic [UO(2)(H(2)O)(SO(4))(2)](2-) chains that hydrogen bond to one-another forming pseudo-layers, and [N(2)C(4)H(14)][UO(2)F(SO(4))](2) is the first example of a templated uranium sulfate fluoride, which consists of uranium fluoride chains linked by sulfate groups to form [UO(2)F(SO(4))](-) layers. The role of F(-) in these reactions is two-fold; it acts as a mineraliser when present in small concentrations, while it is incorporated into the reaction product when present in larger mole fractions. Both of the new materials have been characterised using a range of physical techniques including single crystal X-ray structure analysis. PMID:15540122

  20. Seventy per cent hydrofluoric acid burns: delayed decontamination with hexafluorine® and treatment with calcium gluconate.

    PubMed

    Yoshimura, Carlos Alberto; Mathieu, Laurence; Hall, Alan H; Monteiro, Mário G Kool; de Almeida, Décio Moreira

    2011-01-01

    This is a case report of decontamination and treatment of a 70% hydrofluoric acid (HF) dermal splash injury. A worker was splashed with 70% HF, sustaining approximately 10% TBSA first- to third-degree chemical skin burns of the face, trunk, and left thigh and leg. Initial decontamination involved water rinsing, removal of contaminated clothing, more water rinsing, topical application of magnesium oxide, and administration of intravenous narcotics for management of severe pain. After a delay of approximately 3 hours, active skin washing with Hexafluorine®, 5 L, was performed, followed by intravenous, intradermal perilesional, and topical inunction administration of calcium gluconate. Pain relief and a cooling sensation were quite prompt after Hexafluorine® decontamination. Surgical debridement and skin grafting of the more severe burns were required. No significant systemic toxicity developed, although this has occurred in previously reported similar concentrated HF dermal splash exposure cases, some of which resulted in fatality. While burns did develop, the patient was released from the intensive care service after 2 days and, after skin grafting, had a good outcome at 90-day follow-up. Even after a long delay, decontamination with Hexafluorine® appeared to be beneficial in this case. PMID:21747332

  1. Comparison of skin effects of immediate treatment modalities in experimentally induced hydrofluoric acid skin burns.

    PubMed

    Songur, Meltem K; Akdemir, Ovunc; Lineaweaver, William C; Cavusoglu, Turker; Ozsarac, Murat; Aktug, Huseyin; Songur, Ecmel; Tiftikcioglu, Yigit O

    2014-01-29

    Hydrofluoric acid (HF) burns cause immediate damage and painful long-term sequellae. Traditionally, chelating agents have been used as the initial treatment for such burns. We have introduced epidermal growth factor (EGF) into an HF model to compare EGF with Ca(2+) and Mg(2+) treatments; 40 Sprague Dawley rats were divided into five groups. Each rat suffered a 6?×?4?cm(2) burn induced by 40% HF. Group 1 had no treatment, group 2 had saline injected beneath the burn, group 3 received magnesium sulphate injections, group 4 received calcium gluconate and group 5 received EGF. Specimens were evaluated via planimetry and biopsy at intervals of 4, 8, 24 and 72?hours. Fluid losses were significantly less in the Mg(2+) and EGF groups. The EGF group had the smallest burn area, least oedema, least polymorphonuclear granulocyte (PMN) infiltration, most angiogenesis and highest fibroblast proliferation of any group (P?

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

    PubMed

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

    2009-05-01

    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

  3. [Acid etching technic in the mixed dentition].

    PubMed

    Mayer, R; Schierle, E

    1980-04-01

    Clinical experience with defect and filling therapy has been good, even with deciduous teeth, a form of therapy which has not been considered promising because of the "prismless enamel of deciduous teeth". Examination with the scanning electron microscope supported our positive findings. If the aforementioned surface layer is removed mechanically prior to treatment with etching agents, the same retentive etching pattern could be obtained as was found on the remaining teeth. The best results were obtained with a 37% solution of phosphoric acid. PMID:6997013

  4. Effect of different etching periods on the bond strength of a composite resin to a machinable porcelain

    Microsoft Academic Search

    J.-H. Chen; H. Matsumura; M. Atsuta

    1998-01-01

    Objectives: The purpose of this study was to evaluate microstructure changes of Cerec 2 Vitablocs Mark II porcelain etched by a 5% hydrofluoric acid and examine the effect of different etching times on the bond strength between the porcelain and a composite resin.Methods: Six different etching times (0, 5, 30, 60, 120 and 180 s) were used to etch the

  5. Hydrofluoric Acid Corrosion Testing on Unplated and Electroless Gold-Plated Samples

    SciTech Connect

    Osborne, P.E.

    2000-08-03

    The Molten Salt Reactor Experiment (MSRE) remediation requires that almost 40 kg of uranium hexafluoride (UF{sub 6}) be converted to uranium oxide (U{sub 3}O{sub 8}). In the process of this conversion, six moles of hydrofluoric acid (HF) are produced for each mole of UF{sub 6} converted. The entire conversion process can be summarized by the following reaction: UF{sub 6} + 3H{sub 2}O {yields} UO{sub 3} + 6HF. (The UO{sub 3} is not stable at high temperatures and therefore decomposes to U{sub 3}O{sub 8}). HF is well known for its ability to attack most metals and silica-containing compounds. It reacts rapidly to destroy protective films and can be fatal in very small quantities (e.g., 2% exposure of the body or 50 ppm in air). Because most of the conversion system is made of various metals, the sections that come in contact with HF must be able to withstand corrosion, high temperatures, elevated pressures, and radiation. Consequently, most of these sections will be plated with gold for increased protection of the metal. This report summarizes the results from the tests that were performed on the metal samples. Section 2 covers the approach to the tests, gives a general background of the sample preparation, and then reports the data from the tests. The final section presents a discussion of what was learned from the data and recommendations for uses of these metals in the MSRE conversion process.

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

    SciTech Connect

    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

    {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.

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

    E-print Network

    Woodall, Jerry M.

    process stations 2, 3, 11, acid & base fume hood2. If heated only acid & base fume hood. Additional and Mixing 4. Hotplates 5. Hydrofluoric Acid 6. Haz Waste Management Ammonium Fluoride Process: Highly toxic with acids will cause toxic HF outgassing. Personal Protective Equipment: Goggles, face shield, heavy

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

    PubMed

    Henßge, Antje; Acker, Jörg

    2007-09-15

    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

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

    SciTech Connect

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

    1993-04-01

    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.

  10. Solution of rocks and refractory minerals by acids at high temperatures and pressures. Determination of silica after decomposition with hydrofluoric acid

    USGS Publications Warehouse

    May, I.; Rowe, J.J.

    1965-01-01

    A modified Morey bomb was designed which contains a removable nichromecased 3.5-ml platinium crucible. This bomb is particularly useful for decompositions of refractory samples for micro- and semimicro-analysis. Temperatures of 400-450?? and pressures estimated as great as 6000 p.s.i. were maintained in the bomb for periods as long as 24 h. Complete decompositions of rocks, garnet, beryl, chrysoberyl, phenacite, sapphirine, and kyanite were obtained with hydrofluoric acid or a mixture of hydrofluoric and sulfuric acids; the decomposition of chrome refractory was made with hydrochloric acid. Aluminum-rich samples formed difficultly soluble aluminum fluoride precipitates. Because no volatilization losses occur, silica can be determined on sample solutions by a molybdenum-blue procedure using aluminum(III) to complex interfering fluoride. ?? 1965.

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

    PubMed Central

    2012-01-01

    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. PMID:22738277

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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.

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

    PubMed Central

    Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

    2013-01-01

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

  14. Hydrofluoric-nitric-sulphuric-acid surface treatment of tungsten for carbon fibre-reinforced composite hybrids in space applications

    NASA Astrophysics Data System (ADS)

    Kanerva, M.; Johansson, L.-S.; Campbell, J. M.; Revitzer, H.; Sarlin, E.; Brander, T.; Saarela, O.

    2015-02-01

    Hybrid material systems, such as combinations of tungsten foils and carbon fibre-reinforced plastic (CFRP), are replacing metal alloy concepts in spacecraft enclosures. However, a good adhesion between the tungsten oxide scale and the epoxy resin used is required. Here, the effects of a hydrofluoric-nitric-sulphuric-acid (HFNS) treatment on tungsten oxides and subsequent adhesion to CFRP are analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fracture testing. The work shows that HFNS treatment results in decreased oxygen content, over 50% thinner tungsten trioxide (WO3) layer and increased nano-roughness on thin tungsten foils. Fracture testing established a 39% increase in the average critical strain for tungsten-CFRP specimens after HFNS treatment was carried out on tungsten. The effect of the oxide scale modification regarding the critical strain energy release rate was ?Gc? 8.4 J/m2.

  15. Nitride-Based LEDs With Phosphoric Acid Etched Undercut Sidewalls

    Microsoft Academic Search

    D. S. Kuo; Shoou-Jinn Chang; T. K. Ko; C. F. Shen; S. J. Hon; S. C. Hung

    2009-01-01

    We propose a simple defect-selective wet etching method to form oblique sidewalls for GaN-based epitaxial layers with phosphoric acid. Using the same defect-selective wet etching, we also prepared GaN-based light-emitting diodes (LEDs) with undercut sidewalls. Compared with conventional LEDs with vertical sidewalls, it was found that output intensity of the LEDs prepared by defect-selective wet etching was 30% higher.

  16. Hydrofluoric-acid-resistant and hydrophobic pure-silica-zeolite MEL low-dielectric-constant films.

    PubMed

    Lew, Christopher M; Liu, Yan; Day, Brandon; Kloster, Grant M; Tiznado, Hugo; Sun, Minwei; Zaera, Francisco; Wang, Junlan; Yan, Yushan

    2009-05-01

    A new technique for the silylation of pure-silica-zeolite MEL low-k films has been developed in which the spin-on films are calcined directly in trimethylchlorosilane or 1,1,1,3,3,3-hexamethyldisilazane (HMDS) in order to protect the films against corrosive wet etch chemicals and ambient moisture adsorption. In an alternative procedure, HMDS is also added to the zeolite suspension before film preparation. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water-soak tests, and HF etch tests are performed to characterize the films. The dielectric constant is as low as 1.51, and the films resist HF attack up to 5.5 min. These properties are highly desirable by the semiconductor industry for next-generation microprocessors. PMID:19344154

  17. Effect of Phosphoric Acid Pre-etching on Fatigue Limits of Self-etching Adhesives.

    PubMed

    Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Scheidel, D D; Erickson, R L; Latta, M A; Miyazaki, M

    2015-01-01

    The purpose of this study was to use shear bond strength (SBS) and shear fatigue limit (SFL) testing to determine the effect of phosphoric acid pre-etching of enamel and dentin prior to application of self-etch adhesives for bonding resin composite to these substrates. Three self-etch adhesives-1) G- ænial Bond (GC Corporation, Tokyo, Japan); 2) OptiBond XTR (Kerr Corp, Orange, CA, USA); and 3) Scotchbond Universal (3M ESPE Dental Products, St Paul, MN, USA)-were used to bond Z100 Restorative resin composite to enamel and dentin surfaces. A stainless-steel metal ring with an inner diameter of 2.4 mm was used to bond the resin composite to flat-ground (4000 grit) tooth surfaces for determination of both SBS and SFL. Fifteen specimens each were used to determine initial SBS to human enamel/dentin, with and without pre-etching with a 35% phosphoric acid (Ultra-Etch, Ultradent Products Inc, South Jordan, UT, USA) for 15 seconds prior to the application of the adhesives. A staircase method of fatigue testing (25 specimens for each test) was then used to determine the SFL of resin composite bonded to enamel/dentin using a frequency of 10 Hz for 50,000 cycles or until failure occurred. A two-way analysis of variance and Tukey post hoc test were used for analysis of SBS data, and a modified t-test with Bonferroni correction was used for the SFL data. Scanning electron microscopy was used to examine the area of the bonded restorative/tooth interface. For all three adhesive systems, phosphoric acid pre-etching of enamel demonstrated significantly higher (p<0.05) SBS and SFL with pre-etching than it did without pre-etching. The SBS and SFL of dentin bonds decreased with phosphoric acid pre-etching. The SBS and SFL of bonds using phosphoric acid prior to application of self-etching adhesives clearly demonstrated different tendencies between enamel and dentin. The effect of using phosphoric acid, prior to the application of the self-etching adhesives, on SBS and SFL was dependent on the adhesive material and tooth substrate and should be carefully considered in clinical situations. PMID:25706611

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

    E-print Network

    Zhou, Yaoqi

    -control (no etching), G2-30s, G3-60s, G4-90s, G5-120s, G6-60s+60s. Meanwhile, G7-G12 were treated in the same fashion as G1-G6, but followed by silane and UR applications. Surface morphology of G1-G12 than G7 (p=0.0392). Furthermore, flexural strength was significantly higher for G7-G12 than for G1-G6

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

    SciTech Connect

    Khuat, Vanthanh [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Collaborative Innovation Center of Suzhou Nano Science and Technology, School of Electronics and Information Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049 (China); Le Quy Don Technical University, No. 100, Hoang Quoc Viet Street, Hanoi 7EN-248 (Viet Nam); Chen, Tao; Gao, Bo; Si, Jinhai, E-mail: jinhaisi@mail.xjtu.edu.cn; Ma, Yuncan; Hou, Xun [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Collaborative Innovation Center of Suzhou Nano Science and Technology, School of Electronics and Information Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049 (China)

    2014-06-16

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

  20. Laboratory-scale fracture conductivity created by acid etching 

    E-print Network

    Pournik, Maysam

    2009-05-15

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

  1. High-quality near-field optical probes by tube etching

    Microsoft Academic Search

    Raoul Stöckle; Christian Fokas; Volker Deckert; Renato Zenobi; Beate Sick; Bert Hecht; Urs P. Wild

    1999-01-01

    A method called tube etching for the fabrication of near-field optical probes is presented. Tip formation occurs inside a cylindrical cavity formed by the polymer coating of an optical fiber which is not stripped away prior to etching in hydrofluoric acid. The influence of temperature, etchant concentration, and fiber type on the tip quality is studied. A tip formation mechanism

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

    PubMed Central

    Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

    2013-01-01

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

  3. Crystal growth vs. conventional acid etching: a comparative evaluation of etch patterns, penetration depths, and bond strengths.

    PubMed

    Devanna, Raghu; Keluskar, K M

    2008-01-01

    The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength. PMID:19075433

  4. Glasstech. Ber. Glass Sci. Technol. 75 C2 (2002) 298 Photoinduced Chemical Etching of Silicate and Borosilicate Glasses

    E-print Network

    Glebov, Leon

    2002-01-01

    of the surfaces of rotation, only. Modern techniques, like ion and plasma etching through the sequence of high with iron content in the range of 400 ppm); 3) BK-7 borosilicate and K-10 silicate optical glass with iron were etched in diluted hydrofluoric acid. A part of unexposed area was masked by wax coating to provide

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

    E-print Network

    La Rosa, Andres H.

    fiber which is not stripped away prior to etching in hydrofluoric acid. The influence of temperature a process for tip formation called tube etching that overcomes these problems: instead of strip- ping of 8 tips, respec- tively. An organic overlayer p-xylene or iso-octane was used to protect the fiber

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

    DOEpatents

    Toor, Fatima; Branz, Howard

    2014-08-26

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

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

    PubMed Central

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

    2014-01-01

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

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

    E-print Network

    Mou, Jianye

    2010-10-12

    fracture simulations in which the grid block size is much larger than the scale of local heterogeneities. Acid fracture conductivity depends on fracture surface etching patterns. Existing acid fracture conductivity correlations are for random asperity...

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

    PubMed Central

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

    2011-01-01

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

  10. HYDROFLUORIC ACID SCRUBBER SYSTEMS

    SciTech Connect

    PANESKO JV; MERRITT HD

    2011-05-18

    Each year over a million gallons of water are used to scrub hydrogen fluoride (HP) vapors from waste off-gas streams. Use of other potential scrubber solutions such as potassium hydroxide (KOH), aluminum nitrate nonahydrate (ANN), and monobasic aluminum nitrate (monoban) would result in significant volume reductions. A laboratory study was initiated to (1) demonstrate the effectiveness of these scrubber solutions to sorb HF, (2) determine if unexpected reactions occurred at flowsheet conditions, and (3) determine the consequences of deviation from flowsheet conditions. Caustic or aluminum scrubber solutions remove hydrogen fluoride from off-gas streams. Solids which appear with aluminum could be avoided by heating the scrubber solution.

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

    E-print Network

    Mou, Jianye

    2010-10-12

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

  12. A new chemical method for etching metal frameworks of the acid-etched prosthesis.

    PubMed

    Doukoudakis, A; Cohen, B; Tsoutsos, A

    1987-10-01

    Alloys containing beryllium, silicon, boron, and all nickel base alloys are etched well by the method described, with the exception of Fore alloy manufactured by the Unitek Corp. Alloys containing chrome and cobalt cannot be etched with Met-Etch gel. The advantages of using this method of chemical etching are (1) this conservative procedure can be performed in two clinical sessions, (2) the etching of the framework can be effectively controlled by the dentist or the laboratory technician, and (3) if the metal framework is dislodged it can be cleaned, etched, and reattached during the same appointment. PMID:3312579

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

    SciTech Connect

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

    2006-12-04

    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.

  14. Trapping of hydrochloric and hydrofluoric acid at vacancies on and underneath the ice I(h) basal-plane surface.

    PubMed

    Pinheiro Moreira, Pedro Augusto Franco; de Koning, Maurice

    2013-10-31

    We investigate the uptake of HCl and HF at lattice vacancies in ice Ih as a function of their distance to the basal-plane surface layer using density-functional theory calculations. The results for HCl display large dispersions in the binding-energy results due to the appearance of distinct dissociation states. The layer-averaged results suggest that the uptake of HCl is most favorable in the two layers just below the surface, which is consistent with available experimental indications. The behavior of HF is found to be manifestly different due to the fact that it is a weaker acid. The dispersion in the binding-energy values is significantly less compared to the case of HCl, and the average values are essentially equal to the bulk value, regardless of layer position. This suggests that, in contrast to the case of HCl, there should not be any tendency for accumulation of HF near the surface. PMID:24102399

  15. Nanoparticle-based etching of silicon surfaces

    DOEpatents

    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

    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.

  16. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    SciTech Connect

    Despotopulos, J D; Sudowe, R

    2012-02-21

    Studies of the chemical properties of superheavy elements (SHE) pose interesting challenges due to their short half-lives and low production rates. Chemical systems must have extremely fast kinetics, fast enough kinetics to be able to examine the chemical properties of interest before the SHE decays to another nuclide. To achieve chemistry on such time scales, the chemical system must also be easily automated. Most importantly however, a chemical system must be developed which provides suitable separation and kinetics before an on-line study of a SHE can be performed. Relativistic effects make studying the chemical properties of SHEs interesting due to the impact these effects could have on the SHEs chemical properties. Relativistic effects arise when the velocity of the s orbital electrons approach the speed of light. As this velocity increases, the Bohr radius of the inner electron orbitals decreases and there is an increase in the particles mass. This contraction results in a destabilization of the energy of the outer d and f electron orbitals (5f and 6d in the case of SHE), which can cause these to expand due to their increased shielding from the nuclear charge. Another relativistic effect is the spin-orbit splitting for p, d, and f orbitals into j = 1 {+-} 1/2 states. This can lead most interestingly to a possible increased stability of element 114, which due to large spin-orbit splitting of the 7p orbital and the relativistically stabilized 7p{sub 1/2} and 7s orbital gives rise to a closed shell ground state of 7s{sup 2}7p{sub 1/2}{sup 2}. The homologs of element 105, dubnium (Db), Ta and Nb and the pseudo-homolog Pa, are well known to hydrolyze and form both neutral and non-neutral monoatomic and polyatomic species that may cause issues with extraction from a given chemical system. Early ion-exchange and solvent-extraction studies show mixed results for the behavior of Db. Some studies show Db behaving most similar to Ta, while others show it behaving somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent, which separates analytes based on steric interactions between the cavity of the crown ether and electrostatic interac

  17. HYDROFLUORIC ACID FIRST AID INSTRUCTIONS

    E-print Network

    Jalali. Bahram

    Move the victim immediately under an emergency shower or other water source and flush the affected area respiration. 3 Call 911 for immediate medical assistance. Swallowing 1 Rinse the mouth with cold water. Do

  18. Acid Solutions for Etching Corrosion-Resistant Metals

    NASA Technical Reports Server (NTRS)

    Simmons, J. R.

    1982-01-01

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

  19. THE KINETICS OF THE CORROSION OF LOW-HAFNIUM ZIRCONIUM IN AQUEOUS SULFURIC ACID SOLUTIONS

    Microsoft Academic Search

    Tennyson Smith

    1960-01-01

    The rates of corrosion of low-hafnium zirconium in aqueous sulfuric acid ; solutions over the concentration range 9 to 97% by weight, were studied. ; Corrosion was detected by measuring the concentration of zirconium in solution ; with a radioactive tracer, Zr⁹⁵. The samples first were etched in an ; aqueous hydrofluoric-nitric acid solution then placed directly into the sulfuric

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

    PubMed

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

    2012-01-01

    Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine. PMID:22414518

  1. Silicon microholes array fabricated by femtosecond laser pulses directly writing assisted with further electrochemical etching

    Microsoft Academic Search

    Zhongyi Guo; Keya Zhou; Yanjun Xiao; Jin-Young Jung; Han-don Um; S. A. Moiz; Shiliang Qu; Shutian Liu; Jung-Ho Lee

    2011-01-01

    Silicon microholes array have been fabricated using femtosecond laser directly writing followed by electrochemical etching in a hydrofluoric acid (HF) and the isopropyl alcohol ((CH3)2CHOH) solution. Firstly, the micro size scratches array were directly written on a surface of the n-type, 1–5 ?cm, Si(100) wafer by using the femtosecond laser pulses. Shallow micro holes array could be obtained on the

  2. Investigation of the formation of undercut during the fabrication of silicon microchannels by electrochemical etching

    Microsoft Academic Search

    Jilei Lin; Xiaoming Chen; Shaohui Xu; Peisheng Xin; Lianwei Wang

    2008-01-01

    Silicon microchannel plates have been explored intensively for numerous applications especially for weak light detection and night vision. The electrochemical etching in hydrofluoric acid-based solutions is known as a technique for porous silicon formation. This paper presents a new process for the formation of microchannel structure and the separation of the Si MCP from p-type starting substrates by a single-step

  3. The effects of acid etching time on surface mechanical properties of dental hard tissues.

    PubMed

    Zafar, Muhammad Sohail; Ahmed, Naseer

    2015-06-01

    The objective of this study was to evaluate the effect of etching time on the surface properties of dental hard tissues including enamel and dentin. For this purpose, samples were prepared using extracted human teeth and treated with 37% phosphoric acid for various length of time using the set protocol. The effects of etching time on surface roughness were assessed using non-contact surface roughness profilometer and surface hardness was measured using nanoindentation technique. All results were analyzed statistically using SPSS computer software. Within the limitation of this study, it was concluded that etching time influences on the surface properties of dental hard tissues particularly the enamel. Enamel surface properties such as roughness and hardness can be altered remarkable as a matter of few seconds. Prolonged etching time than recommended is likely to increase the surface roughness and decrease surface hardness; compromising the bond strength of adhesive materials in clinical applications. PMID:25904167

  4. Self-etching primer vs phosphoric acid: an alternative concept for composite-to-enamel bonding.

    PubMed

    Hannig, M; Reinhardt, K J; Bott, B

    1999-01-01

    The purpose of this in vitro study was (1) to investigate the composite-to-enamel bond strength and (2) to analyze the marginal adaptation of resin composite restorations in class 2 cavities using three self-etching priming agents in comparison to conventional phosphoric acid etching and bonding application. In the first part of the study 24 extracted bovine incisors were embedded in acrylic resin and ground flat with 800-grit paper. The following three self-etching priming agents/composite resins were applied to the enamel surfaces of six teeth each: Clearfil Liner Bond 2/Clearfil AP-X (Group I), Etch & Prime 3.0/Degufill mineral (Group II), Resulcin AquaPrime + MonoBond/Ecusit (Group III). In Group IV Ecusit-Mono/Ecusit was used after enamel etching with phosphoric acid (37%). Shear bond strength values measured on a T22 K testing machine at a crosshead speed of 1 mm/min were: 24.2 +/- 3.0 MPa (Group I), 21.9 +/- 1.4 MPa (II), 34.0 +/- 3.6 MPa (III), and 26.3 +/- 1.8 MPa (IV). ANOVA revealed significant (P < 0.05) differences in shear bond strength between groups, except comparison of Group I and II, and Group I and IV. In the second part of the study 24 standardized class 2 cavity preparations with the approximal box extending 1 mm above the CEJ were prepared in extracted human molars. Enamel margins were beveled and the teeth were divided into four groups of six teeth each. Cavities were restored using the self-etching priming agents Clearfil Liner Bond 2 (Group I), Etch & Prime 3.0 (Group II), and Resulcin AquaPrime + MonoBond (Group III). In Group IV composite resin restorations were placed after 37% phosphoric acid etching and bonding application (Ecusit-Mono). Quantitative SEM analysis of the marginal adaptation of the restorations after thermocycling (5-55 degrees C, 2500 cycles) and mechanical loading (100 N, 500,000 cycles) revealed excellent, gap-free margins in 91.2% (Group I), 93.0% (Group II), 92.0% (Group III), and 92.5% (Group IV) of the restorations' approximal area. There were no statistically significant differences between the four groups (P < 0.05). In conclusion, results of the present in vitro study indicate that use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in composite-to-enamel bonding restorative techniques. PMID:10530279

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  6. Optimization of fiber-optic readout of LSO scintillation crystals with acid etching

    Microsoft Academic Search

    D. Strul; J. Sutcliffe-Goulden; P. Halstead; P. K. Marsden

    2002-01-01

    Optimizing the collection of scintillation light is essential for good positron emission tomography scanner performance, and even more so when the crystals are read out through optical fibers. Acid etching has been proposed as a cost-effective alternative to mechanical polishing, but there are discrepancies between the results published so far. The aim of this paper is to gain a better

  7. Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants.

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

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

  9. Acid etch resistance of automotive clearcoats. I: Laboratory test method development

    Microsoft Academic Search

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

    2000-01-01

    This paper reports on the development of a laboratory test procedure for the evaluation of the environmental etch resistance\\u000a of clearcoats. The test evaluates the bulk acid hydrolysis resistance of clearcoats by gravimetrically following material\\u000a weight loss as a function of exposure time to a sulfuric acid solution, under conditions that simulate outdoor exposure. The\\u000a bulk hydrolysis resistance of five

  10. Acid-etched microtexture for enhancement of bone growth into porous-coated implants.

    PubMed

    Hacking, S A; Harvey, E J; Tanzer, M; Krygier, J J; Bobyn, J D

    2003-11-01

    We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant. These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation. PMID:14653605

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

    E-print Network

    Woodall, Jerry M.

    toxic mixture for etching Silicon Oxide with high selectivity to photoresist. Materials: Ammonium will contaminate bath. Personal Protective Equipment: Goggles, face shield, heavy chemical gloves (blue disposable the skin, so burns are typically not apparent until a day later. Watch very carefully for splashes because

  12. Bend measurement using an etched fiber incorporating a fiber Bragg grating.

    PubMed

    Rauf, Abdul; Zhao, Jianlin; Jiang, Biqiang; Jiang, Yajun; Jiang, Wei

    2013-01-15

    A fiber Bragg grating (FBG) based bend measurement method using an etched fiber is proposed that utilizes the coupling of the core mode to the cladding and radiation modes at the bending region. An etching region of 99 µm diameter that serves as bend sensing head is achieved at 10 mm upstream the FBG through processing in 40% hydrofluoric acid, while the FBG acts as a narrowband reflector to enhance the sensitivity. The power variation curves are obtained for a wide range of bend angles, but the performance is limited due to the presence of the loss peaks. The sensing response is improved by immersing the etching region in a refractive index matching gel. The results are analyzed by using curve fitting formulas and are in good agreement. A large dynamic range of -27° to +27° and sensitivity of 0.43 dBm/deg is achieved, which can be enhanced by reducing the etched diameter. PMID:23454966

  13. Hydrogen content in titanium and a titanium-zirconium alloy after acid etching.

    PubMed

    Frank, Matthias J; Walter, Martin S; Lyngstadaas, S Petter; Wintermantel, Erich; Haugen, Håvard J

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium-zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p<0.01) on the titanium-zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium. PMID:23827573

  14. Ultraviolet irradiation of melamine containing clearcoats for improved acid etch resistance

    Microsoft Academic Search

    P. H. Lamers; B. K. Johnston; W. H. Tyger

    1997-01-01

    The acid etch and water spot resistance of conventional acrylic\\/melamine and polyester\\/melamine automotive clearcoats are significantly improved by ambient air ultraviolet irradiation of freshly cured coatings. Infrared and NMR analysis of cured films and model compounds indicate that surface photochemical oxidation of the melamine NR?CH2?OR linkage to a urethane NR?CO2?R occurs in the coating under these irradiation conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

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

    DOEpatents

    Copley, Stephen M. (Palos Verdes, CA); Tao, Hongyi (Covina, CA); Todd-Copley, Judith A. (Palos Verdes, CA)

    1991-01-01

    A process for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength.

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

    DOEpatents

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

    1991-06-11

    A process is disclosed for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength. 1 figure.

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

    PubMed

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

    2012-01-01

    : Analysis methods for electrochemical etching baths consisting of various concentrations of hydrofluoric acid (HF) and an additional organic surface wetting agent are presented. These electrolytes are used for the formation of meso- and macroporous silicon. Monitoring the etching bath composition requires at least one method each for the determination of the HF concentration and the organic content of the bath. However, it is a precondition that the analysis equipment withstands the aggressive HF. Titration and a fluoride ion-selective electrode are used for the determination of the HF and a cuvette test method for the analysis of the organic content, respectively. The most suitable analysis method is identified depending on the components in the electrolyte with the focus on capability of resistance against the aggressive HF. PMID:22805742

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

    PubMed Central

    2012-01-01

    Analysis methods for electrochemical etching baths consisting of various concentrations of hydrofluoric acid (HF) and an additional organic surface wetting agent are presented. These electrolytes are used for the formation of meso- and macroporous silicon. Monitoring the etching bath composition requires at least one method each for the determination of the HF concentration and the organic content of the bath. However, it is a precondition that the analysis equipment withstands the aggressive HF. Titration and a fluoride ion-selective electrode are used for the determination of the HF and a cuvette test method for the analysis of the organic content, respectively. The most suitable analysis method is identified depending on the components in the electrolyte with the focus on capability of resistance against the aggressive HF. PMID:22805742

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

    SciTech Connect

    Schmidt, Torsten; Zhang, Miao; Linnros, Jan, E-mail: linnros@kth.se [Department of Materials and Nano Physics, School of Information and Communication Technology, KTH Royal Institute of Technology, Isafjordsgatan 22, SE-164 40 Kista (Sweden); Yu, Shun [Department of Fibre and Polymer Technology, Polymeric Materials and Wallenberg Wood Science Center, KTH Royal Institute of Technology, SE-100 44 Stockholm (Sweden)

    2014-09-22

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

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

    USGS Publications Warehouse

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

    1996-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    Bioactive and inductive silicate-based bioceramics play an important role in hard tissue prosthetics such as bone and teeth. In the present study, a model was established to study the acid-etched enamel remineralization with tricalcium silicate (Ca 3SiO 5, C 3S) paste in vitro. After soaking in simulated oral fluid (SOF), Ca-P precipitation layer was formed on the enamel surface, with the prolonged soaking time, apatite layer turned into density and uniformity and thickness increasingly from 250 to 350 nm for 1 day to 1.7-1.9 ?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.

  3. Reliability evaluation of alumina-blasted/acid-etched versus laser-sintered dental implants.

    PubMed

    Almeida, Erika O; Júnior, Amilcar C Freitas; Bonfante, Estevam A; Silva, Nelson R F A; Coelho, Paulo G

    2013-05-01

    Step-stress accelerated life testing (SSALT) and fractographic analysis were performed to evaluate the reliability and failure modes of dental implant fabricated by machining (surface treated with alumina blasting/acid etching) or laser sintering for anterior single-unit replacements. Forty-two dental implants (3.75 × 10 mm) were divided in two groups (n=21 each): laser sintered (LS) and alumina blasting/acid etching (AB/AE). The abutments were screwed to the implants and standardized maxillary central incisor metallic crowns were cemented and subjected to SSALT in water. Use-level probability Weibull curves and reliability for a mission of 50,000 cycles at 200 N were calculated. Polarized light and scanning electron microscopes were used for failure analyses. The Beta (?) value derived from use-level probability Weibull calculation of 1.48 for group AB/AE indicated that damage accumulation likely was an accelerating factor, whereas the ? of 0.78 for group LS indicated that load alone likely dictated the failure mechanism for this group, and that fatigue damage did not appear to accumulate. The reliability was not significantly different (p>0.9) between AB/AE (61 %) and LS (62 %). Fracture of the abutment and fixation screw was the chief failure mode. No implant fractures were observed. No differences in reliability and fracture mode were observed between LS and AB/AE implants used for anterior single-unit crowns. PMID:22843309

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    PubMed Central

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

    2015-01-01

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

  6. Nanostructure evaluation of healthy and fluorotic dentin by atomic force microscopy before and after phosphoric acid etching.

    PubMed

    Zavala-Alonso, Veronica; Aguilera-Flores, Rafael; Patiño-Marin, Nuria; Martinez-Castañon, Gabriel A; Anusavice, Kenneth J; Loyola-Rodriguez, Juan Pablo

    2011-01-01

    The aim was to characterize by atomic force microscopy (AFM) the nanostructure of human dentin surfaces affected by dental fluorosis (DF) before and after phosphoric acid etching. This study included 240 human dentin samples classified according to the severity of DF, which were divided into four groups using the Thylstrup-Fejerskov Index (TFI). Samples were analyzed by AFM before and after acid etching for 15, 30, and 60 s. The roughness (R(a)) for healthy dentin, and dentin with mild, moderate, and severe fluorosis were 440 nm, 442 nm, 445 nm, and 449 nm, respectively. After 15, 30, and 60 s of acid etching, all healthy and fluorotic dentin samples increased in roughness (p<0.05). The diameter of dentinal tubule orifices (D(t)) in healthy human dentin increased after acid etching for 60 s. We conclude that effective etching times are 15 s for healthy and mild dentin fluorosis, 30-s for moderately fluorosed dentin, and 45-60 s for severe fluorotic dentin. PMID:21778600

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

    PubMed

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

    2006-04-19

    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

  8. Chemical Etching of CdTe in Aqueous Solutions of H2O2-HI-Citric Acid

    NASA Astrophysics Data System (ADS)

    Ivanits'ka, V. G.; Moravec, P.; Franc, J.; Tomashik, Z. F.; Feychuk, P. I.; Tomashik, V. M.; Shcherbak, L. P.; Mašek, K.; Höschl, P.

    2007-08-01

    An iodine-based etching system, H2O2-HI-citric acid, has been developed and tested on CdTe samples with orientations (111)A, (111)B, (110), and (100). The etching velocity of CdTe was shown to depend on sample orientation and other etching conditions. The surface roughness was comparable with that of the surfaces after Br-methanol treatment. A comparative study of the chemical composition of the (211)B CdZnTe surfaces etched under different conditions was performed. X-ray photoelectron spectroscopy (XPS) measurements showed that all treated surfaces of CdZnTe samples are enriched with Te. The HI-based treatment seems to be more acceptable than the Br-methanol treatment in terms of elimination of Te oxides from the surface, however.

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

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

    2014-01-01

    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

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

    PubMed Central

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

    2015-01-01

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

  12. In situ scanning tunneling microscopy imaging of well-defined Rh(111) electrodes in KNO{sub 2}-containing 0.5 M hydrofluoric acid solutions

    SciTech Connect

    Zang, Z.H.; Wu, Z.L.; Yau, S.L.

    1999-12-07

    This work examined the spatial structure and bonding configuration of nitric oxide (NO) at a well-defined Rh(111) electrode surface by in situ scanning tunneling microscope (STM) imaging under potential control. Immersing Rh(111) electrodes into acidic KNO{sub 2} solutions (pH 2, 0.5 M HF) resulted in a long-range ordered (3{times}3) structure, possibly owing to irreversibly adsorbed NO molecules. Although this structure predominated between 1.0 and 0.3 V, cathodic polarization to 0.2 V or more negative caused local roughening. In the absence of HNO{sub 2}, cathodic polarization of a Rh(111) electrode to 0.05 V completely reduced the surface-bound NO molecules. Coulometric and in situ STM measurements revealed a saturated coverage of 0.48 and 0.44 respectively, for NO molecules in the ordered (3 x 3) structure. This work also proposed a tentative model of the (3 x 3) structure containing 4 NO molecules. One fourth of the NO molecules adsorbed at near-top sites, whereas the remaining resided at 2-fold bridging sites. Real-time in situ STM imaging provided a direct view of the reduction processes at potential negative of 0.2 V. Reactions preferentially occurred at atomically flat terraces, rather than at surface defects such as step edges, kinks, and vacancies. Moreover, the initial reaction fronts were spatially concentrated, rather than randomly distributed.

  13. Determination of Cd and Pb in seawater by graphite furnace atomic absorption spectrometry with the use of hydrofluoric acid as a chemical modifier

    NASA Astrophysics Data System (ADS)

    Cabon, J. Y.

    2002-03-01

    High concentration of added hydrogen fluoride converted the seawater chloride to the corresponding fluoride matrix, and the liberated hydrochloric acid could be removed during the drying step. The atomization of cadmium and lead could be performed at a relatively low temperature (˜1300 °C) at which the vaporization of the fluoride matrix was relatively slow, and the corresponding weak background signals could be separated from the analytical signals in time. Experimental conditions for the determination of Cd and Pb in seawater in the presence of HF were optimized with the use of the a priori calculation of the limit of detection. The experimental limit of detection obtained for Cd and Pb were, respectively, 0.007 and 0.25 ?g l -1 for a 15-?l seawater sample (3?, 20 replicates). The concentrations of Cd determined in a SLEW-1 estuarine water and a CASS-2 seawater were 0.020±0.002 and 0.016±0.002 ?g l -1 Cd, respectively, in good agreement with the 0.018±0.003 and 0.019±0.004 ?g l -1 Cd certified values (At the 95% confident level, 10 replicates).

  14. 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

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

    2008-09-01

    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

  15. Vacuum-jacketed hydrofluoric acid solution calorimeter

    USGS Publications Warehouse

    Robie, R.A.

    1965-01-01

    A vacuum-jacketed metal calorimeter for determining heats of solution in aqueous HF was constructed. The reaction vessel was made of copper and was heavily gold plated. The calorimeter has a cooling constant of 0.6 cal-deg -1-min-1, approximately 1/4 that of the air-jacketed calorimeters most commonly used with HF. It reaches equilibrium within 10 min after turning off the heater current. Measurements of the heat of solution of reagent grade KCl(-100 mesh dried 2 h at 200??C) at a mole ratio of 1 KCl to 200 H2O gave ??H = 4198??11 cal at 25??C. ?? 1965 The American Institute of Physics.

  16. HF-(NH4)2S2O8-HCl Mixtures for HNO3- and NOx-free Etching of Diamond Wire- and SiC-Slurry-Sawn Silicon Wafers: Reactivity Studies, Surface Chemistry, and Unexpected Pyramidal Surface Morphologies.

    PubMed

    Stapf, André; Gondek, Christoph; Lippold, Marcus; Kroke, Edwin

    2015-04-29

    The wet-chemical treatment of silicon wafers is an important production step in photovoltaic and semiconductor industries. Solutions containing hydrofluoric acid, ammonium peroxodisulfate, and hydrochloric acid were investigated as novel acidic, NOx-free etching mixtures for texturization and polishing of monocrystalline silicon wafers. Etching rates as well as generated surface morphologies and properties are discussed in terms of the composition of the etching mixture. The solutions were analyzed with Raman and UV/vis spectroscopy as well as ion chromatography (IC). The silicon surfaces were investigated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), diffuse reflection infrared spectroscopy (DRIFT), and X-ray photoelectron spectroscopy (XPS). Surprisingly, pyramidal surface structures were found after etching SiC-slurry as well as diamond wire-sawn monocrystalline Si(100) wafers with hydrochloric acid-rich HF-(NH4)2S2O8-HCl mixtures. Acidic etching solutions are generally not known for anisotropic etching. Thus, the HNO3-free mixtures might allow to replace KOH/i-propanol and similar alkaline solutions for texturization of monosilicon wafers at room temperature with less surface contamination. Besides, common HNO3-based etching mixtures may be replaced by the nitrate-free system, leading to significant economic and ecological advantages. PMID:25826145

  17. Porous siliconformation and etching process for use in silicon micromachining

    DOEpatents

    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

    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%.

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

    PubMed

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

    2014-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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.

  1. 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)

    Costescu, Ruxandra M.

    2011-10-01

    "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.

  2. Time-varying wetting behavior on copper wafer treated by wet-etching

    NASA Astrophysics Data System (ADS)

    Tu, Sheng-Hung; Wu, Chuan-Chang; Wu, Hsing-Chen; Cheng, Shao-Liang; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2015-06-01

    The wet cleaning process in semiconductor fabrication often involves the immersion of the copper wafer into etching solutions and thereby its surface properties are significantly altered. The wetting behavior of a copper film deposited on silicon wafer is investigated after a short dip in various etching solutions. The etchants include glacial acetic acid and dilute solutions of nitric acid, hydrofluoric acid, and tetramethylammonium hydroxide. It was found that in most cases a thin oxide layer still remains on the surface of as-received Cu wafers when they are subject to etching treatments. However, a pure Cu wafer can be obtained by the glacial acetic acid treatment and its water contact angle (CA) is about 45°. As the pure Cu wafer is placed in the ambient condition, the oxide thickness grows rapidly to the range of 10-20 Å within 3 h and the CA on the hydrophilic surface also rises. In the vacuum, it is surprising to find that the CA and surface roughness of the pure Cu wafer can grow significantly. These interesting results may be attributed to the rearrangement of surface Cu atoms to reduce the surface free energy.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  4. Enhanced bioactivity of sandblasted and acid-etched titanium surfaces Enwei Zhang 1, a

    E-print Network

    Zheng, Yufeng

    , SLA implants need at least 6 weeks before initiating to load [2]. However, dental implant therapy. Introduction Altering the surface topography of titanium implants has been seen as a method for hastening etching and subsequently in NaOH is a suitable method for providing the metal implant with bone

  5. Optical fibre nanotips fabricated by a dynamic chemical etching for sensing applications

    NASA Astrophysics Data System (ADS)

    Barucci, A.; Cosi, F.; Giannetti, A.; Pelli, S.; Griffini, D.; Insinna, M.; Salvadori, S.; Tiribilli, B.; Righini, G. C.

    2015-02-01

    Nanoprobe tips are key components in many applications such as scanning probe microscopes, nanoscale imaging, nanofabrication and sensing. This paper describes a dynamic chemical etching method for the fabrication of optical nanoprobes. The tips are produced by mechanically rotating and dipping a silica optical fibre in a chemical etching solution (aqueous hydrofluoric acid) covered with a protection layer. Using different dynamic regimes of the mechanical movements during the chemical etching process, it is possible to vary the cone angle, the shape, and the roughness of the nanoprobes. It is found that the tip profiles are determined by the nonlinear dynamic evolution of the meniscus of the etchant near the fibre. Computational fluid dynamic simulations have been performed, showing that different flow regimes correspond to different shear forces acting on the forming nanotip, in agreement with experimental results. With this method, a high yield of reproducible nanotips can be obtained, thus overcoming the drawbacks of conventional etching techniques. Typical tip features are short taper length (˜200 ?m), large cone angle (up to 40°), and small probe tip dimension (less than 30 nm).

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

    PubMed

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

    2014-05-01

    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

  7. Evaluation of bone healing on sandblasted and Acid etched implants coated with nanocrystalline hydroxyapatite: an in vivo study in rabbit femur.

    PubMed

    Melin Svanborg, Lory; Meirelles, Luiz; Franke Stenport, Victoria; Kjellin, Per; Currie, Fredrik; Andersson, Martin; Wennerberg, Ann

    2014-01-01

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

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

    PubMed

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

    2014-06-01

    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

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

    E-print Network

    Oeth, Cassandra V

    2013-11-25

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

  10. Osseointegration of rough acid-etched titanium implants: 5-year follow-up of 100 minimatic implants.

    PubMed

    De Leonardis, D; Garg, A K; Pecora, G E

    1999-01-01

    During 1992, 100 Minimatic screw implants made of titanium alloy (titanium-aluminum-vanadium) with a machined rough acid-etched surface were placed in 63 consecutive partially edentulous patients. At second-stage surgery, which was performed after a 4- to 6-month healing period, none of the implants showed signs of mobility, peri-implant infection, or bone loss from the crest of the ridge. Each patient was restored with a fixed prosthesis and reexamined every 3 months during the first year. Periapical radiographs were taken annually up to 5 years. These revealed no signs of peri-implant radiolucencies involving any of the implants, and mean alveolar bone loss was less than 1 mm at the 5-year examination. One implant was considered a late failure because of a peri-implant infection that developed during the first year, although the implant was still functional at year 5. Another patient with 2 implants dropped out during the fifth year of the study, although both implants had been considered successful up to that point. Based on annual measurements of Plaque Index, Sulcular Bleeding index, pocket probing depth, attachment level, width of keratinized mucosa, and hand-tested mobility, 97 of the remaining 98 implants were considered successful, resulting in a 98% success rate. This 5-year study confirms that Minimatic machined acid-etched implants provide predictable osseointegration results and supports the conclusion of other reports that titanium implants with a rough surface can fulfill the requirements of Albrektsson et al (1986) for implant success. PMID:10379112

  11. Effect of self-etching primer vs phosphoric acid etchant on bonding to bur-prepared dentin.

    PubMed

    Ogata, M; Harada, N; Yamaguchi, S; Nakajima, M; Tagami, J

    2002-01-01

    This study evaluated the effect of dentin conditioner on tensile bond strength to dentin prepared with different types of burs. A self-etching primer system, Mac-Bond II (MB, Tokuyama Dental) and a phosphoric acid etching system, Single Bond (SB, 3M) were used for conditioning. Twenty-four extracted intact human molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with #600 SiC paper, the teeth were randomly divided into a control group and three experimental groups according to the bur grits used: #600 SiC paper only as the control, fine cut steel bur (SB600), crosscut steel bur (SB703) and regular grit diamond bur (DB) mounted in a dental handpiece utilizing water cooling. The dentin surfaces were treated with one of two adhesive systems, then composite buildups were done with Clearfil AP-X (Kuraray Medical). After soaking the bond specimens for 24 hours in 37 degrees C water, multiple vertical serial sections (0.7 mm thick, 7-8 slices per one tooth) were made, trimmed to form an hour-glass shape with a 1.0 mm2 cross-section and tensile bond strengths were determined at a crosshead speed of 1 mm/minute. Statistical analysis was made using one and two-way ANOVA and Fisher's PLSD test (p<0.05). Six additional molars were used for SEM observations of the dentin surfaces of each group before and after treatment with the self-etching primer of MB, and another four teeth were used to observe the resin-dentin interface of each group of SB. Using MB, the DB group produced the lowest tensile bond strength (TBS) among the groups that received bur preparation, and there were no statistical differences among SB600, SB703 and the control. For SB, the TBS of SB703 was the highest, and there were no statistical differences among the other groups and the control. The influence of the method used to prepare dentin for micro-tensile bond strength testing was dependent on the adhesive system used. PMID:12216562

  12. Surface composition and electrical and electrochemical properties of freshly deposited and acid-etched indium tin oxide electrodes.

    PubMed

    Brumbach, Michael; Veneman, P Alex; Marrikar, F Saneeha; Schulmeyer, Thomas; Simmonds, Adam; Xia, Wei; Lee, Paul; Armstrong, Neal R

    2007-10-23

    We compare the near-surface composition and electroactivity of commercial indium tin oxide (ITO) thin films, activated by plasma cleaning or etching with strong haloacids, with ITO films that have been freshly deposited in high vacuum, before and after exposure to the atmosphere or water vapor. Conductive-tip AFM, X-ray photoelectron spectroscopy (XPS), and the electrochemistry of probe molecules in solution were used to compare the relative degrees of electroactivity and the near-surface composition of these materials. Brief etching of commercial ITO samples with concentrated HCl or HI significantly enhances the electrical activity of these oxides as revealed by C-AFM. XPS was used to compare the composition of these activated surfaces, focusing on the intrinsically asymmetric O 1s line shape. Energy-loss processes associated with photoemission from the tin-doped, oxygen-deficient oxides complicate the interpretation of the O 1s spectra. O 1s spectra from the stoichiometric indium oxide lattice are accompanied by higher-binding-energy peaks associated with hydroxylated forms of the oxide (and in some cases carbonaceous impurities) and overlapping photoemission associated with energy-loss processes. Characterization of freshly sputter-deposited indium oxide (IO) and ITO films, transferred under high vacuum to the surface analysis environment, allowed us to differentiate the contributions of tin doping and oxygen-vacancy doping to the O 1s line shape, relative to higher-binding-energy O 1s components associated with hydroxyl species and carbonaceous impurities. Using these approaches, we determined that acid activation and O2 plasma etching create an ITO surface that is still covered with an average of one to two monolayers of hydroxide. Both of these activation treatments lead to significantly higher rates of electron transfer to solution probe molecules, such as dimethyferrocene in acetonitrile. Solution electron-transfer events appear to occur at no more than 4x10(7) electroactive sites per cm2 (each with diameters of ca. 50-200 nm) (i.e., a small fraction of the geometric area of the electrode). Electron-transfer rates correlate with the near-surface tin dopant concentration, suggesting that these electroactive sites arise from near-surface tin enrichment. PMID:17880253

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

    PubMed

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

    2012-09-26

    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

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

    PubMed Central

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

    2012-01-01

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

  15. From acid etching treatments to tribocorrosive properties of dental implants: do some experimental results on surface treatments have an influence on the tribocorrosion behaviour of dental implants?

    NASA Astrophysics Data System (ADS)

    Geringer, Jean; Demanget, Nicolas; Pellier, Julie

    2013-10-01

    Surface treatments of dental implants aim at promoting osseointegration, i.e. the anchorage of the metallic part. Titanium-, grade II-V, based material is used as a bulk material for dental implants. For promoting the anchorage of this metallic biomaterial in human jaw, some strategies have been applied for improving the surface state, i.e. roughness, topography and coatings. A case study, experimental study, is described with the method of acid etching on titanium grade 4, CpTi. The main goal is to find the right proportion in a mixture of two acids in order to obtain the best surface state. Finally, a pure theoretical prediction is quite impossible and some experimental investigations are necessary to improve the surface state. The described acid etching is compared with some other acid etching treatments and some coatings available on dental implants. Thus, the discussion is focused on the tribocorrosion behaviour of titanium-based materials. The purpose of the coating is that the lifetime under tribocorrosion is limited. Moreover, the surgery related to the implantation has a huge impact on the stability of dental implants. Thus, the performance of dental implants depends on factors related to surgery (implantation) that are difficult to predict from the biomaterial characteristics. From the tribocorrosion point of view, i.e. during the mastication step, the titanium material is submitted to some deleterious factors that cause the performance of dental implants to decrease.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

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

    PubMed Central

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

    2009-01-01

    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. PMID:18571228

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2014-01-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 ?m with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films. PMID:25349554

  20. Influence of etching parameters on optoelectronic properties of c-Si/porous silicon heterojunction - application to solar cells

    NASA Astrophysics Data System (ADS)

    Bechiri, Fatiha; Zerdali, Mokhtar; Rahmoun, Ilham; Hamzaoui, Saad; Adnane, Mohamed; Sahraoui, Taoufik

    2013-03-01

    Thin layers of nanoporous silicon PS were synthesized by anodic etching, in order to develop photovoltaic cells. We proposed a diluted concentration of hydrofluoric acid with different etching current densities (1, 3, 5 mA/cm2) on a fairly short time anodization. Observations by scanning electron microscope, electrical measurements and optical measurements revealed that the structural properties of PS layers depended on strong conditions of prints. The reverse and forward component of the I-V characteristics showed an appropriate method to explore and extract the parameters of the diode ideality factor n. The optimum conditions of formation of PS were: HF concentration of 1% and an etching current density of mA/cm2. Unlike silicon, which has a low absorption of short visible wavelengths, it was shown that the PS had wide energy gap of ? 2 eV, and a marked improvement in the absorption between 400 and 600 nm. This property has been used to optimize the response of the solar cell Ni/PS/c-Si. Efficiency performance close to 4.2% was obtained with a Voc of 400 mV, and fill factor of 46%. The solar cell exhibited better response than the reference cell Ni/c-Si. These results show that PS/c-Si heterojunction has a potential for photovoltaic applications.

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

    PubMed

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

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (??=?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

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

    PubMed Central

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

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (??=?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

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

    Microsoft Academic Search

    Tomohisa Ino; Tatsuya Hayashi; Keiji Ueno; Hajime Shirai

    2011-01-01

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

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

    PubMed Central

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

    2012-01-01

    The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal–Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm3, (0.053±0.002) mm3, (0.003 6±0.001) mm3 and (0.005 9±0.002) mm3 respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA. PMID:23306857

  5. 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)

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

    2014-01-01

    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.

  6. Continuous-flow mass production of silicon nanowires via substrate-enhanced metal-catalyzed electroless etching of silicon with dissolved oxygen as an oxidant.

    PubMed

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

    2014-01-01

    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. PMID:24413157

  7. Quantitative coverage and stability of hydrogen-passivation layers on HF-etched Si(1-x)Gex surfaces

    NASA Astrophysics Data System (ADS)

    Wilde, Markus; Fukutani, Katsuyuki; Koh, Shinji; Sawano, Kentarou; Shiraki, Yasuhiro

    2005-07-01

    This study investigates the stability of surface hydride layers passivating silicon-germanium alloys against contamination in ambient conditions after treatment in dilute hydrofluoric acid (HF), which is of central importance to the fabrication of SiGe-based semiconductor devices. We report quantitative hydrogen coverages on HF-etched Si(1-x)Gex surfaces (x=0,0.30,0.60,0.82), determined after air-to-vacuum transfer by H-specific H1(N15,??)C12 nuclear reaction analysis. Combination of this coverage information with analysis of the zero-point vibrational properties and N15-ion-induced desorption kinetics of the surface H atoms enables the distinction of well-passivated SiGe surfaces terminated exclusively by hydrides of Si and Ge from those partially covered by contaminating adsorbates. It is found that the resistance of HF-etched Si(1-x)Gex alloys against recontamination is drastically reduced at increasing Ge contents. Pure Si(100)-H is stably passivated at least up to 1week in air by a layer of 1.3±0.1 monolayer total H coverage. Si0.70Ge0.30 initially resembles H-passivated Si(100) but shows indications of moderate contamination after 1week in air. The HF treatment does not produce stable passivation layers on Ge-rich alloys (x?0.60), which suffer heavy recontamination within minutes after removal from the HF solution.

  8. Process for etching mixed metal oxides

    DOEpatents

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

    1994-10-18

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

  9. Process for etching mixed metal oxides

    DOEpatents

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

    1994-01-01

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

  10. A New Approach to Designing the Optimum Acid Treatment for Sandstone Reservoirs 

    E-print Network

    Abdelmoneim Mahmoud, Sherif

    2014-08-08

    Since the early days, various acid types have been developed along with additives to help make acidizing more effective. Hydrofluoric acid (HF), unlike other acids, has a specific reactivity with silica which makes it more effective for use...

  11. An Improved Model for Sandstone Acidizing and Study of the Effect of Mineralogy and Temperature on Sandstone Acidizing Treatments and Simulation 

    E-print Network

    Agarwal, Amit Kumar

    2013-01-14

    Sandstone acidizing is a complex operation because the acidizing fluid reacts with a variety of minerals present in the formation that results in a wide range of reaction products. The hydrofluoric acid (HF) reaction rate differs widely from mineral...

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-06-01

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

  16. Sputtered gold mask for deep chemical etching of silicon

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  17. Optical properties of silicon nanowire arrays formed by metal-assisted chemical etching: evidences for light localization effect.

    PubMed

    Osminkina, Liubov A; Gonchar, Kirill A; Marshov, Vladimir S; Bunkov, Konstantin V; Petrov, Dmitry V; Golovan, Leonid A; Talkenberg, Florian; Sivakov, Vladimir A; Timoshenko, Victor Yu

    2012-01-01

    We study the structure and optical properties of arrays of silicon nanowires (SiNWs) with a mean diameter of approximately 100?nm and length of about 1-25??m formed on crystalline silicon (c-Si) substrates by using metal-assisted chemical etching in hydrofluoric acid solutions. In the middle infrared spectral region, the reflectance and transmittance of the formed SiNW arrays can be described in the framework of an effective medium with the effective refractive index of about 1.3 (porosity, approximately 75%), while a strong light scattering for wavelength of 0.3 ÷ 1??m results in a decrease of the total reflectance of 1%-5%, which cannot be described in the effective medium approximation. The Raman scattering intensity under excitation at approximately 1??m increases strongly in the sample with SiNWs in comparison with that in c-Si substrate. This effect is related to an increase of the light-matter interaction time due to the strong scattering of the excitation light in SiNW array. The prepared SiNWs are discussed as a kind of 'black silicon', which can be formed in a large scale and can be used for photonic applications as well as in molecular sensing. PMID:23009051

  18. Single etch patterning of stacked silver and molybdenum alloy layers on glass using microcontact wave printing.

    PubMed

    Burdinski, Dirk; Brans, Harold J A; Decré, Michel M J

    2005-08-10

    Stacked thin layers of silver alloy (AgPdCu) and MoCr layers on 10 x 15 cm2 glass substrates were patterned by microcontact wave printing and etching. Patterns of etch-resistant octadecanethiol self-assembled monolayers (SAMs) were wave printed with regular backplane stabilized PDMS stamps. Pattern development was achieved by etching both metal layers in a single step, employing a nitric acid-based etching bath. Trifluoroacetic acid and a nitrite salt were identified as essential bath components for a homogeneous etching process. Etch defects could be eliminated by the addition of a decanesulfonate, which stabilizes the SAM resist via a defect healing mechanism. PMID:16076157

  19. Gate etch process control

    Microsoft Academic Search

    Ole Krogh; Mark Freeland; Ron Mori; Tito Chowdhury

    2003-01-01

    Studies on photomask Cr and MoSi etch processes were carried out and etch kinetics and modeling were performed. The photomasks were etched using an AMAT Centura II DPS and compared with a Unaxis VLE 770 ICP etcher. Mask metrology to support theoretical suppositions was performed on several tools: a KLA-Tencor P-12 profiler was used for depth measurement, while the KLA-Tencor

  20. Thermal Etching of Silver

    Microsoft Academic Search

    R. Shuttleworth; R. King; B. Chalmers

    1946-01-01

    NUMEROUS workers have observed that polished surfaces of metal specimens frequently develop an etched appearance when the specimens are heated in atmospheres with which chemical reactions would not be expected. Two types of etching effect have been recorded : (a) the formation of grooves at the grain boundaries, and (b) the development, on the surfaces of crystal grains, of striations

  1. Gate etch process control

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

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

    PubMed Central

    Shahabi, Sima; Chiniforush, Nasim; Juybanpoor, Nasrin

    2013-01-01

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

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

    SciTech Connect

    Brown, E V

    1988-06-01

    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.

  4. Etch resistance: comparison and development of etch rate models

    Microsoft Academic Search

    Damien Perret; Cecily E. Andes; Kap-Soo Cheon; Mani Sobhian; Charles R. Szmanda; George G. Barclay; Peter Trefonas

    2007-01-01

    Etch resistance and post etch roughness of ArF photoresists still remain some of the critical issues during process integration for sub-100nm technology nodes. Compared to phenyl-containing KrF polymers, methacrylate polymers commonly used for ArF lithography show weak bulk etch resistance in addition to a highly damaged surface after standard etch processes. Counter to the photoresist, the etch rates of BARC

  5. Chrome (Cr) Etching Instructions The CEPSR Clean Room stores CR-1A, a pre-made product used for removing or etching

    E-print Network

    Kim, Philip

    Chrome (Cr) Etching Instructions The CEPSR Clean Room stores CR-1A, a pre-made product used next to the eye wash in the large yellow room. A clean room staff member will take it for proper in the large yellow room, below the acid aprons and orange acid gloves. The etch rate of this particular

  6. Inverse metal-assisted chemical etching produces smooth high aspect ratio InP nanostructures.

    PubMed

    Kim, Seung Hyun; Mohseni, Parsian K; Song, Yi; Ishihara, Tatsumi; Li, Xiuling

    2015-01-14

    Creating high aspect ratio (AR) nanostructures by top-down fabrication without surface damage remains challenging for III-V semiconductors. Here, we demonstrate uniform, array-based InP nanostructures with lateral dimensions as small as sub-20 nm and AR > 35 using inverse metal-assisted chemical etching (I-MacEtch) in hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), a purely solution-based yet anisotropic etching method. The mechanism of I-MacEtch, in contrast to regular MacEtch, is explored through surface characterization. Unique to I-MacEtch, the sidewall etching profile is remarkably smooth, independent of metal pattern edge roughness. The capability of this simple method to create various InP nanostructures, including high AR fins, can potentially enable the aggressive scaling of InP based transistors and optoelectronic devices with better performance and at lower cost than conventional etching methods. PMID:25521615

  7. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

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

  8. Etching fission tracks in zircons

    USGS Publications Warehouse

    Naeser, C.W.

    1969-01-01

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

  9. Efficiency in bracket bonding with the use of pretreatment methods to tooth enamel before acid etching: sodium hypochlorite vs. hydrogen peroxide techniques.

    PubMed

    Rivera-Prado, Hermann; Moyaho-Bernal, Ángeles; Andrade-Torres, Alejandro; Franco-Romero, Guillermo; Montiel-Jarquín, Álvaro; Mendoza-Pinto, Claudia; García-Cano, Eugenio; Hernández-Ruíz, Ana K

    2015-04-01

    Bond failures are produced by the existence of biofilm on the tooth surface. Because biofilm is impermeable, it prevents contact in many areas, reducing the etching effect which selectively dissolves calcified tissues but does not seem to eliminate biofilm from the tooth surface, and thus the bond between the tooth and the bracket is not strong enough. The aim of this study is to compare bracket bonding efficiency with two dental surface pretreatments: sodium hypochlorite vs. hydrogen peroxide techniques. This was a cross-sectional, comparative, in vitro study. Seventy-five premolars extracted for orthodontic purposes were evaluated. They were divided into three groups of 25 teeth and assigned randomly toone of the pretreatment techniques (5.25%sodium hypochlorite or 3.5% hydrogen peroxide) or to a control group. The most efficient pretreatment technique for bonding to brackets was sodium hypochlorite, with an average of 17.15 (kg/F). Significant differences were observed between groups (p=0.0001). The post hoc bond strength test showed statistically significant differences between the sodium hypochlorite technique and the control group (p=0.0001). The sodium hypochlorite technique improves bracket adhesion to tooth enamel. PMID:25950167

  10. Resin-bonded retainers. Part I: Resin bond to electrolytically etched nonprecious alloys.

    PubMed

    Thompson, V P; Del Castillo, E; Livaditis, G J

    1983-12-01

    Nonprecious Ni-Cr casting alloys can be electrolytically etched to yield a highly retentive surface for micromechanical bonding of dental resins. The acid, current density, and etching time to achieve the retentive features are specific for each alloy. Conditions for etching one beryllium-containing and one non-beryllium-containing alloy are described. The tensile strength of a resin system to these alloys has been determined to be over two times the accepted value of the resin bond to acid-etched enamel. PMID:6361240

  11. Investigation of Cr etch kinetics

    NASA Astrophysics Data System (ADS)

    Wu, Banqiu

    2003-12-01

    Studies on Cr etch and its kinetics were carried out using a 50KeV photomask e-beam writing system, an ICP plasma etcher, chemically amplified resist (CAR), and a scanning electron microscope (SEM) metrology tool. A Cr etch rate equation was developed, showing good agreement with experimental data. Both the theoretical rate equation and experimental results showed that the main Cr etch rate effect parameters were oxygen mass flow rate, oxygen partial pressure, and ICP power. It was found that pressure plays a very important role in critical dimension (CD) uniformity etch contribution, loading effects, isolated/dense (I/D) etch CD bias, and etch CD movement. Etch kinetic information was found to be very helpful for improving CD uniformity, reducing pattern (local loading) effects, and controlling CD movement at the etch step. Some obsolete-pattern photomasks were used in the kinetic study. The main advantages of using obsolete photomasks include reducing resist effects on Cr etch rate investigation, obtaining much more etch kinetics data, and significantly lowering process development costs normally incurred from lithography tool time and raw photomask material consumption.

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

    PubMed

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

    2012-04-01

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

  13. Selective Etching of Semiconductor Glassivation

    NASA Technical Reports Server (NTRS)

    Casper, N.

    1982-01-01

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

  14. Investigation of Cr etch kinetics

    Microsoft Academic Search

    Banqiu Wu

    2003-01-01

    Studies on Cr etch and its kinetics were carried out using a 50KeV photomask e-beam writing system, an ICP plasma etcher, chemically amplified resist (CAR), and a scanning electron microscope (SEM) metrology tool. A Cr etch rate equation was developed, showing good agreement with experimental data. Both the theoretical rate equation and experimental results showed that the main Cr etch

  15. Mechanism of copper deposition on silicon from dilute hydrofluoric acid solution

    Microsoft Academic Search

    G. J. Norga; M. Platero; A. J. Reddy; J. Michel; L. C. Kimerling; K. A. Black

    1997-01-01

    Metal deposition on silicon from HF-based solutions is initiated by electrochemical reduction of metal ions, a process which is driven by the difference between the electron quasi Fermi energy in the silicon, E{sub Fn}, and the redox energy level of the ions in solution, eE{sub M{sup z+}\\/M{sup o}}. Mechanisms for metal ion reduction are elucidated by aligning the silicon bands

  16. Mechanism of copper deposition on silicon from dilute hydrofluoric acid solution

    SciTech Connect

    Norga, G.J.; Platero, M.; Reddy, A.J.; Michel, J.; Kimerling, L.C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering; Black, K.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering]|[Digital Equipment Corp., Hudson, MA (United States)

    1997-08-01

    Metal deposition on silicon from HF-based solutions is initiated by electrochemical reduction of metal ions, a process which is driven by the difference between the electron quasi Fermi energy in the silicon, E{sub Fn}, and the redox energy level of the ions in solution, eE{sub M{sup z+}/M{sup o}}. Mechanisms for metal ion reduction are elucidated by aligning the silicon bands with the redox levels of ions in solution. For copper, the reduction reaction occurs by capture of conduction band electrons, a process which requires nucleation of nanometer-sized precipitates on the silicon surface. As the concentration of electrons at the surface is increased (e.g., by n-type doping, illumination, or cathodic biasing), the nucleation rate of precipitates, N, increases steeply. N is further dependent on the activity of the metal ion in solution and the amount of surface charge at the Si/HF interface. The growth rate, v, of copper nuclei is determined by the surface concentration of holes and is increased by illumination and p-type doping. The predicted effects on N and v of illumination level, doping level, and substrate bias were verified by immersion tests on Czochralski wafers in 1:100 HF. Total reflection x-ray fluorescence was used to measure copper coverage; atomic force microscopy and surface-sensitive minority carrier lifetime measurements were used to determine the areal density of copper precipitates. Application of these findings to reduce copper deposition from HF in industrial wafer cleaning practice are discussed.

  17. Comparative behavior of titanium and zirconium in hydrofluoric-nitric acid pickling solutions

    Microsoft Academic Search

    E. M. M. Sutter; F. Hlawka; A. Cornet

    1990-01-01

    The different behavior of titanium and zirconium in HF-HNOâ pickling solutions has been studied using electrochemical methods and Raman spectrometry. In each case, the depleting of the solutions during a pickling experiment could be correlated with the consumption of HF to form metal oxo or oxofluoro complexes. However, the mechanism of metal dissolution is quite different for the two metals.

  18. Influence of impurities on chemical etch pits in gypsum single crystals

    Microsoft Academic Search

    KS Raju

    1981-01-01

    Basal cleavages of gypsum are etched in nitric acid and potassium hydroxide solution. Terraced pits are commonly observed\\u000a independent of the etchants used. Varying degrees of widths of terraces are observed on etching matched cleavage pairs as\\u000a well as thin flakes. The terraced nature of etch pits has been attributed to the inhibitive action of the etchant due to the

  19. An All-in-One Adhesive Does Not Etch beyond Hybrid Layers

    Microsoft Academic Search

    J. Kim; S. Mai; M. R. Carrilho; C. K. Y. Yiu; D. H. Pashley; F. R. Tay

    2010-01-01

    Continuous etching of aggressive all-in-one adhesives occurs in wet dentin tubules after polymerization of the adhesives. This study challenged the hypothesis that unpolymerized acidic monomers from an aggressive all-in-one self-etching adhesive continue to etch beyond dentin hybrid layers. Dentin surfaces bonded with Adper Prompt L-Pop were sectioned into 0.3-mm-thick slabs. Some of the slabs were stored in water (pH 6.8)

  20. Etching and plating of nominal U-6 wt % Nb alloys

    SciTech Connect

    Johnson, H.R.; Dini, J.W.; Wood, D.H.

    1980-08-01

    The adhesion of electrodeposited nickel to U-Nb alloys is of interest for joining materials by plating and for protection from corrosive environments. Because uranium alloys are passive, a surface preparation procedure such as etching in acid is necessary before plating to provide mechanical keying of the electrodeposit. When nitric acid has served as the etchant, there have been occasional violent reactions between the oxidizing acid and the alloy. We have observed that a sulfuric acid/hydrochloric acid etchant eliminates this problem. Furthermore, quantitative test data for nominal U-6 wt % Nb alloys plated with nickel demonstrated that with parts etched anodically in a solution of sulfuric and hydrochloric acids, high-strength bonds can be obtained; nominal shear and tensile bond strengths were 250 and 115 MN/m/sup 2/ respectively. Electrochemically etched U-Nb rods joined to 7075-T6 Al rods with thick nickel plating showed a nominal fracture stress in excess of 470 MN/m/sup 2/. Bare and Ni-plated tensile bars showed no significant changes in mechanical properties due to electrochemical etching and plating, but did exhibit changes due to Nb content and heat treatment.

  1. Improved Elemental Recoveries in Soils with Heating Boric Acid Following Microwave Total Digestion

    Microsoft Academic Search

    Michael A. Wilson; Rebecca Burt; Chris W. Lee

    2006-01-01

    Microwave digestion of soils for elemental analysis commonly uses hydrofluoric acid (HF) because of insolubility of aluminosilicate minerals in other acids. Boric acid is added following digestion to complex F in solution. Low recoveries of calcium (Ca), aluminum (Al), and magnesium (Mg) of soil reference materials led to this investigation of a secondary heating of the boric acid with digested

  2. Continuing Etching of an All-in-One Adhesive in Wet Dentin Tubules

    Microsoft Academic Search

    Y. Wang; P. Spencer

    2005-01-01

    Self-etch adhesives that etch and prime simultaneously are becoming more acidic. We hypothesized that the degree of acidic monomer conversion at the interface and within the tubules was high enough that the acidic reaction would be very self-limiting. Dentin surfaces prepared from extracted, unerupted human third molars were treated with Prompt L-Pop (3M ESPE). The prepared teeth were stored in

  3. Individualized Learning Package about Etching.

    ERIC Educational Resources Information Center

    Sauer, Michael J.

    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…

  4. THE IMPACT OF SAW DAMAGE ETCHING ON MICROCRACKS IN SOLAR CELL PRODUCTION

    Microsoft Academic Search

    Hanna Larsson; Jörgen Gustafsson; Hans Jørgen Solheim; Tobias Boström

    Multi-crystalline silicon wafers with micro cracks have been analyzed in a micro crack detection system before and after alkaline and acidic saw damage etching. In addition, a test was performed where saw damage etched wafers with micro cracks were exposed to repeated mechanical stress in a twist test setup. It was found that the length of micro cracks does not

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

    PubMed Central

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

    2012-01-01

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

  6. ZERODUR: bending strength data for etched surfaces

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  7. Decontamination of metals using chemical etching

    DOEpatents

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

    1980-01-01

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

  8. On the influence of etch pits in the overall dissolution rate of apatite basal sections

    NASA Astrophysics Data System (ADS)

    Alencar, Igor; Guedes, Sandro; Palissari, Rosane; Hadler, Julio C.

    2015-04-01

    Determination of efficiencies for particle detection plays a central role for proper estimation of reaction rates. If chemical etching is employed in the revelation of latent particle tracks in solid-state detectors, dissolution rates and etchable lengths are important factors governing the revelation and observation. In this work, the mask method, where a reference part of the sample is protected during dissolution, was employed to measure step heights in basal sections of apatite etched with a nitric acid, HNO_3 , solution at a concentration of 1.1 M and a temperature of 20 °C. We show a drastic increase in the etching velocity as the number of etch pits in the surface augments, in accordance with the dissolution stepwave model, where the outcrop of each etch pit generates a continuous sequence of stepwaves. The number of etch pits was varied by irradiation with neutrons and perpendicularly incident heavy ions. The size dependence of the etch-pit opening with etching duration for ion (200-300 MeV 152Sm and 238U) tracks was also investigated. There is no distinction for the etch pits between the different ions, and the dissolution seems to be governed by the opening velocity when a high number of etch pits are present in the surface. Measurements of the etchable lengths of these ion tracks show an increase in these lengths when samples are not pre-annealed before irradiation. We discuss the implications of these findings for fission-track modelling.

  9. Preparing and mixing acid solutions for the use in the Cosmoegnic RadioNuclide (CRN) Target Preparation Facility

    E-print Network

    Bookhagen, Bodo

    and Normality of Acids: Hydrochloric Acid, HCl conc. (36%): 12N ( = 1.19 g/mL) Nitric Acid, HNO3 conc. (69%): 15% Hydrofluoric and 1% Nitric acid mixture For a 20 L solution, you use 49% HF: 0.2 / 0.49 = 0.41L and 69% HNO3: 0.2 / 0.69 = 0.29L and 19.3L milliQ water. Making a 5% Hydrofluoric and 5% Nitric acid mixture For a 20 L

  10. Etching and Growth of GaAs

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  11. State of the art etch-and-rinse adhesives

    PubMed Central

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

    2013-01-01

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

  12. Northern Arabia Etched Terrain

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (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

  13. Etching Of Semiconductor Wafer Edges

    DOEpatents

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

    2003-12-09

    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.

  14. Lucian Freud: The Painter's Etchings

    NSDL National Science Digital Library

    2008-01-01

    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.

  15. Influence of chlorine on etched sidewalls in chemically assisted ion beam etching

    E-print Network

    Fainman, Yeshaiahu

    is then developed in propylene glycol methyl ether acetate, rinsed in isopropyl alcohol, and dried in air. 3 Etching etch mask in a chemically assisted ion beam etching (CAIBE) system. The effect of the chlorine gas flow

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

    PubMed Central

    Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

    2012-01-01

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

  17. 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....

  18. Investigation of KOH anisotropic etching of Si wafers for improving etched surface quality

    Microsoft Academic Search

    Wang Wei; Liu Xiaowei; Wang Xilian; Liu Yuqiang; Fan Maojun

    1998-01-01

    The main influences of KOH anisotropic etching of Si ?100? wafers on etched surface flatness are investigated experimentally. In the Si membrane etching with Si3N4 mask, the Si3N4 etching and the sediments in KOH aqueous solution are found as the main influences. The effective method to improve surface quality is presented by the mechanism analysis

  19. Plasma etched polymer microelectrochemical systems.

    PubMed

    Rossier, Joël S; Vollet, Christine; Carnal, Amanda; Lagger, Grégoire; Gobry, Véronique; Girault, Hubert H; Michel, Philippe; Reymond, Frédéric

    2002-08-01

    This paper presents a novel technique based on plasma etching for the mass production of polymer microchip devices. The method consists of the patterning of a photo-resist by a high resolution printer on a foil composed of three layers (5 microm copper/50 microm polyimide/5 microm copper). After this step, both copper layers are chemically etched in order to serve as a contact mask on the polyimide surface so as to produce the desired microstructure pattern. The foil is placed into a reactive plasma chamber in order to etch the exposed polyimide by means of an oxidizing plasma. The method enables holes, lines or larger areas to be etched, thereby generating either microholes, microchannels or electrodes in the plastic material. The copper can then be chemically removed or further patterned to produce conductive pads which are further electroplated with gold. The microchannel is then covered with a polyethylene terephthalate/polyethylene (PET/PE) lamination. The strength of this technology is that access holes for the fluid inlet and outlet, as well as gold coated electrodes can be fabricated without post-processing in a batch process. Demonstration of the application of such microelectrochemical systems is shown here by voltammetric detection inside a 60 nL microchannel, which presents the special feature of linear depletion of the analytes in the direction parallel to the microchannel. PMID:15100825

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

    NASA Astrophysics Data System (ADS)

    Hui, Wing C.

    2004-04-01

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

  1. Improved device reliability in organic light emitting devices by controlling the etching of indium zinc oxide anode

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Jie; Lou, Yan-Hui; Wang, Zhao-Kui; Liao, Liang-Sheng

    2014-11-01

    A controllable etching process for indium zinc oxide (IZO) films was developed by using a weak etchant of oxalic acid with a slow etching ratio. With controllable etching time and temperature, a patterned IZO electrode with smoothed surface morphology and slope edge was achieved. For the practical application in organic light emitting devices (OLEDs), a suppression of the leak current in the current—voltage characteristics of OLEDs was observed. It resulted in a 1.6 times longer half lifetime in the IZO-based OLEDs compared to that using an indium tin oxide (ITO) anode etched by a conventional strong etchant of aqua regia.

  2. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  3. Do endotoxins devoid of 3-deoxy-D-manno-2-octulosonic acid exist?

    PubMed

    Caroff, M; Lebbar, S; Szabó, L

    1987-03-30

    After treatment with aqueous, 50% hydrofluoric acid, a well-known dephosphorylating agent, the presence of 3-deoxy-D-manno-2-octulosonic acid (KDO), an essential and characteristic constituent of endotoxins, can be readily demonstrated in reportedly KDO-deficient bacterial lipopolysaccharides. PMID:3566759

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

    DOEpatents

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

    1981-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Bonyár, Attila; Szabó, Peter J

    2012-12-01

    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

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

    PubMed

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

    2015-01-01

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

  8. Cryogenic electron beam induced chemical etching.

    PubMed

    Martin, Aiden A; Toth, Milos

    2014-11-12

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

  9. AIN as a Dry-Etch Durable Resist for Electron and Ion Beam Lithography

    Microsoft Academic Search

    Tetsuya Tada; Toshihiko Kanayama

    1993-01-01

    Irradiation with an electron or ion beam has been found to reduce the etching rate of rf-sputtered AIN in alkaline or acidic solutions, which shows that this material acts as a negative-type electron and ion beam resist. It has a good resolution and high dry-etch durability. The performance of this resist was demonstrated by defining a 30-50 nm pattern with

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

    PubMed Central

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

    2010-01-01

    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-HNO3 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

  11. Antireflection structure of silicon solar cells formed by wet process using catalysis of single nano-sized gold or silver particle

    Microsoft Academic Search

    K. Nishioka; T. Sueto; N. Saito

    2009-01-01

    Antireflection nano structure was formed by simple wet chemical etching using catalysis of gold (Au) or silver (Ag) nanoparticle. Single nano-sized particle dispersion solution was coated onto Si(100) substrate with polished surface. Then, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. The surface of etched Si substrate appeared black, and the reflectivity was

  12. Etch challenges for DSA implementation in CMOS via patterning

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  13. Etching of glass microchips with supercritical water.

    PubMed

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

    2015-01-01

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent. PMID:25372151

  14. Laser-driven fusion etching process

    DOEpatents

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

    1987-08-25

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

  15. Calibrating etch model with SEM contours

    NASA Astrophysics Data System (ADS)

    Weisbuch, François; Omran, A.; Jantzen, Kenneth

    2015-03-01

    To ensure a high patterning quality, the etch effects have to be corrected within the OPC recipe in addition to the traditional lithographic effects. This requires the calibration of an accurate etch model and optimization of its implementation in the OPC flow. Using SEM contours is a promising approach to get numerous and highly reliable measurements especially for 2D structures for etch model calibration. A 28nm active layer was selected to calibrate and verify an etch model with 50 structures in total. We optimized the selection of the calibration structures as well as the model density. The implementation of the etch model to adjust the litho target layer allows a significant reduction of weak points. We also demonstrate that the etch model incorporated to the ORC recipe and run on large design can predict many hotspots.

  16. Laser-driven fusion etching process

    DOEpatents

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

    1989-01-01

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

  17. Etching method for photoresists or polymers

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  18. Simple wet etching of GaN

    NASA Astrophysics Data System (ADS)

    Parish, Giacinta; Scali, Paul A.; Spaargaren, Sue M.; Nener, Brett D.

    2001-11-01

    We discuss investigations into a contactless UV-enhanced wet etching technique for GaN. The technique utilizes the oxidising agent potassium persulfate to consume photogenerated electrons, thus avoiding the need for an electrical contact to an external cathode. The etch rate is strongly dependent on illumination intensity and uniformity and on the pH of the KOH solution, as is the roughness of the etched surface. The implementation of a dual illumination scheme whereby an additional UVC lamp was used to illuminate only the solution and not the wafer, resulted in an increased etch rate and smoother etched surface. Finally, the ohmic nature of contacts deposited on n-type GaN that had been etched in this manner was found to be improved compared to contacts on the unetched surface.

  19. Etching characteristics of a chromium-nitride hardmask for x-ray mask fabrication

    NASA Astrophysics Data System (ADS)

    Tsuboi, Shinji; Seki, Miyoshi; Suzuki, Katsumi

    1998-09-01

    To achieve high-precision x-ray masks, we have developed an extremely low-stress chromium-nitride (CrN) film for use as a hardmask for x-ray absorber etching. We have fabricated 0.10-micrometers line-and-space patterns in a 0.4-micrometers -thick tantalum-germanium (TaGe) alloy x-ray absorber using a 75- nm-thick CrN hardmask. The CrN film was etched by reactive- ion etching using chlorine gas mixed with oxygen. The etching selectivity between the TaGe alloy and the CrN was 13 when using electron-cyclotron-resonance plasma etching with sulfur hexafluoride (SF6) gas. We have also investigated the durability of the CrN film to various acids which are widely used for silicon-wafer cleaning processes. The CrN etching rate for those acids was 3 nm/min or less. These results demonstrate that a sputtered CrN film is an excellent hardmask for precise x-ray mask fabrication.

  20. Modeling and optimization of the chemical etching process in niobium cavities

    SciTech Connect

    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

    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)

  1. Dry etching of polydimethylsiloxane for microfluidic systems

    Microsoft Academic Search

    J. Garra; T. Long; J. Currie; T. Schneider; R. White; M. Paranjape

    2002-01-01

    A fluorine-based reactive ion etch (RIE) process has been developed to anisotropically dry etch the silicone elastomer polydimethylsiloxane (PDMS). This technique complements the standard molding procedure that makes use of forms made of thick SU-8 photoresist to produce features in the PDMS. Total gas pressure and the ratio of O2 to CF4 were varied to optimize etch rate. The RIE

  2. Dry etching technologies for reflective multilayer

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  3. Bulk and track etch properties of CR-39 SSNTD etched in NaOH/ethanol

    E-print Network

    Yu, K.N.

    Bulk and track etch properties of CR-39 SSNTD etched in NaOH/ethanol K.F. Chan, F.M.F. Ng, D. described the use of NaOH/ethanol as an etchant for the CR-39 detector, and have determined the corre and track etch properties of CR- 39 in NaOH/ethanol were derived from direct measurements. The bulk etch

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

    PubMed

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

    2012-01-01

    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

  5. Anisotropic Etching of Submicronic Resist Structures by Resonant Inductive Plasma Etching

    Microsoft Academic Search

    Jackie Etrillard; Jean-Marc Francou; Alain Inard; Daniel Henry

    1994-01-01

    The etching of submicronic resist structures in an oxygen plasma has been investigated in a helicon wave reactor. Systematic investigations have been conducted on the structure profile dependences on ion energy and on plasma pressure. For resist etching, the result of these investigations revealed the considerable heat transfer between the plasma species and the substrate. To obtain anisotropically etched resist

  6. The effect of erbium, chromium:yttrium-scandium-gallium-garnet laser etching on marginal integrity of a resin-based fissure sealant in primary teeth.

    PubMed

    Sungurtekin, Elif; Ozta?, Nurhan

    2010-11-01

    The aim of this in vitro study was to evaluate the effect of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser pretreatment alone, or associated with acid etching, on the quality of marginal integrity (microleakage and marginal gap) of a resin-based fissure sealant in primary teeth. Fifty sound primary molar teeth were randomly assigned to one of five study groups, pretreated as follows: (1) 35% orthophosphoric acid etching; (2) 2.5 W laser etching; (3) 3.5 W laser etching; (4) 2.5 W laser + 35% orthophosphoric acid etching; (5) 3.5 W laser + 35% orthophosphoric acid etching. After surface pretreatment, a resin-based sealant (ClinPro) was applied to the fissures. Sample teeth were then subjected to thermocycling and stored thereafter in distilled water at 37 degrees C for 1 month. Following immersion in 0.5% basic fuchsin solution for 24 h, three bucco-lingual slices of each sample tooth were scored under a stereo-microscope. Statistical analysis was performed with Kruskal-Wallis one-way analysis of variance (ANOVA) and Pearson chi-square tests. The level of significance was set at P < 0.05. Microleakage scores of group 1 were significantly less than those of groups 2 and 3 (P < 0.05), whereas no statistically significant difference was observed between groups 1, 4 and 5 (P > 0.05). In terms of marginal gap formation, no significant difference was observed between groups (P > 0.05). It was concluded that Er,Cr:YSGG laser etching did not eliminate the need for acid etching. When combined with acid etching, Er,Cr:YSGG laser seems to be as effective as conventional acid etching. PMID:19653059

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

    PubMed

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

    2015-07-21

    Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce(3+) fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications. PMID:26098593

  8. Polishing and etching langasite and quartz crystals

    Microsoft Academic Search

    Sally Laffey; Mary Hendrickson; John R. Vig

    1994-01-01

    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

  9. Hydrofluoric Acid Policy Procedure: 5.08 Created: 7/2007 Version: 2.0 Revised: 9/2014

    E-print Network

    Jia, Songtao

    of HF, Facilities workers, and first-responders to incidents involving a HF releases. C. Definitions airflow, sufficient airflow should be able to pull the tissue inward. This is known as a Kimwipe test, alkalis, combustibles, organics and ceramics. HF must be stored in tightly closed containers made

  10. Reactive sputter etching of silicon with very low mask-material etch rates

    SciTech Connect

    Horwitz, C.M.

    1981-11-01

    Directional etching of deep structures in silicon is often made difficult by a high mask erosion rate. Recent results have given a Si/SiO/sub 2/ etch rate ratio of up to 8 without the undercut problems associated with other selective etches. In this paper a new selectivity mechanism is described which can reproducibly give Si/SiO/sub 2/ etch rate ratios of more than 100 with a nonloading target, and more than about 50 with a loading target. Similar etch ratios are also obtained with masks of MgF/sub 2/, Al/sub 2/O/sub 3/, Al, and Cr. The inherently high Si/SiO/sub 2/ etch rate ratio obtained in Ar/Cl/sub 2/ discharges is here enhanced by causing selective deposition of SiO/sub 2/ onto slowly etched materials. The silicon may be obtained from the target, or, for easier control, from input gases such as SiCl/sub 4/. The deposition rate is controlled by the oxygen concentration. The results of etching deep grooves in Si are presented. Etch-mask faceting and Si surface decoration appear to limit the attainable etch rate ratios with fine structures; however, 18-..mu..m-deep gratings of 4.5-..mu..m period have been etched in Si.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    The tip of multimode fused silica fiber (core diameter: 550 ?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.

  12. Etching Behavior of Aluminum Alloy Extrusions

    NASA Astrophysics Data System (ADS)

    Zhu, Hanliang

    2014-11-01

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

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

    E-print Network

    Diaz, Jaime O. (Jaime Oscar Diaz Villamil)

    2010-01-01

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

  14. Etch-a-Sketch Nanoelectronics

    NASA Astrophysics Data System (ADS)

    Levy, Jeremy

    2009-10-01

    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.

  15. High density plasma etching of magnetic devices

    NASA Astrophysics Data System (ADS)

    Jung, Kee Bum

    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.

  16. Experimental Study of Acid Fracture Conductivity of Austin Chalk Formation 

    E-print Network

    Nino Penaloza, Andrea

    2013-05-01

    to those in actual acid fracture treatments. After acid etching, fracture conductivity is measured at different closure stresses. This research work presents a systematic study to investigate the effect of temperature, rock-acid contact time and initial...

  17. PECVD silicon carbide as a chemically resistant material for micromachined transducers

    Microsoft Academic Search

    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

    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

  18. Research on deep silicon etching for micro-channel plates

    NASA Astrophysics Data System (ADS)

    Zhou, Shun; Hu, Jiang; Zhu, Yufeng; Nie, Jing; Du, Jiaqiang

    2015-02-01

    In recent years, deep reactive ion etching (DRIE) has become a key process in the fabrication of microelectromechanical systems (MEMS). By combining the etching power of reactive ion etching and sidewall passivation, it provides a precise anisotropic etch that can be used to create very deep etches as well as very narrow structures in silicon. The standard Bosch process for DRIE alternates between two steps: etching and passivation. This combination provides the ability to etch very deep, vertical structures. In this article, silicon was etched with the Bosch process and cryogenic processes for patterning high-aspect-ratio features. The two leading techniques were compared. The influences of process parameters on the aspect ratio, etching rate and sidewall roughness of silicon were studied. Strong dependence of etch rate on loading was observed. The result showed that the etching rate rely on the process parameters. The aspect ratio of 23 was obtained and is able to be further improved.

  19. A simplified etching technique to improve the adhesion of fiber post

    PubMed Central

    Veeramachaneni, Chandrasekhar; Morisetty, Pradeep Kumar; Rao, Saggurti Anitha; Tummala, Muralidhar

    2014-01-01

    PURPOSE Numerous methods were used to etch the fiber posts to improve its bonding to root canal dentin. Our aim was to evaluate the efficacy of 37% phosphoric acid in etching fiber posts in comparison with 24% hydrogen peroxide. MATERIALS AND METHODS Ninety human maxillary central incisors were taken and post space preparation was done. Ninety fiber posts were taken and divided into three groups (n=30) based on the surface treatment they received (H3PO4, H2O2, distilled water) and each group was further divided (n=10) based on the time period of application (15 seconds, 30 seconds, 60 seconds). All the posts were luted into canals using Rely X UniCem-2. Each tooth was then sectioned into six slices and subjected to push out test. Data obtained was subjected to statistical analysis at P<.05. The surface topography was evaluated using scanning electron microscopy. RESULTS Highest bond strength values were noted in 15 seconds etched phosphoric acid group and 60 seconds etched hydrogen peroxide group with no significant difference between two groups. Surface topography revealed complete epoxy layer removal with no damage to its structural integrity in those groups. CONCLUSION H3PO4 etching for a period of 15 seconds is an effective alternative in improving the adhesion of fiber post to root dentin. PMID:25177473

  20. Electroless epitaxial etching for semiconductor applications

    DOEpatents

    McCarthy, Anthony M. (Menlo Park, CA)

    2002-01-01

    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.

  1. Dry etching method for compound semiconductors

    DOEpatents

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

    1997-01-01

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

  2. Method of sputter etching a surface

    DOEpatents

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

    1984-01-01

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

  3. Dry etching method for compound semiconductors

    DOEpatents

    Shul, R.J.; Constantine, C.

    1997-04-29

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

  4. Method of sputter etching a surface

    DOEpatents

    Henager, C.H. Jr.

    1984-02-14

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

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

    DOEpatents

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

    1992-01-01

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

  6. Revelation of stepped dislocations in amethyst crystals by hydrothermal etching

    Microsoft Academic Search

    M. S. Josut; M. A. IrryncHrN

    Triangular etch pits on rhombohedral surfaces due to hydrothermal etching are reported. Our experiments show that the hydrothermal etch pits on rhombohedral surfaces of amethyst have the same dislocation origin they have for quartz. We demonstrate that for a good number of cases successive etching results in the development of another pit away from the geometrical center of the original

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  8. Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala

    E-print Network

    Kushner, Mark

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

  9. Enhancing etch resistance of hydrogen silsesquioxane via postdevelop electron curing*

    E-print Network

    Berggren, Karl K.

    Enhancing etch resistance of hydrogen silsesquioxane via postdevelop electron curing* Joel K. W December 2006 In this work, the authors enhanced the etch resistance of the negative-tone electron resist while increasing their etch resistance. The results of the authors demonstrate that the etch resistance

  10. Epoxy bond and stop etch fabrication method

    DOEpatents

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

    2000-01-01

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

  11. Wafer Backside Anisotropic Wet Etching of Silicon

    NSDL National Science Digital Library

    This animation, created by Southwest Center for Microsystems Education (SCME), illustrates how the "wafer backside anisotropic wet etching of silicon is used to form the pressure sensor chamber." Further information and resources can be found on the SCME website.

  12. Metal assisted anodic etching of silicon

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P+-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N+-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si.Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P+-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N+-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01916h

  13. Metal assisted anodic etching of silicon.

    PubMed

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

    2015-07-01

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

  14. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  15. Plasma Etching of Nano-Scale Features

    NASA Astrophysics Data System (ADS)

    Zhang, Ying

    2007-06-01

    As the technology moving to deep nanometer regime, patterning nano-scale semiconductor features with precision imposes many new challenges for plasma etching. Two of the challenges are evidently critical. One of the challenges is that as the sizes of nano-scale features shrinking down to the sub-10nm regime, plasma etching seems to approach to its `limits' in unprecedented ways. For instance, one may face the question of what is the smallest hole can be actually etched by plasmas. Another challenge is the precision controllability of nano-scale feature pattern transferring as the features sizes, masks materials and thickness being all shrinking down to the molecular cluster dimensions. In this paper, we summarize the recent results of studying plasma etching of true nano-scale features using variety of nano-scale patterns and masks, diblock copolymer (similar to resist) self assembled nano holes and lines and self-assembled organosilicate (similar to silicon oxide) nano patterns. Using samples patterned with arrays of nano hole or nano line dimensions in the range from 25nm down to sub-10nm, we studied plasma etching characteristics and challenges for transferring nano-scale patterns into different materials (silicon, and silicon dioxide) in different plasma chemistries and process conditions. By varying the dimensions and thickness of masks, the characteristics of aspect ratio dependence vs. `true' etching limits due to the sizes of sub-25nm nano-scale features were studied. The impacts and challenges of mask selectivity and line edge roughness (LER) to transfer sub-25nm patterns will be reviewed. A few proposed limiting factors of current etching tooling, underlying principles of different chemistries, and processing parameters and their advantage and drawback to etching nanometer scale features will also be discussed.

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

    PubMed

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

    2002-12-01

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

  17. Solubility of (NH 4) 2SiF 6, K 2SiF 6 and Na 2SiF 6 in acidic solutions

    Microsoft Academic Search

    Jérôme Frayret; Alain Castetbon; Gérard Trouve; Martine Potin-Gautier

    2006-01-01

    Experimental values for the solubilities of three alkaline salts of hexafluorosilicate (K2SiF6, Na2SiF6 and (NH4)2SiF6) in different acidic solutions are reported as a function of the acid concentration in the solution. The acids used for this Letter are hydrofluoric, hydrochloric, sulphuric and nitric acids. The solubilities of the three studied compounds present important variations according to the nature and the

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

    Microsoft Academic Search

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

    2006-01-01

    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

  19. EPA study on HF acid could spell trouble for refiners

    Microsoft Academic Search

    Lobsenz

    1993-01-01

    Hydrofluoric acid, a highly toxic substance used at petroleum refineries, uranium fuel fabrication plants and many other industrial plants, could cause {open_quotes}severe impacts{close_quotes} more than six miles downwind of a worst-case accident, according to preliminary findings of an Environmental Protection Agency study. The study, also found that local governments and communities near some HF facilities were largely unaware of the

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

    PubMed Central

    2014-01-01

    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. PMID:24495647

  1. Plasma etching a ceramic composite. [evaluating microstructure

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  2. Silicon acoustic lens for scanning acoustic microscope (SAM)

    Microsoft Academic Search

    Hisayoshi Hashimoto; Sinji Tanaka; Kazuo Sato

    1991-01-01

    A single crystal silicon lens for a scanning acoustic microscope (SAM) has been developed by using lithography and chemical etching. Excellent sphericity and the minimal surface roughness demanded for a lens profile have been obtained through suitable etching. The optimum etchant conditions are with hydrofluoric, nitric, and acetic acids in the ratio of 2:3:3 at 50°C. A silicon lens designed

  3. Lateral homogeneity of porous silicon for large area transfer solar cells

    Microsoft Academic Search

    O. Tobail; Z. Yan; M. Reuter; J. H. Werner

    2008-01-01

    Transfer solar cells are monocrystalline silicon thin film cells grown epitaxially on annealed double layer porous silicon then transferred from the host wafer onto a foreign substrate. Porous silicon forms by electrochemical etching of the silicon wafer in hydrofluoric acid. An upper low porosity layer forms at low etch current density and a buried high porosity layer forms by increasing

  4. Light-activated photoluminescence of porous silicon

    Microsoft Academic Search

    Mykola S. Boltovec; Oleksandr I. Dacenko; Svitlana M. Naumenko; Tetjana V. Ostapchuk; Olga V. Rudenko

    1998-01-01

    Samples of porous silicon (PS) were etched in concentrated hydrofluoric acid. The initial and etched samples were exposed to the air by pairs at room temperature either in the dark or in daylight. In the process of exposition the integrated intensity of photoluminescence (IPL) excited by a nitrogen laser (337 nm) was measured in regular time intervals on all samples.

  5. Thermally controlled widening of droplet etched nanoholes

    NASA Astrophysics Data System (ADS)

    Heyn, Christian; Schnüll, Sandra; Jesson, David E.; Hansen, Wolfgang

    2014-06-01

    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.

  6. Thermal etching of SiC

    NASA Astrophysics Data System (ADS)

    van der Berg, N. G.; Malherbe, Johan B.; Botha, A. J.; Friedland, E.

    2012-05-01

    Thermal etching of SiC or its decomposition at high temperatures is of significance because of the many industrial applications of SiC at high temperatures. The effect of vacuum annealing at relatively high temperatures (1200-1800 °C) on the surface microstructure of 6H-SiC and polycrystalline SiC was investigated using a modern high resolution scanning electron microscope (FEG-SEM) with an in-lens detector. Crystal defects such as stacking faults and twins on the SiC surfaces were easily observed in this system. Thermal etching of SiC already started at 1200 °C with evidence of step bunching and grain boundary grooving. Preferred etching occurred on certain crystal surfaces of polycrystalline SiC. Significant decomposition of SiC occurred at 1800 °C. The resulting decomposition structures have possible nanotechnological applications.

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

    SciTech Connect

    Posseme, N., E-mail: nicolas.posseme@cea.fr; Pollet, O.; Barnola, S. [CEA-LETI-Minatec, 17 rue des martyrs, 38054 Grenoble cedex 09 (France)

    2014-08-04

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  9. Systematically controlling Kapitza conductance via chemical etching

    NASA Astrophysics Data System (ADS)

    Duda, John C.; Hopkins, Patrick E.

    2012-03-01

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

  10. Diagnostics for plasma processing (etching plasmas) (invited)

    SciTech Connect

    Hershkowitz, N.; Breun, R.A. [Engineering Research Center for Plasma Aided Manufacturing, University of Wisconsin--Madison, Madison, Wisconsin 53706 (United States)] [Engineering Research Center for Plasma Aided Manufacturing, University of Wisconsin--Madison, Madison, Wisconsin 53706 (United States)

    1997-01-01

    Plasma processing diagnostics play two different roles{emdash}characterization and control. The goal of plasma characterization is to establish connections of data with external parameters and to verify models. The goal of control diagnostics is to make noninvasive {ital in situ} measurements of relevant processing parameters. Diagnostics used in semiconductor etching are considered. These include Langmuir probes, laser induced fluorescence, optical emission spectroscopy, infrared and Fourier transform infrared absorption spectroscopy, mass spectrometry, microwave interferometry, and radio frequency diagnostics. An example is given of the use of many diagnostics in characterizing SiO{sub 2} and Si etching by fluorocarbons. {copyright} {ital 1997 American Institute of Physics.}

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

    SciTech Connect

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

    2012-11-30

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

  12. A Novel Model for Fracture Acidizing with Important Thermal Effects

    E-print Network

    Lyons, John

    2013-12-05

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

  13. Etching of Graphene Devices with a Helium Ion Beam

    E-print Network

    Baugher, Britton William Herb

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

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

    PubMed Central

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

    2014-01-01

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

  15. 3-Hydroxybenzoic acid as AISI 316L stainless steel corrosion inhibitorin a H 2 SO 4 –HF–H 2 O 2 pickling solution

    Microsoft Academic Search

    L. Narváez; E. Cano; D. M. Bastidas

    2005-01-01

    3-Hydroxybenzoic acid (3-HBA) was studied for possible use as a AISI 316L stainless steel (SS) corrosion inhibitor in an environmental-friendly aqueous pickling solution of 75 g l-1 sulphuric acid (H2SO4), 25 g l-1 hydrofluoric acid (HF) and 30 g l-1 hydrogen peroxide (H2O2). 3-HBA was tested in concentrations from 5 × 10-5 to 5 × 10-1M at 298 and 313

  16. Atomic layer in situ etching and MBE regrowth

    Microsoft Academic Search

    K. Eberl; M. Lipinski; H. Schuler

    1999-01-01

    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

  17. Excimer laser induced etching of InP

    Microsoft Academic Search

    V. M. Donnelly; T. R. Hayes

    1990-01-01

    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

  18. Plasma etching of chromium films in the fabrication of photomasks

    Microsoft Academic Search

    Thomas P. Coleman; Peter D. Buck

    1995-01-01

    To meet the advanced CD uniformity and resolution requirements of state-of-the-art maskmaking, dry chrome etch processing may be required. Dry etching is a more anisotropic process, significantly reducing etch undercut. The absence of undercutting allows the lithographer to image the resist at the iso-focal point, eliminating the need to underexpose to maintain CDs. Also, dry etch parameters can be precisely

  19. Anisotropic Etching, Silicon Crystal Orientation, and MEMS

    NSDL National Science Digital Library

    Lopez, Fabian

    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.

  20. Etch Profile Simulation Using Level Set Methods

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Etching and deposition of materials are critical steps in semiconductor processing for device manufacturing. Both etching and deposition may have isotropic and anisotropic components, due to directional sputtering and redeposition of materials, for example. Previous attempts at modeling profile evolution have used so-called "string theory" to simulate the moving solid-gas interface between the semiconductor and the plasma. One complication of this method is that extensive de-looping schemes are required at the profile corners. We will present a 2D profile evolution simulation using level set theory to model the surface. (1) By embedding the location of the interface in a field variable, the need for de-looping schemes is eliminated and profile corners are more accurately modeled. This level set profile evolution model will calculate both isotropic and anisotropic etch and deposition rates of a substrate in low pressure (10s mTorr) plasmas, considering the incident ion energy angular distribution functions and neutral fluxes. We will present etching profiles of Si substrates in Ar/Cl2 discharges for various incident ion energies and trench geometries.

  1. Structural investigation of electrochemically etched silicon

    Microsoft Academic Search

    B. J. Heuser; S. Spooner; C. J. Glinka; D. L. Gilliam; N. A. Winslow; M. S. Boley

    1992-01-01

    Small-angle neutron scattering (SANS) measurements of four electrochemically etched, porous (PS) samples have been performed over a wide wavevector transfer (Q) range. The intermediate to high Q results can be modeled with a non-particulate, random phase model. Correlation length scales on the order of 1 to 2 nm thought to characterize the PS skeleton have been deduced from the SANS

  2. Orientation Dependence of Etch Pit Density in (111) and (211) CdZnTe Everson Etch

    NASA Astrophysics Data System (ADS)

    Burgess, Lindsay; Kumar, Francis Joseph; Mackenzie, Jason

    2015-05-01

    Everson solution is widely used for dislocation etching on (111)B and (211)B facets of CdTe and CdZnTe (CZT) wafers, but (211)B etch pit density (EPD) counts are lower. In this study, the correlation between the (111) and (211) Everson EPD counts was quantified by etching incrementally misoriented (111)B and (211)B facets of CdZnTe with counting by semi-automated optical microscopy. The EPD was found to decrease exponentially with increasing misorientation angle from (111)B. The results indicate that, for EPD to be a quantitative indicator of crystalline quality, precise crystal orientation angles must be taken into account. Based on the exponential curve fit, an estimation of the (111)B EPD values can be extrapolated from the EPD measured for (211)B etching.

  3. CR-39 track etching and blow-up method

    DOEpatents

    Hankins, Dale E. (Livermore, CA)

    1987-01-01

    This invention is a method of etching tracks in CR-39 foil to obtain uniformly sized tracks. The invention comprises a step of electrochemically etching the foil at a low frequency and a "blow-up" step of electrochemically etching the foil at a high frequency.

  4. Cryogenic dry etching for high aspect ratio microstructures

    Microsoft Academic Search

    Kenji Murakami; Yuji Wakabayashi; Kazuyuki Minami; Masayoshi Esashi

    1993-01-01

    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

  5. Ga+ beam lithography for nanoscale silicon reactive ion etching

    Microsoft Academic Search

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

    2010-01-01

    By using a dry etch chemistry which relies on the highly preferential etching of silicon, over that of gallium (Ga), we show resist-free fabrication of precision, high aspect ratio nanostructures and microstructures in silicon using a focused ion beam (FIB) and an inductively coupled plasma reactive ion etcher (ICP-RIE). Silicon etch masks are patterned via Ga + ion implantation in

  6. Etching 200-mm diameter SCALPEL masks with the ASE process

    Microsoft Academic Search

    Ian R. Johnston; Huma Ashraf; Jy K. Bhardwaj; Janet Hopkins; Alan M. Hynes; Glenn Nicholls; Serrita A. McAuley; Stephen Hall; Lilian Atabo; Gregory R. Bogart; Avi Kornblit; Anthony E. Novembre

    2000-01-01

    The Advanced Silicon Etch (ASER) process has been used for silicon substrate etching for the manufacture of SCALPELR (SCattering using Angular Limitation Projection E-beam Lithography) masks. The current SCALPELR mask fabrication process uses an aqueous solution of KOH to etch the membrane support struts in 100 mm diameter, crystalline silicon wafers. This technique is undesirable for the manufacture of large

  7. Etching 200 mm diameter SCALPEL® masks with the ASE® process

    Microsoft Academic Search

    Ian R. Johnston; Huma Ashraf; Jy K. Bhardwaj; Alan M. Hynes; Stephen Hall; Gregory R. Bogart; Anthony E. Novembre

    The Advanced Silicon Etch (ASE ® ) process has been used for silicon substrate etching for the manufacture of SCALPEL ® (SCattering using Angular Limitation Projection E-beam Lithography) masks. The current SCALPEL® mask fabrication process uses an aqueous solution of KOH to etch the membrane support struts in 100mm diameter, <100> crystalline silicon wafers. This technique is undesirable for the

  8. Pits and Fissures: Etch Resistance in Prismless Enamel Walls

    Microsoft Academic Search

    MF Burrow; JF Burrow

    2001-01-01

    Background: In a previous study to examine the nature of etching on the walls of fissures, there was a consistent result of resistance to deep etching on parts of the walls and a zone of lesser etching on part of the walls as evidenced by the uptake of stain. The staining had been used to examine the nature of the

  9. Fabrication of 1m Rib Waveguides on SOI: Etching Process

    E-print Network

    Barthelat, Francois

    etching was used to transfer the pattern from the resist to the silicon layer. The S1813 resist layer to the surface. Gas used during the etching stage could have flowed under the resist layer and caused the gradualFabrication of 1µm Rib Waveguides on SOI: Etching Process Nicholas Hemsworth, Sina Dhane, Professor

  10. Imaging capabilities of etched (100) and (210) garnet films

    NASA Astrophysics Data System (ADS)

    Tkachuk, S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

    2009-04-01

    Imaging capabilities of etched (100) and (210) oriented garnet films are studied and compared. It is demonstrated that the etching of out-of-plane (100) garnet films may result in drastic reduction in saturation fields. Concurrently, the appreciable increase in contrast and resolution of images produced by the etched films has been observed.

  11. Selective wet etching of Ge2Sb2Te5 phase-change thin films in thermal lithography with tetramethylammonium

    NASA Astrophysics Data System (ADS)

    Deng, Changmeng; Geng, Yongyou; Wu, Yiqun

    2011-09-01

    In this paper, we study Ge2Sb2Te5 phase-change film as a promising inorganic photoresist using organic alkaline: tetramethylammonium hydroxide (TMAH) solution, instead of inorganic alkali or acid as etchant. The basic etching properties are investigated by prior and posterior annealing Ge2Sb2Te5 films. Selectivity is found to be dependent on concentration of TMAH. There is a good selectivity in the 25% TMAH solution, in which the amorphous state is etched away, whereas the crystalline state remains. The etching rate decreases when the concentration of TMAH is diluted; and an opposite selectivity, compared with 25% TMAH solution, is observed in the 0.125% TMAH solution. Selective etching with laser crystallization in different power levels is also studied, and an excellent wet selectivity in the 25% TMAH solution is obtained. The remaining crystalline lines are observed by atomic force microscopy. The surface roughness after etching is at a good level. The selective wet-etching mechanism is also discussed.

  12. Highly selective PEC etching of gallium nitride device structures

    NASA Astrophysics Data System (ADS)

    Gao, Yan

    Photoelectrochemical (PEC) wet etching is an attractive wet etch approach for III-Nitride materials. Compared to dry etch techniques normally applied in prevalent GaN device fabrications, PEC wet etching can provide low damage, selective etching and understanding of material defects. This dissertation work has carried out an in-depth exploration of the dependence of PEC etching on both process variables and materials composition. In particular, a detailed study of bandgap-selective etching is carried out. To focus these studies, we describe the fabrication of a novel vertical electronic device, the CAVET (C&barbelow;urrent A&barbelow;perture V&barbelow;ertical E&barbelow;lectron ?ransistor). The key feature of this device is a current aperture that restricts the flow of current in a 2DEG to a direction perpendicular to the surface. By keeping current away from surface states, this device geometry provides low DC-RF dispersion compared to a more conventional AlGaN/GaN HEMT. The composition and dimensions of the aperture cannot otherwise interfere with the operation of the device, thus the fabrication process will involve highly selective etching of a very thin sacrificial layer. We utilized PEC bandgap selective etching of a 60nm InGaN sacrificial layer, and great effort was employed to optimize the etch process to obtain smooth, controllable lateral undercut etching. We describe two generations of device fabrication and the accompanying modifications in selective etch process that were required. In developing a selective undercut etch process in our initial devices, it becomes important to understand the differences in etch rate and mechanism for both the Ga-face and N-face (0001¯) crystallographic planes. Tremendous insights were provided by PEC etch studies on LEO (Lateral Epitaxial Overgrowth) a-plane GaN, where we could compare the effects of dislocation and crystallographic plane on etch rate and etch morphology. It is observed that dislocations retard the etch process. The N-face is far more chemically active than the Ga-face, producing a crystallographic etching morphology of {101¯1¯} hexagonal pyramids. The N-face can even be etched without illumination, thus limiting the selectivity obtainable in a photo-enhanced etch process. This morphology can be used to increase the light extraction efficiency of GaN LEDs by a factor of 2-3.

  13. Etched profile control in anisotropic etching of silicon by TMAH+Triton

    NASA Astrophysics Data System (ADS)

    Pal, Prem; Gosálvez, M. A.; Sato, K.

    2012-06-01

    The adverse effect of mechanical agitation (magnetic bead stirring) as well as galvanic interaction between the evolving facets of the etch front on the amount of undercutting during anisotropic etching of Si{1?0?0} wafers in surfactant-added tetramethylammonium hydroxide (TMAH) is studied by etching different mask patterns in magnetically stirred and nonstirred solutions. Triton X-100, with formula C14H22O(C2H4O)n, where n = 9-10, is used as the surfactant. The stirring results conclude that the adsorption of the surfactant on the etched silicon surfaces is predominantly physical in nature rather than chemical (physisorption versus chemisorption). The proposed model to account for the galvanic interaction between the evolving facets indicates that the underlying chemical etching process can be significantly surpassed by the onset of an electrochemical etching contribution when the relative area of the exposed {1?0?0} surface becomes relatively small in comparison to that of the developed {1?1?1} sidewalls. This study is useful for engineering applications where surfactant-added TMAH is used for the fabrication of silicon MEMS structures that should contain negligible undercutting.

  14. Chemical vapour etching of silicon and porous silicon: silicon solar cells and micromachining applications

    Microsoft Academic Search

    A. Ben Jaballah; M. Hassen; M. Hajji; M. Saadoun; B. Bessais; H. Ezzaouia

    2005-01-01

    In this work, we used HNO3\\/HF Vapour Etching (VE) of silicon (Si) wafers for the formation of different porous structures. Depending on the volume ratio of the HNO3\\/HF acid mixture, we can obtain Porous Silicon (PS) layers or a (NH4)2SiF6 like powder phase. These two kind of porous structures may be used in silicon solar cells and in micromachining applications.

  15. Plasma polymer thin film depositions to regulate gas permeability through nanoporous track etched membranes

    Microsoft Academic Search

    Christopher L. Chapman; Dhiman Bhattacharyya; Robert C. Eberhart; Richard B. Timmons; Cheng-Jen Chuong

    2008-01-01

    Deposition of thin polymeric films on nanoporous membranes is shown to provide a mechanically simple and inexpensive approach to regulate trans-membrane gas flows. For this purpose, polymeric films were deposited on polycarbonate track-etched (PCTE) membranes of 50nm and 100nm pore size. The films were generated by low-pressure glow discharge plasma polymerization of vinyl acetic acid (CH2CHCH2COOH) or perfluorohexane (n-C6F14) monomers.

  16. ICP etching of GaAs via hole contacts

    SciTech Connect

    Shul, R.J.; Baca, A.G.; Briggs, R.D.; McClellan, G.B. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J. [University of Florida, Gainesville, FL (United States); Constantine, C. [Plasma-Therm Inc., St. Petersburg, FL (United States)

    1996-09-01

    Deep etching of GaAs is a critical process step required for many device applications including fabrication of through-substrate via holes for monolithic microwave integrated circuits (MMICs). Use of high-density plasmas, including inductively coupled plasmas (ICP), offers an alternative approach to etching vias as compared to more conventional parallel plate reactive ion etch systems. This paper reports ICP etching of GaAs vias at etch rates of about 5.3 {mu}m/min with via profiles ranging from highly anistropic to conical.

  17. Reactive Ion Etching of Al-1%Cu alloy thin films

    NASA Astrophysics Data System (ADS)

    Gou, Jun; Wu, Zhi-ming; Tai, Hui-ling; Yuan, Kai

    2009-11-01

    The special technical process was demaned for the reactive ion etching (RIE) of AlCu alloy thin films, such as the removal of doped Cu, the protection of sidewall and the prevention of chlorine corrosion after etching. In this paper, Al-1%Cu alloy was etched using BCl3, Cl2 and N2 gases, and CH4 was also added in the etching gases in order to enhance the sidewall protection. The process was optimized and the multi-step process were abtained. The effect of CH4 on sidewall protection was analyzed. The removal of residue after the etch was also studied.

  18. Impact of recess-etching-assisting resist-openings on the shapes of gate grooves for short gate length InAlAs\\/InGaAs heterojunction FET's

    Microsoft Academic Search

    Dong Xu; Takatomo Enoki; Yasunobu Ishii

    1999-01-01

    When resist openings are employed to monitor the drain current of InAlAs\\/InGaAs-heterojunction-based FET's during wet-chemical gate recess, etching rates for InGaAs and InAlAs can be significantly modified by the exposure of the surface metal on the nonalloyed ohmic electrodes to citric-acid-based etchants. Surface metal of Ni enhances the recess etching rate to a degree that is much higher than that

  19. Determination of the Efficiency of Mixed-Acid Digestions of Sediments

    SciTech Connect

    Huerta Vazquez, Alejandra I.; Gill, Gary A.

    2007-01-01

    Mixed-acid digestion is a method often used for the determination of elemental analysis of sediment samples. It is crucial that efficiency details associated with the digestion method be well understood on an element by element basis. Battelle’s Marine Sciences Laboratory Standard Operating Procedure for Sediment Mixed-Acid Digestions was modified to identify conditions which produce optimal recovery of elements. The parameters that were adjusted for testing were mass of sediment, mixed-acid volume, mixed-acid composition and digestion time. Digestion involves treatment of the sediment sample with mixed-acid mixtures at 135º C ± 10º in a Teflon® digestion bomb. Typical analytical methods include Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). Initial experiments involved determining the optimal ratio of acid volume to mass of sediment. Experiments were designed to identify the point at which insufficient acid was used to effectively digest a given mass of sediment. When the mass of sediment was varied between 0.2 and 1.0 gram using a 4 mL aqua regia acid mixture (3 mL hydrochloric acid and 1 mL nitric acid), there was no effect on the recovery of the elements Al, Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Ti, V, and Zn. The next experiments focused on a time study to resolve the shortest digestive time for optimal elemental recovery. Two masses of sediment were investigated, 0.25 and 0.7 g, again utilizing aqua regia digestion (4 mL). Maximum recovery was reached after 4 hours of digestion; additional digestion time released no or only minimal amounts of elements from the sediments. The final set of experiments was designed to identify optimal conditions for the total digestion of sediment using a mixture of hydrochloric acid, nitric acid, hydrofluoric acid, hydrogen peroxide, and boric acid. These experiments were designed to determine the optimal volume of hydrofluoric acid needed to achieve a total digestion. Utilizing two masses of sediment 0.25 and 0.5 g and varying the volume of hydrofluoric acid and boric acid. Total digestion was achieved with a minimum volume of 0.5 mL hydrofluoric acid and a .25 g of sediment. Future experiments incorporating the findings in these experiments will be executed using a heated carbon block as the source for thermal energy.

  20. Method of undercut anisotropic etching of semiconductor material

    SciTech Connect

    Aine, H.E.; Block, B.

    1986-07-15

    This patent describes a method for undercut anisotropic etching of an etch stopped layer portion of a (110) face of diamond cubic semiconductor material, to form beam or bridge structures, the etch stopped layer portion which is to be undercut having a pair of opposing side edges, the steps of: orienting the pair of opposing side edges of the etch stopped layer portion which is to be undercut at an angle to the most nearly parallel one of the )111) traces on the (110) face being etched, so that the oriented side edges will be undercut from the sides; and contacting the (110) face being etched with an isotropic etchant for the semiconductive material so as to essentially completely undercut the etch stopped layer portion from both of the side edges in a direction toward the opposing side edge.

  1. Structure dependent hydrogen induced etching features of graphene crystals

    NASA Astrophysics Data System (ADS)

    Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap; Papon, Remi; Sharma, Subash; Vishwakarma, Riteshkumar; Sharma, Kamal P.; Tanemura, Masaki

    2015-06-01

    H2 induced etching of graphene is of significant interest to understand graphene growth process as well as to fabricate nanoribbons and various other structures. Here, we demonstrate the structure dependent H2 induced etching behavior of graphene crystals. We synthesized graphene crystals on electro-polished Cu foil by an atmospheric pressure chemical vapor deposition process, where some of the crystals showed hexagonal shaped snowflake-dendritic morphology. Significant differences in H2 induced etching behavior were observed for the snowflake-dendritic and regular graphene crystals by annealing in a gas mixture of H2 and Ar. The regular graphene crystals were etched anisotropically creating hexagonal holes with pronounced edges, while etching of all the dendritic crystals occurred from the branches of lobs creating symmetrical fractal structures. The etching behavior provides important clue of graphene nucleation and growth as well as their selective etching to fabricate well-defined structures for nanoelectronics.

  2. Attachment and spreadout study of 3T3 cells onto PP track etched films

    NASA Astrophysics Data System (ADS)

    Smolko, Eduardo; Mazzei, Ruben; Tadey, Daniel; Lombardo, Daniel

    2001-12-01

    Polymer surface modifications are obtained by the application of radiation treatments and other physico-chemical methods: fission fragment (ff) irradiation and etching. The biocompatibility of the surface is then observed by cell seeding and cell adhesion experiments. Approaches to improvement of the cell adhesion are obtained by different methods: for example, in PS, cell adhesion is improved after ion implantation; in PMMA, after bombarding the polymer, the surface is reconditioned with surfactants and proteins and in PVDF, cell adhesion is assayed on nuclear tracks membranes. In this work, we obtained important cell adhesion improvements in PP films by irradiation with swift heavy ions and subsequent etching of the nuclear tracks. We use BOPP (isotactic -25 ?m thickness). Irrradiations were performed with a Cf-252 californium ff source. The source has a heavy ff and a light one, with 160-200 MeV energy divided among them corresponding to ff energies between 1 and 2 MeV/amu. A chemical etching procedure consisting of a solution of sulphuric acid and chromium three oxide at 85 °C was used. The 3T3 NIH fibroblast cell line was used for the cell adhesion experiment. Here we report for the first time, the results of a series of experiments by varying the ff fluence and the etching time showing that attachment and spreadout of cells are very much improved in this cell line according to the number of pores and the pore size.

  3. Fabrication of Semiconductors by Wet Chemical Etch

    E-print Network

    Francoviglia, Laura

    2008-07-01

    for removing GaAs, was used in the proportions of 1:8:640. !e reaction occurs in a sequence of steps involving an oxidation reaction of the hydroxide ions when the semi- conductor is immersed in an electro- lyte system to produce Ga2O3 and As2O3. !ese... etching will use InGaAsSb wafers. However, because indium is the most di#cult layer to etch, InGaP is a good starting point. Epi Layer Structures of V3338 350 Å GaAs 5E18 Si Doping (Top) 400 Å GaAs 1E17 Si Doping 160 Å InGaP not intentionly doped...

  4. Etch Overview for Microsystems Learning Module

    NSDL National Science Digital Library

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

  5. Photoluminescence from photochemically etched highly resistive silicon

    Microsoft Academic Search

    T. Hadjersi; N Gabouze; N Yamamoto; K Sakamaki; H Takai

    2004-01-01

    The photochemical etching method has been performed on n-type Si(111) wafer with a resitivity of 4.2 k? cm, in a mixture of HF and H2O2, under He–Ne laser (633 nm) irradiation. The morphology of the porous films grown after exposure to a He–Ne laser at normal incidence were analysed by scanning electron microscopy (SEM). The results show that the films

  6. Etching of moldavities under natural conditions

    NASA Technical Reports Server (NTRS)

    Knobloch, V.; Knoblochova, Z.; Urbanec, Z.

    1983-01-01

    The hypothesis that a part of the lechatellierites which originated by etching from a basic moldavite mass became broken off after deposition of moldavite in the sedimentation layer is advanced. Those found close to the original moldavite were measured for statistical averaging of length. The average length of lechatelierite fibers per cubic mm of moldavite mass volume was determined by measurement under a microscope in toluene. The data were used to calculate the depth of the moldavite layer that had to be etched to produce the corresponding amount of lechatelierite fragments. The calculations from five "fields" of moldavite surface, where layers of fixed lechatelierite fragments were preserved, produced values of 2.0, 3.1, 3.5, 3.9 and 4.5. Due to inadvertent loss of some fragments the determined values are somewhat lower than those found in references. The difference may be explained by the fact that the depth of the layer is only that caused by etching after moldavite deposition.

  7. Capability of etched multilayer EUV mask fabrication

    NASA Astrophysics Data System (ADS)

    Takai, Kosuke; Murano, Koji; Kamo, Takashi; Morikawa, Yasutaka; Hayashi, Naoya

    2014-09-01

    Recently, development of next generation extremely ultraviolet lithography (EUVL) equipment with high-NA (Numerical Aperture) optics for less than hp10nm node is accelerated. Increasing magnification of projection optics or mask size using conventional mask structure has been studied, but these methods make lithography cost high because of low through put and preparing new large mask infrastructures. To avoid these issues, etched multilayer EUV mask has been proposed. As a result of improvement of binary etched multilayer mask process, hp40nm line and space pattern on mask (hp10nm on wafer using 4x optics) has been demonstrated. However, mask patterns are easily collapsed by wet cleaning process due to their low durability caused by high aspect ratio. We propose reducing the number of multilayer pairs from 40 to 20 in order to increase durability against multilayer pattern collapse. With 20pair multilayer blank, durable minimum feature size of isolated line is extended from 80nm to 56nm. CD uniformity and linearity of 20pair etched multilayer pattern are catching up EUV mask requirement of 2014.

  8. Laser etching of polymer masked leadframes

    NASA Astrophysics Data System (ADS)

    Ho, C. K.; Man, H. C.; Yue, T. M.; Yuen, C. W.

    1997-02-01

    A typical electroplating production line for the deposition of silver pattern on copper leadframes in the semiconductor industry involves twenty to twenty five steps of cleaning, pickling, plating, stripping etc. This complex production process occupies large floor space and has also a number of problems such as difficulty in the production of rubber masks and alignment, generation of toxic fumes, high cost of water consumption and sometimes uncertainty on the cleanliness of the surfaces to be plated. A novel laser patterning process is proposed in this paper which can replace many steps in the existing electroplating line. The proposed process involves the application of high speed laser etching techniques on leadframes which were protected with polymer coating. The desired pattern for silver electroplating is produced by laser ablation of the polymer coating. Excimer laser was found to be most effective for this process as it can expose a pattern of clean copper substrate which can be silver plated successfully. Previous working of Nd:YAG laser ablation showed that 1.06 ?m radiation was not suitable for this etching process because a thin organic and transparent film remained on the laser etched region. The effect of excimer pulse frequency and energy density upon the removal rate of the polymer coating was studied.

  9. Optimization of etching and reading procedures for the Autoscan 60 track etch system

    SciTech Connect

    McKeever, R.; Devine, R.; Coennen, C.

    1997-02-11

    The Los Alamos National Laboratory is charged with measuring the occupational exposure to radiological workers and contractors throughout the Laboratory, which includes many different sites with multiple and varied radiation fields. Of concern here are the high energy neutrons such as those generated during accelerator operations at Los Alamos Neutron Science Center (LANSCE). In 1993, the Los Alamos National Laboratory purchased an Autoscan 60 automated reader for use with chemically etched CR39 detectors. The dosimeter design employed at LANL uses a plastic, hemispherical case, encompassing a polystyrene pyramidal detector holder. The pyramidal holder supports three detectors at a 35{degree} angle. Averaging the results of the three detectors minimizes the angular dependence normally associated with a planar dosimeter. The Autoscan 60 is an automated reading system for use with CR39 chemical etch detectors. The detectors are immersed in an etch solution to enhance the visibility of the damage sites caused by recoil proton impact with the hydrogen atoms in the detector. The authors decided to increase the etch time from six hours to 15 hours, while retaining the 70 C temperature. The reason for the change in the etch is to enhance the sensitivity and precision of the CR39 detector as indicated by this study.

  10. Deep reactive ion etching of silicon using an aluminum etching mask

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Ho, Joe N.; Reinhall, Per G.

    2003-03-01

    A method for fast and efficient deep anisotropic etching of bulk silicon, using a parallel capacitively coupled plasma is presented. The effect of the masking materials and RIE conditions are discussed. Based on the experimental results, a 1000 angstrom thick Al film sufficiently protects the unexposed substrate while allowing the etching of a 350mm deep hole with an area of 3x3mm2 when etching with SF6 /CHF3/O2 plasma. A 2000mm long and 100mm wide (with layers of Al/SiO2/Si and thicknesses of 0.1mm/2.2mm/40mm respectively) cantilever is also achieved. A silicon etch rate up to 2.2 mm/min has be obtained and an anisotropy of A= 0.5 (A=1-V/H, where V=horizontal undercut, H=etch depth) has been observed. The technique was developed mainly for bulk micromachining of silicon or composite silicon cantilever structures.

  11. Bi/In thermal resist for both Si anisotropic wet etching and Si/SiO2 plasma etching

    NASA Astrophysics Data System (ADS)

    Chapman, Glenn H.; Tu, Yuqiang; Peng, Jun

    2004-01-01

    Bi/In thermal resist is a bilayer structure of Bi over In films which can be exposed by laser with a wide range of wavelengths and can be developed by diluted RCA2 solutions. Current research shows bimetallic resist can work as etch masking layer for both dry plasma etching and wet anisotropic etching. It can act as both patterning and masking layers for Si and SiO2 with plasma "dry" etch using CF4/CHF3. The etching condition is CF4 flow rate 50 sccm, pressure 150 mTorr, and RF power 100 - 600W. The profile of etched structures can be tuned by adding CHF3 and other gases such as Ar, and by changing the CF4/CHF3 ratio. Depending on the fluorocarbon plasma etching recipe the etch rate of laser exposed Bi/In can be as low as 0.1 nm/min, 500 times lower than organic photoresists. O2 plasma ashing has little etching effect on exposed Bi/In. Bi/In also creates etch masking layers for alkaline-based (KOH, TMAH and EDP) "wet" anisotropic bulk Si etch without the need of SiO2 masking steps. The laser exposed Bi/In etches two times more slowly than SiO2. Experiment result shows that single metal Indium film exhibits thermal resist characteristics but at twice the exposure levels. It can be developed in diluted RCA2 solution and used as an etch mask layer for Si anisotropic etch. X-ray diffraction analysis shows that laser exposure causes both Bi and In single film to oxidize. In film may become amorphous when exposed to high laser power.

  12. NiCr etching in a reactive gas

    SciTech Connect

    Ritter, J.; Boucher, R.; Morgenroth, W.; Meyer, H. G. [Institute of Physical High Technology, 9 Albert Einstein Strasse 07745 Jena (Germany)

    2007-05-15

    The authors have etched NiCr through a resist mask using Cl/Ar based chemistry in an electron cyclotron resonance etch system. The optimum gas mixture and etch parameters were found for various ratios of Ni to Cr, based on the etch rate, redeposits, and the etch ratio to the mask. The introduction of O{sub 2} into the chamber, which is often used in the etching of Cr, served to both increase and decrease the etch rate depending explicitly on the etching parameters. Etch rates of >50 nm min{sup -1} and ratios of >1 (NiCr:Mask) were achieved for NiCr (80:20). Pattern transfer from the mask into the NiCr was achieved with a high fidelity and without redeposits for a Cl/Ar mix of 10% Ar (90% Cl{sub 2}) at an etch rate of {approx_equal}50 nm min{sup -1} and a ratio of 0.42 (NiCr:ZEP 7000 e-beam mask)

  13. Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn;

    E-print Network

    Garmestani, Hamid

    Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn; SnO2; Ti; Zn Hydrofluoric Acid (HF): GaAs; Ni; SiO2; Ti Nitric Acid (HNO3): C; Cu; GaAs; In; Fe; Pb; Ni; Ag; Pd; Pt; Sn; Ti; Zn; ZnO Phosphoric Acid (H3PO4): Al; Cu; GaAs; Ga

  14. Formation of antireflection nanostructure for silicon solar cells using catalysis of single nano-sized silver particle

    Microsoft Academic Search

    Kensuke Nishioka; Tsuyoshi Sueto; Nobuo Saito

    2009-01-01

    Antireflection nanostructure was formed by simple wet chemical etching using catalysis of silver (Ag) nanoparticle. Single nano-sized Ag particle dispersion solution was coated onto Si(100) substrate with polished surface. Then, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. The surface of 9-min-etched Si substrate appeared black, and the reflectivity was reduced to below

  15. Antireflection subwavelength structure of silicon surface formed by wet process using catalysis of single nano-sized gold particle

    Microsoft Academic Search

    Kensuke Nishioka; Susumu Horita; Keisuke Ohdaira; Hideki Matsumura

    2008-01-01

    Subwavelength structure (SWS) was formed by simple wet chemical etching using catalysis of gold (Au) nanoparticle. Single nano-sized Au particle dispersion solution was coated onto silicon (Si)(111) substrate with polished surface. Then, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. The surface of 15-min-etched Si substrate appeared black. The reflectivity of the Si

  16. Extreme ultraviolet lithography mask etch study and overview

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  17. Washable and wear-resistant superhydrophobic surfaces with self-cleaning property by chemical etching of fibers and hydrophobization.

    PubMed

    Xue, Chao-Hua; Li, Ya-Ru; Zhang, Ping; Ma, Jian-Zhong; Jia, Shun-Tian

    2014-07-01

    Superhydrophobic poly(ethylene terephthalate) (PET) textile surfaces with a self-cleaning property were fabricated by treating the microscale fibers with alkali followed by coating with polydimethylsiloxane (PDMS). Scanning electron microscopy analysis showed that alkali treatment etched the PET and resulted in nanoscale pits on the fiber surfaces, making the textiles have hierarchical structures. Coating of PDMS on the etched fibers affected little the roughening structures while lowered the surface energy of the fibers, thus making the textiles show slippery superhydrophobicity with a self-cleaning effect. Wettability tests showed that the superhydrophobic textiles were robust to acid/alkaline etching, UV irradiation, and long-time laundering. Importantly, the textiles maintained superhydrophobicity even when the textiles are ruptured by severe abrasion. Also colorful images could be imparted to the superhydrophobic textiles by a conventional transfer printing without affecting the superhydrophobicity. PMID:24942304

  18. Corrosion resistance studies on grain-boundary etched drug-eluting stents.

    PubMed

    Rettig, Ralf; Kunze, Julia; Stöver, Michael; Wintermantel, Erich; Virtanen, Sannakaisa

    2007-07-01

    In this paper we compare the influence of different microstructures on the corrosion resistance of new drug-eluting stainless steel stents, which have been produced by grain-boundary-selective electrochemical etching processes. The morphology of the stent surfaces was analysed by scanning electron microscopy (SEM), and the surface composition was investigated with Auger electron spectroscopy (AES) as well as with energy dispersive X-ray analysis (EDX). The passivity of the different microstructured stents was studied by cyclovoltammetry in Ringer solution. Release of nickel and chromium was assessed after potentiostatic experiments in Ringer solution by analysing the collected electrolyte with AAS. For stents produced by different two-step etching procedures bringing about ideal morphologies regarding the mechanical and biological properties of the surface, no significant differences in the passivation behaviour could be observed. A two-step process using first nitric acid and oxalic acid in a second step produces stent surfaces with very good corrosion properties: electrochemical analysis shows that the range of stable passivity is the same as for conventional stent surfaces, and low rates of nickel and chromium release are observed. The etching procedures do not seem to change the surface oxide layer composition. PMID:17277971

  19. Refractory resistors with etch stop for superconductor integrated circuits

    SciTech Connect

    Przybysz, J.X.; Buttan, J.

    1990-02-27

    This patent describes a method for preparing molybdenum resistors in a superconductor integrated circuit. It comprises: depositing superconductor film on a support; patterning the superconductor film to provide a patterned superconductor and exposed support; applying an aluminum film on the superconductor film and the exposed support; applying a molybdenum film on the aluminum film to provide an aluminum-molybdenum, etch-stop interface; applying a patterned resist film on the molybdenum film to provide exposed molybdenum film and unexposed molybdenum film; etching the exposed molybdenum film to define the molybdenum resistor and expose a portion of the aluminum-molybdenum, etch-stop interface; and oxidizing the exposed aluminum-molybdenum, etch-stop interface. The aluminum-molybdenum, etch-stop interface protects the patterned superconductor film and the support and increases processing margins for the etch time. Also described is a molybdenum resistor configuration for a superconductor integrated circuit.

  20. Bulk filling of Class II cavities with a dual-cure composite: Effect of curing mode and enamel etching on marginal adaptation

    PubMed Central

    Bortolotto, Tissiana; Roig, Miguel; Krejci, Ivo

    2014-01-01

    Objectives: This study attempted to find a simple adhesive restorative technique for class I and II cavities on posterior teeth. Study Design: The tested materials were a self-etching adhesive (Parabond, Coltène/Whaledent) and a dual-cure composite (Paracore, Coltène/Whaledent) used in bulk to restore the cavities. Class II MO cavities were performed and assigned to 4 groups depending on the orthophosphoric acid (H3PO4) conditioning of enamel and polymerization method used (chemical or dual). Specimens were subjected to quantitative marginal analysis before and after thermo-mechanical loading. Results: Higher percentages of marginal adaptation at the total margin length, both before and after thermo-mechanical loading, were found in groups in which enamel was etched with phosphoric acid, without significant differences between the chemically and dual-cured modes. The restorations performance was similar on enamel and dentin, obtaining low results of adaptation on occlusal enamel in the groups without enamel etching, the lowest scores were on cervical dentin in the group with no ortophosphoric acid and self-cured. Conclusions: A dual-cure composite applied in bulk on acid etched enamel obtained acceptable marginal adaptation results, and may be an alternative technique for the restoration of class II cavities. Key words:Dual-cure composite, bulk technique, class II restoration, selective enamel etching, marginal adaptation. PMID:25674316

  1. A new back-etch for silicon devices

    SciTech Connect

    Malberti, P.; Ciappa, M.; Scacco, P. [Swiss Federal Inst. of Tech., Zuerich (Switzerland)

    1995-12-31

    This paper reports on a new application of tetramethylammonium-hydroxide in aqueous solution (TMAHW) as back-etch for silicon integrated circuits. TMAHW has many advantages upon traditional back-etch solutions: it is selective, safe, non-toxic, inexpensive, and fully compatible with materials used in semiconductor device technology. The efficiency of this backside etching technique is demonstrated by a case history concerning aluminum silicon interdiffusion.

  2. Microwave enhanced fast anisotropic etching of monocrystalline silicon

    Microsoft Academic Search

    Jan A Dziuban

    2000-01-01

    A wet microwave enhanced selective anisotropic fast etching of single-crystal silicon has been developed. Deep square cavities with flat thin silicon membranes of very good quality were etched in standard (100) n-type substrate. Si3N4 CVD layer served as the mask. For microwaves 2.54 GHz and 100 W of microwave power, etching velocity of (100) plane was increased almost 30 times

  3. Etched Laser Filament Tracks in Glasses and Polymers

    Microsoft Academic Search

    E. E. Uzgiris; R. L. Fleischer

    1973-01-01

    Self-focused laser filament tracks in various glasses and polymers were chemically etched to produce conical voids in a manner similar to the etching of charged-particle tracks in these same materials. The etched filament cones were related to the sharpest Cf252 fission-fragment cones by roughly the same ratio of cone angle for all the different materials tested. One interpretation of this

  4. CF 4 plasma etching of materials used in microelectronics manufacturing

    Microsoft Academic Search

    O. V Balachova; M. A. R Alves; J. W Swart; E. S Braga; L Cescato

    2000-01-01

    Amorphous hydrogenated carbon a-C:H films, deposited on silicon substrates by radio frequency plasma-enhanced chemical vapor deposition (RF PECVD), and AZ® 5214 organic photoresist have been etched in a low-pressure and high frequency tetrafluoromethane (CF4) plasma. The etching of Si and SiO2 was also measured in order to determine their selectivities to a-C:H films and AZ 5214 photoresist. The etch rates

  5. Sustainable technologies for the regeneration of acidic tin stripping solutions used in PCB fabrication

    Microsoft Academic Search

    Charlie Kerr

    2004-01-01

    Electroplated tin deposits are used as etch resists during the processing of printed circuit boards. The tin coating protects the copper tracks during etching but is subsequently removed (stripped) to expose the defined copper circuitry. The commonly used stripping solutions are based on nitric acid and after use they represent a very acidic waste product with a high metal content.

  6. Enlargement of halloysite clay nanotube lumen by selective etching of aluminum oxide.

    PubMed

    Abdullayev, Elshad; Joshi, Anupam; Wei, Wenbo; Zhao, Yafei; Lvov, Yuri

    2012-08-28

    Halloysite clay tubes have 50 nm diameter and chemically different inner and outer walls (inner surface of aluminum oxide and outer surface of silica). Due to this different chemistry, the selective etching of alumina from inside the tube was realized, while preserving their external diameter (lumen diameter changed from 15 to 25 nm). This increases 2-3 times the tube lumen capacity for loading and further sustained release of active chemical agents such as metals, corrosion inhibitors, and drugs. In particular, halloysite loading efficiency for the benzotriazole increased 4 times by selective etching of 60% alumina within the tubes' lumens. Specific surface area of the tubes increased over 6 times, from 40 to 250 m(2)/g, upon acid treatment. PMID:22838310

  7. Release-etch modeling for complex surface micromachined structures

    SciTech Connect

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

    1996-10-01

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

  8. Studies on the variation of the track etch rate along alpha particle trajectories in CR39

    Microsoft Academic Search

    B Dörschel; H Hartmann; K Kadner; P Rö?ler

    1995-01-01

    At the beginning of the etching process a constant track etch rate can be assumed. In deeper detector layers, however, the etch rate varies drastically along the particle trajectories. Consequently, the indirect determination of the track etch rate by measuring the etch pit diameters on the detector surface does not yield correct results. Therefore, a method for the direct measurement

  9. Reflectometry for TSV etching depth inspection

    NASA Astrophysics Data System (ADS)

    Hsu, Wei-Te; Ku, Yi-Sha

    2011-05-01

    TSV (Through Silicon Via) is a vertical via that passes through a silicon wafer or chip. This technology is a major enabler for three-dimensional integrated circuits (3D ICs) of stacking different functional chips. Vertical stacking chips of 3D ICs allows gates to be placed closer and thereby provides more computing process in a compact space. As TSV technique with unique processing steps that are not used in standard 2D ICs, a number of new parameters need to be measured and controlled. TSV etching depth is a critical parameter for ensuring the performance of 3D ICs, thus metrology and inspection of the TSV etching depth are very profitability of the overall manufacturing process. Spectroscopic reflectometry (SR) is currently being used in industry to measure the internal reflectance of thin films, from which the thickness and other properties can be obtained. It is a non-contact and non-destructive in-line metrology tool. In this study, we demonstrate the use of SR by employing the fast Fourier transform (FFT) algorithm for measuring the etching via depth and the thickness of oxide layer in one shot measurement. First, the specifications of reflectometer system, such as spectral range and resolution of spectrometer for depth analysis are discussed. The depth resolution is better in the longer measuring spectral range, thus small difference of TSVs' depth can be well distinguished. The spectrometer with high resolution is used to collect the authentic spectrum from etching depth with high aspect ratio. We verified our system through a mutual measurement comparison with the national standard traceable step height system. Our system is capable of measuring step height up to 100 um and measurement precision is in the range of 0.6 um. In this report, TSV arrays with nominal CD 5~25 um, and aspect ratio up to 10 are measured. Metrology results from actual 3D interconnect processing wafers indicate our system provides excellent correlation to cross-section scanning electron microscope (SEM) measurement results. The maximum discrepancy between each other is smaller than 1 um.

  10. Mask undercut in deep silicon etch

    NASA Astrophysics Data System (ADS)

    Saraf, I.; Goeckner, M.; Goodlin, Brian; Kirmse, Karen; Overzet, L.

    2011-04-01

    Mask undercut in the time-multiplexed deep silicon etch process is becoming an increasingly significant issue as it is used to produce smaller critical dimension features. Models of the process must contain the necessary physics to reproduce the dependencies of mask undercut. We argue that the reason undercut develops is the dependence of the deposition step on ion flux. Our experiments of C4F8 (and CHF3 not shown) plasmas show that the film growth is dominantly ion-enhanced. This leads naturally to a mask undercut that increases in time. A more neutral flux dominant deposition step would result in reduced mask undercut.

  11. Photoresist 3D profile related etch process simulation and its application to full chip etch compact modeling

    NASA Astrophysics Data System (ADS)

    Wu, Cheng-En; Yang, Wayne; Luan, Lan; Song, Hua

    2015-03-01

    The optical proximity correction (OPC) model and post-OPC verification that takes the developed photoresist (PR) 3D profile into account is needed in the advanced 2Xnm node. The etch process hotspots caused by poor resist profile may not be fully identified during the lithography inspection but will only be observed after the subsequent etch process. A complete mask correction that targets to final etch CD requires not only a lithography R3D profile model but also a etch process compact model. The drawback of existing etch model is to treat the etch CD bias as a function of visibility and pattern density which do not contain the information of resist profile. One important factor to affect the etch CD is the PR lateral erosion during the etch process due to non-vertical PR side wall angle (SWA) and anisotropy of etch plasma source. A simple example is in transferring patterns from PR layer to thin hard mask (HM) layer, which is frequently used in the double pattern (DPT) process. The PR lateral erosion contributes an extra HM etch CD bias which is deviated from PR CD defined by lithography process. This CD bias is found to have a nontrivial dependency on the PR profile and cannot be described by the pattern density or visibility. In this report, we study the etch CD variation to resist SWA under various etch conditions. Physical effects during etch process such as plasma ion reflection and source anisotropy, which modify the local etch rate, are taken into considerations in simulation. The virtual data are generated by Synopsys TCAD tool Sentaurus Topography 3D using Monte Carlo engine. A simple geometry compact model is applied first to explain the behavior of virtual data, however, it works to some extent but lacks accuracy when plasma ion reflection comes into play. A modified version is proposed, for the first time, by including the effects of plasma ion reflection and source anisotropy. The new compact model fits the nonlinear etch CD bias very well for a wide range of resist SWAs from 65 to 90 degrees, which covers the resist profile diversities in most real situations. This result offers a potential application for both resist profile aware and etch process aware mask correction model in the mask synthesis flow.

  12. Deep reactive ion etching of borosilicate glass using an anodically bonded silicon wafer as an etching mask

    NASA Astrophysics Data System (ADS)

    Akashi, T.; Yoshimura, Y.

    2006-05-01

    A new dry-etching method for fabricating anisotropic deep grooves on a borosilicate glass wafer is reported. The method uses a 200 µm thick bulk silicon wafer bonded to a borosilicate glass wafer by anodic bonding as an etching mask and inductively coupled plasma generated by C4F8 or CHF3 gases for etching. The measured etching rate showed that the deep reactive ion etching conditions for achieving a high etching rate are low gas pressure, high gas-flow rate, high antenna power and high bias power. The measured groove profile revealed that the sidewall angles of the etched grooves were less than 80° and C4F8 plasma provided a slight difference in width between the mask opening and etched groove. These results indicate that C4F8 plasma is suitable for precise groove fabrication. Even after fabrication of a 430 µm deep groove, enough silicon mask (135 µm thickness) remained to fabricate a deeper groove. Consequently, our etching method using an anodically bonded silicon mask and C4F8 plasma enables the fabrication of very deep grooves in borosilicate glass.

  13. The Effects of Initial Condition of Fracture Surfaces, Acid Spending, and Type on Conductivity of Acid Fracture 

    E-print Network

    Almomen, Ali Mansour

    2013-07-24

    was found to be more effective in etching rock and controlling acid leakoff compared with linear-gelled acid. Also, crosslinked acid reduces the number of pits and the pit diameters. Based on conductivity tests, linear-gelled acid is more favorable at higher...

  14. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  15. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  16. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  17. Reactive ion etched substrates and methods of making and using

    DOEpatents

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

    2007-08-07

    Disclosed herein are substrates comprising reactive ion etched surfaces and specific binding agents immobilized thereon. The substrates may be used in methods and devices for assaying or isolating analytes in a sample. Also disclosed are methods of making the reactive ion etched surfaces.

  18. Rapid Dry Etching Of Photoresists Without Toxic Gases

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R.; Wydeven, Theodore

    1991-01-01

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

  19. Micromachined Faraday cup array using deep reactive ion etching

    Microsoft Academic Search

    Robert B Darling; Adi A Scheidemann; K. N Bhat; T.-C Chen

    2002-01-01

    A micromachined Faraday cup array (MFCA) has been developed using a deep reactive ion etching (DRIE) process for applications in position sensitive charged particle detection. Deeply etched trenches with vertical sidewalls create an effective ion collection structure, and the formation of MOS capacitors on the interior surfaces produces an array of low-leakage, high stability Faraday cups that can be independently

  20. Plasma-Therm Workshop: Fundamentals of Plasma Processing (Etching & Deposition)

    E-print Network

    Martin, Jan M.L.

    Plasma-Therm Workshop: Fundamentals of Plasma Processing (Etching & Deposition) Nanofabrication The workshop will focus on the fundamentals of plasma etching and deposition. Lectures will include an introduction to vacuum technology, the basics of plasma and plasma reactors and an overview of mechanisms

  1. A step towards accreditation: A robustness test of etching process.

    PubMed

    Leonardi, F; Veschetti, M; Tonnarini, S; Cardellini, F; Trevisi, R

    2015-08-01

    In the present study the robustness of the etching process used by our laboratory was assessed. The strategy followed was based on the procedure suggested by Youden. Critical factors for the process were estimated using both Lenth's method and Dong's algorithm. The robustness test evidences that particular attention needs to be paid to the control of the etching solution's temperature. PMID:26002275

  2. Mechanism study of sidewall damage in deep silicon etch

    NASA Astrophysics Data System (ADS)

    Meng, Lingkuan; Yan, Jiang

    2014-09-01

    The formation and etch mechanism of sidewall damage in deep silicon etch using standard Bosch process have been investigated in this work for the first time. The sidewall damage occurs at a certain depth where the sidewall is not sufficiently protected from lateral etch during long-time ion bombardment, and further, we demonstrate that the formation of sidewall damage is not only related to passivation film on the trench sidewall, but also closely relies on ion-enhanced etch mechanism. In addition, it is found that the starting depth of sidewall damage is almost inversely proportional to etch pressure and ion incidence angle, which can be attributed to a broader ion angular distribution (IAD) at higher chamber pressure. Then, a quantitative etch model based on IAD function has been also proposed to investigate the dependence of the starting depth of sidewall damage on ion incidence angle. Finally, by optimizing process parameters, high-quality etch profile without any observable sidewall damage has been successfully achieved at etch pressure of 60 mTorr.

  3. Mechanism study of sidewall damage in deep silicon etch

    NASA Astrophysics Data System (ADS)

    Meng, Lingkuan; Yan, Jiang

    2014-12-01

    The formation and etch mechanism of sidewall damage in deep silicon etch using standard Bosch process have been investigated in this work for the first time. The sidewall damage occurs at a certain depth where the sidewall is not sufficiently protected from lateral etch during long-time ion bombardment, and further, we demonstrate that the formation of sidewall damage is not only related to passivation film on the trench sidewall, but also closely relies on ion-enhanced etch mechanism. In addition, it is found that the starting depth of sidewall damage is almost inversely proportional to etch pressure and ion incidence angle, which can be attributed to a broader ion angular distribution (IAD) at higher chamber pressure. Then, a quantitative etch model based on IAD function has been also proposed to investigate the dependence of the starting depth of sidewall damage on ion incidence angle. Finally, by optimizing process parameters, high-quality etch profile without any observable sidewall damage has been successfully achieved at etch pressure of 60 mTorr.

  4. Ga+ beam lithography for nanoscale silicon reactive ion etching

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    By using a dry etch chemistry which relies on the highly preferential etching of silicon, over that of gallium (Ga), we show resist-free fabrication of precision, high aspect ratio nanostructures and microstructures in silicon using a focused ion beam (FIB) and an inductively coupled plasma reactive ion etcher (ICP-RIE). Silicon etch masks are patterned via Ga + ion implantation in a FIB and then anisotropically etched in an ICP-RIE using fluorinated etch chemistries. We determine the critical areal density of the implanted Ga layer in silicon required to achieve a desired etch depth for both a Pseudo Bosch (SF6/C4F8) and cryogenic fluorine (SF6/O2) silicon etching. High fidelity nanoscale structures down to 30 nm and high aspect ratio structures of 17:1 are demonstrated. Since etch masks may be patterned on uneven surfaces, we utilize this lithography to create multilayer structures in silicon. The linear selectivity versus implanted Ga density enables grayscale lithography. Limits on the ultimate resolution and selectivity of Ga lithography are also discussed.

  5. Nanoscale etching of resists in view of a mechanistic framework

    Microsoft Academic Search

    Falco C. M. J. M. van Delft; J. Ben Giesbers; Gert-Jan Nienhuis

    1997-01-01

    In our previously developed mechanistic framework for dry etching, the three consecutive reaction steps (reactant chemisorption, surface reaction and product desorption) are assumed to be activated thermally and in parallel mechanically by fast particle impacts. According to this model, profiles with perpendicular side walls should be obtained if (a) the rate determining step in the etch mechanism is not the

  6. Improvement of Dry Etching Resistance of Resists by Deep UVCure

    Microsoft Academic Search

    Shinji Kishimura; YoshikaKimura YoshikaKimura; Junjiro Sakai; Kouichirou Tsujita; Yasuji Matsui

    1999-01-01

    The improvement of dry etching resistance of photoresists by the deep UV cure has been attempted. We have tried deep UV cure under N2 gas flow for KrF chemically amplified resists and obtained the same level of etching rates as novolak resists. While the rates increased under dry air. The resists after deep UV cure under both N2 and dry

  7. Consideration of VT5 etch-based OPC modeling

    NASA Astrophysics Data System (ADS)

    Lim, ChinTeong; Temchenko, Vlad; Kaiser, Dieter; Meusel, Ingo; Schmidt, Sebastian; Schneider, Jens; Niehoff, Martin

    2008-03-01

    Including etch-based empirical data during OPC model calibration is a desired yet controversial decision for OPC modeling, especially for process with a large litho to etch biasing. While many OPC software tools are capable of providing this functionality nowadays; yet few were implemented in manufacturing due to various risks considerations such as compromises in resist and optical effects prediction, etch model accuracy or even runtime concern. Conventional method of applying rule-based alongside resist model is popular but requires a lot of lengthy code generation to provide a leaner OPC input. This work discusses risk factors and their considerations, together with introduction of techniques used within Mentor Calibre VT5 etch-based modeling at sub 90nm technology node. Various strategies are discussed with the aim of better handling of large etch bias offset without adding complexity into final OPC package. Finally, results were presented to assess the advantages and limitations of the final method chosen.

  8. Composition/bandgap selective dry photochemical etching of semiconductor materials

    DOEpatents

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

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  9. Miniature pulse compressor of deep-etched gratings.

    PubMed

    Jia, Wei; Zhou, Changhe; Feng, Jijun; Dai, Enwen

    2008-11-10

    We propose a miniature pulse compressor that can be used to compensate the group velocity dispersion that is produced by a commercial femtosecond laser cavity. The compressor is composed of two identical highly efficient deep-etched transmissive gratings. Compared with prism pairs, highly efficient deep-etched transmissive grating pairs are lightweight and small. With an optimized groove depth and a duty cycle, 98% diffraction efficiency of the -1 transmissive order can be achieved at a wavelength of 800 nm under Littrow conditions. The deep-etched gratings are fabricated in fused silica by inductively coupled plasma etching. With a pair of the fabricated gratings, the input positively chirped 73.9 fs pulses are neatly compressed into the nearly Fourier transform-limited 43.2 fs pulses. The miniature deep-etched grating-based pulse compressor should be of interest for practical applications. PMID:19002230

  10. Low-doped etch stopping for micromechanical device production

    NASA Astrophysics Data System (ADS)

    Murfett, David B.; Haskard, Malcolm R.; Marriage, Alan J.

    1995-09-01

    This paper describes significant advancements to a low doped etch-stop technique which increases the differential etch rate of high doped to low doped silicon (Rh/l) by a factor of 4 or greater, to a value of up to Rh/l approximately equals 50:1. The objective of the research was to achieve this increase in the differential etch rate by decreasing the etch rate of the low doped silicon epilayer, resulting in the development of an exceptional technique for rapid, safe, and high-quality etching of complex micro-structures. The technique has been confirmed by the production of devices. These include both 10 micrometers thick diaphragms and a complete accelerometer structure, created fom n on n+ epitaxial samples.

  11. Study of high aspect ratio silicon etching based on ICP

    NASA Astrophysics Data System (ADS)

    Hu, Jiang; Zhou, Shun; Hu, Shuai; Zhu, Yufeng; Liu, Weiguo

    2015-02-01

    The etching process of the high aspect ratio of Si deep trench is the key technology in MEMS field. Having used Oxford Plasmalabsystem100 ICP-180 etcher with SF6 and C4F8 as the etching gas, the influence on the deep Si etching process of Bosch under different ICP power, bias voltage, temperature, pressure and other parameters has been studied. The experimental result shows that under appropriate parameters, the high-aspect ratio of silicon deep trench is greater than 26:1, the sidewalls' vertical degree is 89.9°, and the etching rate is greater than 2?m/min the high aspect ratio of SOI deep trench is greater than 28:1, the sidewalls' vertical degree is 89.7°, and the etching rate is greater than 2?m/min.

  12. UV-photoassisted etching of GaN in KOH

    SciTech Connect

    Cho, H.; Donovan, S.M.; Abernathy, C.R.; Lambers, E.S.; Pearton, S.J. [Univ. of Florida, Gainesville, FL (United States); Auh, K.H. [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Ceramic Engineering; Han, J.; Shul, R.J. [Sandia National Labs., Albuquerque, NM (United States)

    1999-03-01

    The etch rate of GaN under ultraviolet-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias, and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n {approximately} 3 {times} 10{sup 16} cm{sup {minus}3}) GaN are {ge} 1,000 {angstrom} {center_dot} min{sup {minus}1}. The etching is diffusion-limited under the conditions with an activation energy of {approximately} 0.8 kCal{center_dot}mol{sup {minus}1}. The etched surfaces are rough, but retain their stoichiometry.

  13. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    DOEpatents

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

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  14. Optimization of graphene dry etching conditions via combined microscopic and spectroscopic analysis

    SciTech Connect

    Prado, Mariana C. [Departamento de Fisica, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte (Brazil)] [Departamento de Fisica, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte (Brazil); Jariwala, Deep [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)] [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Marks, Tobin J.; Hersam, Mark C. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States) [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)

    2013-05-13

    Single-layer graphene structures and devices are commonly defined using reactive ion etching and plasma etching with O{sub 2} or Ar as the gaseous etchants. Although optical microscopy and Raman spectroscopy are widely used to determine the appropriate duration of dry etching, additional characterization with atomic force microscopy (AFM) reveals that residual graphene and/or etching byproducts persist beyond the point where the aforementioned methods suggest complete graphene etching. Recognizing that incomplete etching may have deleterious effects on devices and/or downstream processing, AFM characterization is used here to determine optimal etching conditions that eliminate graphene dry etching residues.

  15. Computer-aided mask layout synthesis for anisotropic etch photolithography

    NASA Astrophysics Data System (ADS)

    Long, Mark K.

    1999-10-01

    The increasing penetration of MEMS technology into new application domains suggests the need for sophisticated engineering tools that can automate routine MEMS engineering design functions. This thesis discusses the development of algorithms and automated software tools that are intended to automate the mask-layout process for bulk etch micro-machining. At present, a designer conceives of a MEMS function, then (informally) creates a mask-layout that the designer believes will process into a shape that will exhibit the desired function. Because of the highly anisotropic nature of the bulk etching process, the mask design process relies heavily upon the designer's intuitive understanding of the etching process. A prototype device is created from the candidate mask, and its actual function is tested. This process can result in many iterations, and many prototypes. This dissertation presents a method to automatically synthesize the mask layout for a bulk etching process. That is, given a desired part geometry and process parameters, the algorithm determines a candidate mask geometry that will etch to the final desired shape even in the case of highly anisotropic etchants. It will also compute compensation structures for difficult to etch features. Conceptually, the algorithm is based on the use of a forward etch simulation in reverse time. Since the forward etch process is a many-to-one map, the reverse time simulation is augmented to include a choice of valid preimages. Timing models are introduced to develop mask layouts that have appearing crystal planes during the etch and shown to allow more complex compenstation structures. Finally, calibration masks are developed that allow the experimental determination of etch rate parameters without painstaking measurements.

  16. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    PubMed

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise. PMID:25958585

  17. Morphological study of {311} crystal planes anisotropically etched in (100) silicon: role of etchants and etching parameters

    NASA Astrophysics Data System (ADS)

    Resnik, Drago; Vrtacnik, Danilo; Amon, Slavko

    2000-09-01

    Investigation was focused on the formation of {311} planes by wet anisotropic etching of (100) silicon and, in particular, on the characterization by means of surface roughness, etch rates and related convex and concave corner dynamic behaviour during maskless etching. KOH and TMAH water solutions were tested for their influence on previously mentioned parameters as well as the effect of isopropyl alcohol (IPA). It was found that convex corner undercutting is significantly reduced if {311} bounding planes are utilized instead of {111} bounding planes. For shallow structures a self-compensation can be obtained with KOH and when certain conditions are met, also with TMAH. The rounding of the concave corner that arises through prolonged etching is reported, which is particularly emphasized in KOH and less in TMAH etchant. Addition of IPA in maskless mode is experimentally investigated, showing minor influence on etching conditions and on reducing the undercut of convex corners. Etch rates and dimensional control of some microstructures are discussed and presented comparatively for different etching systems in a temperature range of 50-100 °C. By evaluation of surface quality with a surface profiler and SEM, it was found that the smoothest surface was achieved by etching in TMAH. The role of solution temperature in surface roughness was found to be of minor importance, as well as the stirring of the solution. It was determined that the IPA additive increases roughness when used with KOH, while with TMAH, the influence on roughness of the {311} planes is insignificant.

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

    SciTech Connect

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

    1993-06-01

    Nonuniform etching is a serious problem in plasma processing of semiconductor materials and has important consequences in the quality and yield of microelectronic components. In many plasmas, etching occurs at a faster rate near the periphery of the wafer, resulting in nonuniform removal of specific materials over the wafer surface. This research was to investigate in situ optical diagnostic techniques for monitoring etch uniformity during plasma processing of microelectronic components. We measured 2-D images of atomic chlorine at 726 nm in a chlorine-helium plasma during plasma etching of polysilicon in a parallel-plate plasma etching reactor. The 3-D distribution of atomic chlorine was determined by Abel inversion of the plasma image. The experimental results showed that the chlorine atomic emission intensity is at a maximum near the outer radius of the plasma and decreases toward the center. Likewise, the actual etch rate, as determined by profilometry on the processed wafer, was approximately 20% greater near the edge of the wafer than at its center. There was a direct correlation between the atomic chlorine emission intensity and the etch rate of polysilicon over the wafer surface. Based on these analyses, 3-D imaging would be a useful diagnostic technique for in situ monitoring of etch uniformity on wafers.

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

    Microsoft Academic Search

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

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

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

    SciTech Connect

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

    2002-02-25

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

  1. SPENT ACID RECOVERY USING DIFFUSION DIALYSIS

    EPA Science Inventory

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  3. Role of sulfur atoms in microwave plasma etching of silicon

    NASA Astrophysics Data System (ADS)

    Ninomiya, Ken; Suzuki, Keizo; Nishimatsu, Shigeru; Okada, Osami

    1987-08-01

    The Si etch rate in an (F2+O2) microwave plasma has been measured as a function of O2 mixing ratio at a fixed total pressure of 5.3×10-2 Pa. The etch rate significantly decreases with the mixing ratio. This etch rate decrease is due primarily to surface oxidation. When sulfur is added to the (F2+O2) plasma, the Si surface is much less oxidized and the etch rate increases by about a factor of 4. Such sulfur-containing species as S atoms react with O atoms or ions in the plasma and form O atom-containing species, such as SO2, SO+, SOF+, and SOF+2, thereby reducing the O atom and O+ ion concentrations in the plasma. As a result, the Si surface is scarcely oxidized, so that the etching reaction can easily proceed. Sulfur atoms inhibit surface oxidation and promote Si etching. Sulfur atoms contained in SF6, which is usually used in microwave plasma etching of Si, are expected to have the same role.

  4. Dry etching technologies for the advanced binary film

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    ABF (Advanced Binary Film) developed by Hoya as a photomask for 32 (nm) and larger specifications provides excellent resistance to both mask cleaning and 193 (nm) excimer laser and thereby helps extend the lifetime of the mask itself compared to conventional photomasks and consequently reduces the semiconductor manufacturing cost [1,2,3]. Because ABF uses Ta-based films, which are different from Cr film or MoSi films commonly used for photomask, a new process is required for its etching technology. A patterning technology for ABF was established to perform the dry etching process for Ta-based films by using the knowledge gained from absorption layer etching for EUV mask that required the same Ta-film etching process [4]. Using the mask etching system ARES, which is manufactured by Shibaura Mechatronics, and its optimized etching process, a favorable CD (Critical Dimension) uniformity, a CD linearity and other etching characteristics were obtained in ABF patterning. Those results are reported here.

  5. Determination of Cu and Mn in seawater by graphite furnace atomic absorption spectrometry with the use of hydrofluoric acid as a chemical modifier

    NASA Astrophysics Data System (ADS)

    Cabon, J. Y.

    2002-05-01

    The addition of hydrogen fluoride to a seawater sample in a graphite tube atomizer makes possible the removal of the major matrix components in an optimized pre-heating step, thus a near interference free determination of copper and manganese trace metals is achieved. The optimization studies were supported by a priori calculation of limit of detection (LOD) data. For optimized conditions, the experimentally determined LOD values (3?, n=20) were 0.11 and 0.03 ?g l -1 for Cu and Mn, respectively, for 20 ?l applied seawater volume. With the use of calibration with standard addition, determined concentrations of Cu and Mn in CASS-2 seawater and in SLEW-1 estuarine water were in good agreement with certified values at the 95% confidence level ( n=10).

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. Parametric study on the solderability of etched PWB copper

    SciTech Connect

    Hosking, F.M.; Stevenson, J.O.; Hernandez, C.L.

    1996-10-01

    The rapid advancement of interconnect technology has resulted in a more engineered approach to designing and fabricating printed wiring board (PWB) surface features. Recent research at Sandia National Laboratories has demonstrated the importance of surface roughness on solder flow. This paper describes how chemical etching was used to enhance the solderability of surfaces that were normally difficult to wet. The effects of circuit geometry, etch concentration, and etching time on solder flow are discussed. Surface roughness and solder flow data are presented. The results clearly demonstrate the importance of surface roughness on the solderability of fine PWB surface mount features.

  8. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P. (Livermore, CA); Wilson, William D. (Pleasanton, CA); Barbee, Jr., Troy W. (Palo Alto, CA); Lane, Stephen M. (Oakland, CA)

    2006-06-27

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  9. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2004-11-16

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  10. Resin bond to electrolytically etched cobalt-chromium alloys.

    PubMed

    Jokela-Hietamäki, M; Rantanen, T

    1987-02-01

    Disks of four cobalt-chromium alloys were electrolytically etched and bonded together using a microfilled restorative resin. The bonds of the resin to two of the tested alloys, Bondi-loy and Vitallium, showed tensile strengths of approximately 18 MPa. The bonds were significantly stronger than those obtained using the other two alloys, Dentitan and Novarex. The tensile bond strengths of etched Dentitan and Novarex were 5.3 and 7.5 MPa respectively. The etched and debonded surfaces were studied in SEM. PMID:3551039

  11. Vertical mirrors fabricated by deep reactive ion etching for fiber-optic switching applications

    Microsoft Academic Search

    Cornel Marxer; Christian Thio; M.-A. Gretillat; N. F. de Rooij; R. Battig; O. Anthamatten; B. Valk; P. Vogel

    1997-01-01

    We report on vertical mirrors fabricated by deep reactive ion etching of silicon. The mirror height is 75 ?m, covering the fiber core of a single-mode fiber when the latter is placed into a groove of equal depth and etched simultaneously with the mirror. To obtain a uniform etch depth, etching is stopped on a buried oxide layer. Using the

  12. The black silicon method. VI. High aspect ratio trench etching for MEMS applications

    Microsoft Academic Search

    Henri Jansen; Boer de Meint; Miko Elwenspoek

    1996-01-01

    Etching high aspect ratio trenches (HARTs) in silicon is becoming increasingly important for MEMS applications. Currently, the most important technique is dry reactive ion etching (RIE). This paper presents solutions for the most notorious problems during etching HARTs: tilting and the aspect ratio dependent etching effects such as bowing, RIE lag, bottling, and micrograss or black silicon. To handle these

  13. Title of Document: RATIONAL DESIGN OF NON-DAMAGING CAPACITIVELY COUPLED PLASMA ETCHING

    E-print Network

    Anlage, Steven

    of the post-etching photoresist (PR) mask, and surface cleaning of plasma-etching-related residues, withoutABSTRACT Title of Document: RATIONAL DESIGN OF NON-DAMAGING CAPACITIVELY COUPLED PLASMA ETCHING. Process integration of ULK dielectrics requires plasma etching of dielectric material, stripping

  14. Elsevier Science 1 Resist trimming etch process control using dynamic scatterometry

    E-print Network

    Paris-Sud XI, Université de

    Elsevier Science 1 Resist trimming etch process control using dynamic scatterometry M. El kodadia to monitor the resist etch process in an industrial etch chamber from Applied Materials equipped with an in, resist trimming process. The etching process chosen for this first validation consists in trimming 500nm

  15. Development of metal etch mask by single layer lift-off for silicon nitride photonic crystals

    E-print Network

    Waks, Edo

    - lied on direct patterning of a polymer etch mask from ebeam resist, followed by dry etching using fluorine chemistry. However, SiN generally exhibits poor etch selectivity relative to ebeam resist un- derDevelopment of metal etch mask by single layer lift-off for silicon nitride photonic crystals Kang

  16. CCMR: Effect of Etchant Concentration and Etch Duration on the Morphology of Potassium-Hydroxide-Etched Si(100) Surfaces

    NSDL National Science Digital Library

    Hallman, Kent A.

    2009-08-15

    Infrared spectroscopy was employed in the multiple-internal-reflectance geometry to analyze the nanoscale morphology of H-terminated Si(100) samples etched in dilute potassium hydroxide solutions. The effect of etch time and etchant concentration on hillock formation was measured from the relative intensities of the absorption bands associated with Si–H stretch vibrations on Si(111) and Si(110) microfacets. Under some etch conditions, a nominally flat Si(100) surface would spontaneously transform into a microfaceted surface, which is evidence of nanoscale hillock formation.

  17. Piranha Etch General Instructions Piranha etch is used to remove organic residues from substrates.

    E-print Network

    Kim, Philip

    stored in a closed container will likely explode. 9. Adding any acids or bases to piranha or spraying. The standard acid piranha used in the CEPSR Cleanroom is a 3:1 mixture of concentrated sulfuric acid (H2SO4) with hydrogen peroxide (H2O2). Acid piranha is a self starting reaction an is extremely exothermic; this mixture

  18. Visible luminescence from silicon wafers subjected to stain etches

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Etching of Si in a variety of solutions is known to cause staining. These stain layers consist of porous material similar to that produced by anodic etching of Si in HF solutions. In this work, photoluminescence peaked in the red from stain-etched Si wafers of different dopant types, concentrations, and orientations produced in solutions of HF:HNO3:H2O was observed. Luminescence is also observed in stain films produced in solutions of NaNO2 in HF, but not in stain films produced in solutions of CrO3 in HF. The luminescence spectra are similar to those reported recently for porous Si films produced by anodic etching in HF solutions. However, stain films are much easier to produce, requiring no special equipment.

  19. Evaluation of unsaturated fluorocarbons for dielectric Etch applications

    E-print Network

    Chatterjee, Ritwik, 1974-

    2003-01-01

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

  20. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, R.J.; Mayer, S.T.; Tarte, L.A.

    1996-01-23

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment. 6 figs.

  1. 155. Copy of Louis Rosenberg Etching (original in the Tower ...

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

    155. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) EXCAVATION OF TRACK AREA TO THE SOUTH OF HURON ROAD, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

  2. Analysis of EUV mask durability under various absorber etch conditions

    NASA Astrophysics Data System (ADS)

    Lee, Dong Wook; Jo, Sang Jin; Oh, Sung Hyun; Ha, Tae Joong; Kim, Sang Pyo; Yim, Dong Gyu

    2013-09-01

    During EUV exposure, more frequent mask cleaning is essential for removing not only particles from lack of pellicle but also the carbon contamination due to accumulative EUV exposure. Because of this reason, process improvement for minimize corrosion and etching of the Ru capping layer is urgently needed. In this work, the influence of TaBN absorber etch condition on Ru integrity followed by repetitive cleaning was evaluated and the effects on long-term durability of Ru are compared under various cleaning conditions. Consequently, it was shown that Ru durability was strongly influenced by the gas contents and over etch time of absorber dry etch, not only as a function of cleaning conditions.

  3. Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene

    E-print Network

    Campos, Leonardo

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

  4. Plasma Etching of Tapered Features in Silicon for MEMS and Wafer Level Packaging Applications

    NASA Astrophysics Data System (ADS)

    Ngo, Ha-Duong; Hiess, Andre; Seidemann, Volker; Studzinski, Daniel; Lange, Martin; Leib, Jürgen; Shariff, Dzafir; Ashraf, Huma; Steel, Mike; Atabo, Lilian; Reast, Jon

    2006-04-01

    This paper is a brief report of plasma etching as applied to pattern transfer in silicon. It will focus more on concept overview and strategies for etching of tapered features of interest for MEMS and Wafer Level Packaging (WLP). The basis of plasma etching, the dry etching technique, is explained [1] and plasma configurations are described elsewhere [2][3]. An important feature of plasma etching is the possibility to achieve etch anisotropy. The plasma etch process is extremely sensitive to many variables such as mask material, mask openings and more important the plasma parameters.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

  6. Deposition Step in MEMS Time Multiplexed Etch

    NASA Astrophysics Data System (ADS)

    Overzet, Lawrence; Saraf, Iqbal; Goeckner, Matthew

    2011-10-01

    The deposition step of the Bosch process is examined by first forming standard trenches using a Plasma-Therm DSE-II and then depositing on those for an extended time. The deposition profiles at the bottom and sidewalls of trenches provide useful insights into the physical processes driving deposition process. SEMs reveal a dense film at the top and bottom of the trench as expected; however, it has an isolated fiber structure (like blades of grass) along sidewalls. This sidewall ``film'' structure is independent of the reactor used to deposit, is not caused by the original sidewall scallops, and is not affected by an air break between trench formation and deposition. It is critically dependent upon the ion flux and energy. Our model shows that neutral flux alone cannot form such a deposit inside trenches. This indicates that the deposition step can be highly ion-enhanced and suggests that one reduce the ion flux during Bosch deposition steps to limit the deposition rate at the bottom of the trench/via and thereby increase the etch rate as well as prevent feature closing. Acknowledgement: This material is based upon work supported by the SRC under award number 2008-KJ-1831.

  7. Structural investigation of electrochemically etched silicon

    SciTech Connect

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

    1992-12-31

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

  8. Organization of silicon nanocrystals by localized electrochemical etching

    SciTech Connect

    Ayari-Kanoun, Asma; Drouin, Dominique; Beauvais, Jacques [Department of Electrical Engineering, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1 (Canada); Lysenko, Vladimir; Nychyporuk, Tetyana; Souifi, Abdelkader [Institut des Nanotechnologies de Lyon (INL), UMR-CNRS 5270, INSA de Lyon, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France)

    2009-10-12

    An approach to form a monolayer of organized silicon nanocrystals on a monocrystalline Si wafer is reported. Ordered arrays of nanoholes in a silicon nitride layer were obtained by combining electron beam lithography and plasma etching. Then, a short electrochemical etching current pulse led to formation of a single Si nanocrystal per each nanohole. As a result, high quality silicon nanocrystal arrays were formed with well controlled and reproducible morphologies. In future, this approach can be used to fabricate single electron devices.

  9. Wet etching of undercut sidewalls in {001}-silicon

    Microsoft Academic Search

    J Frühauf; B Hannemann

    2000-01-01

    The development of undercut sidewalls along ?100? directions of {001}-silicon by a two-step orientation dependent wet etching process is described. Thereby the first step generates vertical {100}-sidewalls in a pure aqueous potassium hydroxide etchant (KOH). The following second step in an etchant consisting of KOH saturated with isopropanol (KOH:IPA) develops slowly etched {101}-faces with undercutting inclination. A principal calculation is

  10. Copper decoration and etching of crystal defects in SOI materials

    Microsoft Academic Search

    Hanan Idrisi; Bernd O. Kolbesen

    2009-01-01

    Crystal defects in Silicon-On-Insulator (SOI)-wafers can be delineated with etching solutions. To visualize even small defects (of some nanometer in size) a combination of copper decoration of the defects and subsequent defect etching may be applied. A shortcoming of copper decoration is the possible formation of artefacts on the SOI-film which appears like defects and gives rise to much higher

  11. Plasma Diagnostics for the Characterization of Etching and Deposition Reactors

    Microsoft Academic Search

    Chun-Wah Cheah

    1993-01-01

    The characterization of plasmas in realistic etching\\/deposition tools, using two fast, non-intrusive diagnostics, microwave interferometry and radio-frequency (rf) current-voltage measurements, are presented here. The advantage of these kinds of diagnostics is that they allow real-time plasma data to be taken without interference to the process. Using these diagnostic tools, the plasma characteristics of three etch\\/deposition systems, the rf-parallel-plate diode and

  12. Fabrication of black silicon materials by wet etching and characterization

    Microsoft Academic Search

    Zhengyu Guo; Zhiming Wu; Anyuan Zhang; Jing Jiang; Guodong Zhao; Yadong Jiang

    2010-01-01

    In this paper we use Si3N4 membrane acting as mask in fabrication of black silicon by wet etching technique, and the sample have nearly 90% absorptance at wavelength from 250 nm to 1000 nm. The experiments result shows that Si3N4 membrane as mask wet etching technique for fabrication of black silicon is feasibility, and has much more advantages compared to

  13. Three-dimensional force sensor by novel alkaline etching technique

    Microsoft Academic Search

    É. Vázsonyi; M. Ádám; Cs. Dücs?; Z. Vízváry; A. L. Tóth; I. Bársony

    2005-01-01

    Silicon based three-dimensional (3D) force sensor was designed and fabricated for detection of normal and shear forces. The sensor contains a rectangular rod emerging out of the centre of the membrane. The technology involves ion-implanted piezoresistors formation on the backside and a novel anisotropic etching on the front side of an n-type wafer. The two-component, two-step anisotropic etching process forms

  14. Reactive ion etching of dielectrics and silicon for photovoltaic applications

    Microsoft Academic Search

    Prakash N. K. Deenapanray; C. S. Athukorala; Daniel Macdonald; W. E. Jellett; E. Franklin; V. E. Everett; K. J. Weber; A. W. Blakers

    2006-01-01

    This paper investigates the reactive ion etching of SiO2, Si3N4 and Si using CHF3\\/O2 plasma. In particular, we have characterized the time and rf power dependence of the carrier lifetimes in n- and p-type FZ Si. The time dependence of reactive ion etching at different rf powers provides insight into the two competing processes of damage accumulation and damage removal

  15. Active Photonic Crystals, edited by Sharon M. Weiss, Ganapathi S. Subramania, Florencio Garcia-Santamaria Proc. of SPIE Vol. 6640, 6640C, (2007) 0277-786X/07/$18 doi: 10.1117/12.736193

    E-print Network

    Weiss, Sharon

    2007-01-01

    etching in a hydrofluoric acid-based (HF) solution.10 In this work, boron doped p-type silicon the local optical properties of porous silicon photonic crystals is reported. The porous silicon photonic of the photonic crystal. The sample was then soaked in an alcohol solution. Unmasked regions of the porous silicon

  16. Porous silicon in solar cell structures: a review of achievements and modern directions of further use

    Microsoft Academic Search

    Valery Yu Yerokhov; Ihor I. Melnyk

    1999-01-01

    Porous silicon, which is being obtained by electrochemical etching of silicon wafers in electrolytes on the base of hydrofluoric acid, recently attracted the attention of specialists in photovoltaics even more due to a number of its unique properties. However, at present, acceptable results are obtained for the use of porous silicon as antireflecting coating for silicon solar cells only. In

  17. Effects of HF attack on the surface and interface microchemistry of W tips for use in the STM microscope: a scanning Auger microscopy (SAM) study

    Microsoft Academic Search

    E. Paparazzo; L. Moretto; S. Selci; M. Righini; I. Farné

    1999-01-01

    Scanning Auger microscopy techniques are used to study the effects of hydrofluoric acid on the surface chemical composition of STM W tips prepared by electrochemical etching in base solution. Auger point spectra performed on a series of ad hoc prepared samples allow us to evaluate how the separate chemical and electrochemical processes involved in the making and cleaning of a

  18. Solid-state synthesis of luminescent silicon nitride nanocrystals.

    PubMed

    Dasog, Mita; Veinot, Jonathan G C

    2012-04-18

    Silicon nitride nanocrystals (NCs) have been prepared via in situ nitridation of magnesium followed by a metathesis reaction with sol-gel derived silica particles. Highly luminescent, freestanding ?-Si(3)N(4) NCs with complex surface chemistry dominated by Si-H and N-H moieties were isolated upon etching with hydrofluoric acid. PMID:22430493

  19. Modification of vapor sensitivity in ellipsometric gas sensing by copper deposition in porous silicon

    Microsoft Academic Search

    Guoliang Wang; Hans Arwin

    2002-01-01

    The sensitivities of porous silicon layers modified by copper deposition to low vapor concentrations of methanol, ethanol and 2-propanol are studied with spectroscopic ellipsometry. The porous silicon layers are prepared with electrochemical etching in hydrofluoric acid, and copper deposition is done in aqueous CuSO4. The ellipsometric vapor sensitivities, in terms of the ellipsometric spectral shifts due to gas exposures, of

  20. Growth of ZnO Nanowires Without Catalyst on Porous Silicon

    Microsoft Academic Search

    H. I. Abdulgafour; Z. Hassan; F. K. Yam; M. J. Jawad

    2011-01-01

    In this paper, porous silicon (PS) technology is used to achieve a wide range of high-quality ZnO nanowires on the porous silicon substrate (PS) with a rough morphology without any catalyst, by a simple thermal evaporation technique. The NPSi have been prepared by electrochemical etching method in the mixture of hydrofluoric acid and ethanol electrolyte using an optimized parameter by

  1. Vapor etching of nuclear tracks in dielectric materials

    DOEpatents

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

    2000-01-01

    A process involving vapor etching of nuclear tracks in dielectric materials for creating high aspect ratio (i.e., length much greater than diameter), isolated cylindrical holes in dielectric materials that have been exposed to high-energy atomic particles. The process includes cleaning the surface of the tracked material and exposing the cleaned surface to a vapor of a suitable etchant. Independent control of the temperatures of the vapor and the tracked materials provide the means to vary separately the etch rates for the latent track region and the non-tracked material. As a rule, the tracked regions etch at a greater rate than the non-tracked regions. In addition, the vapor-etched holes can be enlarged and smoothed by subsequent dipping in a liquid etchant. The 20-1000 nm diameter holes resulting from the vapor etching process can be useful as molds for electroplating nanometer-sized filaments, etching gate cavities for deposition of nano-cones, developing high-aspect ratio holes in trackable resists, and as filters for a variety of molecular-sized particles in virtually any liquid or gas by selecting the dielectric material that is compatible with the liquid or gas of interest.

  2. Dry etch challenges for CD shrinkage in memory process

    NASA Astrophysics Data System (ADS)

    Matsushita, Takaya; Matsumoto, Takanori; Mukai, Hidefumi; Kyoh, Suigen; Hashimoto, Kohji

    2015-03-01

    Line pattern collapse attracts attention as a new problem of the L&S formation in sub-20nm H.P feature. Line pattern collapse that occurs in a slight non-uniformity of adjacent CD (Critical dimension) space using double patterning process has been studied with focus on micro-loading effect in Si etching. Bias RF pulsing plasma etching process using low duty cycle helped increase of selectivity Si to SiO2. In addition to the effect of Bias RF pulsing process, the thin mask obtained from improvement of selectivity has greatly suppressed micro-loading in Si etching. However it was found that micro-loading effect worsen again in sub-20nm space width. It has been confirmed that by using cycle etch process to remove deposition with CFx based etching micro-loading effect could be suppressed. Finally, Si etching process condition using combination of results above could provide finer line and space without "line pattern collapse" in sub-20nm.

  3. Integration of Nanotubes, Etch Tracks, and Nanoribbons in Crystallographic Alignment

    NASA Astrophysics Data System (ADS)

    Boland, Mathias J.; Hunley, D. Patrick; Sundrarajan, Abhishek; Nasseri, Mohsen; Strachan, Douglas R.

    2015-03-01

    Three nanomaterial components, carbon nanotubes (CNTs), few-layer graphene (FLG), and etch tracks exposing insulating SiO2 regions, are integrated to form crystallographically-aligned nanoscale systems. These integrated systems consist of CNTs grown across nanogap etch tracks and nanoribbons formed within the FLG films as a result of chemical vapor deposition (CVD) processing. Each nanoscale component is aligned along the underlying graphene lattice, resulting in their orientations being locked into precise values, with CNTs maintaining alignment even after crossing etch tracks. The growth of aligned CNTs across nanogap etch tracks and nanoribbons suggests that integrated formations can be achieved by growing CNTs directly over nanogap etch tracks and nanoribbons. This is supported by calculations of the vibrational energy of CNTs indicating that they should be capable of maintaining atomic registry with an underlying graphene lattice as they grow across a typical etch track, in agreement with our experimental results. Thus, this work is relevant to the integration of semiconducting, conducting, and insulating nano-materials all together into precise nano-electronic systems.

  4. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Paetzelt, H.; Böhm, G.; Arnold, Th

    2015-04-01

    Local plasma-assisted etching of crystalline silicon by fine focused plasma jets provides a method for high accuracy computer controlled surface waviness and figure error correction as well as free form processing and manufacturing. We investigate a radio-frequency powered atmospheric pressure He/N2/CF4 plasma jet for the local chemical etching of silicon using fluorine as reactive plasma gas component. This plasma jet tool has a typical tool function width of about 0.5 to 1.8 mm and a material removal rate up to 0.068 mm3 min?1. The relationship between etching rate and plasma jet parameters is discussed in detail regarding gas composition, working distance, scan velocity and RF power. Surface roughness after etching was characterized using atomic force microscopy and white light interferometry. A strong smoothing effect was observed for etching rough silicon surfaces like wet chemically-etched silicon wafer backsides. Using the dwell-time algorithm for a deterministic surface machining by superposition of the local removal function of the plasma tool we show a fast and efficient way for manufacturing complex silicon structures. In this article we present two examples of surface processing using small local plasma jets.

  5. The chemical mechanisms of metal etching in high density plasmas

    NASA Astrophysics Data System (ADS)

    Orland, Aaron Seth

    Films of magnetic materials are used in a variety of electronic devices. They are currently used primarily in both the giant magnetoresistive (GMR) read/write heads of hard drives and in magnetoresistive memory (MRAM). Patterning of the metals in GMR heads is usually accomplished using ion-milling techniques, whereas non-selective metal etch techniques are used in the patterning of MRAM devices. As the size of devices continues to shrink, new selective etch chemistries will become more important. The composition of CO/NH3, CO/H2, CO2/NH3, and CO2/H 2 plasmas suitable for the etching of magnetic materials has been studied by supersonic pulse, plasma sampling mass spectrometry. The composition of the plasma's major components has been determined by a variety of approaches including isotopic labeling, and the identification of clusters formed by the sampling technique. All four of the different etch chemistries were investigated individually. The major components of the gas flows and the plasmas for each system were identified. The chemical mechanism of etching has been identified for all four etch recipes.

  6. Anisotropy of synthetic diamond in catalytic etching using iron powder

    NASA Astrophysics Data System (ADS)

    Wang, Junsha; Wan, Long; Chen, Jing; Yan, Jiwang

    2015-08-01

    This paper demonstrated a novel technique for catalytic etching of synthetic diamond crystallites using iron (Fe) powder without flowing gas. The effect of temperature on the etching behaviour on different crystal planes of diamond was investigated. The surface morphology and surface roughness of the processed diamond were examined by scanning electron microscope (SEM) and laser-probe surface profiling. In addition, the material composition of the Fe-treated diamond was characterized using micro-Raman spectroscopy and the distribution of chemical elements and structural changes on Fe-loaded diamond surfaces were analyzed by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. Results showed that at the same temperature the {1 0 0} plane was etched faster than the {1 1 1} plane, and that the etching rate of both {1 0 0} and {1 1 1} plane increased with temperature. The etch pits on {1 0 0} plane were reversed pyramid with flat {1 1 1} walls, while the etch holes on {1 1 1} plane were characterized with flat bottom. It was also demonstrated that graphitization of diamond and subsequent carbon diffusion in molten iron were two main factors resulting in the removal of carbon from the diamond surface.

  7. Photoelectrochemical etching of gallium nitride for high quality optical devices

    NASA Astrophysics Data System (ADS)

    Tamboli, Adele C.

    Gallium nitride has become an important semiconductor material for a variety of device applications, including light emitting diodes (LEDs), lasers, and transistors. One of the main challenges in GaN device fabrication is the chemical stability of GaN which leads to a lack of wet etching techniques. Instead, dry etching is used almost exclusively, leading to ion damage and poor selectivity between different layers. In this dissertation, we discuss photoelectrochemical (PEC) etching, a photoassisted wet etch technique that can be used to etch GaN and its alloys. We develop new aspects of this technique to extend its applicability to a larger variety of devices and use the technique to fabricate a few optical devices, including microdisk lasers. Microdisks are circular resonant cavities that support whispering gallery modes, which propagate around the periphery of the disk, confined by total internal reflection. This geometry has been used to achieve high quality modes, small mode volume, and low threshold lasing in semiconductors such as GaAs and InGaAsP, but has been difficult to fabricate in GaN because it requires a selective wet etch to form undercut, optically isolated cavities. In this dissertation, we discuss the application of PEC etching to the fabrication of GaN microdisks. In our optically pumped, c-plane microdisks, we observe record low threshold lasing under room temperature, continuous-wave operation. In our nonpolar m-plane microdisks, we discovered that the quantum well reabsorption losses that reduce the efficiency of many GaAs and InP microdisks also limit the performance of our nonpolar microdisks, while the piezoelectric fields and corresponding Stokes shift in our c-plane microdisks lead to quantum-dot like behavior and actually lead to superior performance in the polar, c-planemicrodisks. Finally, we report of electrically driven operation of c-plane microdisks for the first time. In these microdisks, first order whispering gallery modes are observed under both optical and electrical injection. We also examine new applications of PEC etching in this dissertation. We have discovered that m-plane GaN, grown homoepitaxially on bulk GaN substrates, etches much more smoothly and predictably than c-plane GaN on sapphire because of the lower defect density and reduced chemical stability of the nonpolar facets. We are able to obtain highly bandgap-selective top-down etching, deep, anisotropic etching, and etches with angled facets. These etch studies open up the possibility of a variety of new m-plane devices fabricated with PEC etching, such as chip-shaped LEDs. We also develop a method for PEC etching of p-type GaN, which has been very difficult to achieve in any semiconductor system. We apply this technique to surface roughening of the p-type, Ga-face side of c-plane LEDs, increasing the light extraction efficiency without the need for flip-chip bonding or substrate removal.

  8. Microtensile bond strength of total-etch and self-etching adhesives to caries-affected dentine

    Microsoft Academic Search

    Laura Ceballos; Defrén G. Camejo; M. Victoria Fuentes; Raquel Osorio; Manuel Toledano; Ricardo M. Carvalho; David H. Pashley

    2003-01-01

    Objectives. To evaluate the microtensile bond strength of total-etch or self-etch adhesives to caries-affected versus normal dentine, and to correlate these bond strengths with DIAGNOdent laser fluorescence and Knoop microhardness (KH) measurements of the substrates.Methods. Extracted carious human molars were ground to expose flat surfaces where the caries lesion was surrounded by normal dentine. Surfaces were bonded with either Prime

  9. A model explaining mask-corner undercut phenomena in anisotropic silicon etching: a saddle point in the etching-rate diagram

    Microsoft Academic Search

    Mitsuhiro Shikida; Ken-ichi Nanbara; Tohru Koizumi; Hikaru Sasaki; Michiaki Odagaki; Kazuo Sato; Masaki Ando; Shinji Furuta; Kazuo Asaumi

    2002-01-01

    We investigated undercut phenomena on a (100) silicon wafer to explain why a (311) plane appears under the convex corner of a masking area, and why the plane is stable during the etching process. We analyzed the etching rate as a function of crystallographic orientations and found that the (311) plane has unique etching characteristics. The (311) plane is located

  10. Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint

    SciTech Connect

    Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M.; Metzger, W. K.; Li, X.; Al-Jassim, M. M.

    2006-05-01

    We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated at grains boundaries, and may short circuit the device if the CdTe is too thin. The etching process facilitates the Cu diffusion and results in thicker conductive layers. The existence of this inhomogeneous conductive layer directly affects the current transport and is probably the reason for needing thick CdTe in these devices.

  11. Study on the formation of dodecagonal pyramid on nitrogen polar GaN surface etched by hot H3PO4

    NASA Astrophysics Data System (ADS)

    Qi, S. L.; Chen, Z. Z.; Fang, H.; Sun, Y. J.; Sang, L. W.; Yang, X. L.; Zhao, L. B.; Tian, P. F.; Deng, J. J.; Tao, Y. B.; Yu, T. J.; Qin, Z. X.; Zhang, G. Y.

    2009-08-01

    Hot phosphor acid (H3PO4) etching is presented to form a roughened surface with dodecagonal pyramids on laser lift-off N face GaN grown by metalorganic chemical vapor deposition. A detailed analysis of time evolution of surface morphology is described as a function of etching temperature. The activation energy of the H3PO4 etching process is 1.25 eV, indicating the process is reaction-limited scheme. And it is found that the oblique angle between the facets and the base plane increases as the temperature increases. Thermodynamics and kinetics related factors of the formation mechanism of the dodecagonal pyramid are also discussed. The light output power of a vertical injection light-emitting-diode (LED) with proper roughened surface shows about 2.5 fold increase compared with that of LED without roughened surface.

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

    PubMed

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

    2011-05-20

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

  13. Reconstruction of colloidal spheres by targeted etching: a generalized self-template route to porous amphoteric metal oxide hollow spheres.

    PubMed

    Pan, Jia Hong; Bai, Yuqing; Wang, Qing

    2015-04-21

    Despite the significant progress in developing various synthetic strategies for metal oxide hollow spheres (h-MO), the so-far explored materials are mostly chemically inert metal oxides. Very few attempts have been made for amphoteric metal oxides such as Al2O3 and ZnO due to the difficulties in the control of the dissolution and recrystallization process. Herein, a facile self-template route to the synthesis of amphoteric h-MO with tunable size and shell thickness is developed by targeted etching via an acid-base reaction. With the protection of polyvinylpyrrolidone (PVP) on the surface, the interior of metal oxide solid colloidal spheres (c-MOs) that possess radially divergent structures could be selectively etched with acid/alkali as an etchant, forming h-MO of Al2O3 and ZnO. Our results also show that a wide variety of metal oxide colloidal spheres can be potential self-templates for targeted etching, which paves the way for developing a generalized strategy for the synthesis of various metal oxide hollow spheres. PMID:25835084

  14. Surfactant-enhanced control of track-etch pore morphology

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  15. Generation of low-energy neutral beam for Si etching

    NASA Astrophysics Data System (ADS)

    Kim, S. J.; Wang, S. J.; Lee, J. K.; Lee, D. H.; Yeom, G. Y.

    2004-09-01

    As the feature size shrinks toward the nanoscale, charge-up damage from ion-induced etching becomes a very serious problem. Neutral beam etching is one of the most popular techniques used to reduce charge-up damage. We have performed a neutral beam simulation to optimize the neutral beam, which is generated by collisions between ions produced by a plasma source with an ion gun and low angle reflectors. An ion gun is simulated using the two-dimensional Xgrafic object oriented particle-in-cell (XOOPIC) code to obtain a higher ion flux and to improve the directionality of ions. For neutral beam simulation, we use the modified XOOPIC code to which reflection data obtained by the transport of ions in matter (TRIM) code are appended. Neutral flux, energy and angle distributions, which have an influence upon the etch rate, are calculated in the neutral beam simulation. A low-energy neutral beam from an ion gun with two grids has a low neutral flux and a broad angle distribution. Therefore, we propose a three-grid ion gun that has one additional grid with positive voltage, allowing independent control of the ion flux and ion energy. By increasing the ion flux, the neutral flux by three grids is three times larger than that by two grids. The neutral beam source using a three-grid ion gun has several advantages for trench etching: increased etch rate, decreased sidewall etching, and reduced variation in the etch rate as the trench size changes. A low-energy neutral beam source using the three-grid ion g 0un and low-angle reflectors is experimentally tested.

  16. ?A cylindrical specimen holder for electron cryo-tomography

    E-print Network

    Palmer, Colin Michael

    2013-03-12

    .1.1 Pulling of glass micropipettes . . . . . . . . . . . . . . . . . . 41 2.1.2 Carbon coating . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.1.3 Oxygen plasma etching . . . . . . . . . . . . . . . . . . . . . 43 2.1.4 Hydrofluoric acid etching... intuitive understanding of the problems caused by missing information. 21 1.2.1 The projection theorem Fourier reconstruction methods are based on the projection theorem (also called the central section theorem or the Fourier slice theorem). The derivation...

  17. Enhancement on photocatalytic activity of an amorphous titanium oxide film with nano-textured surface by selective-fluorination etching process

    SciTech Connect

    Shih, Pin-Chun; Huang, Cheng-Hao [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin 63201, Taiwan, ROC (China); Chen, Tai-Hong; Lai, Li-Wen [ITRI South, Industrial Technology Research Institute, Liujia, Tainan 73445, Taiwan, ROC (China); Lu, Yi-Shan [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin 63201, Taiwan, ROC (China); Liu, Day-Shan, E-mail: dsliu@sunws.nfu.edu.tw [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin 63201, Taiwan, ROC (China)

    2014-04-01

    Highlights: • The amorphous TiO{sub x} film surface was modified via selective fluorination etching process. • The resulting nano-textured surface markedly enriched the specific surface area and surface acidity. • The photocatalytic activity was comparable to an annealed TiO{sub x} film with anatase structure. - Abstract: A selective-fluorination etching process achieved by an UV light pre-irradiation and the subsequently fluorination etching was developed to enhance the photocatalytic activity of a low-temperature deposited amorphous titanium oxide (a-TiO{sub x}) film. Textured surface on the a-TiO{sub x} films formed by this process were investigated using atomic force microscope and field emission scanning electron microscope. Evidence of the fluorine ions introduced into the a-TiO{sub x} films was examined using Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. The etching thickness of the a-TiO{sub x} film was found to be deeply relevant to the film pre-irradiated by the UV light. An a-TiO{sub x} film with nano-textured surface, which was favorable to enlarge the specific surface area, thus was obtainable from the notable etching selectivity of the film pre-irradiated by UV light through a nano-sized mask. In addition, the surface acidity of the a-TiO{sub x} film was enhanced by the formation of the Ti-F chemical bonds originating from the fluorination etching process, which also was functional to facilitate the production of surface OH free radicals. Accordingly, the resulting fluorinated a-TiO{sub x} film with nano-textured surface performed a quality photocatalytic activity comparable to that of the high-temperature achieved TiO{sub x} film with anatase structures.

  18. Efficient polymer solar cells fabricated on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-etched old indium tin oxide substrates.

    PubMed

    Elshobaki, Moneim; Anderegg, James; Chaudhary, Sumit

    2014-08-13

    In organic electronic devices, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are the most common transparent electrode and anodic buffer layer materials, respectively. A widespread concern is that PEDOT:PSS is acidic and etches ITO. We show that this issue is not serious: only a few nanometers of ITO are etched in typical device processing conditions and storage thereafter; conductivity losses are affordable; and optical transmission gains further offset these losses. Organic photovoltaic (OPV) devices fabricated on old ITO (with PEDOT:PSS history) were similar or higher in efficiency than devices on fresh ITO. Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

  19. Chemical etching of boron-rich layer and its impact on high efficiency n-type silicon solar cells

    NASA Astrophysics Data System (ADS)

    Ryu, Kyungsun; Upadhyaya, Ajay; Song, Hyun-Jin; Choi, Chel-Jong; Rohatgi, Ajeet; Ok, Young-Woo

    2012-08-01

    This paper reports on an effective chemical etching treatment to remove a boron-rich layer which has a significant negative impact on n-type silicon (Si) solar cells with boron emitter. A nitric acid-grown oxide/silicon nitride stack passivation on the boron-rich layer-etched boron emitter markedly decreases the emitter saturation current density J0e from 430 to 100 fA/cm2. This led to 1.6% increase in absolute cell efficiency including 22 mV increase in open-circuit voltage Voc and 1.9 mA/cm2 increase in short-circuit current density Jsc. This resulted in screen-printed large area (239 cm2) n-type Si solar cells with efficiency of 19.0%.

  20. Facile preparation of superhydrophobic copper surface by HNO 3 etching technique with the assistance of CTAB and ultrasonication

    NASA Astrophysics Data System (ADS)

    Pan, Lining; Dong, Huiru; Bi, Pengyu

    2010-12-01

    Superhydrophobic rough structure was prepared on copper wafer via HNO 3 etching technique with the assistance of Cetyltrimethyl Ammonium Bromide (CTAB) and ultrasonication. After modification of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FDTES), the copper wafer showed stable superhydrophobicity. The morphologies, chemical compositions and hydrophobicity of the substrates were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Dense and spherical micropits appeared on copper wafer after it was etched by 5 M nitric acid with 1.2 mM CTAB under ultrasonication for 20 min. The SEM results indicated that the joint action of CTAB and ultrasonication caused the formation of dense and spherical micropits.

  1. Scanning electron microscopic observation on intracellular structures of ion-etched materials.

    PubMed

    Tanaka, K; Iino, A; Naguro, T

    1976-07-01

    Ion-etching technique on the cracked surface of biological material may give a plastic visualization of intracellular structures under the scanning electron microscope, because membraneous structures in the cell are generally etch-resistant and the cytoplasmic matrix is easily ion-etched. Mild ion-etching using low voltage was applied to the cells of the pancreas. Nuclear pores were clearly disclosed but were enlarged slightly in the process of etching. Endoplasmic reticulum with ribosomes, Golgi apparatus, mitochondria, some filamentous structures and crystalline inclusions (B cell granules) were also effectively disclosed by ion-etching technique. It is necessary, however, to compare the etched specimens carefully with non-etched ones to determine whether given structures observed are intrinsic ones or artifacts caused by etching. PMID:184753

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

    SciTech Connect

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

    2013-11-18

    Metal-assisted chemical etching (MacEtch) is a simple etching method that uses metal as the catalyst for anisotropic etching of semiconductors. However, producing nano-structures using MacEtch from discrete metal patterns, in contrast to interconnected ones, has been challenging because of the difficulties in keeping the discrete metal features in close contact with the semiconductor. We report the use of magnetic field-guided MacEtch (h-MacEtch) to fabricate periodic nanohole arrays in silicon-on-insulator (SOI) wafers for high reflectance photonic crystal membrane reflectors. This study demonstrates that h-MacEtch can be used in place of conventional dry etching to produce ordered nanohole arrays for photonic devices.

  3. Variations of the track etch rates along the alpha particle trajectories in two types of CR39

    Microsoft Academic Search

    B. Dörschel; H. Hartmann; K. Kadner

    1996-01-01

    The simulation of track formation processes in nuclear etched track detectors requires a quantitative formulation of registration criteria on the basis of the ratio of track etch to bulk etch rate. Whereas the bulk etch rate is measurable with sufficient accuracy by means of relatively simple techniques the track etch rate has been determined up to now indirectly by measuring

  4. Nanolithographic patterning of transparent, conductive single-walled carbon nanotube films by inductively coupled plasma reactive ion etching

    E-print Network

    Ural, Ant

    and subsequent O2 plasma etching using an inductively coupled plasma reactive ion etching ICP-RIE system. They systematically study the effect of ICP-RIE etch parameters, such as substrate bias power, chamber pressure nanotube films and the effect of ICP reactive ion etching on the resistivity of partially etched nanotube

  5. High-resolution etching of MoSi using electron beam patterned chemically amplified resist

    NASA Astrophysics Data System (ADS)

    Mueller, Mark; Komarov, Serguei; Baik, Ki-Ho

    2003-08-01

    High resolution etching of MoSi for photomask processing places new requirements on etching processes. As resist features are sized to 100 nm and below, it is first necessary to duplicate these features first into a chrome over-layer. After resist is stripped, this chrome over-layer is used for etching MoSi. Both chrome and MoSi etched profiles require near-vertical sidewalls, good CD (critical dimension) uniformity, good linearity, and CD mean-to-target (MTT). Additional requirements of etched MoSi include minimal roughness on exposed quartz, selectivity to chrome and quartz, phase angle target and phase angle uniformity, etch depth global uniformity, and etch depth uniformity as a function of feature size. An ETEC integrated process is used for the application of resist, patterning, and all subsequent processing. Chemically amplified resist is patterned with the 50 kV MEBES Quadra or MEBES eXara raster scan electron beam writer, allowing for patterning of small features with vertical resist profiles. Plates are etched in a Tetra photomask etch system for projecting resist images into chrome and MoSi. Etch processes have been developed specifically for etching small features in order to meet the requirements of 65 nm node lithography. An optimized etch process window is capable of patterning MoSi features below 100 nm sizes with near-vertical sidewall, < 20 nm etch bias, and with similar profile and etch bias for lines and spaces between 100 nm and > 1 um. Excellent CD uniformity and CD etch loading performance are demonstrated. Micro-profilometry is employed to measure the MoSi etch depths of features of varying sizes, and to quantify the effect of loading on MoSi etch depth. SEM micrographs illustrate sidewall profiles resulting from small feature etching.

  6. SO2 passivating chemistry for silicon cryogenic deep etching

    NASA Astrophysics Data System (ADS)

    Duluard, C. Y.; Dussart, R.; Tillocher, T.; Pichon, L. E.; Lefaucheux, P.; Puech, M.; Ranson, P.

    2008-11-01

    Cryogenic deep etching of silicon is investigated using SO2 for passivating the sidewalls of the etched features. The passivating efficiency of SO2 in a SF6/SO2 inductively coupled plasma is assessed comparatively with the traditional SF6/O2 chemistry by means of mass spectrometry and optical emission spectroscopy diagnostics. Emphasis is placed on the evolution of the density of various neutral species (e.g. SiF4, F, O, SOxFy, SFx). These measurements allow us to determine the SO2/SF6 and O2/SF6 gas flow ratios above which a passivation layer forms and inhibits silicon etching. Furthermore, different reaction schemes are proposed to explain the variations in relative densities measured for the two plasma chemistries. In SF6/SO2 plasmas, surface reactions involving SOF and SO2 species with F radicals are favoured, providing a greater number of SOF2 and SO2F2 molecules in the gas phase. In SF6/O2 plasmas, a higher rate of O radicals available for reacting with SFx species can account for the greater concentration in SOF4 molecules. However, these trends are significant for high passivating gas concentrations only. This is consistent with the similar etch results obtained for both chemistries when etching silicon at cryogenic temperatures with a low percentage of passivating gas.

  7. Generic modeling of surface reaction kinetics in plasma etching systems

    NASA Astrophysics Data System (ADS)

    Bray, Raymond Paul

    The complexity of both the bulk plasma phase physics and the substrate surface reaction chemistry indicate the need for simplified phenomenological modeling of etching systems. Simplified models are useful for design, analysis and control, within a reasonable time after data collection, and at modest cost. A current typical method in industry is a response surface model (an empirical polynomial), which has no predictive properties outside the range of fitted data, is completely arbitrary, and offers little physical understanding of the system. A set of generic etch rate expressions based on simplified representations of physical phenomena are presented in this dissertation. The model parameter values are regressed from data with a constrained, nonlinear optimization routine. Also presented are a statistical method for discriminating which model best represents the phenomenon of a particular etching system and a statistical model validation procedure. The benefits of this approach are a predictive, statistically validated model; the small number of model parameters may reduce the number of data points required for regression; and there is no need to re-derive a polynomial fit for each new data set. The method will be demonstrated on experimental data for chlorine plasma etching of polysilicon; tetrafluoromethane/oxygen plasma etching of polysilicon and silicon dioxide; and oxygen plasma ashing of photoresist.

  8. Prediction of etch microtrenching using a neural network

    SciTech Connect

    Kim, Byungwhan; Lee, Duk Woo; Kwon, Kwang Ho [Department of Electronic Engineering, Information Display Research Center, Sejong University, 98, Kunja-Dong, Kwangjin-Ku, Seoul 143-747 (Korea, Republic of); Department of Electronic Engineering, Strategic Energy Research Institute, Sejong University, 98, Kunja-Dong, Kwangjin-Ku, Seoul 143-747 (Korea, Republic of); Department of Electronic Engineering, Hanseo University, Seasan (Korea, Republic of)

    2004-10-01

    Microtrenching during plasma etching was characterized by using a generalized regression neural network (GRNN). Plasma etching of oxide films was conducted in a magnetically enhanced reactive ion etch system. The etch process was characterized by means of a 2{sup 4-1} fractional factorial experiment. The process parameters concerned include CHF{sub 3} flow rate, CF{sub 4} flow rate, radio frequency power, and pressure. Radicals collected with a dc bias were analyzed by optical emission spectroscopy while being correlated to the microtrenching depth (MD). A genetic algorithm (GA) was used to search an optimized set of multiparametrized spreads. The resultant prediction model had a root mean-squared error of 0.031 A/min. Compared to conventional GRNN and statistical regression models, the GA-GRNN demonstrated more accurate predictions of more than 30% and 70%, respectively. The MD variation with the pressure or CHF{sub 3} flow rate was attributed to the more dominant role of polymer deposition over chemical etching as illustrated by a high correlation with [CF]/[F]. For variations in the rf power, the profile change played a critical role in understanding MD.

  9. Deep-etch visualization of 27S clathrin: a tetrahedral tetramer

    PubMed Central

    1987-01-01

    It has recently been reported that 8S clathrin trimers or "triskelions" form larger 27S oligomers upon dialysis into low ionic strength buffers (Prasad, K., R. E. Lippoldt, H. Edelhoch, and M. S. Lewis, 1986, Biochemistry, 25:5214-5219). Here, deep-etch electron microscopy of the 27S species reveals that they are closed tetrahedra composed of four clathrin triskelions. This was determined by two approaches. First, standard quick-freezing and freeze-etching of unfixed 27S species suspended in 2 mM 2-(N-morpholino)ethane sulfonic acid (MES) buffer, pH 5.9, yielded unambiguous images of tetrahedra that measured 33 nm on each edge. Second, the technique of freeze-drying molecules on mica (Heuser, J. E., 1983, J. Mol. Biol., 169:155-195) was modified to overcome the low affinity of mica in 2 mM MES, by pretreating the mica with polylysine. Thereafter, 27S species adsorbed avidly to it and collapsed into characteristic configurations containing four globular domains, each linked to the others by three approximately 33-nm struts. The globular domains look like vertices of deep-etched clathrin triskelions and the links, numbering 12 in all, look like four sets of triskelion legs. New light scattering and equilibrium centrifugation data confirm that 27S polymer is four times as massive as one clathrin triskelion. We conclude that in conditions that do not favor the formation of standard clathrin cages, low affinity interactions lead to closed, symmetrical assemblies of four triskelions, each of which assumes a unique puckered, straight-legged configuration to create the edges of a tetrahedron. Tetrahedra are similar in construction to the cubic octomers of clathrin recently found in ammonium sulfate solutions (Sorger, P. K., R. A. Crowther, J. T. Finch, and B. M. F. Pearse, 1986, J. Cell Biol., 103:1213-1219) but are still smaller, involving only half as many clathrin triskelions. PMID:3119601

  10. pH-controlled selective etching of Al2O3 over ZnO.

    PubMed

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

    2014-05-28

    We describe pH-controlled selective etching of atomic layer deposition (ALD) Al2O3 over ZnO. Film thickness as a function of etch exposure was measured by spectroscopic ellipsometry. We find that alkaline aqueous solutions with pH between about 9 and 12 will etch Al2O3 at useful rate with minimal attack of ZnO. Highly selective etching of Al2O3 over ZnO (selectivity >400:1) and an Al2O3 etch rate of ?50 nm/min can be obtained using a pH 12 etch solution at 60 °C. PMID:24818868

  11. Triangle pore arrays fabricated on Si (111) substrate by sphere lithography combined with metal-assisted chemical etching and anisotropic chemical etching

    NASA Astrophysics Data System (ADS)

    Asoh, Hidetaka; Fujihara, Kosuke; Ono, Sachiko

    2012-07-01

    The morphological change of silicon macropore arrays formed by metal-assisted chemical etching using shape-controlled Au thin film arrays was investigated during anisotropic chemical etching in tetramethylammonium hydroxide (TMAH) aqueous solution. After the deposition of Au as the etching catalyst on (111) silicon through a honeycomb mask prepared by sphere lithography, the specimens were etched in a mixed solution of HF and H2O2 at room temperature, resulting in the formation of ordered macropores in silicon along the [111] direction, which is not achievable by conventional chemical etching without a catalyst. In the anisotropic etching in TMAH, the macropores changed from being circular to being hexagonal and finally to being triangular, owing to the difference in etching rate between the crystal planes.

  12. Method of plasma etching GA-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2013-01-01

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

  13. Method of plasma etching Ga-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2012-12-25

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

  14. Reactive ion etching of deep trenches in silicon

    NASA Astrophysics Data System (ADS)

    Bliznetsov, Vladimir N.; Gutshin, Oleg P.; Yachmenev, V.

    1992-08-01

    We have developed a new production technology of deep trenches RIE with a photoresist mask. RIE was performed in a low-pressure batch diode reactor. Wafers were placed on RF (5,28 MHz) electrode covered by organic lacquer. The maximum loading was 24 wafers having a diameter of 100 mm. Positive photoresist with 2 micron thickness was used for masking without any thermal treatment after development. The line width was 1.5 - 2.0 micron. Because earlier investigated mixtures of chlorine and bromine-containing halocarbons with SF6 didn't allow sufficient selectivity silicon/photoresist, we have proposed to use for deep silicon etching the mixture of CF3I/SF6 and investigated the dependence of silicon and photoresist etch rates and etch anisotropy on basic controlled plasma parameters.

  15. Change in surface morphology of polytetrafluoroethylene by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Takahashi, Tomohiro; Hirano, Yuki; Takasawa, Yuya; Gowa, Tomoko; Fukutake, Naoyuki; Oshima, Akihiro; Tagawa, Seiichi; Washio, Masakazu

    2011-02-01

    Polytetrafluoroethylene (PTFE) was exposed to Ar, CF 4, N 2 and O 2 plasmas using a reactive ion etching facility. After the exposure, the change in the surface morphology of PTFE was examined and characterization studies were performed for the etching rate, surface roughness, radical yields, chemical structures, water repellency and so on. The etching rates of Ar, CF 4, N 2 and O 2 plasmas were 0.58, 7.2, 4.4 and 17 ?m/h, respectively. It was observed that needle-like nano-fiber structures on the surface were irregularly fabricated by the CF 4 plasma. In addition, when the water repellency of exposed samples was evaluated by contact angle, they showed super-hydrophobic properties: contact angle over 150°.

  16. Fabrication of sub-15?nm aluminum wires by controlled etching

    SciTech Connect

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; Markovi?, N. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); McQueen, T. M. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2014-04-28

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15?nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  17. Fabrication of sub-15 nm aluminum wires by controlled etching

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Markovi?, N.

    2014-04-01

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  18. Method and apparatus for spatially uniform electropolishing and electrolytic etching

    DOEpatents

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

    1992-01-01

    In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed.

  19. Study of etching rate uniformity in SRF cavities

    SciTech Connect

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

    2012-07-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in the gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and chlorine concentration in the Argon/Chlorine gas mixtures.

  20. Surface Modification of Nitinol by Chemical and Electrochemical Etching

    NASA Astrophysics Data System (ADS)

    Yang, Zhendi; Wei, Xiaojin; Cao, Peng; Gao, Wei

    2013-07-01

    In this paper, Nitinol, an equiatomic binary alloy of nickel and titanium, was surface modified for its potential biomedical applications by chemical and electrochemical etching. The main objective of the surface modification is to reduce the nickel content on the surface of Nitinol and simultaneously to a rough surface microstructure. As a result, better biocompatibility and better cell attachment would be achieved. The effect of the etching parameters was investigated, using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectrometry (XPS). The corrosion property of modified Nitinol surfaces was investigated by electrochemical work station. After etching, the Ni content in the surface layer has been reduced and the oxidation of Ti has been enhanced.

  1. Influence of water storage time on the bond strength of etch-and-rinse and self-etching adhesive systems.

    PubMed

    Dantas, Darlene Cristina Ramos Eloy; Ribeiro, Ana Isabella Arruda Meira; Lima, Lúcia Helena Marques de Almeida; de Lima, Marcelino Guedes; Guênes, Gymenna Maria Tenório; Braz, Ana Karla Souza; Braz, Rodivan

    2008-01-01

    The purpose of this study was to evaluate comparatively the shear bond strength (SBS) of etch-and-rinse (Adper Scotch Bond Multi Purpose--ASBMP and Adper Single Bond 2--ASB2) and self-etching (AdheSe--AD and Adper Prompt--AP) adhesive systems after short- and long-term water storage. Eighty bovine teeth were randomly assigned to 4 groups (n=20, 10 teeth for 24 h and 10 for 6 months). After surface treatment, composite resin cylinders were made with Tetric Ceram using a bisected metallic matrix. The specimens were stored in distilled water at 37 degrees C for either 24 h or 6 months. After these periods, shear strength was assessed in a universal testing machine (0.5 mm/min). Data were submitted to ANOVA and F test at 5% significance level. Mean SBSs (MPa) for ASBMP (10.03 +/- 3.78) and ASB2 (6.10 +/- 2.67) showed no statistically significant differences (p>0.05) between times. The self-etching systems did not differ significantly from each other within the 24-h period, but significant difference was found for AD (1.37 +/- 0.64) after 6 months of water storage. In conclusion, the tested etch-and-rinse systems had a better performance in terms of bond durability over time than the self-etching systems. PMID:18949294

  2. Characterization of etched facets for GaN-based lasers

    NASA Astrophysics Data System (ADS)

    Scherer, M.; Schwegler, V.; Seyboth, M.; Eberhard, F.; Kirchner, C.; Kamp, M.; Ulu, G.; Ünlü, M. S.; Gruhler, R.; Hollricher, O.

    2001-09-01

    Dry-etching of laser facets is commonly used for (InAl)GaN/sapphire-based structures since the epitaxial planes of the nitride layers are rotated with respect to the substrate planes making cleaving impractical. To achieve steep and smooth facets by chemically assisted ion beam etching, a 3-layer resist system is developed for patterning. Characterization by scanning electron microscopy and atomic force microscopy shows facets with root-mean-square roughnesses of 7 nm and inclination angles of 2-4°. Optically pumped lasers yield low threshold excitation densities for fully doped separate confinement heterostructure lasers.

  3. Gamma Dosimetry with CR-39 Etch Track Detector

    NASA Astrophysics Data System (ADS)

    Matiullah, Matiullah; Dogar, Ashiq; Ahmad, Nasir; Amin, Masood; Kudo, Katsuhisa

    1999-06-01

    To preserve and improve the safety of food for commercial purposes, it is exposed to high gamma-ray doses. The gamma-ray doses used for this purpose range from 0.15 kGy to 50 kGy. At such high doses, the etching characteristics of CR-39 are severely affected. This property, therefore, can be used to develop a CR-39-based gamma dosimeter. In this context, systematic studies were carried out and the bulk etching rate was determined as a function of gamma-ray dose using different methods.

  4. 41. THE BEAR PIT (OLD SIDE DINING ROOM). THE ETCHINGS ...

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

    41. THE BEAR PIT (OLD SIDE DINING ROOM). THE ETCHINGS ON THE CEILING BEAMS AND COLUMNS OF PARK WILDLIFE ARE ORIGINAL TO THE OLD SIDE DINING ROOM. THE SIDE DINING ROOM WAS DESIGNED AND BUILT BY ROBERT REAMER IN 1927. IN 1962 WHEN IT WAS CONVERTED INTO THE BEAR PIT A WALL WAS ADDED BETWEEN THE THREE COLUMNS THAT SEPARATE THIS ROOM FROM THE MAIN DINING ROOM. THE ORIGINAL BEAR PIT ETCHINGS DEPICTING BEARS TENDING BAR AND PLAYING THE PIANO WERE MOUNTED ON THE WALL BETWEEN THE COLUMNS. - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

  5. Evaluation of Acid Fracturing Using the Method of Distributed Volumetric Sources 

    E-print Network

    Lee, Jaehun

    2010-01-14

    conductivity path may remain in the formation, connected to the well. The important factors controlling the effectiveness of acid fracturing are the etched-fracture penetration and conductivity. In this research, I use the distributed volumetric sources (DVS...

  6. 21 CFR 179.43 - Carbon dioxide laser for etching food.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Carbon dioxide laser for etching food. 179.43...Radiation and Radiation Sources § 179.43 Carbon dioxide laser for etching food. Carbon dioxide laser light may be safely used...

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

    PubMed Central

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

    2010-01-01

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

  8. The ICP etching technology of 3C-SiC films

    NASA Astrophysics Data System (ADS)

    Jin, Ning; Quancheng, Gong; Guosheng, Sun; Zhongli, Liu

    2006-04-01

    The dry etching technology is one of the key process in the 3C-SiC MEMS fabrication. In this paper, the 3C-SiC ICP etching technology will be studied. The etching gas components we used include CHF3, SF6 and O2. The polycrystal 3C-SiC films deposited on SiO2 layer were etched in different condition. The effects of the key process parameters such as the etching gas component, the gas flow, the source power, the bias power and the etching pressure on the etch characteristics are studied detailedly. According to the results, the optimal process was obtained. Finally, we used the optimal ICP etching process to fabricate resonator successfully. The work is important and useful to fabricate the 3C-SiC MEMS devices.

  9. Simultaneous, multilayer plasma etching and deposition of fluorocarbon layers on silicon

    NASA Astrophysics Data System (ADS)

    Abraham-Shrauner, Barbara

    2003-10-01

    The plasma etching and deposition of a fluorocarbon layer on a silicon substrate are modeled by the simultaneous etching and deposition of a stack of fluorocarbon monolayers. Langmuir kinetics apply in each of the monolayers to a depth where the energy of the bombarding ions exceeds or equals the threshold energy for breaking carbon fluorine bonds. The ion energy controls many of the terms in the etch rate and deposition rate expressions. The model is based on the diffusion of fluorine etchant through the fluorocarbon layer to the silicon substrate. The deposition and etching of the fluorocarbon layer are ion assisted; the etching of the silicon is thermal and is assumed self-similar based on experiments. The model covers three regimes: reactive sputtering, fluorocarbon suppression, and fluorocarbon deposition. Etch and deposition curves model CF+ ion beam deposition and etch on silicon and CHF3 and C2F6 etch and deposition on fluorocarbon covered silicon substrates.

  10. Boric\\/Sulfuric Acid Anodizing of Aluminum Alloys 2024 and 7075: Film Growth and Corrosion Resistance

    Microsoft Academic Search

    G. E. Thompson; C. J. E. Smith; P. E. Skeldon; L. E. Zhang

    1999-01-01

    The influence of boric acid (HâBOâ) additions to sulfuric acid (HâSOâ) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (NaâCrâOâ)\\/HâSOâ (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of HâBOâ to 50 g\\/L. Pretreatments affected

  11. Inorganic Bi/In thermal resist as a high-etch-ratio patterning layer for CF4/CHF3/O2 plasma etch

    NASA Astrophysics Data System (ADS)

    Tu, Yuqiang; Chapman, Glenn H.; Peng, Jun

    2004-05-01

    Bimetallic thin films containing indium and with low eutectic points, such as Bi/In, have been found to form highly sensitive thermal resists. They can be exposed by lasers with a wide range of wavelengths and be developed by diluted RCA2 solutions. The exposed bimetallic resist Bi/In can work as an etch masking layer for alkaline-based (KOH, TMAH and EDP) "wet" Si anisotropic etching. Current research shows that it can also act as a patterning and masking layer for Si and SiO2 plasma "dry" etch using CF4/CHF3. The profile of etched structures can be tuned by adding CHF3 and other gases such as Ar, and by changing the CF4/CHF3 ratio. Depending on the fluorocarbon plasma etching recipe the etch rate of laser exposed Bi/In can be as low as 0.1nm/min, 500 times lower than organic photoresists. O2 plasma ashing has little etching effect on exposed Bi/In, indicating that laser exposure is an oxidation process. Experiment result shows that single metal Indium film and bilayer Sn/In exhibit thermal resist characteristics but at higher exposure levels. They can be developed in diluted RCA2 solution and used as etch mask layers for Si anisotropic etch and plasma etch.

  12. A Comparative Evaluation of the Efficacy of Etching by the Total Etch and Self-etch Dentin Bonding Systems in the Primary Teeth: An in vitro Study

    PubMed Central

    Chaugule, Vishwas; Katge, Farhin; Poojari, Manohar; Pujari, Prashant; Pammi, Thejokrishna

    2015-01-01

    ABSTRACT Objective: Early childhood caries is now affecting the children in dangerous proportions. There is a wide spread loss of the tooth material irrespective of the type of the carious lesion. Restoration of such lesions with a strong permanent bond between the dental tissues and the restorative dental materials would be a highly desirable requisite. Ultramorphological characterizations show that the interfacial morphology and the chemical characterization of the bonding systems appear to be strongly associated with each other and, therefore, observing and understanding the interfacial phenomenon and its quality would be of great importance in the selection of a dental adhesive for its use in pediatric restorative dentistry. Study design: Human primary molars, which were indicated for extraction, for an array of reasons like caries, normal exfoliation, pathological root resorption, over-retained and serial extraction, were collected for the study purpose. Total number of teeth was then equally distributed into two subgroups, each namely A1 (Prime and Bond NT) and A2 (Xeno III). Results: The type of etching pattern that was observed in group A1 (Prime and Bond NT) of Silverstone’s type II compared to the Silverstone’s type III observed in group A2 (Xeno III). Conclusion: Results of this study indicate that the use of an etchant separately followed by the application of the bonding system–Prime and Bond NT–would provide a better quality of adhesion thus improving the quality and longevity of the restoration done within the limits of enamel in primary dentition. How to cite this article: Mithiborwala SH, Chaugule V, Katge F, Poojari M, Pujari P, Pammi T. A Comparative Evaluation of the Efficacy of Etching by the Total Etch and Self-etch Dentin Bonding Systems in the Primary Teeth: An in vitro Study. Int J Clin Pediatr Dent 2015;8(1):30-36.

  13. A study of lead zirconate titanate etching characteristics using magnetized inductively coupled plasmas

    Microsoft Academic Search

    Y. J. Lee; H. R. Han; J. Lee; G. Y. Yeom

    2000-01-01

    In this study, Pb(Zr1?xTix)O3 (PZT) thin films were etched using magnetized inductively coupled plasmas (MICP) and their etch characteristics were compared with those by non-magnetized conventional inductively coupled plasmas (ICP). The use of Helmholtz type axial electromagnets around the chamber wall increased the PZT etch rates while decreasing etch uniformity. By using both the multidipole magnets and the axial electromagnets

  14. Etch pit shapes on {110} surfaces of CaF 2 crystals

    Microsoft Academic Search

    G C Jain; L C Jain; T S Murty

    1981-01-01

    {110} surfaces of CaF2 crystals are etched with different concentrations of HCl. It is found that concentrated HCl produces characteristic rectangular\\u000a pyramidal etch pits and 2 volume percent HCl produces boat shaped etch pits. Such variations in the etch pit shapes on {110}\\u000a surfaces of CaF2 crystals with different concentrations of HCl have been explained. Concentrated H2SO4 is found to

  15. Tensile bond strengths of an electrolytically and chemically etched base metal.

    PubMed

    Aquilino, S A; Diaz-Arnold, A M; Krueger, G E

    1990-01-01

    This study compared the tensile bond strengths of a Ni-Cr-Be alloy electrolytically etched and chemically etched with three commercially available gels. Etched metal cylinders were bonded end-to-end with a resin luting agent and subsequently tested for tensile strength. Mean bond strengths and the character of bond failure were recorded. Significant differences were found between the electrolytically and chemically etched specimens. PMID:2196897

  16. Dry etching of GaN and related materials: comparison of techniques

    Microsoft Academic Search

    Jewon Lee; Hyun Cho; David C. Hays; Cammy R. Abernathy; Stephen J. Pearton; Randy J. Shul; G. Allen Vawter; J. Han

    1998-01-01

    The etch rates and feature anisotropy for GaN, AlN, and InN etched in Cl2-Ar plasmas with four different techniques were examined. Conventional reactive ion etching produces the slowest etch rates, even when high dc self-biases (>-900 V) are employed, and this leads to mask erosion and sloped feature sidewalls during ridge waveguide fabrication. Two high-ion-density techniques, inductively coupled plasma and

  17. Electrochemical properties and chemical passivity of etch-resistant surface films on steel

    Microsoft Academic Search

    I. V. Karpenko; E. M. Gutman; A. K. Mindyuk

    1966-01-01

    1.All the types of etch-resistant surface films studied are electropositive with respect to the underlying metal. The most electropositive potential was recorded for films of maximum thickness.2.Adjacent steel surfaces with and without etch-resistant films form galvanic macro- and microcells in which the etch-resistant films act as cathodes.3.The etch-resistant films can, under specified conditions, considerably reduce the corrosion rate of steel

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  19. Rapid plasma etching of silicon, silicon dioxide and silicon nitride using microwave discharges

    Microsoft Academic Search

    S. K. Ray; C. K. Maiti; N. B. Chakraborti

    1993-01-01

    Microwave plasma discharges of CF4, SF6 and CHF3 at high pressures (0.5-1.5 Torr) have been used for rapid etching of silicon, silicon dioxide and silicon nitride suitable for single-wafer etching applications. Etch rates and selectivities have been studied as a function of pressure, gas flow and the amount of O2 as the additive gas. Extremely high etch rates of 2.0-3.6

  20. Alternated process for the deep etching of titanium

    NASA Astrophysics Data System (ADS)

    Tillocher, T.; Lefaucheux, P.; Boutaud, B.; Dussart, R.

    2014-07-01

    Titanium is increasingly used as a platform material in microdevices dedicated to biological and bio medical applications. Existing processes for titanium deep etching use a chlorine based chemistry. This paper reports on a low reproducibility for such chemistries when titanium samples are glued onto a silicon carrier wafer. In this case, a SiOCl layer redeposits on the chamber walls as well as on the sample surface. This leads to a decrease of the etch rate and the formation of a very high roughness with a similar morphology as black silicon. The alternated process for the deep etching of titanium (APETi) described in this paper has been designed to improve the overall reproducibility by preventing high roughness formation. It is a time-multiplexed process where Cl2/Ar plasma steps are alternated with SF6 plasma steps. The first step aims at etching with vertical walls (anisotropy) while the second aims at reducing the roughness by removing SiOCl from the sample surface.

  1. Bulk etch characteristics of colorless LR 115 SSNTD

    Microsoft Academic Search

    K. C. C. Tse; F. M. F. Ng; D. Nikezic; K. N. Yu

    2007-01-01

    The colorless LR 115 solid-state nuclear track detector (SSNTD) (from DOSIRAD) is based on cellulose nitrate and was first studied in view of its applicability in radiobiological experiments with alpha particles. In this paper, the bulk etch characteristics were studied. We first showed that the shape of the alpha-particle tracks are irregular with blurred contours under the optical microscope. This

  2. Oxygen ECR stream etching of dichromated gelatin films

    Microsoft Academic Search

    J. M Villalvilla; J Crespo; J. A Quintana; C Santos; J. A Valles-Abarca

    1998-01-01

    An experimental study of the development of dichromated gelatin (DCG) films using an ECR source with oxygen is presented in order to evaluate DCG as a photoresist material in microlithography. The kinetics of the etching process shows saturation behavior for high exposure levels and long development times. From the initial linear dependence, values for development rate are obtained ranging from

  3. Laser Etching: A Novel Technology to Label Florida Grapefruit

    E-print Network

    Etxeberria, Edgardo

    Laser Etching: A Novel Technology to Label Florida Grapefruit Preeti Sood1 , Chris Ference2 , Jan matrix-style letters and numbers, each dot created by a pin-hole depression. The advantages of laser potential adverse effects dur- ing storage. The pinhole depressions applied after washing and waxing dis

  4. Conductive black silicon surface made by silver nanonetwork assisted etching.

    PubMed

    Guo, Chuan Fei; Sun, Tianyi; Wang, Yang; Gao, Jinwei; Liu, Qian; Kempa, Krzysztof; Ren, Zhifeng

    2013-07-22

    Conductive black silicon surfaces (CBSSs) are fabricated by Ag network-assisted catalytic etching, with the Ag network buried in silicon for low reflectance. The CBSSs present a high light absorbance of 97% and good electrical conductivity of less than 10 ?/?. The CBSSs might be used as anti-reflection-coating free light-harvesting devices. PMID:23761137

  5. Mechanical etching of micro pockets by powder blasting

    Microsoft Academic Search

    D. S. Park; T. I. Seo; M. W. Cho

    2005-01-01

    The main objective of this research is to develop a mechanical etching technique to produce micro mould dies having micro pockets of hundreds of µm. A powder blasting technique is applied to stainless steel plates based on predefined process conditions. This paper describes the performance of a powder blasting technique and the effect of the number of nozzle scanning times

  6. Micromachined Faraday cup array using deep reactive ion etching

    Microsoft Academic Search

    R. B. Darling; A. A. Scheidemann; K. N. Bhat; Tai-Chang Chen

    2001-01-01

    A micromachined Faraday cup array (MFCA) for position sensitive ion detection has been developed using a deep reactive ion etching (DRIE) process. Linear, closely spaced arrays of 64, 128, and 256 cups have been produced with pitches of 250 ?m and 150 ?m. Low leakage MOS capacitors formed into DRIE trenches form effective ion collection traps with stable and electrostatically

  7. Ink jet printing nozzle arrays etched in silicon

    Microsoft Academic Search

    E. Bassous; H. H. Taub; L. Kuhn

    1977-01-01

    Ink jet printing nozzle arrays in the form of truncated pyramidal holes anisotropically etched into a silicon substrate have been fabricated. Eight-nozzle arrays dixplay excellent performance characteristics with regard to uniformity of direction (<+\\/- 1mra), velocity (<+\\/- 10 cm\\/sec) at 1000-3000 cm\\/sec), and drop formation.

  8. Chemical etching of manganese oxides for electrocatalytic oxygen reduction reaction.

    PubMed

    Lei, Kaixiang; Han, Xiaopeng; Hu, Yuxiang; Liu, Xue; Cong, Liang; Cheng, Fangyi; Chen, Jun

    2015-07-25

    Mixed-valent MnOx (1 < x < 2) was selectively synthesized by chemically etching MnO and Mn2O3 with ceric ammonium nitrate. The obtained MnOx exhibited greatly enhanced electrocatalytic activity toward the oxygen reduction reaction (ORR) as compared to the corresponding pristine oxides. PMID:26097914

  9. A theoretical analysis of etched grating couplers for integrated optics

    Microsoft Academic Search

    K. Ogawa; W. Chang; B. Sopori; F. Rosenbaum

    1973-01-01

    Grating couplers provide an attractive method for the excitation of optical thin-film waveguides. We present here a perturbation analysis of etched or deposited grating couplers based upon both the transmission line and the Green's Function approaches, which predict the coupling efficiency, the output radiation beamwidth, the angular dependence of excitation, and the intensities of the other orders of the diffracted

  10. Analysis on the metal etch resist selectivity measurement

    Microsoft Academic Search

    Vayalakkara Premachandran; Raymond Joy; Paul H. Keung; Lee W. Lok; Thomas Schuelke; Young Tsai

    1997-01-01

    Absence of a good resist selectivity is a key issue in the metal etch. It becomes increasingly critical when the geometry shrinks below the sub-half micron and the resist thickness reduces further for lithography to get smaller features resolved. Measured values are often quoted based on various techniques like surface profiler or cross section analysis, etc. For a multi step

  11. Novel diamantane polymer platform for enhanced etch resistance

    Microsoft Academic Search

    Munirathna Padmanaban; Srinivasan Chakrapani; Guanyang Lin; Takanori Kudo; Deepa Parthasarathy; Dalil Rahman; Clement Anyadiegwu; Charito Antonio; Ralph R. Dammel; Shenggao Liu; Frederick Lam; Anthony Waitz; Masao Yamagchi; Takayuki Maehara

    2007-01-01

    The dominant current 193 nm photoresist platform is based on adamantane derivatives. This paper reports on the use of derivatives of diamantane, the next higher homolog of adamantane, in the diamondoid series, as monomers in photoresists. Due to their low Ohnishi number and incremental structural parameter (ISP), such molecules are expected to enhance dry etch stability when incorporated into polymers

  12. Ion-assisted etching and profile development of silicon in molecular chlorine

    E-print Network

    Shaqfeh, Eric

    a low temperature rf plasma etching process. The ion-induced etching yield scaled with the square root applicability to etching topography was tested with additional experiments where patterned silicon wafers development were performed using the kinetic model and a line-of-sight re-emission model for the chlorine

  13. Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas

    NASA Astrophysics Data System (ADS)

    Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M.; Economou, Demetre J.

    2014-05-01

    Cl2, Br2, HBr, Br2/Cl2, and HBr/Cl2 feed gases diluted in Ar (50%-50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br2/Ar and HBr/Cl2/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF2, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl2/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to ?110? cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

  14. Dielectric membranes manufactured by isotropic etching of ?111? oriented silicon for microwave applications

    Microsoft Academic Search

    A. Muller; I. Petrini; V. Avramescu; C. Schor; V. Badilita; G. Simion; M. Mihali; N. Nastase

    1998-01-01

    The paper presents the manufacturing of thin dielectric membranes by isotropic etching vs. anisotropic etching of silicon. The isotropic etching technique of ?111? oriented silicon was developed in our laboratories for the first time. The quality of membranes was investigated by atomic force microscope (AFM) analysis. There were manufactured meander and S-line inductors and interdigitated capacitors supported on thin dielectric

  15. Analysis of large-area beam attacks on surfaces and testing of etching reactions

    Microsoft Academic Search

    J. Janes; U. Baenziger; Ch Huth; P. Hoffmann; G. Neumann; H.-C. Scheer; B. Schneemann; U. Koehler

    1992-01-01

    An apparatus has been constructed to analyze the particle flux of positive ions on surfaces from dry etching reactors. The particle flux can emerge from a great variety of reactive ion etching systems or from reactive ion beam etching sources. The particle beam passes through a small orifice with a diameter of 100 ?m. A differentially pumped quadrupole mass spectrometer

  16. Title: COMPARISON OF ADVANCED RESIST ETCHING IN E-BEAM GENERATED

    E-print Network

    Anlage, Steven

    ABSTRACT Title: COMPARISON OF ADVANCED RESIST ETCHING IN E-BEAM GENERATED PLASMAS Bryan J. Orf is deposited. #12;COMPARISON OF ADVANCED RESIST ETCHING IN E-BEAM GENERATED PLASMAS By Bryan J. Orf Thesis significantly in polymer structure. The influence of Ar+ bombardment energy, chemically-assisted etching using

  17. GaN etching in BCl{sub 3}Cl{sub 2} plasmas

    SciTech Connect

    Shul, R.J.; Ashby, C.I.H.; Willison, C.G.; Zhang, L.; Han, J.; Bridges, M.M. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J.; Lee, J.W. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Lester, L.F. [Univ. of New Mexico, Albuquerque, NM (United States)

    1998-04-01

    GaN etching can be affected by a wide variety of parameters including plasma chemistry and plasma density. Chlorine-based plasmas have been the most widely used plasma chemistries to etch GaN due to the high volatility of the GaCl{sub 3} and NCl etch products. The source of Cl and the addition of secondary gases can dramatically influence the etch characteristics primarily due to their effect on the concentration of reactive Cl generated in the plasma. In addition, high-density plasma etch systems have yielded high quality etching of GaN due to plasma densities which are 2 to 4 orders of magnitude higher than reactive ion etch (RIE) plasma systems. The high plasma densities enhance the bond breaking efficiency of the GaN, the formation of volatile etch products, and the sputter desorption of the etch products from the surface. In this study, the authors report GaN etch results for a high-density inductively coupled plasma (ICP) as a function of BCl{sub 3}:Cl{sub 2} flow ratio, dc-bias, chamber-pressure, and ICP source power. GaN etch rates ranging from {approximately}100 {angstrom}/min to > 8,000 {angstrom}/min were obtained with smooth etch morphology and anisotropic profiles.

  18. Absolute density measurement of FCN in CHF3 ECR plasma etching of Si_3N_4

    NASA Astrophysics Data System (ADS)

    Miyata, Koji; Arai, Hiroyoshi; Ito, Masafumi; Hori, Masaru; Goto, Toshio

    1997-10-01

    Si_3N4 has been widely used as masks in the local oxidation and etch-stop layers in self-aligned contact fabrication. As the devices are developed, the Si_3N4 etching requires higher controllability to achieve ideal etch characteristics. However, it is difficult to develop the Si_3N4 etching without knowledge of etching mechanisms. To study the etching mechanism, it is very helpful to know absolute densities of etch products. In this study, the absolute density of cyanogen fluoride (FCN), which is one of etch products of the Si_3N_4, was measured for the first time in a CHF3 ECR plasma using infrared diode laser absorption spectroscopy (IRLAS). The typical FCN density during Si_3N4 etching was derived to be 4 ×10^11 cm-3 in the CHF3 plasma at an etch rate of 48 Ås. Substrates of 25 cm^2 were used in this experiment. The FCN density during Si_3N4 etching is so large that the FCN is considered to be a major etch product of the Si_3N_4. Moreover, disappearance processes of the FCN will be discussed on the basis of FCN decay rates after discharge termination in CHF_3/N2 mixtures.

  19. Recent advances in silicon etching for MEMS using the ASE™ process

    Microsoft Academic Search

    A. M. Hynes; H. Ashraf; J. K. Bhardwaj; J. Hopkins; I. Johnston; J. N. Shepherd

    1999-01-01

    In the ongoing enhancement of MEMS applications, the STS Advanced Silicon Etch, ASE™, process satisfies the demanding requirements of the industry. Typically, highly anisotropic, high aspect ratios profiles with fine CD control are required. Selectivities to photoresist of 150:1 with Si etch rates of up to 7 ?m\\/min are achievable. Applications range from shallow etched optical devices to through wafer

  20. Plasma etching: principles, mechanisms, application to micro- and nano-technologies

    Microsoft Academic Search

    Christophe Cardinaud; Marie-Claude Peignon; Pierre-Yves Tessier

    2000-01-01

    Nowadays, plasma-etching processes are asked to produce patterns from the nanometer to the micrometer range with the same efficiency. The very severe requirements in terms of etch rate, selectivity, profile control and surface damage plasma-etching processes lead to, have been at the origin of the development of mechanistic studies by means of plasma diagnostics and surface analysis, as well as