Science.gov

Sample records for hydrofluoric acid etching

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  2. Study on the mechanism of platinum-assisted hydrofluoric acid etching of SiC using density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Bui, P. V.; Isohashi, A.; Kizaki, H.; Sano, Y.; Yamauchi, K.; Morikawa, Y.; Inagaki, K.

    2015-11-01

    Hydrofluoric acid (HF) etching of the SiC surface assisted by Pt as a catalyst is investigated using density functional theory. Etching is initiated by the dissociative adsorption of HF on step-edge Si, forming a five-fold coordinated Si moiety as a metastable state. This is followed by breaking of the Si-C back-bond by a H-transfer process. The gross activation barrier strongly correlates with the stability of the metastable state and is reduced by the formation of Pt-O chemical bonds, leading to an enhancement of the etching reaction.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  5. Hydrofluoric acid poisoning

    MedlinePlus

    Chemical Emergencies: Case Definition: Hydrofluoric Acid . Centers for Disease Control and Prevention, U.S. Dept of Health and Human Services; 2005. Goldfrank LR, ed. Goldfrank's Toxicologic Emergencies . 8th ed. New ...

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  7. 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

  8. [Treatment of hydrofluoric acid burns].

    PubMed

    Thiele, B; Winter, U J; Mahrle, G; Steigleder, G K

    1986-01-31

    A chemical-plant worker sustained hydrofluoric acid burns during cleaning procedures. Intra-arterial perfusion and intralesional injections of calcium gluconate solution prevented progression of the burns into deeper tissue layers. PMID:3943470

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

    PubMed

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

    2016-07-13

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

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

    PubMed

    Ahmad, Muthanna; Grime, Geoffrey W

    2013-04-01

    Porous silicon (PS) has been prepared using a microwave-assisted hydrofluoric acid (HF) etching method from a silicon wafer pre-implanted with 5 MeV Cu ions. The use of microbeam proton-induced X-ray emission (micro-PIXE) and microbeam Rutherford backscattering techniques reveals for the first time the capability of these techniques for studying the formation of micropores. The porous structures observed from micro-PIXE imaging results are compared to scanning electron microscope images. It was observed that the implanted copper accumulates in the same location as the pores and that at high implanted dose the pores form large-scale patterns of lines and concentric circles. This is the first work demonstrating the use of microwave-assisted HF etching in the formation of PS. PMID:23388452

  11. 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.

  12. 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.

  13. 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

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

    DOEpatents

    Hankins, Matthew G.

    2009-10-06

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

  15. Hydrofluoric acid burns of the eye.

    PubMed

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

    1983-06-01

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

  16. A review of hydrofluoric acid burn management.

    PubMed

    McKee, Daniel; Thoma, Achilleas; Bailey, Kristy; Fish, Joel

    2014-01-01

    Hydrofluoric acid (HF) causes a unique chemical burn. Much of the current treatment knowledge of HF burns is derived from case reports, small case series, animal studies and anecdotal evidence. The management can be challenging because clinical presentation and severity of these burns vary widely. Plastic surgeons managing burn patients must have a basic understanding of the pathophysiology, the range of severity in presentation and the current treatment options available for HF burns. The present article reviews the current understanding of the pathophysiology and systemic effects associated with severe HF burns. Furthermore, it distinguishes between minor and life-threatening HF burns and describes several of the basic techniques that are available to treat patients with HF burns. PMID:25114621

  17. Hydrofluoric acid burn: latent period was key factor

    SciTech Connect

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

    1987-07-01

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

  18. 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.

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

    DOEpatents

    Ostenak, Carl A.; Mackay, Harold A.

    1987-01-01

    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.

  20. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction...

  1. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction...

  4. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction...

  5. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction...

  6. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction...

  7. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction...

  10. 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

  11. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects.

    PubMed

    Grant, Nicholas E

    2016-01-01

    A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<10(12) cm(-3)). PMID:26779939

  12. Injuries following a serious hydrofluoric acid leak: First aid and lessons.

    PubMed

    Zhang, Yuanhai; Wang, Xingang; Sharma, Komal; Mao, Xinxing; Qiu, Xuguang; Ni, Liangfang; Han, Chunmao

    2015-11-01

    Hydrofluoric acid is a dangerous inorganic acid that can cause local corrosion and systemic effects by ongoing absorption via the skin, mucosae, respiratory tract and digestive system. Recently, a serious toxic leak of low-concentration hydrofluoric acid solution occurred in the Pujiang area of Zhejiang Province, China. This accident resulted in 253 cases of chemical injury due to hydrofluoric acid exposure. Despite an immediate response by the local and provincial health-care system, as well as the local government, three people died due to acute poisoning and related complications. This article describes the events that took place leading to casualties as well as presenting the first-aid experience and the lessons learnt from this kind of mass injury. PMID:26188892

  13. Hydrofluoric Acid Corrosion Study of High-Alloy Materials

    SciTech Connect

    Osborne, P.E.

    2002-09-11

    A corrosion study involving high-alloy materials and concentrated hydrofluoric acid (HF) was conducted in support of the Molten Salt Reactor Experiment Conversion Project (CP). The purpose of the test was to obtain a greater understanding of the corrosion rates of materials of construction currently used in the CP vs those of proposed replacement parts. Results of the study will help formulate a change-out schedule for CP parts. The CP will convert slightly less than 40 kg of {sup 233}U from a gas (UF{sub 6}) sorbed on sodium fluoride pellets to a more stable oxide (U{sub 3}O{sub 8}). One by-product of the conversion is the formation of concentrated HF. Six moles of highly corrosive HF are produced for each mole of UF{sub 6} converted. This acid is particularly corrosive to most metals, elastomers, and silica-containing materials. A common impurity found in {sup 233}U is {sup 232}U. This impurity isotope has several daughters that make the handling of the {sup 233}U difficult. Traps of {sup 233}U may have radiation fields of up to 400 R at contact, a situation that makes the process of changing valves or working on the CP more challenging. It is also for this reason that a comprehensive part change-out schedule must be established. Laboratory experiments involving the repeated transfer of HF through 1/2-in. metal tubing and valves have proven difficult due to the corrosivity of the HF upon contact with all wetted parts. Each batch of HF is approximately 1.5 L of 33 wt% HF and is transferred most often as a vapor under vacuum and at temperatures of up to 250 C. Materials used in the HF side of the CP include Hastelloy C-276 and Monel 400 tubing, Haynes 230 and alloy C-276 vessels, and alloy 400 valve bodies with Inconel (alloy 600) bellows. The chemical compositions of the metals discussed in this report are displayed in Table 1. Of particular concern are the almost 30 vendor-supplied UG valves that have the potential for exposure to HF. These valves have been

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Applicability; description of the hydrofluoric acid production subcategory. 415.80 Section 415.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the hydrofluoric acid production subcategory. 415.80 Section 415.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING...

  16. Evaluation of intravenous magnesium sulfate for the treatment of hydrofluoric acid burns.

    PubMed

    Cox, R D; Osgood, K A

    1994-01-01

    Hydrofluoric acid exposures to the skin can produce severe, progressive burns. Medical treatment of these burns is aimed at neutralizing the free fluoride ion, which is felt to be responsible for burn progression. Both calcium and magnesium will form complexes with free fluoride and have been used as topical or intradermal treatments in the past. This study evaluated the efficacy of intravenous magnesium sulfate for the treatment of hydrofluoric acid burns and compared this treatment to controls and burns treated with intradermal calcium gluconate in a rabbit model. Both treatments demonstrated a reduction in burn area over time, wound depth, healing time and final scar area compared to controls. The intravenous magnesium treatment showed trends toward improved outcome compared to the intradermal calcium treatment in all parameters evaluated, but these differences did not reach statistical significance. This investigation found intravenous magnesium to be an effective method for treating hydrofluoric acid burns. Intravenous magnesium may have significant utility for treating hydrofluoric acid burns that are not amenable to current therapies. PMID:8145352

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

    PubMed

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

    1995-01-01

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

  18. Topical treatments for hydrofluoric acid dermal burns. Further assessment of efficacy using an experimental piq model.

    PubMed

    Dunn, B J; MacKinnon, M A; Knowlden, N F; Billmaier, D J; Derelanko, M J; Rusch, G M; Naas, D J; Dahlgren, R R

    1996-05-01

    Several topical treatments for hydrofluoric acid dermal burns (Zephiran, calcium acetate and magnesium hydroxide antacid soaks, and calcium gluconate gel) were assessed for efficacy in a pig model. Gross appearance and histopathology of treated and untreated burn sites were evaluated. For superficial burns, Zephiran was most effective; calcium acetate, magnesium hydroxide antacid, and calcium gluconate gel were less effective. For deep burns, gross observations showed that calcium acetate and Zephiran were most efficacious, whereas histopathology indicated comparable efficacy of Zephiran, calcium acetate, and calcium gluconate gel for all skin layers. Magnesium hydroxide antacid demonstrated efficacy only for the subdermis. The clinically beneficial effects of both Zephiran and calcium gluconate gel were affirmed. Although results suggest that calcium acetate and magnesium-containing antacids may be beneficial for human hydrofluoric acid dermal burns, these are not established clinical treatments. PMID:8733642

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    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.

  1. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    PubMed

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

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology. PMID:20441916

  2. Fatality due to acute systemic fluoride poisoning following a hydrofluoric acid skin burn.

    PubMed

    Tepperman, P B

    1980-10-01

    Reports indicate that death due to hydrofluoric acid exposure is usually the result of inhalation of vapor causing pulmonary edema and fluoride poisoning. Absorption via the skin route of fluoride ion sufficient to cause serious systemic problems and even death has rarely been reported. A fatality resulting from a severe facial burn, which produced acute systemic fluoride poisoning with profound hypocalcemia and hypomagnesemia, is presented. The importance of proper personal protective equipment as well as the immediate initiation of first aid and appropriate medical measures, including the monitoring and replacement of serum calcium and magnesium, are emphasized. PMID:7431138

  3. Occupational Hydrofluoric Acid Injury from Car and Truck Washing--Washington State, 2001-2013.

    PubMed

    Reeb-Whitaker, Carolyn K; Eckert, Carly M; Anderson, Naomi J; Bonauto, David K

    2015-08-21

    Exposure to hydrofluoric acid (HF) causes corrosive chemical burns and potentially fatal systemic toxicity. Car and truck wash cleaning products, rust removers, and aluminum brighteners often contain HF because it is efficient in breaking down roadway matter. The death of a truck wash worker from ingestion of an HF-based wash product and 48 occupational HF burn cases associated with car and truck washing in Washington State during 2001-2013 are summarized in this report. Among seven hospitalized workers, two required surgery, and all but one worker returned to the job. Among 48 injured workers, job titles were primarily auto detailer, car wash worker, truck wash worker, and truck driver. Because HF exposure can result in potentially severe health outcomes, efforts to identify less hazardous alternatives to HF-based industrial wash products are warranted. PMID:26292206

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  5. Texturing a pyramid-like structure on a silicon surface via the synergetic effect of copper and Fe(III) in hydrofluoric acid solution

    NASA Astrophysics Data System (ADS)

    Cao, Ming; Li, Shaoyuan; Deng, Jianxin; Li, Yuping; Ma, Wenhui; Zhou, Yang

    2016-05-01

    An innovative approach is proposed to texture a pyramid structure on a silicon surface via Cu-catalyzed chemical etching in the HF/FeCl3 system. The surface and cross-section morphologies of the formed pyramid structure were examined by scanning electron microscopy and atomic force microscopy. The results revealed that numerous silicon pyramid-like structures with hemlines of 0.1 ∼ 3 μm and height of 0.1 ∼ 2 μm are close together, and the top angle of the pyramid structure is 90°. Additionally, the systematic study of the effects of the etching time and the concentration of FeCl3 on the pyramid-like structures by the atom configuration model of silicon crystal faces demonstrated that the etching proceeds preferentially along the <1 0 0> directions of silicon. A formation mechanism of the pyramid-like structure is proposed. The results imply that the synergetic effect of Cu nanoparticles and Fe(III) could conveniently generate a pyramid-like architecture on the surface of silicon in hydrofluoric acid solution.

  6. EXAFS study of the speciation of protactinium(V) in aqueous hydrofluoric acid solutions.

    PubMed

    De Sio, Stéphanie M; Wilson, Richard E

    2014-12-01

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

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

    SciTech Connect

    Thomas, D. Jaeger, U.; Sagoschen, I.; Lamberti, C.; Wilhelm, K.

    2009-01-15

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

  8. Characteristics of fluoride in pore-water at accidental hydrofluoric acid spillage site, Gumi, Korea

    NASA Astrophysics Data System (ADS)

    Kwon, E. H.; Lee, H. A.; Lee, J.; Kim, D.; Lee, S.; Yoon, H. O.

    2015-12-01

    A leakage accident of hydrofluoric acid (HF) occurred in Gumi, South Korea at Sep. 2012. The study site is located in the borderline between a large-scale industrial complex and a rural area. The HF plume was made immediately, and moved toward the rural area through air. After the accident, 212 ha of farm land were influenced and most of crops were withered. To recover the soil, CaO was applied after six months. Although several studies have done to estimate the extension and movement of HF plume in the air and to assess the impact on human health or plant after the incident, the long-term fate of fluoride (F) in the affected soils is not identified clearly. Thus, this study aimed to understand the behavior of F in the soil after HF releasing from accident site through chemical analysis and geochemical modeling. Within the radius of 1 km of accident site, 16 pore-water and soil samples were collected. The semi-quantitative soil composition (i.e., Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti), total F, total P, OM contents in soil, and soil pH have already been measured, and pore-water compositions are also identified. From these experimental and modeling data, we could be evaluate if impact of accident exists until now, and also could be select and identify existing form of fluoride in soil and pore-water.

  9. Fluorine distribution in soil in the vicinity of an accidental spillage of hydrofluoric acid in Korea.

    PubMed

    An, Jinsung; Lee, Hyun A; Lee, Junseok; Yoon, Hye-On

    2015-01-01

    This study assessed the status of fluorine (F) in soil in the vicinity of a spillage of anhydrous hydrofluoric acid in Korea. Gaseous hydrogen fluoride dispersed was suspected to have contaminated the surrounding soil environment. Total and water soluble F concentrations in soil within a 1 km radius of the spillage were determined. Total F concentrations (mean=222±70.1 mg kg(-1)) were lower than the Korean limit value (i.e., 400 mg kg(-1)) and several reported measurements of background F concentrations in soils except for a single outlying case. Soluble F concentrations ranged from 0.111 to 6.40 mg kg(-1) (mean=2.20±1.80 mg kg(-1)). A negative correlation between the soluble F concentration of soil and distance from the spillage was observed. This indicates that the soluble F concentration has a crucial role in fractionating the F concentration arising from a 'non natural input' i.e., the spillage. The F content of rice samples seemed to be significantly influenced by the soluble F concentrations of soils. Rice samples collected from the control and affected areas contained 41 mg kg(-1) and 578 mg kg(-1) of total F, respectively. PMID:25128889

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

    SciTech Connect

    Hui Tian; Charles Reece; Michael Kelley; Sean Corcoran

    2008-02-12

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

  11. 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. )

    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.

  12. Is demineralization with dilute hydrofluoric acid a viable method for isolating mineral stabilized soil organic matter?

    NASA Astrophysics Data System (ADS)

    Sanderman, J.; Baldock, J.; Farrell, M.; Macreadie, P.; McGowan, J.

    2015-12-01

    While you might not be able to dispose of a body with hydrofluoric acid (HF), as fans of Breaking Bad know HF will break silicon-oxygen bonds. These dual properties make HF a powerful tool in investigations of soil organic matter (SOM). When a soil sample is treated with HF, any low molecular weight OM that was bound to mineral surfaces will be released into solution allowing study of the amount and composition of this stable SOM pool. In the work presented here, we take advantage of this property of HF to explore if different forms of SOM are becoming stabilized to mineral surfaces in terrestrial and marine environments. Difference spectra obtained from solid-state 13C NMR spectroscopic analysis of bulk and 10% HF treated soil samples suggest that in aerobic terrestrial environments alkyl-C and aryl-C compounds can dominate the mineral stabilized fraction. However, in anoxic coastal environments this fraction is dominated by O-alkyl C. Demineralization of soil samples with HF is often necessary for removing paramagnetic interferences and concentrating carbon prior to obtaining NMR spectra. The working assumption using dilute HF is that the resultant SOM chemistry determined by NMR spectroscopy has not been significantly biased by the HF treatment process. This assumption has been validated in several studies but also refuted in others. A second goal of this study was to revisit this critical assumption by looking at carbon loss and resulting 13C NMR chemistry from a diverse set of soils and organic materials using HF in 2% and 10% concentrations. We found that 10% HF resulted in slightly greater loss of C than 2% HF but in cases where a preferential shift in chemistry was observed it was observed in both the 2% and 10% treatments. The implications of both of these findings will be discussed in the context of understanding the sources, stability and potential loss mechanisms of mineral stabilized SOM.

  13. 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.

  14. Etching of nanostructures on soda-lime glass.

    PubMed

    Wang, Elmer; Zhao, Yang

    2014-07-01

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

  15. Gas Cluster Ion Beam Etching under Acetic Acid Vapor for Etch-Resistant Material

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akira; Hinoura, Ryo; Toyoda, Noriaki; Hara, Ken-ichi; Yamada, Isao

    2013-05-01

    Gas cluster ion beam (GCIB) etching of etch-resistant materials under acetic acid vapor was studied for development of new manufacturing process of future nonvolatile memory. Etching depths of various etch-resistant materials (Pt, Ru, Ta, CoFe) with acetic acid vapor during O2-GCIB irradiations were 1.8-10.7 times higher than those without acetic acid. Also, etching depths of Ru, Ta, CoFe by Ar-GCIB with acetic acid vapor were 2.2-16.1 times higher than those without acetic acid. Even after etching of Pt, smoothing of Pt was realized using O2-GCIB under acetic acid. From XPS and angular distribution of sputtered Pt, it was shown that PtOx layer was formed on Pt after O2-GCIB irradiation. PtOx reacted with acetic acid by GCIB bombardments; as a result, increase of etching depth was observed.

  16. 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.

  17. Acid-etched Fabry-Perot micro-cavities in optical fibres

    NASA Astrophysics Data System (ADS)

    Machavaram, V. R.; Badcock, R. A.; Fernando, G. F.

    2007-07-01

    Significant progress has been made in recent years on the design and fabrication of optical fibre-based sensor systems for applications in structural health monitoring. Two sensor designs have tended to dominate namely, fibre Bragg gratings and extrinsic fibre Fabry-Perot sensors. However, the cost and time associated with these sensors is relatively high and as a consequence, the current paper describes a simple procedure to fabricate intrinsic fibre Fabry-Perot interferometric strain sensors. The technique involves the use of hydrofluoric acid to etch a cavity in a cleaved optical fibre. Two such etched cavities were fusion spliced to create an intrinsic fibre Fabry-Perot cavity. The feasibility of using this device for strain monitoring was demonstrated. Excellent correlation was obtained between the optical and surface-mounted electrical resistance strain gauge.

  18. 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 ΔGc≈ 8.4 J/m2.

  19. Silicon wafer-contaminant interactions in dilute hydrofluoric acid solutions and related fundamentals in colloid and interface science

    NASA Astrophysics Data System (ADS)

    Chen, Zhan

    With the continuous decrease in device size, it becomes more and more important to have a contamination-free silicon wafer surface. Hydrofluoric acid is inevitably involved in silicon wafer wet cleaning. However, during dilute hydrofluoric acid (DHF) cleaning, particles and noble metals tend to deposit on the silicon wafer surface and the surface roughness could increase. In this study, the mechanisms of particle deposition, noble metal outplating, and the effects of additives were investigated. Particle deposition from DHF solution onto bare silicon surfaces is due to the large van der Waals interaction between silicon and particles. Additives which can increase electrostatic interaction will reduce particle redeposition, and their effectiveness correlates well with the zeta-potential changes on both silicon surface and particles. Direct force measurements between a silicon surface and a silicon nitride surface reveal that additives not only change electrostatic interaction, but change adhesion forces of particles on silicon surfaces also. Nobel metal ions, especially copper ions, tend to deposit on bare silicon surfaces in DHF solution. The nucleation stage of copper deposition is critical and copper preferrentially deposits on surfaces with high defect densities. A novel technique to detect copper outplating in situ was established. Some additives may increase copper deposition due to the formation of copper complex and the subsequent adsorption of the copper complex on silicon surfaces. Some additive reduces copper outplating significantly. Their effects were discussed. Some fundamental aspects of colloid and interface science have been studied as well, including the approximate and numerical solutions of the electric potential distribution near a planar surface in the presence of highly asymmetric electrolytes. More importantly, the surface interaction in a confined/concentrated system was studied and a theory was established. The mysterious long range

  20. The Effect of Hydrofluoric Acid Concentration on the Bond Strength and Morphology of the Surface and Interface of Glass Ceramics to a Resin Cement.

    PubMed

    Sundfeld Neto, D; Naves, L Z; Costa, A R; Correr, A B; Consani, S; Borges, G A; Correr-Sobrinho, L

    2015-01-01

    The purpose of this study was to evaluate the influence of various concentrations of hydrofluoric acid (HF) on the surface/interface morphology and μ-shear bond strength (μSBS) between IPS Empress Esthetic (EST) (Ivoclar Vivadent) and IPS e.max Press (EMX) (Ivoclar Vivadent) ceramics and resin cement. Ceramic blocks were divided into 12 groups for each kind of ceramic. Six different HF concentrations were evaluated: 1%, 2.5%, 5%, 7.5%, 10%, and 15%. All groups were silanated after etching, and half of the specimens within each group received a thin layer of unfilled resin (UR). Three resin cement cylinders were prepared on each ceramic block for μSBS testing. The specimens were stored in distilled water at 37°C for 24 hours. The μSBS test was carried out in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The data were submitted to three-way analysis of variance and multiple comparisons were performed using the Tukey post hoc test (p<0.05). The etched surfaces and bonded interfaces were evaluated using scanning electron microscopy. μSBS means (MPa) for 1%, 2.5%, 5%, 7.5%, 10%, and 15% HF concentrations were, respectively, 25.2, 27.2, 30.1, 31.4, 33.3, and 31.8. μSBS means with or without UR application measured 32.24 and 27.4, respectively; EST and EMX measured 29.8 and 29.9, respectively. For the HF concentrations, 10% and 15% showed higher μSBS means than did 1% and 2.5% (p<0.05); 7.5% was higher than 1% (p<0.05); and no statistical differences were found among the other concentrations (p>0.05). When evaluating UR, μSBS mean was significantly higher and better infiltration was observed on the etched surfaces. No statistical difference was found between the ceramics. The HF concentration and UR influenced the bond strength and surface/interface morphology. PMID:25764043

  1. 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.

  2. 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

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

    PubMed Central

    Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

    2013-01-01

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

  4. Rapid analysis of acid in etching and pickling solutions

    SciTech Connect

    Tumbina, V.P.; Chinokalov, V.Ya.

    1995-02-01

    A computational method for determining sulfuric and hydrochloric acids in two-component etching solutions has been proposed. The method makes use of linear relationships, assuming that the sum of free and bound acid in solution remains constant.

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

    PubMed

    Hamamci, Nihal; Akkurt, Atilim; Başaran, Güvenç

    2010-11-01

    This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted human premolars were divided randomly into four equal groups and received the following treatment: group 1, acid etching; group 2, self-etching primer (SEP); group 3, erbium:yttrium-aluminum-garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept in distilled water for 1 month and then subjected to 500 thermal cycles. Then, the specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and examined under a stereomicroscope. In addition, they were scored for marginal microleakage at the adhesive-enamel and bracket-adhesive interfaces from the incisal and gingival margins. Statistical analyses consisted of the Kruskal-Wallis test and the Mann-Whitney U test with Bonferroni correction. Microleakage occurred between the adhesive-enamel and bracket-adhesive interfaces in all groups. For the adhesive-enamel surface, a significant difference was observed between group 1 and groups 2 (P = 0.011), 3 (P = 0.002), and 4 (P = 0.000) on the gingival side. Overall, significant differences were observed between group 1 and groups 3 (P = 0.003) and 4 (P = 0.000). In dental bonding procedures, acid etching was found to result in the least microleakage. Since etching with a laser decreases the risk of caries and is time-saving, it may serve as an alternative to acid etching. PMID:19562404

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

    SciTech Connect

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

    1990-07-01

    The different behavior of titanium and zirconium in HF-HNO{sub 3} 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. The titanium dissolution process in such solutions can be interpreted using a passivation model in which dissolution and passivation are two competing reactions at the surface of the bare metal. On the other hand, zirconium dissolution occurs through formation of an oxide film with ionic diffusion through the film being a rate-determining step. The particular role of strong acid added to the HF solution for pickling of titanium and zirconium is also discussed.

  7. Mechanism of hydrofluoric acid formation in ethylene carbonate electrolytes with fluorine salt additives

    NASA Astrophysics Data System (ADS)

    Tebbe, Jonathon L.; Fuerst, Thomas F.; Musgrave, Charles B.

    2015-11-01

    We utilized density functional theory to examine HF generation in lithium-ion battery electrolytes from reactions between H2O and the decomposition products of three electrolyte additives: LiPF6, LiPOF4, and LiAsF6. Decomposition of these additives produces PF5, AsF5, and POF3 along with LiF precipitates. We found PF5 and AsF5 react with H2O in two sequential steps to form two HF molecules and POF3 and AsOF3, respectively. PF5 (or AsF5) complexes with H2O and undergoes ligand exchange to form HF and PF4OH (AsF4OH) with an activation barrier of 114.2 (30.5) kJ mol-1 and reaction enthalpy of 14.6 (-11.3) kJ mol-1. The ethylene carbonate (EC) electrolyte forms a Lewis acid-base complex with the PF4OH (AsF4OH) product, reducing the barrier to HF formation. Reactions of POF3 were examined and are not characterized by complexation of POF3 with H2O or EC, while PF5 and AsF5 complex favorably with H2O and EC. HF formation from POF3 occurs with a reaction enthalpy of -3.8 kJ mol-1 and a 157.7 kJ mol-1 barrier, 43.5 kJ mol-1 higher than forming HF from PF5. HF generation in electrolytes employing LiPOF4 should be significantly lower than those using LiPF6 or LiAsF6 and LiPOF4 should be further investigated as an alternative electrolyte additive.

  8. 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

  9. 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.

  10. Hydrofluoric acid poisoning

    MedlinePlus

    ... with has an exposure, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

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

    SciTech Connect

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

    2014-06-16

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

  12. 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

  13. 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.

  14. 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

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

    SciTech Connect

    Zhao, Xin; Corcoran, Sean G.; Kelley, Michael J.

    2011-06-01

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

  16. SEM ANALYSIS OF THE ACID-ETCHED ENAMEL PATTERNS PROMOTED BY ACIDIC MONOMERS AND PHOSPHORIC ACIDS

    PubMed Central

    Shinohara, Mirela Sanae; de Oliveira, Marcelo Tavares; Hipólito, Vinícius Di; Giannin, Marcelo; de Goes, Mario Fernando

    2006-01-01

    Objective: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. Materials and Methods: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. Results: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. Conclusion: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces. Uniterms: Dental acid etching; Dental enamel; Electron microscopy. PMID:19089243

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    PubMed

    Donaldson, E M

    1970-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Padmanabhan Ramalekshmi Thanu, Dinesh

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

  20. Analysis of fish otoliths by electrothermal vaporization inductively coupled plasma mass spectrometry: aspects of precipitating otolith calcium with hydrofluoric acid for trace element determination.

    PubMed

    Arslan, Zikri

    2005-03-15

    A method is developed for determination of trace elements, including Ag, As, Cd, Co, Cr, Cu, Mn, Ni, Se, Tl and Zn, in fish otoliths by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). Hydrofluoric acid was used to precipitate calcium resulting from acid dissolution of otolith calcium carbonate. Initial acidity of the sample solution influenced the precipitation efficiency of calcium fluoride. Up to 99.5% of Ca was precipitated in solutions that contained less than 2% (v/v) HNO(3). Recoveries of the elements obtained from spiked artificial otolith solutions were between 90 and 103%. Stabilization of the elements within the ETV cell was achieved with 0.3mug Pd/0.2mug Rh chemical modifier that also afforded optimum sensitivity for multielement determination. The method was validated by the analysis of a fish otolith reference material (CRM) of emperor snapper, and then applied to the determination of the trace elements in otoliths of several fish species captured in Raritan Bay, New Jersey. Results indicated that fish physiology and biological processes could influence the levels of Cu, Mn, Se and Zn in the otoliths of fish inhabiting a similar aqueous environment. Otolith concentrations of Cr and Ni did not show any significant differences among different species. Concentrations for Ag, As, Cd, Co and Tl were also not significantly different, but were very low indicating low affinity of otolith calcium carbonate to these elements. PMID:18969949

  1. Acid-etched splinting to a ceramometal abutment.

    PubMed

    Jordan, R D; Aquilino, S A; Krell, K V

    1986-05-01

    This technique describes an acid-etch metal splint with a ceramometal abutment. The internal surface of the DuraLingual Wing Form patterns provide undercuts necessary for composite bonding. The external surface provides a smooth solid metal surface when cast. Since this system uses mechanical undercuts, the resin-bonded splints can have multiple try-ins without the detrimental effects of burnishing and contamination that occur with electrolytically etched metal surfaces. If an abutment for a resin-retained fixed partial denture requires a ceramometal crown, a DuraLingual Wing Form can be incorporated onto its lingual surface thereby providing mechanical undercuts for bonding. The opposite undercuts of the crown and splint provide excellent bond strength for the system. PMID:3519944

  2. In-office technique for selectively etching titanium abutments to improve bonding for interim implant prostheses.

    PubMed

    Wadhwani, Chandur; Chung, Kwok-Hung

    2016-03-01

    A technique is described for increasing the surface area of a titanium abutment with hydrofluoric acid etching. This provides mechanical retention for acrylic resin and composite resins and can be easily and rapidly accomplished in both the laboratory and clinic. PMID:26553255

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

    PubMed Central

    Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  5. Focused electron beam induced etching of copper in sulfuric acid solutions

    NASA Astrophysics Data System (ADS)

    Boehme, Lindsay; Bresin, Matthew; Botman, Aurélien; Ranney, James; Hastings, J. Todd

    2015-12-01

    We show here that copper can be locally etched by an electron-beam induced reaction in a liquid. Aqueous sulfuric acid (H2SO4) is utilized as the etchant and all experiments are conducted in an environmental scanning electron microscope. The extent of etch increases with liquid thickness and dose, and etch resolution improves with H2SO4 concentration. This approach shows the feasibility of liquid phase etching for material selectivity and has the potential for circuit editing.

  6. 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.

  7. 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

    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

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

    PubMed

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

    2012-01-01

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

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

    PubMed

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

    2014-02-01

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

  10. Investigation of laser-induced etching of Ti in phosphoric acid

    SciTech Connect

    Nowak, R.J.; Metev, S.M.; Meteva, K.B.; Sepold, G.

    1996-12-31

    Laser-induced chemical etching of Ti in phosphoric acid has been investigated using cw Nd:YAG (1.064 {micro}m) and Argon lasers (514 nm) operating in the fundamental Gaussian mode. Two different regions of etching were observed, which are separated by a characteristic threshold value of the laser power and ascribed to melting of the metal. Below the threshold an exponential dependence of etch rates on laser power suggest a thermally activated etching mechanism. Time-resolved measurements indicate in this region the dissolution of the passivation layer followed by surface etching of the metal grains. After laser illumination an immediate repassivation of the recooled surface stops the etch reaction.

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

    PubMed Central

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

    2014-01-01

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

  12. Direct observation of silicon surface etching by water with scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Pietsch, G. J.; Köhler, U.; Henzler, M.

    1992-09-01

    One of the key processes in wet chemical preparation of silicon surfaces for device fabrication is a final rinsing step with water after oxide removal and hydrogen-termination with hydrofluoric acid. On rinsing at elevated temperature (boiling water) the slow statistical oxidation of the surface known from conventional treatment with water at room temperature is replaced by a rapid anisotropic etching attack. On Si(111) scanning tunneling microscopy shows characteristic triangular etch defects and flat (111) terraces separated by monatomic steps along <0 overline11>. The resulting surface is chemically homogeneous without any oxide. Structure and removal mechanism are compared to NH 4F-etched samples.

  13. Nanoparticle-based etching of silicon surfaces

    SciTech Connect

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

    2011-12-13

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

  14. Graphene-Assisted Chemical Etching of Silicon Using Anodic Aluminum Oxides as Patterning Templates.

    PubMed

    Kim, Jungkil; Lee, Dae Hun; Kim, Ju Hwan; Choi, Suk-Ho

    2015-11-01

    We first report graphene-assisted chemical etching (GaCE) of silicon by using patterned graphene as an etching catalyst. Chemical-vapor-deposition-grown graphene transferred on a silicon substrate is patterned to a mesh with nanohole arrays by oxygen plasma etching using an anodic- aluminum-oxide etching mask. The prepared graphene mesh/silicon is immersed in a mixture solution of hydrofluoric acid and hydro peroxide with various molecular fractions at optimized temperatures. The silicon underneath graphene mesh is then selectively etched to form aligned nanopillar arrays. The morphology of the nanostructured silicon can be controlled to be smooth or porous depending on the etching conditions. The experimental results are systematically discussed based on possible mechanisms for GaCE of Si. PMID:26473800

  15. AgNO3-Dependent Morphological Change of Si Nanostructures Prepared by Single-Step Metal Assisted Etching Method

    NASA Astrophysics Data System (ADS)

    Shimizu, Tomohiro; Yamaguchi, Takuya; Inoue, Fumihiro; Inada, Mitsuru; Shingubara, Shoso

    2012-11-01

    The morphological changes of a nanostructured Si surface prepared by metal assisted etching were investigated. We used a mixture of silver nitrate (AgNO3) and hydrofluoric acid (HF) as an electroless plating bath of Ag, as well as an etching solution of Si. With a change in silver ion concentration in the etching solution, three types of etched Si nanostructures were observed: “nanowire”, “porous wall”, and “polished”. We developed a phase diagram of the morphology of the etched Si surface. With increasing concentration of AgNO3 in the etching solution, the surface morphology of etched Si changes from nanowire to porous wall, and finally, polished for regardless of Si resistivity.

  16. Effects of acid-etching solutions on human enamel and dentin.

    PubMed

    Fanchi, M; Breschi, L

    1995-06-01

    Nine noncarious human molars were extracted and stored in saline solution. Three standard occlusal cavities with beveled enamel margins were prepared on each tooth and etched with the etching solutions of three dentinal adhesive systems: (1) 37% phosphoric acid solution, (2) 4.3% oxalic acid and 2.6% aluminum salts solution, and (3) 10% maleic acid solution. Scanning electron microscopic analysis revealed that all the etching solutions affected the enamel surface morphology. The solution of oxalic acid and aluminum salts removed primarily the prism core material and partially the periphery of the prisms, but did not affect the nonbeveled enamel surface. Phosphoric and maleic acids removed both prism core materials and prism periphery; these specimens also showed areas in which no prism morphology could be detected. These two acids also removed apatite crystals from the prism core of the intact enamel surface. PMID:8602425

  17. 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.

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

    SciTech Connect

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

    1999-04-02

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    PubMed Central

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

    2016-01-01

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

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

  1. Creation of hollow SAPO-34 single crystals via alkaline or acid etching.

    PubMed

    Qiao, Yuyan; Yang, Miao; Gao, Beibei; Wang, Linying; Tian, Peng; Xu, Shutao; Liu, Zhongmin

    2016-04-14

    Hollow SAPO-34 crystals are created via selective etching of their precursor under controlled alkaline or acid conditions. The abundant/interconnected Si-O-Al domains and Si-O-Si networks at the outer layer of SAPO-34 crystals are revealed to be decisive factors for the base and acid treatments respectively to achieve a well-preserved hollow structure. PMID:27042708

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  3. The influence of H2O2 concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Omar, Hafsa; Jani, Abdul Mutalib Md.; Rusop, Mohamad; Abdullah, Saifollah

    2016-07-01

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. EFFECT OF ACID ETCHING OF GLASS IONOMER CEMENT SURFACE ON THE MICROLEAKAGE OF SANDWICH RESTORATIONS

    PubMed Central

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

    2007-01-01

    The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE – conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN – same as Group CIE, except for acid etching of the CI surface; Group RME – same as CIE, but using a resin modified GIC (RMGIC); Group RMN – same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24°C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (α=0.05). Dye penetration scores were as follow: CIE – 2.5; CIN – 2.5; RME – 0.9; and RMN – 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite- dentin interfaces than CI. PMID:19089135

  6. 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

  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. Fabrication of silicon nanowire arrays by macroscopic galvanic cell-driven metal catalyzed electroless etching in aerated HF solution.

    PubMed

    Liu, Lin; Peng, Kui-Qing; Hu, Ya; Wu, Xiao-Ling; Lee, Shuit-Tong

    2014-03-01

    Macroscopic galvanic cell-driven metal catalyzed electroless etching (MCEE) of silicon in aqueous hydrofluoric acid (HF) solution is devised to fabricate silicon nanowire (SiNW) arrays with dissolved oxygen acting as the one and only oxidizing agent. The key aspect of this strategy is the use of a graphite or other noble metal electrode that is electrically coupled with silicon substrate. PMID:24323873

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

    SciTech Connect

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

    2006-11-15

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

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

    PubMed Central

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

    2015-01-01

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

  11. Formation of nanostructured silicon surfaces by stain etching

    PubMed Central

    2014-01-01

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

  12. Formation of nanostructured silicon surfaces by stain etching.

    PubMed

    Ayat, Maha; Belhousse, Samia; Boarino, Luca; Gabouze, Noureddine; Boukherroub, Rabah; Kechouane, Mohamed

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  14. Metal etching composition

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  15. Polymer protective coating for wet deep silicon etching processes

    NASA Astrophysics Data System (ADS)

    Spencer, Mary; Ruben, Kim; Li, Chenghong; Williams, Paul; Flaim, Tony D.

    2003-01-01

    A need exists for spin-applied polymeric coatings to protect electronic circuitry and other sensitive structures on MEMS devices during deep silicon wet etching processes involving corrosive mixtures of aqueous acids and bases. The challenge exists in developing protective coatings that do not decompose or dissolve in the harsh etchants and, more importantly, that maintain good adhesion to the substrate during the sometimes long etching processes. We have developed a multilayer coating system that is stable and adheres well to silicon nitride and other semiconductor materials and affords chemical protection for at least eight hours in hot potassium hydroxide etchant. The same coating system is also compatible with concentrated hydrofluoric acid etchants, which can diffuse rapidly through many polymeric materials to attack the device substrate.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  18. Acid etching does not improve CoCrMo implant osseointegration in a canine implant model.

    PubMed

    Jakobsen, Stig S; Baas, Jorgen; Jakobsen, Thomas; Soballe, Kjeld

    2010-01-01

    Induction of bone ingrowth by topographical changes to implant surfaces is an attractive concept. Topographical modifications achieved by acid etching are potentially applicable to complex 3D surfaces. Using clinically relevant implant models, we explored the effect of wet etching porous bead-coated CoCrMo. The study was designed as two paired animal experiments with 10 dogs. Each dog received four implants; one in each medial femoral condyle (loaded 0.75-mm-gap model) and one in each proximal tibia (press-fit). The implants were observed for 6 weeks and were evaluated by biomechanical pushout tests and histomorphometry. We found that wet etching porous bead-coated CoCrMo implants failed to improve implant performance. Moreover, a tendency towards increased fibrous tissue formation, decreased new bone formation, and decreased mechanical fixation was observed. Surface topography on implants is able to stimulate bone-forming cells, but the clinical performance of an implant surface perhaps relies more on 3D geometrical structure and biocompatibility. Caution should be exercised regarding the results of wet etching of porous bead-coated CoCrMo and there is a need for more preclinical trials. PMID:20544657

  19. Torque Analysis of a Triple Acid-Etched Titanium Implant Surface

    PubMed Central

    Pontes, Ana Emília Farias; de Toledo, Cássio Torres; Garcia, Valdir Gouveia; Ribeiro, Fernando Salimon; Sakakura, Celso Eduardo

    2015-01-01

    The present study aimed to evaluate the removal torque of titanium implants treated with triple acid etching. Twenty-one rats were used in this study. For all animals, the tibia was prepared with a 2 mm drill, and a titanium implant (2 × 4 mm) was inserted after treatment using the subtraction method of triple acid etching. The flaps were sutured. Seven animals were killed 14, 28, and 63 days after implant installation, and the load necessary for removing the implant from the bone was evaluated by using a torque meter. The torque values were as follows: 3.3 ± 1.7 Ncm (14 days), 2.2 ± 1.3 Ncm (28 days), and 6.7 ± 1.4 Ncm (63 days). The torque value at the final healing period (63 days) was statistically significantly different from that at other time points tested (ANOVA, p = 0.0002). This preliminary study revealed that treatment with triple acid etching can create a promising and efficient surface for the process of osseointegration. PMID:26543898

  20. PHOSPHATED, ACID-ETCHED IMPLANTS DECREASE MINERAL APPOSITION RATES NEAR IMPLANTS IN CANINES

    PubMed Central

    Foley, Christine Hyon; Kerns, David G.; Hallmon, William W.; Rivera-Hidalgo, Francisco; Nelson, Carl J.; Spears, Robert; Dechow, Paul C.; Opperman, Lynne A.

    2010-01-01

    Purpose: This study evaluated the effects of phosphate-coated titanium on mineral apposition rate (MAR) and new bone-to-implant contact (BIC) in canines. Materials and Methods: 2.2 mm × 4 mm electrolytically phosphated or non-phosphated titanium implants with acid-etched surfaces were placed in 48 mandibular sites in 6 foxhounds. Tetracycline and calcein dyes were administered 1 week after implant placement and 1 week before sacrifice. At twelve weeks following implant healing, animals were sacrificed. MAR and BIC were evaluated using fluorescence microscopy. Light microscopic and histological evaluation was performed on undecalcified sections. Results: Microscopic evaluation showed the presence of healthy osteoblasts lining bone surfaces near implants. Similar bone-to-implant contact was observed in phosphated and non-phosphated titanium implant sites. MAR was significantly higher near non-phosphated titanium implant surfaces than the phosphated titanium samples. No significant differences were found between dogs or implant sites. Discussion and Conclusion: Acid-etched only implants showed significantly higher mineral apposition rates compared to acid-etched, phosphate-coated implants. PMID:20369085

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

    PubMed Central

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

    2014-01-01

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

  2. Characterization of deep wet etching of glass

    NASA Astrophysics Data System (ADS)

    Iliescu, Ciprian; Chen, Bangtao; Tay, Francis E. H.; Xu, Guolin; Miao, Jianmin

    2006-01-01

    This paper presents a characterization of wet etching of glass in HF-based solutions with a focus on etching rate, masking layers and quality of the generated surface. The first important factor that affects the deep wet etching process is the glass composition. The presence of oxides such as CaO, MgO or Al IIO 3 that give insoluble products after reaction with HF can generate rough surface and modify the etching rate. A second factor that influences especially the etch rate is the annealing process (560°C / 6 hours in N II environment). For annealed glass samples an increase of the etch rate with 50-60% was achieved. Another important factor is the concentration of the HF solution. For deep wet etching of Pyrex glass in hydrofluoric acid solution, different masking layers such as Cr/Au, PECVD amorphous silicon, LPCVD polysilicon and silicon carbide are analyzed. Detailed studies show that the stress in the masking layer is a critical factor for deep wet etching of glass. A low value of compressive stress is recommended. High value of tensile stress in the masking layer (200-300 MPa) can be an important factor in the generation of the pinholes. Another factor is the surface hydrophilicity. A hydrophobic surface of the masking layer will prevent the etching solution from flowing through the deposition defects (micro/nano channels or cracks) and the generation of pinholes is reduced. The stress gradient in the masking layer can also be an important factor in generation of the notching defects on the edges. Using these considerations a special multilayer masks Cr/Au/Photoresist (AZ7220) and amorphous silicon/silicon carbide/Photoresist were fabricated for deep wet etching of a 500 μm and 1mm-thick respectively Pyrex glass wafers. In both cases the etching was performed through wafer. From our knowledge these are the best results reported in the literature. The quality of the generated surface is another important factor in the fabrication process. We notice that the

  3. 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.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-02-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

    Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

    2013-01-01

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

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

    PubMed

    Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

    2013-01-01

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

  9. 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.

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

    DOEpatents

    Copley, Stephen M.; Tao, Hongyi; Todd-Copley, Judith A.

    1991-01-01

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

  11. 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

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

    PubMed Central

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

    2013-01-01

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

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

    SciTech Connect

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

    2014-09-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    PubMed Central

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

    2014-01-01

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

  16. 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.

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

    PubMed Central

    Alsulaimani, Fahad F.

    2014-01-01

    Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (α = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets. PMID:25006465

  18. 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.

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

    PubMed Central

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

    2015-01-01

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

  20. 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

  1. 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 (β) 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 β 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

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  4. Cell adhesion and in vivo osseointegration of sandblasted/acid etched/anodized dental implants.

    PubMed

    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

  5. 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.

  6. Restoration of obliterated engraved marks on steel surfaces by chemical etching reagent.

    PubMed

    Song, Qingfang

    2015-05-01

    Chemical etching technique is widely used for restoration of obliterated engraved marks on steel surface in the field of public security. The consumed thickness of steel surface during restoration process is considered as a major criterion for evaluating the efficiency of the chemical etching reagent. The thinner the consumed thickness, the higher the restoration efficiency. According to chemical principles, maintaining the continuous oxidative capabilities of etching reagents and increasing the kinetic rate difference of the reaction between the engraved and non-engraved area with the chemical etching reagent can effectively reduce the consumed steel thickness. The study employed steel surface from the engine case of motorcycle and the car frame of automobile. The chemical etching reagents are composed of nitric acid as the oxidizer, hydrofluoric acid as the coordination agent and mixed with glacial acetic acid or acetone as the solvents. Based on the performance evaluation of three different etching reagents, the one composed of HNO3, HF and acetone gave the best result. PMID:25771134

  7. Noble Gases and Nitrogen Released from a Lunar Soil Pyroxene Separate by Acid Etching

    NASA Astrophysics Data System (ADS)

    Rider, P. E.

    1993-07-01

    We report initial results from a series of experiments designed to measure recently implanted solar wind (SW) ions in lunar soil mineral grains [1]. An acid-etching technique similar to the CSSE method developed at ETH Zurich was used to make abundance and isotope measurements of the SW noble gas and nitrogen compositions. Among the samples examined was a pyroxene separate from soil 75081. It was first washed with H2O to remove contamination from the sample finger walls and grain surfaces. H2O also acted as a weak acid, releasing gases from near-surface sites. Treatment with H2SO3 followed the water washes. Acid pH (~1.8 to ~1.0) and temperature (~23 degrees C to ~90 degrees C) and duration of acid attack (several minutes to several days) were varied from step to step. Finally, the sample was pyrolyzed in several steps to remove the remaining gases, culminating with a high-temperature pyrolysis at 1200 degrees C. Measurements of the light noble gases were mostly consistent with those from previous CSSE experiments performed on pyroxene [2,3]. It should be noted, however, that the Zurich SEP component was not easily distinguishable in the steps where it was expected to be observed. We suspect our experimental protocol masked the SEP reservoir, preventing us from seeing its distinctive signature. The most interesting results from this sample are its Kr and Xe isotopic and elemental compositions. Pyroxene apparently retains heavy noble gases as well as ilmenite (and plagioclase [4]). The heavy noble gas element ratios from this sample along with those previously reported [5,6] are, however, considerably heavier than the theoretically determined "solar system" values [7,8]. Explanations for the difference include the possibility that the derivations are incorrect, that there is another component of lunar origin mixing with the solar component, or that some type of loss mechanism is altering the noble gas reservoirs of the grains. The Kr and Xe isotopic compositions for

  8. 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

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

    NASA Astrophysics Data System (ADS)

    Nagarah, John M.; Wagenaar, Daniel A.

    2012-03-01

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

  10. Simplified Etching

    ERIC Educational Resources Information Center

    Saranovitz, Norman S.

    1969-01-01

    The process for making a celluoid etching (drypaint technique) is feasible for the high school art room because the use of acid is avoided. The procedure outlined includes; 1) preparation of the plate, 2) inking the plate, 3) printing the plate, 4) tools necessary for the preceding. (BF)

  11. Acid Etching and Surface Coating of Glass-Fiber Posts: Bond Strength and Interface Analysis.

    PubMed

    Cecchin, Doglas; Farina, Ana Paula; Vitti, Rafael Pino; Moraes, Rafael Ratto; Bacchi, Ataís; Spazzin, Aloísio Oro

    2016-01-01

    The aim of this study was to evaluate the bond strength of a composite resin to glass-fiber post (GFP) treated or not with phosphoric acid, silane coupling agent, and unfilled resin. GFPs were etched or not with 37% phosphoric acid and different surface coating applied: silane coupling agent, unfilled resin, or both. Composite resin blocks were built around a 4-mm height on the GFP. Unfilled resin (20 s) and composite resin (40 s) were light activated by a light-emitting diode unit. The specimens were stored in distilled water at 37 °C for 24 h. Microtensile bond test was performed using a mechanical testing machine until failure (n=10). The data were analyzed using two-way ANOVA followed by Student-Newman-Keuls' test (p<0.05). Failure modes were classified as adhesive, mixed, or cohesive failures. Additional specimens (n=3) were made to analyze the bonded interfaces by scanning electron microscopy. The statistical analysis showed the factor 'surface coating' was significant (p<0.05), whereas the factor 'HP etching' (p=0.131) and interaction between the factors (p=0.171) were not significant. The highest bond strength was found for the silane and unfilled resin group (p<0.05). A predominance of adhesive and cohesive failures was found. Differences regarding the homogeneity and thickness of the unfilled resin layer formed by different GFP surface treatments were observed. The application of silane and unfilled resin can improve the bond strength between GFP and resin composite. PMID:27058389

  12. 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

  13. Polymeric protective coatings for MEMS wet-etch processes

    NASA Astrophysics Data System (ADS)

    Ruben, Kimberly A.; Flaim, Tony D.; Li, Chenghong

    2004-01-01

    Microelectromechanical systems (MEMS) device manufacturers today are faced with the challenge of protecting electronic circuitry and other sensitive device structures during deep silicon wet-etch processes. Etch processes of this nature require prolonged exposure of the device to harsh corrosive mixtures of aqueous acids and bases at higher than ambient temperatures. A need exists for a spin-applied polymeric coating to prevent the exposure of such circuitry against the corrosive etchants. The challenge exists in developing protective coatings that will not decompose or dissolve in the etchants during the etch process. Such coatings require superior adhesion to the substrate without destroying the sensitive features below. Brewer Science, Inc., has developed a multilayer coating system for basic etchants which is compatible with a variety of semiconductor materials and offers protection against concentrated potassium hydroxide (KOH) etchants at prolonged exposure times of more than 8 hours. In addition, a second multilayer coating system is being developed for use with strong hydrofluoric and other various mixed acid etchants (MAEs) for exposures of 30 minutes or longer. These materials are specifically designed to protect circuitry subjected to concentrated MAEs during the wafer thinning processes used by MEMS device manufacturers.

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

    PubMed Central

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

    2013-01-01

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

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

    DOEpatents

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

    1991-01-01

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

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

    PubMed

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

    2003-01-01

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

  17. 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

  18. Parallel fabrication of high-aspect-ratio all-silicon grooves using femtosecond laser irradiation and wet etching

    NASA Astrophysics Data System (ADS)

    Li, Yanna; Chen, Tao; Pan, An; Li, Cunxia; Tang, Litie

    2015-11-01

    This paper introduces a simple method using 800 nm femtosecond laser irradiation and wet etching with a hydrofluoric (HF) acid solution for the parallel fabrication of high-aspect-ratio all-silicon groove arrays. In this method, one laser beam was divided into five beams by a diffractive optical element. Five laser-induced structure change (LISC) zones were formed in the silicon simultaneously with a single scan of the divided beams, and then the materials in the LISC zones were etched by HF acid solution to form groove arrays. Via this method, all-silicon grooves with aspect ratios up to 39.4 were produced, and the processing efficiency could be increased by five times in contrast with that of the single laser beam irradiation. Furthermore, high-aspect-ratio grooves with near uniform morphologies were fabricated using this method in silicon wafers with different crystal orientations.

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

    NASA Astrophysics Data System (ADS)

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

    1999-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  1. Instrumentation With Ultrasonic Scalers Facilitates Cleaning of the Sandblasted and Acid-Etched Titanium Implants.

    PubMed

    Park, Jun-Beom; Lee, Sung-Hoon; Kim, NamRyang; Park, Seojin; Jin, Seong-Ho; Choi, Bong-Kyu; Kim, Kack-Kyun; Ko, Youngkyung

    2015-08-01

    Mechanical instrumentation is widely used to debride dental implants, but this may alter the surface properties of titanium, which in turn may influence bacterial adhesion and make it more difficult to remove the biofilm. This in vitro study was performed (1) to assess the amount of biofilm formation on a sand-blasted and acid-etched titanium fixture treated with ultrasonic scalers with metal, plastic, and carbon tips and (2) to evaluate how this treatment of titanium surfaces affects implant cleaning by brushing with dentifrice. The titanium fixtures were treated with various ultrasonic scaler tips, and surface roughness parameters were measured by confocal microscopy. Biofilm was formed on the treated fixtures by using pooled saliva from 10 subjects, and the quantity of the adherent bacteria was compared with crystal violet assay. The fixture surfaces with biofilm were brushed for total of 30 seconds with a toothbrush with dentifrice. The bacteria remaining on the brushed fixture surfaces were quantified by scanning electron microscopy. Surface changes were evident, and the changes of the surfaces were more discernible when metal tips were used. A statistically significant decrease in roughness value (arithmetic mean height of the surface) was seen in the 2 metal-tip groups and the single plastic-tip group. After brushing with dentifrice, the treated surfaces in all the treatment groups showed significantly fewer bacteria compared with the untreated surfaces in the control group, and the parts of the surfaces left untreated in the test groups. Within the limits of this study, treatment of titanium fixture surfaces with ultrasonic metal, plastic, or carbon tips significantly enhanced the bacterial removal efficacy of brushing. Thorough instrumentation that smooths the whole exposed surface may facilitate maintenance of the implants. PMID:24552131

  2. 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.

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

    SciTech Connect

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

    2013-10-14

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

  4. Online process control of acidic texturisation baths with ion chromatography.

    PubMed

    Zimmer, Martin; Oltersdorf, Antje; Rentsch, Jochen

    2009-12-15

    Etching of silicon with mixtures of hydrofluoric acid and nitric acid is a widely used process in silicon solar cell fabrication. One precondition for an optimized usage of the acidic etching baths is the exact knowledge of the chemical bath composition. In this paper, we investigated a fast and online-capable method for the total analysis of all bath constituents by ion chromatography. The chromatographical system consists of a low-volume injection valve, which injects the concentrated samples directly into the KOH-based eluent. After separation and detection of nitrate and fluoride, a post-column derivatization with sodium molybdate is applied to detect the hexafluorosilicic acid, which enriches in the texturisation bath during the etching process. The results of the presented approach are discussed and compared with already published chromatographical and titration methods found in literature. PMID:19836511

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

    PubMed

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

    2016-08-01

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

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Senthil, A.; Ramasamy, P.; Verma, Sunil

    2011-03-01

    Optically good quality semi-organic single crystal of sodium acid phthalate (NaAP) was successfully grown by Sankaranarayanan-Ramasamy (SR) method. Transparent, colourless <0 0 1> oriented unidirectional bulk single crystals of diameters 10 and 20 mm and length maximum up to 75 mm were grown by the SR method. The grown crystals were subjected to various characterization studies such as etching, birefringence, laser damage threshold, UV-vis spectrum and dielectric measurement. The value of birefringence and quality were ascertained by birefringence studies.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed

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

    2013-05-01

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

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

    PubMed

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

    2014-01-01

    The aim of this in vitro study was to observe the effect of hydrofluoric acid (HF) on the surface of two glass ceramics for Cerec and to compare it with the effect on a conventional glass ceramic. Discs were cut from a feldspathic ceramic block (VitaMKII) and from a leucite reinforced glass ceramic (IPS EMPRESS CAD) for Cerec. 5% and 9% HF concentrations were used during 1 min and 2 min each. Afterwards samples were thoroughly water rinsed for 30 s. Half of the 9% HF 1 min samples were subsequently submitted to a complex post-etching cleaning. All samples were observed under a scanning electron microscope (SEM). The conventional feldspathic ceramic samples were built up on a refractory die and a platinum foil. They were treated with 9% HF for 2 min and water rinsed for 30 s. Half of the samples were submitted to the same post-etching cleaning protocol. All samples were examined under SEM and EDX. The Cerec ceramic samples and the platinum foil ones were clean and free of any precipitate after 30 s of water rinsing. Acid concentration, times of application and the postetching cleaning treatment did not influence the cleanliness of the samples. A thick layer of deposit was observed only on the refractory die samples. This was only diminished after the post-etching treatment. The EDX analysis detected the presence of fluoride (F) only on the refractory die samples. PMID:24757699

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

    PubMed

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

    2016-02-01

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

  14. Effect of ceramic etching protocols on resin bond strength to a feldspar ceramic.

    PubMed

    Bottino, M A; Snellaert, A; Bergoli, C D; Özcan, M; Bottino, M C; Valandro, L F

    2015-01-01

    This study sought to evaluate the resin microtensile bond strength (MTBS) stability of a leucite-reinforced ceramic after different ceramic etching protocols. The microtensile test had 40 ceramic blocks (5×5×6 mm) assigned to five groups (n=8), in accordance with the following surface etching protocols: NE nonetched (control); 9HF: hydrofluoric (HF) acid etching (9%HF)+wash/dry; 4HF: 4%HF+wash/dry; 5HF: 5%HF+wash/dry; and 5HF+N: 5%HF+neutralizer+wash/dry+ultrasonic-cleaning. Etched ceramic surfaces were treated with a silane agent. Next, resin cement blocks were built on the prepared ceramic surface and stored for 24 hours in distilled water at 37°C. The specimens were then sectioned to obtain microtensile beams (32/block), which were randomly assigned to the following conditions, nonaged (immediate test) and aged (water storage for 150 days plus 12,000 thermal cycles), before the microtensile test. Bond strength data were submitted to one-way analysis of variance and Tukey test (α=0.05). Additional ceramic samples were subjected to the different ceramic etching protocols and evaluated using a scanning electron microscope (n=2) and atomic force microscopy (n=2). Aging led to a statistically significant decrease in the MTBS for all groups, except the untreated one (NE). Among the groups submitted to the same aging conditions, the untreated (NE) revealed inferior MTBS values compared to the 9HF and 4HF groups. The 5HF and 5HF+N groups had intermediate mean values, being statistically similar to the higher values presented by the 9HF and 4HF groups and to the lower value associated with the NE group. The neutralization procedure did not enhance the ceramic/resin cement bond strength. HF acid etching is a crucial step in resin/ceramic bonding. PMID:25535782

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  16. Influence of Interface Structure on Chemical Etching Process for Air Gap of Microelectromechanical System Based on Surface Micromachining

    NASA Astrophysics Data System (ADS)

    Yoon, Young; Kim, Joon; Polla, Dennis.; Shin, Young

    1998-12-01

    This paper analyses the problems posed by the interface structure during chemical etching by Hydro-fluoric (HF) acid for creating air gaps in microelectromechnical system (MEMS) devices using PZT(53/47) films and surface micromachining techniques. In order to investigate the influence of interface structure on the HF chemical etching process, Pt/PZT/Pt/Ti/TiO2/polysilicon/Si3N4/PSG/Si (Samples A and C) and Pt/PZT/RuO2/Ru/Si3N4/PSG/Si (Sample B) structures were fabricated. These structures are selected for a microcantilever beam and/or an uncooled IR detectors fabricated with PZT piezoelectric/pyroelectric films based on the surface micromachining technique. Both need etching for the removal of phosphor silicate glass (PSG) to create an air gap. If the devices had a poor interface structure, they would fail during the HF chemical etching process because the poor interface structure would act as a kind of penetration path for etching acid leading to unwanted etching. Therefore, it is very important to investigate the interface structure to fabricate efficient MEMS devices. In this study two different solutions have been suggested to improve the interface structure. The first is post thermal annealing at 900°C for 30 min. after deposition of polycrystalline silicon for sample A. Secondly, a RuO2/Ru hybrid electrode was deposited on Si3N4 directly instead of on the Pt/Ti/TiO2/Polysilicon electrode, which has Pt/PZT/RuO2/Ru/Si3N4/PSG/Si as the device structure. These two solutions suggest that a dense interface structure increases enhances of success of the chemical etching process of MEMS devices fabricated using PZT films and surface micromachining techniques.

  17. Mesoporous Iron Oxide Nanoparticles Prepared by Polyacrylic Acid Etching and Their Application in Gene Delivery to Mesenchymal Stem Cells

    PubMed Central

    CAO, BINRUI; QIU, PENGHE; MAO, CHUANBIN

    2013-01-01

    Novel monodisperse mesoporous iron oxide nanoparticles (m-IONPs) were synthesized by a postsynthesis etching approach and characterized by electron microscopy. In this approach, solid iron oxide nanoparticles (s-IONPs) were first prepared following a solvothermal method, and then etched anisotropically by polyacrylic acid to form the mesoporous nanostructures. MTT cytotoxicity assay demonstrated that the m-IONPs have good biocompatibility with mesenchymal stem cells (MSCs). Owing to their mesoporous structure and good biocompatibility, these monodisperse m-IONPs were used as a nonviral vector for the delivery of a gene of vascular endothelial growth factor (VEGF) tagged with a green fluorescence protein (GFP) into the hard-to-transfect stem cells. Successful gene delivery and transfection were verified by detecting the GFP fluorescence from MSCs using fluorescence microscopy. Our results illustrated that the m-IONPs synthesized in this work can serve as a potential nonviral carrier in gene therapy where stem cells should be first transfected and then implanted into disease sites for disease treatment. PMID:23913581

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

    SciTech Connect

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

    2012-02-01

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

  19. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    PubMed

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p < or = 0.05. The results indicated that there was a significant difference in shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that

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

    PubMed Central

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

    2014-01-01

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

  1. Patterning of platinum (Pt) thin films by chemical wet etching in Aqua Regia

    NASA Astrophysics Data System (ADS)

    Köllensperger, P. A.; Karl, W. J.; Ahmad, M. M.; Pike, W. T.; Green, M.

    2012-06-01

    The chemical and physical properties of platinum (Pt) make it a useful material for microelectromechanical systems and microfluidic applications such as lab-on-a-chip devices. Platinum thin-films are frequently employed in applications where electrodes with high chemical stability, low electrical resistance or a high melting point are needed. Due to its chemical inertness it is however also one of the most difficult metals to pattern. The gold standard for patterning is chlorine RIE etching, a capital-intensive process not available in all labs. Here we present simple fabrication protocols for wet etching Pt thin-films in hot Aqua Regia based on sputtered Ti/Pt/Cr and Cr/Pt/Cr metal multilayers. Chromium (Cr) or titanium (Ti) is used as an adhesion layer for the Pt. Cr is used as a hard masking layer during the Pt etch as it can be easily and accurately patterned with photoresist and withstands the Aqua Regia. The Cr pattern is transferred into the Pt and the Cr mask later removed. Only standard chemicals and cleanroom equipment/tools are required. Prior to the Aqua Regia etch any surface passivation on the Pt is needs to be removed. This is usually achieved by a quick dip in dilute hydrofluoric acid (HF). HF is usually also used for wet-etching the Ti adhesion layer. We avoid the use of HF for both steps by replacing the HF-dip with an argon (Ar) plasma treatment and etching the Ti layer with a hydrogen peroxide (H2O2) based etchant.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

    Oikarinen, K S; Nieminen, T M

    1994-12-01

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

  4. Apparatus For Etching Or Depositing A Desired Profile Onto A Surface

    DOEpatents

    Rushford, Michael C.; Britten, Jerald A.

    2004-05-25

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

  5. Scalable shape-controlled fabrication of curved microstructures using a femtosecond laser wet-etching process.

    PubMed

    Bian, Hao; Yang, Qing; Chen, Feng; Liu, Hewei; Du, Guangqing; Deng, Zefang; Si, Jinhai; Yun, Feng; Hou, Xun

    2013-07-01

    Materials with curvilinear surface microstructures are highly desirable for micro-optical and biomedical devices. However, realization of such devices efficiently remains technically challenging. This paper demonstrates a facile and flexible method to fabricate curvilinear microstructures with controllable shapes and dimensions. The method composes of femtosecond laser exposures and chemical etching process with the hydrofluoric acid solutions. By fixed-point and step-in laser irradiations followed by the chemical treatments, concave microstructures with different profiles such as spherical, conical, bell-like and parabola were fabricated on silica glasses. The convex structures were replicated on polymers by the casting replication process. In this work, we used this technique to fabricate high-quality microlens arrays and high-aspect-ratio microwells which can be used in 3D cell culture. This approach offers several advantages such as high-efficient, scalable shape-controllable and easy manipulations. PMID:23623098

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

    PubMed

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

    2012-07-01

    This study aimed to evaluate the in vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste. One hundred and twenty teeth from 30 volunteers were selected. The teeth were assigned to four treatments: no treatment (negative control); 37% phosphoric acid-etching (PAE) (positive control); PAE + resin-modified glass ionomer cement (RMGIC); and, PAE + composite resin. Patients brushed teeth with fluoridated (n = 15) or non-fluoridated (n = 15) toothpastes, so that etched enamel was protected with screens and it was not in contact with the brush bristles. Remineralization was evaluated by means of laser fluorescence (LF), environmental scanning electronic microscopy, and energy dispersive spectrometry after extraction. The LF means were compared by means of Wilcoxon and Mann Whitney tests. Environmental scanning electron microscopy scores were compared among the groups using a Kruskal Wallis test, whereas the Ca/P ratio was evaluated by means of an Analysis of Variance with subparcels (treatments) and Tukey's post-hoc test. There were no statistically significant differences between the tooth pastes and between the orthodontic adhesives evaluated. Most teeth presented only partial enamel remineralization. Therefore, the fluoride released by the RMGIC was not enough to cause increased crystal regrowth in the acid-etched enamel. The use of fluoridated toothpaste did not provide positive additional effect. PMID:22298375

  7. Method for Fabricating Textured High-Haze ZnO:Al Transparent Conduction Oxide Films on Chemically Etched Glass Substrates.

    PubMed

    Park, Hyeongsik; Nam, Sang-Hun; Shin, Myunghun; Ju, Minkyu; Lee, Youn-Jung; Yu, Jung-Hoon; Jung, Junhee; Kim, Sunbo; Ahn, Shihyun; Boo, Jin-Hyo; Yi, Junsin

    2016-05-01

    We developed a technique for forming textured aluminum-doped zinc oxide (ZnO:Al) transparent conductive oxide (TCO) films on glass substrates, which were etched using a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids. The etching depth and surface roughness increased with an increase in the HF content and the etching time. The HF-based residues produced insoluble hexafluorosilicate anion- and oxide impurity-based semipermeable films, which reduced the etching rate. Using a small amount of HCl dissolved the Ca compounds, helping to fragment the semipermeable film. This formed random, complex structures on the glass substrates. The angled deposition of three layers of ZnO:Al led to the synthesis of multiscaled ZnO:Al textures on the glass substrates. The proposed approach resulted in textured ZnO:Al TCO films that exhibited high transmittance (-80%) and high haze (> 40%) values over wavelengths of 400-1000 nm, as well as low sheet resistances (< 18 Ω/sq)..Si tandem solar cells based on the ZnO:Al textured TCO films exhibited photocurrents and cell efficiencies that were 40% higher than those of cells with conventional TCO films. PMID:27483840

  8. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Yun; Wong, Ching-Ping

    2014-12-01

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag

  9. 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.

  10. The Effect of Carbon Dioxide (CO2) Laser on Sandblasting with Large Grit and Acid Etching (SLA) Surface

    PubMed Central

    Foroutan, Tahereh; Ayoubian, Nader

    2013-01-01

    Introduction: The purpose of this study was to investigate the effect of 6W power Carbon Dioxide Laser (CO2) on the biologic compatibility of the Sandblasting with large grit and acid etching (SLA) titanium discs through studying of the Sarcoma Osteogenic (SaOS-2) human osteoblast-like cells viability. Methods: Sterilized titanium discs were used together with SaOS-2 human osteoblast-like cells. 6 sterilized SLA titanium discs of the experimental group were exposed to irradiation by CO2 laser with a power of 6W and 10.600nm wavelength, at fixed frequency of 80Hz during 45 seconds in both pulse and non-contact settings. SaOS-2 human osteoblast-like cells were incubated under 37°C in humid atmosphere (95% weather, 5% CO2) for 72 hours. MTT test was performed to measure the ratio level of cellular proliferation. Results: The results indicated that at 570nm wavelength, the 6W CO2 laser power have not affected the cellular viability. Conclusion: CO2 laser in 6w power has had no effect on the biologic compatibility of the SLA titanium surface PMID:25606313

  11. Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid

    SciTech Connect

    Timothy M. Swager

    2005-03-17

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

  12. 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

  13. 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 μm 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 μm 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.

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

    PubMed Central

    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 μm 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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. 24% Indigenously Prepared Ethylene Diamine Tetra Acetic Acid Compared to Self-Etching Adhesives and their Effect on Shear Bond Strength of Composites in Primary Teeth: An In-vitro Study

    PubMed Central

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

    2015-01-01

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

  19. 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.

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

    PubMed Central

    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

  1. A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process.

    PubMed

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

    2009-03-15

    Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed. PMID:18639982

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

    PubMed

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

    2016-06-01

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

  3. Etching Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Kennedy, B. W.

    1983-01-01

    20-page report reviews methods available for etching specific layers on wafers and discusses automation techniques and features on one particular automated system. Compares two major etching methods, chemical (wet) and plasma (dry), and discusses areas in need of development. Methods covered include "dip-and-dunk" manual method of chemical etching, automated chemical etching, and plasma etching.

  4. Towards refractive index sensitivity of long-period gratings at level of tens of µm per refractive index unit: fiber cladding etching and nano-coating deposition.

    PubMed

    Śmietana, Mateusz; Koba, Marcin; Mikulic, Predrag; Bock, Wojtek J

    2016-05-30

    In this work we report experimental results on optimizing the refractive index (RI) sensitivity of long-period gratings (LPGs) by fiber cladding etching and thin aluminum oxide (Al2O3) overlay deposition. The presented LPG takes advantage of work in the dispersion turning point (DTP) regime as well as the mode transition (MT) effect for higher-order cladding modes (LP09 and LP010). The MT was obtained by depositing Al2O3 overlays with single-nanometer precision using the Atomic Layer Deposition method (ALD). Etching of both the overlay and the fiber cladding was performed using hydrofluoric acid (HF). For shallow etching of the cladding, i.e., DTP observed at next = 1.429 and 1.439 RIU for an LPG with no overlay, followed by deposition of an overlay of up to 167 nm in thickness, HF etching allowed for post-deposition fine-tuning of the overlay thickness resulting in a significant increase in RI sensitivity mainly at the DTP of the LP09 cladding mode. However, at an external RI (next) above 1.39 RIU, the DTP of LP010 was noticed, and its RI sensitivity exceeded 9,000 nm/RIU. Deeper etching of the cladding, i.e., DTP observed for next above 1.45 RIU, followed by the deposition of thicker overlays (up to 201 nm in thickness) allowed the sensitivity to reach values of over 40,000 nm/RIU in a narrow RI range. Sensitivity exceeding 20,000 nm/RIU was obtained in an RI range suitable for label-free biosensing applications. PMID:27410112

  5. Examination of the laser-induced variations in the chemical etch rate of a photosensitive glass ceramic

    NASA Astrophysics Data System (ADS)

    Voges, Melanie; Beversdorff, Manfred; Willert, Chris; Krain, Hartmut

    2007-10-01

    Previous studies in our laboratory have reported that the chemical etch rate of a commercial photosensitive glass ceramic (FoturanTM, Schott Corp., Germany) in dilute hydrofluoric acid is strongly dependent on the incident laser irradiance during patterning at λ=266 nm and λ=355 nm. To help elucidate the underlying chemical and physical processes associated with the laser-induced variations in the chemical etch rate, several complimentary techniques were employed at various stages of the UV laser exposure and thermal treatment. X-ray diffraction (XRD) was used to identify the crystalline phases that are formed in Foturan following laser irradiation and annealing, and monitor the crystalline content as a function of laser irradiance at λ=266 nm and λ=355 nm. The XRD results indicate the nucleation of lithium metasilicate (Li2SiO3) crystals as the exclusive phase following laser irradiation and thermal treatment at temperatures not exceeding 605 °C. The XRD studies also show that the Li2SiO3 density increases with increasing laser irradiance and saturates at high laser irradiance. For our thermal treatment protocol, the average Li2SiO3 crystal diameters are 117.0±10.0 nm and 91.2±5.8 nm for λ=266 nm and λ=355 nm, respectively. Transmission electron microscopy (TEM) was utilized to examine the microscopic structural features of the lithium metasilicate crystals. The TEM results reveal that the growth of lithium metasilicate crystals proceeds dendritically, and produces Li2SiO3 crystals that are ˜700 1000 nm in length for saturation exposures. Optical transmission spectroscopy (OTS) was used to study the growth of metallic silver clusters that act as nucleation sites for the Li2SiO3 crystalline phase. The OTS results show that the (Ag0)x cluster concentration has a dependence on incident laser irradiance that is similar to the etch rate ratios and Li2SiO3 concentration. A comparison between the XRD and optical transmission results and our prior etch rate

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

    PubMed

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

    2016-06-01

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

  7. Effects of heat treating silane and different etching techniques on glass fiber post push-out bond strength.

    PubMed

    Samimi, P; Mortazavi, V; Salamat, F

    2014-01-01

    The aims of this study were to compare two pretreatment methods of a fiber post and to evaluate the effect of heat treatment to applied silane on the push-out bond strength for different levels of root. In this in vitro study, 40 glass fiber posts were divided into five groups (n=8) according to the kind of surface treatment applied. They were then inserted into extracted and endodontically treated human canines using a self-etch resin cement (Panavia F2.0, Kuraray, Japan). Group HF+S = hydrofluoric acid (HF) etching and silane (S) application; group HF+S+WP = HF etching and heat-treated silane application and warmed posts (WP); group H2O2+S = hydrogen peroxide etching and silane application; group H2O2+S+WP = hydrogen peroxide and heat-treated-silane application and warmed post; and group C, the control group, received no pretreatment. After completion of thermal cycling (1000 cycles, 5-55°C), all specimens were cut horizontally to obtain three sections. Each section was subjected to a push-out test, and the test results were analyzed using two-way analysis of variance, post-hoc Tukey honestly significant difference test, and a paired sample t-test (α=0.05). It was found that bond strength was not statistically influenced by the kind of etching material used (p=0.224), but was significantly affected by heat treatment of applied silane (p<0.001). The interaction between these two factors was not statistically significant (p=0.142). Group HF+S+WP showed the highest bond strength (12.56±1.73 MPa) (p<0.05). Scanning electron microscopy revealed the effect of the different treatments on the surface characteristics of posts. In the four pretreated groups, the bond strength decreased significantly from the coronal to the apical root canal sections (p≤0.05). The results of this study show that the use of heat-treated silane significantly enhances the push-out bond strength of the fiber posts to root. HF acid etching with heat-treated silane application led to the

  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.; Ginley, David S.

    1994-01-01

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

  10. Influence of different pre-etching times on fatigue strength of self-etch adhesives to dentin.

    PubMed

    Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Suzuki, Takayuki; Scheidel, Donal D; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

    2016-04-01

    The purpose of this study was to use shear bond strength (SBS) and shear fatigue strength (SFS) testing to determine the influence on dentin bonding of phosphoric acid pre-etching times before the application of self-etch adhesives. Two single-step self-etch universal adhesives [Prime & Bond Elect (EL) and Scotchbond Universal (SU)], a conventional single-step self-etch adhesive [G-aenial Bond (GB)], and a two-step self-etch adhesive [OptiBond XTR (OX)] were used. The SBS and SFS values were obtained with phosphoric acid pre-etching times of 3, 10, or 15 s before application of the adhesives, and for a control without pre-etching. For groups with 3 s of pre-etching, SU and EL showed higher SBS values than control groups. No significant difference was observed for GB among the 3 s, 10 s, and control groups, but the 15 s pre-etching group showed significantly lower SBS and SFS values than the control group. No significant difference was found for OX among the pre-etching groups. Reducing phosphoric acid pre-etching time can minimize the adverse effect on dentin bonding durability for the conventional self-etch adhesives. Furthermore, a short phosphoric acid pre-etching time enhances the dentin bonding performance of universal adhesives. PMID:26918658

  11. Dry etching of metallization

    NASA Technical Reports Server (NTRS)

    Bollinger, D.

    1983-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

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

    2015-01-01

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

  14. Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sand blasting and acid-etching.

    PubMed

    Medvedev, A E; Ng, H P; Lapovok, R; Estrin, Y; Lowe, T C; Anumalasetty, V N

    2016-04-01

    Surface modification techniques are widely used to enhance the biological response to the implant materials. These techniques generally create a roughened surface, effectively increasing the surface area thus promoting cell adhesion. However, a negative side effect is a higher susceptibility of a roughened surface to failure due to the presence of multiple stress concentrators. The purpose of the study reported here was to examine the effects of surface modification by sand blasting and acid-etching (SLA) on the microstructure and fatigue performance of coarse-grained and ultrafine-grained (UFG) commercially pure titanium. Finer grain sizes, produced by equal channel angular pressing, resulted in lower values of surface roughness in SLA-processed material. This effect was associated with greater resistance of the UFG structure to plastic deformation. The fatigue properties of UFG Ti were found to be superior to those of coarse-grained Ti and conventional Ti-6Al-4V, both before and after SLA-treatment. PMID:26703365

  15. 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

  16. 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

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

    PubMed

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

    2016-02-01

    The purpose of the present study was to examine early tissue response and osseointegration in the animal model. The surface morphologies of SLAffinity were characterized using scanning electron microscopy and atomic force microscopy. The microstructures were examined by X-ray diffraction, and hardness was measured by nanoindentation. Moreover, the safety and toxicity properties were evaluated using computer-aided programs and cell cytotoxicity assays. In the animal model, implants were installed in the mandibular canine-premolar area of 12 miniature pigs. Each pig received three implants: machine, sandblasted, large grit, acid-etched, and SLAffinity-treated implants. The results showed that surface treatment did affect bone-to-implant contact (BIC) significantly. At 3 weeks, the SLAffinity-treated implants were found to present significantly higher BIC values than the untreated implants. The SLAffinity treatments enhanced osseointegration significantly, especially at early stages of bone tissue healing. As described above, the results of the present study demonstrate that the SLAffinity treatment is a reliable surface modification method. PMID:26418567

  18. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu(2+)/bicinchoninic acid pair with improved sensitivity.

    PubMed

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

    2016-01-14

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu(2+). The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu(2+)/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu(2+) and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml(-1)) and a wide working range (0.5 to 1000 μg ml(-1)) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications. PMID:26669539

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

    PubMed Central

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

    2015-01-01

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

  20. The Influence of Low-Level Laser on Osseointegration Around Machined and Sandblasted Acid-Etched Implants: A Removal Torque and Histomorphometric Analyses.

    PubMed

    Teixeira, Eduardo Rolim; Torres, Marco Antônio Rambo Osório; Meyer, Kleber Ricardo Monteiro; Zani, Sabrina Rebollo; Shinkai, Rosemary Sadami Arai; Grossi, Márcio Lima

    2015-08-01

    Evaluation of the influence of laser application on osseointegration around implants with different surface characteristics is limited. This study aims to evaluate the influence of low-level lasers on the early stages of osseointegration. Ninety-six external hex implants (3.75 mm × 5.0 mm) were placed in 24 rabbits-one machined and one sandblasted acid-etched per tibia. The rabbits were later divided into the laser group, which received a total dose of 24 J/cm(2) of gallium-aluminum-arsenide laser over 15 days, and a control group. At 16 and 30 days after surgery, removal torque and histomorphometric analyses were performed. No statistical differences in removal torque or histomorphometric analyses were verified between laser and control groups regardless of implant surface (P > .05). Time was the only variable presenting significant differences between measurements (P < .05). Low-level laser had no significant short-term effect on bone-to-implant contact and removal torque values regardless of implant surface characteristics. PMID:23834724

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

    PubMed Central

    Li, Lin-Jie; Kim, So-Nam

    2016-01-01

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

  2. Alkaline etch system qualification

    SciTech Connect

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

    1997-04-01

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

  3. Regulation of Osteoblast Differentiation by Acid-Etched and/or Grit-Blasted Titanium Substrate Topography Is Enhanced by 1,25(OH)2D3 in a Sex-Dependent Manner.

    PubMed

    Olivares-Navarrete, Rene; Hyzy, Sharon L; Boyan, Barbara D; Schwartz, Zvi

    2015-01-01

    This study assessed contributions of micron-scale topography on clinically relevant titanium (Ti) to differentiation of osteoprogenitor cells and osteoblasts; the interaction of this effect with 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3); and if the effects are sex-dependent. Male and female rat bone marrow cells (BMCs) were cultured on acid-etched (A, R a = 0.87 μm), grit-blasted (GB, R a = 3.90 μm), or grit-blasted/acid-etched (SLA, R a = 3.22 μm) Ti. BMCs were sensitive to surface topography and underwent osteoblast differentiation. This was greatest on SLA; acid etching and grit blasting contributed additively. Primary osteoblasts were also sensitive to SLA, with less effect from individual structural components, demonstrated by enhanced local factor production. Sex-dependent responses of BMCs to topography varied with parameter whereas male and female osteoblasts responded similarly to surface treatment. 1α,25(OH)2D3 enhanced cell responses on all surfaces similarly. Effects were sex-dependent and male cells grown on a complex microstructured surface were much more sensitive than female cells. These results indicate that effects of the complex SLA topography are greater than acid etching or grit blasting alone on multipotent BMCs and committed osteoblasts and that individual parameters are sex-specific. The effect of 1α,25(OH)2D3 was sex dependent. The results also suggest that levels of 1α,25(OH)2D3 in the patient may be important in osseointegration. PMID:25945332

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

    PubMed

    Bücker, Stefan; Acker, Jörg

    2012-05-30

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

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

    SciTech Connect

    Toyoda, Noriaki; Yamada, Isao

    2012-11-06

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

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

    PubMed Central

    2015-01-01

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

  7. Sputtered gold mask for deep chemical etching of silicon

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

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

    SciTech Connect

    Maish, A.B.

    1991-01-01

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

  9. 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.

  10. Ion-Assisted Plasma Etching

    NASA Astrophysics Data System (ADS)

    Wang, C. Daniel; Abraham-Shrauner, Barbara

    1996-11-01

    We analyze plasma etching of two-dimensional, long trenches where directed ions modeled by drifted Maxwellian distribution functions and isotropic neutral molecules contribute to the etch rate. Analytic expressions for the etch rates enable the user to plot the etch profiles by using standard computer packages for nonlinear first-order ordinary differential equations for the point and its slope. First, etch profiles are shown for ion-assisted etching where the thermal etching of the neutrals is enhanced by the ions. Second, we show etch profiles of a multiple layer device where one layer is n-type silicon (arsenic doped) that etches isotropically (G.S. Oehrlein, "Reactive Ion Etching," Handbook of Plasma Processing, Technology, Ed. S.M. Rossnagel, et al., Noyes Pub., NJ, 1990) The etch rates for the other layers are in the ion flux-limited regime. The lateral etching of the n-type silicon illustrates the necessity of sidewall passivation for this structure.

  11. Assessment of Microleakage of Class V Composite Resin Restoration Following Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) Laser Conditioning and Acid Etching with Two Different Bonding Systems

    PubMed Central

    Arbabzadeh Zavareh, Farahnaz; Samimi, Pouran; Birang, Reza; Eskini, Massoumeh; Bouraima, Stephane Ayoub

    2013-01-01

    Introduction: The use of laser for cavity preparation or conditioning of dentin and enamelsurfaces as an alternative for dental tissue acid-etch have increased in recent years. Theaim of this in vitro study was to compare microleakage at enamel-composite and dentincompositeinterfaces following Erbium-Doped Yttrium Aluminum Garnet(Er:YAG) laserconditioning or acid-etching of enamel and dentin, hybridized with different bonding systems. Methods: Class V cavities were prepared on the lingual and buccal surfaces of 50 recentlyextracted intact human posterior teeth with occlusal margin in the enamel and gingival marginin the dentin. The cavities were randomly assigned to five groups: group1:conditioned withlaser (Energy=120mJ, Frequency=10Hz, Pulse duration=100μs for Enamel and Energy=80mJ,Frequency=10Hz, Pulse duration=100μs for Dentin) + Optibond FL, group2:conditioned withlaser + etching with 35% phosphoric acid + Optibond FL, group3:conditioned with laser+ Clearfil SE Bond, group 4 (control):acid etched with 35% phosphoric acid + OptibondFL, group 5 (control): Clearfil SE Bond. All cavities were restored using Point 4 compositeresin. All samples were stored in distilled water at 37°c for 24 h, then were thermocycled for500 cycles and immersed in 50% silver nitrate solution for 24 h. The teeth were sectionedbucco-lingually to evaluate the dye penetration. Kruskal-Wallis & Mann-Whitney testswere used for statistical analysis. Results: In occlusal margins, the least microleakage showed in groups 2, 4 and 5. Themaximum microleakage was observed in group 3 (P=0.009). In gingival margins, the leastmicroleakage was recorded in group2, while the most microleakage was found in group5 (P=0.001). Differences between 5 study groups were statistically significant (P<0.05).The microleakage scores were higher at the gingival margins. Conclusion: The use of the Er:YAG laser for conditioning with different dentin adhesivesystems influenced the marginal sealing of composite resin

  12. Motor fuel alkylation process utilizing low acid

    SciTech Connect

    Kocal, J.A.; Imai, T.

    1987-01-06

    A process is described for the alkylation of an isoparaffin with an olefin acting agent comprising contacting the isoparaffin with the olefin acting agent at alkylation conditions in the presence of a catalyst. The catalyst consists essentially of an anhydrous, nonalcoholic mixture of from about 5 to 15 wt. % methyl tert-butyl ether and from 85 to 95 wt. % hydrofluoric acid. The volumetric ratio of hydrofluoric acid to isoparaffin and olefin acting agent is less than 0.75.

  13. Excimer Laser Etching

    SciTech Connect

    Boatner, Lynn A; Longmire, Hu Foster; Rouleau, Christopher M; Gray, Allison S

    2008-04-01

    Excimer laser radiation at a wavelength of = 248 nm represents a new etching method for the preparation of metallographic specimens. The method is shown to be particularly effective for enhancing the contrast between different phases in a multiphase metallographic specimen.

  14. Optical scattering modeling of etched ZnO:Al superstrates and device simulation studies of a-Si:H solar cells with different texture morphologies.

    PubMed

    Yan, Xia; Li, Weimin; Aberle, Armin G; Venkataraj, Selvaraj

    2016-08-20

    Transparent conductive oxide (TCO) materials have been widely used as the front electrodes of thin-film amorphous silicon (a-Si:H) solar cells. To improve the performance of solar cells, textured front TCO is required as the optical layer which effectively scatters the incoming light and thus enhances the photon absorption within the device. One promising TCO material is aluminum-doped zinc oxide (AZO), which is most commonly prepared by magnetron sputtering. After deposition, sputtered AZO films are typically wet-chemically etched using diluted hydrochloric (HCl) or hydrofluoric (HF) acid to obtain rough surface morphologies. In this paper, we report the effects of a textured AZO front electrode on the performance of a-Si:H solar cells based on optical scattering modeling and electrical device simulations, involving four different AZO surface morphologies. The simulated light scattering behaviors indicate that a better textured surface not only scatters more light, but also allows more light get transmitted into the absorber (∼90% of visible light), due to greatly reduced front reflection by the rough surface. Device simulation results show that the two-step AZO texturing process should give improved a-Si:H solar cell performance, with an enhanced short-circuit current density of 16.5  mA/cm2, which leads to a high photovoltaic (PV) efficiency of 9.9%. PMID:27556994

  15. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

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

  16. Enhanced ferro-actuator with a porosity-controlled membrane using the sol-gel process and the HF etching method

    NASA Astrophysics Data System (ADS)

    Kim, KiSu; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2016-01-01

    In this paper, we propose a ferro-actuator using a porous polyvinylidene difluoride (PVDF) membrane. In detail, we fabricated the silica-embedded PVDF membrane using a sol-gel process with PVDF solution and tetraethyl orthosilicate (TEOS) solution, where the size of the silica was determined by the ratio of the PVDF and TEOS solutions. Using hydrofluoric acid (HF) etching, the silica were removed from the silica-embedded PVDF membrane, and porous PVDF membranes with different porosities were obtained. Finally, through absorption of a ferrofluid on the porous PVDF membrane, the proposed ferro-actuator using porous PVDF membranes with different porosities was fabricated. We executed the characterization and actuation test as follows. First, the silica size of the silica-embedded PVDF membrane and the pore size of the porous PVDF membrane were analyzed using scanning electron microscopy (SEM) imaging. Second, energy-dispersive x-ray spectroscopy analysis showed that the silica had clearly been removed from the silica-embedded PVDF membrane by HF etching. Third, through x-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) of the ferro-actuators, we found that more ferrofluids were absorbed by the porous PVDF membrane when the pore of the membrane was smaller and uniformly distributed. Finally, we executed tip displacement and a blocking force test of the proposed ferro-actuator using the porous PVDF membrane. Similar to the VSM result, the ferro-actuator that used a porous PVDF membrane with smaller pores exhibited better actuation performance. The ferro-actuator that used a porous PVDF membrane displayed a tip displacement that was about 7.2-fold better and a blocking force that was about 6.5-fold better than the ferro-actuator that used a pure PVDF membrane. Thus, we controlled the pore size of the porous PVDF membrane and enhanced the actuation performance of the ferro-actuator using a porous PVDF membrane.

  17. Chemical downstream etching of tungsten

    SciTech Connect

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

    1998-07-01

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

  18. 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.

  19. Multiple-mask chemical etching

    NASA Technical Reports Server (NTRS)

    Cannon, D. L.

    1969-01-01

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

  20. Effect of additional etching and ethanol-wet bonding on the dentin bond strength of one-step self-etch adhesives

    PubMed Central

    Ahn, Joonghee; Jung, Kyoung-Hwa; Son, Sung-Ae; Hur, Bock; Kwon, Yong-Hoon

    2015-01-01

    Objectives This study examined the effects of additional acid etching on the dentin bond strength of one-step self-etch adhesives with different compositions and pH. The effect of ethanol wetting on etched dentin bond strength of self-etch adhesives was also evaluated. Materials and Methods Forty-two human permanent molars were classified into 21 groups according to the adhesive types (Clearfil SE Bond [SE, control]; G-aenial Bond [GB]; Xeno V [XV]; Beauti Bond [BB]; Adper Easy Bond [AE]; Single Bond Universal [SU]; All Bond Universal [AU]), and the dentin conditioning methods. Composite resins were placed on the dentin surfaces, and the teeth were sectioned. The microtensile bond strength was measured, and the failure mode of the fractured specimens was examined. The data were analyzed statistically using two-way ANOVA and Duncan's post hoc test. Results In GB, XV and SE (pH ≤ 2), the bond strength was decreased significantly when the dentin was etched (p < 0.05). In BB, AE and SU (pH 2.4 - 2.7), additional etching did not affect the bond strength (p > 0.05). In AU (pH = 3.2), additional etching increased the bond strength significantly (p < 0.05). When adhesives were applied to the acid etched dentin with ethanol-wet bonding, the bond strength was significantly higher than that of the no ethanol-wet bonding groups, and the incidence of cohesive failure was increased. Conclusions The effect of additional acid etching on the dentin bond strength was influenced by the pH of one-step self-etch adhesives. Ethanol wetting on etched dentin could create a stronger bonding performance of one-step self-etch adhesives for acid etched dentin. PMID:25671215

  1. Orthodox etching of HVPE-grown GaN

    SciTech Connect

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

    2006-08-10

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

  2. Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M. P.; Hihn, J. Y.

    2015-11-01

    Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

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

    NASA Astrophysics Data System (ADS)

    Kabaş Sarp, Ayşe S.; Gülsoy, Murat

    2011-03-01

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

  4. 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.

  5. Containment of nitric acid solutions of Plutonium-238

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

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

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

    PubMed

    Sungurtekin-Ekci, Elif; Oztas, Nurhan

    2016-05-01

    The aim of this study was to evaluate the effect of Er,Cr:YSGG laser pre-treatment alone, or associated with acid-etching, on the microtensile bond strength of a resin-based fissure sealant to primary enamel. Twenty-five human primary molars were randomly divided into five groups including (1) 35 % acid etching, (2) 2.5-W laser etching, (3) 3.5-W laser etching, (4) 2.5-W laser etching + acid etching, and (5) 3.5-W laser etching + acid etching. Er,Cr:YSGG laser was used at a wavelength of 2.780 nm and pulse duration of 140-200 μs with a repetition rate of 20 Hz. Following surface pre-treatment, the fissure sealant (ClinPro™, 3M Dental Products) was applied. Each tooth was sectioned and subjected to microtensile testing. Kruskal-Wallis test was used for statistical analysis. The level of significance was set at p < 0.05. The microtensile bond strength values of group 1 were significantly higher than those of group 2, while no statistically significant difference was detected between groups 1, 3, 4, and 5. It was concluded that 3.5-W laser etching produced results comparable to conventional acid etching technique, whereas 2.5-W laser etching was not able to yield adequate bonding performance. PMID:25847685

  7. 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…

  8. Ultrasonic metal etching for metallographic analysis

    NASA Technical Reports Server (NTRS)

    Young, S. G.

    1971-01-01

    Ultrasonic etching delineates microstructural features not discernible in specimens prepared for metallographic analysis by standard chemical etching procedures. Cavitation bubbles in ultrasonically excited water produce preferential damage /etching/ of metallurgical phases or grain boundaries, depending on hardness of metal specimens.

  9. Effects of Acid Treatment on Dental Zirconia: An In Vitro Study

    PubMed Central

    Xie, Haifeng; Shen, Shuping; Qian, Mengke; Zhang, Feimin; Chen, Chen; Tay, Franklin R.

    2015-01-01

    The aim of this study was to evaluate the effects of hydrofluoric (HF) acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C) received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0), 1 day (5HF1, 40HF1), and 5 days (5HF5, 40HF5), while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7) and 14 days (AC14, CI14). X-ray diffraction (XRD) was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM) was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe. PMID:26301413

  10. Submicron patterned metal hole etching

    DOEpatents

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

    2000-01-01

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

  11. 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.

  12. Photosensitive etch protection coating for silicon wet-etch applications

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

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

    SciTech Connect

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

    1991-07-01

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

  14. Decontamination of metals using chemical etching

    DOEpatents

    Lerch, Ronald E.; Partridge, Jerry A.

    1980-01-01

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

  15. Sputter etching of hemispherical bearings

    NASA Technical Reports Server (NTRS)

    Schiesser, R. J.

    1972-01-01

    Technique was developed for fabricating three dimensional pumping grooves on gas bearings by sputter etching. Method eliminates problems such as groove nonuniformity, profile, and finish, which are associated with normal grooving methods.

  16. High aspect ratio silicon etch: A review

    NASA Astrophysics Data System (ADS)

    Wu, Banqiu; Kumar, Ajay; Pamarthy, Sharma

    2010-09-01

    High aspect ratio (HAR) silicon etch is reviewed, including commonly used terms, history, main applications, different technological methods, critical challenges, and main theories of the technologies. Chronologically, HAR silicon etch has been conducted using wet etch in solution, reactive ion etch (RIE) in low density plasma, single-step etch at cryogenic conditions in inductively coupled plasma (ICP) combined with RIE, time-multiplexed deep silicon etch in ICP-RIE configuration reactor, and single-step etch in high density plasma at room or near room temperature. Key specifications are HAR, high etch rate, good trench sidewall profile with smooth surface, low aspect ratio dependent etch, and low etch loading effects. Till now, time-multiplexed etch process is a popular industrial practice but the intrinsic scalloped profile of a time-multiplexed etch process, resulting from alternating between passivation and etch, poses a challenge. Previously, HAR silicon etch was an application associated primarily with microelectromechanical systems. In recent years, through-silicon-via (TSV) etch applications for three-dimensional integrated circuit stacking technology has spurred research and development of this enabling technology. This potential large scale application requires HAR etch with high and stable throughput, controllable profile and surface properties, and low costs.

  17. Controlled in situ etch-back

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  18. 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.

  19. Distributed etched diffraction grating demultiplexer

    NASA Astrophysics Data System (ADS)

    Jafari, Amir

    This doctoral thesis studies the concept of a distributed etched diffraction grating (DEDG) and presents a methodology to engineer the spectral response of the device. The design which incorporates a distributed Bragg reflector (DBR) at the facets of a conventional etched diffraction grating demultiplexer promises for a superior performance in multiple aspects. Where in a conventional etched diffraction grating, smooth vertical deep etched walls are required in order to realize a low insertion loss device; in the DEDG such requirement is significantly mitigated. Deep etched walls are replaced with shallowly etched diffraction grating facets followed by a DBR structure and as a result devices with significantly lower insertion loss are achievable. The feasibility of the application of DEDG as a wavelength demultiplexer was demonstrated through fabrication and characterization of a prototype device. The proof of concept device was fabricated using the state of the art deep UV optical lithography and reactive ion etching in a nano-photonic silicon-on-insulator (SOI) material platform. The fabricated device was then characterized in the lab. Furthermore, incorporation of the DBR structure at the facets of the conventional etched diffraction grating decouples the reflection and diffraction functionalities, rendering the DEDG suitable for spectral response engineering. According to the application, the output spectral response of the device can be tailored through careful design and optimization of the incorporated DBR. In this thesis, through numerical simulations we have shown that functionalities such as polarization independent performance and at top insertion loss envelop are viable. A methodology to engineer the spectral response of the DEDG is discussed in details.

  20. Etching Of Semiconductor Wafer Edges

    DOEpatents

    Kardauskas, Michael J.; Piwczyk, Bernhard P.

    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.

  1. Method of etching zirconium diboride

    SciTech Connect

    Heath, L.S.; Kwiatkowski, B.

    1988-03-31

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

  2. Serially etched shark enameloid observed by incident light microscopy.

    PubMed

    Risnes, S; Fosse, G

    1979-01-01

    Longitudinal and transverse tooth sections of Isurus oxyrinchus were serially etched in 2.6% nitric acid. The changing optical properties of the etched surfaces were observed during the serial etchings, and the descent of the enameloid surfaces was measured. Shark enameloid seems to be less effectively etched by acid than human enamel; this difference may be due to differences in solubility between fluorapatite and hydroxyapatite. Most of the information regarding the structure of the enameloid was gained during the first five of ten etchings. The reflection of light from the surface was influenced by the orientation of the crystallites, longitudinally sectioned crystallites reflecting the light better than transversely sectioned crystallites. The dentinal extensions were continuous with and of the same structure as the underlying dentine. The radial fibers originated from the dentinal extensions, and they both contained organic material and were accompanied by crystallites. When the specimens were imbibed with water the distinctness of the dentinal extensions and radial fibers was improved. PMID:525241

  3. Dry Ice Etches Terrain

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

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

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

  4. 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

  5. Wet Chemical Etching Survey of III-Nitrides

    SciTech Connect

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

    1999-02-04

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

  6. Adiabatic tapered optical fiber fabrication in two step etching

    NASA Astrophysics Data System (ADS)

    Chenari, Z.; Latifi, H.; Ghamari, S.; Hashemi, R. S.; Doroodmand, F.

    2016-01-01

    A two-step etching method using HF acid and Buffered HF is proposed to fabricate adiabatic biconical optical fiber tapers. Due to the fact that the etching rate in second step is almost 3 times slower than the previous droplet etching method, terminating the fabrication process is controllable enough to achieve a desirable fiber diameter. By monitoring transmitted spectrum, final diameter and adiabaticity of tapers are deduced. Tapers with losses about 0.3 dB in air and 4.2 dB in water are produced. The biconical fiber taper fabricated using this method is used to excite whispering gallery modes (WGMs) on a microsphere surface in an aquatic environment. So that they are suitable to be used in applications like WGM biosensors.

  7. Tuning photonic crystal nanocavity modes by wet chemical digital etching

    NASA Astrophysics Data System (ADS)

    Hennessy, K.; Badolato, A.; Tamboli, A.; Petroff, P. M.; Hu, E.; Atatüre, M.; Dreiser, J.; Imamoǧlu, A.

    2005-07-01

    We have developed a wet chemical digital etching technique for tuning the resonant wavelengths of photonic crystal (PC) nanocavities over a wide range of 80nm in precise 2-3nm steps while preserving high cavity quality factors. In one tuning step, a few monolayers of material are removed from the cavity surface by etching a self-formed native oxide in 1mol citric acid. Due to the self-limiting oxide thickness, total tuning range is based only on the number of etch steps, resulting in a highly controlled, digital tuning ability. We have characterized the tuning behavior of GaAs PC defect cavities of both square and triangular lattice symmetry and proven the effectiveness of this method by tuning a mode into resonance with the charged exciton, and then later the biexciton, transition of a single InAs /GaAs self-assembled quantum dot.

  8. Nanostructured porous silicon by laser assisted electrochemical etching

    NASA Astrophysics Data System (ADS)

    Li, J.; Lu, C.; Hu, X. K.; Yang, Xiujuan; Loboda, A. V.; Lipson, R. H.

    2009-08-01

    Nanostructured porous silicon (pSi) was fabricated by combining electrochemical etching with 355 nm laser processing. pSi prepared in this way proves to be an excellent substrate for desorption/ionization on silicon (DIOS) mass spectrometry (MS). Surfaces prepared by electrochemical etching and laser irradiation exhibit strong quantum confinement as evidenced by the observation of a red shift in the Si Raman band at ~520-500 cm-1. The height of the nanostructured columns produced by electrochemical etching and laser processing is on the order of microns compared with tens of nanometers obtained without laser irradiation. The threshold for laser desorption and ionization of 12 mJ/cm2 using the pSi substrates prepared in this work is lower than that obtained for conventional matrix assisted laser desorption ionization (MALDI)-MS using a standard matrix compound such as [alpha]-cyano-4-hydroxycinnamic acid (CHCA; 30 mJ/cm2). Furthermore, the substrates prepared by etching and laser irradiation appear to resist laser damage better than those prepared by etching alone. These results enhance the capability of pSi for the detection of small molecular weight analytes by DIOS-MS.

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

    PubMed

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

    2002-05-01

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

  10. 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....

  11. Plasma Etching Improves Solar Cells

    NASA Technical Reports Server (NTRS)

    Bunyan, S. M.

    1982-01-01

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

  12. 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.

  13. Nanoscrews: Asymmetrical Etching of Silver Nanowires.

    PubMed

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

    2016-08-31

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

  14. Apparatus for edge etching of semiconductor wafers

    NASA Technical Reports Server (NTRS)

    Casajus, A.

    1986-01-01

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

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

    PubMed

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

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG. PMID:26521000

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed Central

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

    2013-01-01

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

  18. 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.

  19. Ion-beam-assisted etching of diamond

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  20. Plasmoids for etching and deposition

    NASA Astrophysics Data System (ADS)

    Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter

    2014-11-01

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

  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. Reactive Ion Etching of Polymers in Oxygen Based Plasmas: a Study of Etch Mechanisms.

    NASA Astrophysics Data System (ADS)

    Graham, Sandra Wolterman

    The reactive ion etching of polymers has been studied in oxygen-based plasmas in an effort to understand the contributions of various mechanisms to the etching of these materials. Of the four active etch mechanisms; surface damage promoted etching, chemical sputtering, chemically enhanced physical sputtering, and direct reactive ion etching; the emphasis of this work has been on determining the relative contribution of direct reactive ion etching to the overall etching process. The etching of photoresist, polyimide, and amorphous carbon in O_2-CF_4 plasmas was studied in an asymmetrical reactive ion etcher at pressures ranging from 5 to 100 mtorr. Etch yield, ion flux, and oxygen atom concentration data were collected. The fit of this data to a linear model proposed by Joubert et al. (J. Appl. Phys., 65, 1989, 5096) was compared to the fit of the data to a nonlinear model proposed by the author. The linear model accounts for contribution due to three of the four etch mechanisms, but does not include contributions due to direct reactive ion etching. The nonlinear model accounts for contributions due to all four etch mechanisms. Experimental results indicate that the nonlinear model provides a better fit to the data than does the linear model. The relative contribution of direct reactive ion etching to the etching of photoresist ranges from 27% to 81% as the pressure decreases from 100 to 5 mtorr. Similar results are obtained for polyimide and amorphous carbon.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2013-11-01

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

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

    DOEpatents

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

    1981-01-01

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

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

    DOEpatents

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

    1979-11-23

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

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

    PubMed

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

    2009-01-01

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

  8. In-Plasma Photo-Assisted Etching

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2015-09-01

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

  9. Laser-driven fusion etching process

    DOEpatents

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

    1987-08-25

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

  10. Laser-driven fusion etching process

    DOEpatents

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

    1989-01-01

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

  11. Etching 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.

  12. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

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

  13. Controlled ion implant damage profile for etching

    DOEpatents

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

    1990-01-01

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

  14. Etching anisotropy mechanisms lead to morphology-controlled silicon nanoporous structures by metal assisted chemical etching.

    PubMed

    Jiang, Bing; Li, Meicheng; Liang, Yu; Bai, Yang; Song, Dandan; Li, Yingfeng; Luo, Jian

    2016-02-01

    The etching anisotropy induced by the morphology and rotation of silver particles controls the morphology of silicon nanoporous structures, through various underlying complex etching mechanisms. The level of etching anisotropy can be modulated by controlling the morphology of the silver catalyst to obtain silicon nanoporous structures with straight pores, cone-shaped pores and pyramid-shaped pores. In addition, the structures with helical pores are obtained by taking advantage of the special anisotropic etching, which is induced by the rotation and revolution of silver particles during the etching process. An investigation of the etching anisotropy during metal assisted chemical etching will promote a deep understanding of the chemical etching mechanism of silicon, and provide a feasible approach to fabricate Si nanoporous structures with special morphologies. PMID:26785718

  15. 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.

  16. Method for dry etching of transition metals

    DOEpatents

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

    1998-01-01

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

  17. Method for dry etching of transition metals

    DOEpatents

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

    1998-09-29

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

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    SciTech Connect

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

    2008-01-09

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

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

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Sriram; Raghavan, Srini

    2008-06-01

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

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

    PubMed

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

    2012-08-27

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  4. Etching with electron beam generated plasmas

    SciTech Connect

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

    2004-11-01

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

  5. Graphene nanoribbons: Relevance of etching process

    SciTech Connect

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

    2015-05-14

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

  6. 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.

  7. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  8. Etching characteristics of LiNbO3 in reactive ion etching and inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Ren, Z.; Heard, P. J.; Marshall, J. M.; Thomas, P. A.; Yu, S.

    2008-02-01

    The etching characteristics of congruent LiNbO3 single crystals including doped LiNbO3 and proton-changed LiNbO3 have been studied in reactive ion etching (RIE) and inductively coupled plasma (ICP) etching tools, using different recipes of gas mixtures. The effects of parameters including working pressure, RIE power, and ICP power are investigated and analyzed by measurement of etching depth, selectivity, uniformity, etched surface state, and sidewall profile by means of focused ion beam etching, energy-dispersive x-ray analysis, secondary ion mass spectroscopy, scanning electron microscopy, and surface profilometry. The effects of a sample carrier wafer coating have also been investigated. Optimized processes with high etching rates, good mask selectivity, and a near-vertical profile have been achieved. Ridge waveguides on proton-exchanged LiNbO3 have been fabricated and optically measured.

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

    SciTech Connect

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

    2009-09-15

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

  10. Characteristics of Indium-Tin Oxide Thin Film Etched by Reactive Ion Etching

    NASA Astrophysics Data System (ADS)

    Yokoyama, Meiso; Li, Jiin; Su, Shui; Su, Yan

    1994-12-01

    Indium-tin oxide (ITO) films coated on glass have been etched by reactive ion etching (RIE) with a gas mixture of Ar and Cl2. The etching rates of ITO films depend strongly on power density, gas pressure, the composition of reactive gases, and the total flow rate of etchants. According to the results from the study, we can postulate that the ITO films' etching follows the ion-assisted chemical etching. A high etching rate above 100 Å/min can be achieved, and an etching mechanism will be proposed. The selectivity of ITO films to glass reaches 35 with a 30 line/mm pattern. After exposure of ITO films to an Ar/Cl2 mixed gas plasma discharge, their sheet resistance does not markedly change. The residue of Cl atoms exists only in the region near the surface. By means of parameter control, we can obtain good pattern images of ITO films measured by scanning electron microscopy (SEM).

  11. 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.

  12. 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

  13. Galvanic etch stop for Si in KOH

    NASA Astrophysics Data System (ADS)

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

    2004-08-01

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

  14. Fe-catalyzed etching of graphene layers

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

    2012-01-01

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

  16. Etching-limiting process and origin of loading effects in silicon etching with hydrogen chloride gas

    NASA Astrophysics Data System (ADS)

    Morioka, Naoya; Suda, Jun; Kimoto, Tsunenobu

    2014-01-01

    The etching-limiting step in slow Si etching with HCl/H2 at atmospheric pressure was investigated. The etching was performed at a low etching rate below 10 nm/min in the temperature range of 1000-1100 °C. In the case of bare Si etching, it was confirmed that the etching rate showed little temperature dependence and was proportional to the equilibrium pressure of the etching by-product SiCl2 calculated by thermochemical analysis. In addition, the etching rates of Si(100) and (110) faces were almost the same. These results indicate that SiCl2 diffusion in the gas phase is the rate-limiting step. In the etching of the Si surface with SiO2 mask patterns, a strong loading effect (mask/opening pattern dependence of the etching rate) was observed. The simulation of the diffusion of gas species immediately above the Si surface revealed that the loading effect was attributed to the pattern-dependent diffusion of SiCl2.

  17. Dry etching method for compound semiconductors

    DOEpatents

    Shul, Randy J.; Constantine, Christopher

    1997-01-01

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

  18. 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.

  19. Method of sputter etching a surface

    DOEpatents

    Henager, Jr., Charles H.

    1984-01-01

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

  20. Electroless epitaxial etching for semiconductor applications

    DOEpatents

    McCarthy, Anthony M.

    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. 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.

  2. Etching Semiconductors With Beams Of Reactive Atoms

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K.; Giapis, Konstantinos P.; Moore, Teresa A.

    1995-01-01

    Method of etching semiconductors with energetic beams of electrically neutral, but chemically reactive, species undergoing development. Enables etching of straight walls into semiconductor substrates at edges of masks without damage to underlying semiconductor material. In addition to elimination of charge damage, technique reduces substrate bombardment damage because translational energy of neutral species in range 2-12 eV, below damage threshold of many semiconductor materials. Furthermore, low-energy neutrals cause no mask erosion allowing for etching features with very high aspect ratios.

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

    SciTech Connect

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

    2012-07-01

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

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

    DOEpatents

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

    1992-01-01

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

  5. Dry Etching of Organic Low Dielectric Constant Film without Etch Stop Layer

    NASA Astrophysics Data System (ADS)

    Mizumura, Michinobu; Fukuyama, Ryouji; Oomoto, Yutaka

    2002-04-01

    We investigated the trade-off between the increase of etch rate and the control of subtrenching in H2/N2 etching of a SiLK film (SiLK is a trademark of The Dow Chemical Company) without an etch stop layer for a Cu/low-k dual damascene structure. Based on our results, it is clear that the re-incident distribution of the reaction product influenced the mechanism of subtrenching strongly. As H etchant had the ability to remove the reaction product efficiently, we have successfully obtained good etching performance (an average etch rate of 128 nm/min, no subtrenching, and an etch rate uniformity of 8.9% within a 200 mm wafer) using an H2 high-flow-rate process in order to increase the amount of H etchant.

  6. Back-etch method for plan view transmission electron microscopy sample preparation of optically opaque films.

    PubMed

    Yao, Bo; Coffey, Kevin R

    2008-04-01

    Back-etch methods have been widely used to prepare plan view transmission electron microscopy (TEM) samples of thin films on membranes by removal of the Si substrate below the membrane by backside etching. The conventional means to determine when to stop the etch process is to observe the color of the light transmitted through the sample, which is sensitive to the remaining Si thickness. However, most metallic films thicker than 75 nm are opaque, and there is no detectable color change prior to film perforation. In this paper, a back-etch method based on the observation of an abrupt change of optical reflection contrast is introduced as a means to determine the etch endpoint to prepare TEM samples for these films. As the acid etchant removes the Si substrate material a rough interface is generated. This interface becomes a relatively smooth and featureless region when the etchant reaches the membrane (film/SiO2). This featureless region is caused by the mirror reflection of the film plane (film/SiO2 interface) through the optically transparent SiO2 layer. The lower etch rate of SiO2 (compared with Si) gives the operator enough time to stop the etching without perforating the film. A clear view of the morphology and control of Si roughness during etching are critical to this method, which are discussed in detail. The procedures of mounting wax removal and sample rinsing are also described in detail, as during these steps damage to the membrane may easily occur without appropriate consideration. As examples, the preparation of 100-nm-thick Fe-based amorphous alloy thin film and 160-nm-thick Cu-thin film samples for TEM imaging is described. PMID:18227137

  7. Epoxy bond and stop etch fabrication method

    DOEpatents

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

    2000-01-01

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

  8. 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

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

    DOEpatents

    Koontz, Steven L.; Cross, Jon B.

    1993-01-01

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

  10. 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.

  11. Enhancement of RIE: etched Diffractive Optical Elements surfaces by using Ion Beam Etching

    NASA Astrophysics Data System (ADS)

    Schmitt, J.; Bischoff, Ch.; Rädel, U.; Grau, M.; Wallrabe, U.; Völklein, F.

    2015-09-01

    Shaping of laser light intensities by using Diffractive Optical Elements allows the adaption of the incident light to its application. Fused silica is used where for example UV-light or high temperatures are mandatory. For high diffraction efficiency the quality of the etched surface areas is important. The investigation of different process parameters for Ion Beam and Reactive Ion Etching reveals that only Ion Beam Etching provides surfaces with optical quality. Measurements of the influence of the surface quality on the diffraction efficiencies prove that the surfaces generated by Reactive Ion Etching are not suitable. Due to the high selectivity of the process Reactive Ion Etching is nevertheless a reasonable choice for the fabrication of Diffractive Optical Elements. To improve the quality of the etched surfaces a post processing with Ion Beam Etching is developed. Simulations in MATLAB display that the angle dependent removal of the surface during the Ion Beam Etching causes a smoothing of the surface roughness. The positive influence of a post processing on the diffraction efficiency is outlined by measurements. The ion beam post processing leads to an increase of the etching depth. For the fabrication of high efficient Diffractive Optical Elements this has to be taken into account. The relation is investigated and transferred to the fabrication of four-level gratings. Diffraction efficiencies up to 78 % instead of the ideal 81 % underline the practicability of the developed post processing.

  12. Optimization of inductively coupled plasma deep etching of GaN and etching damage analysis

    NASA Astrophysics Data System (ADS)

    Qiu, Rongfu; Lu, Hai; Chen, Dunjun; Zhang, Rong; Zheng, Youdou

    2011-01-01

    Inductively coupled plasma (ICP) etching of GaN with an etching depth up to 4 μm is systemically studied by varying ICP power, RF power and chamber pressure, respectively, which results in etch rates ranging from ∼370 nm/min to 900 nm/min. The surface morphology and damages of the etched surface are characterized by optical microscope, scanning electron microscope, atomic force microscopy, cathodoluminescence mapping and photoluminescence (PL) spectroscopy. Sub-micrometer-scale hexagonal pits and pillars originating from part of the structural defects within the original GaN layer are observed on the etched surface. The density of these surface features varies with etching conditions. Considerable reduction of PL band-edge emission from the etched GaN surface indicates that high-density non-radiative recombination centers are created by ICP etching. The density of these non-radiative recombination centers is found largely dependent on the degree of physical bombardments, which is a strong function of the RF power applied. Finally, a low-surface-damage etch recipe with high ICP power, low RF power, high chamber pressure is suggested.

  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: Yesterday, today, and tomorrow

    SciTech Connect

    Donnelly, Vincent M.; Kornblit, Avinoam

    2013-09-15

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

  16. Etching studies on lutetium yttrium orthosilicate LuxY2-xSiO5:Ce (LYSO) scintillator crystals

    NASA Astrophysics Data System (ADS)

    Péter, Á.; Berze, N.; Lengyel, K.; Lörincz, E.

    2010-11-01

    Surface dissolution has been investigated on {100}, {010}, {001}, {110} and {101} oriented Lu1.6Y0.4SiO5:Ce crystal samples by using orthophosphoric acid up to 180°C. Depending on the etching temperature and surface orientation smooth or bunched surfaces were produced. In order to study the effect of the etching process on the scintillation properties temperature dependent optical absorption measurements were carried out up to 236°C. It was found that depending on the post-growth history of the sample, etching may influence the scintillation mechanism by modifying the concentration of shallow traps.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  18. Incorporation of stratospheric acids into water ice

    NASA Technical Reports Server (NTRS)

    Elliott, Scott; Turco, Richard P.; Toon, Owen B.; Hamill, Patrick

    1990-01-01

    Hydrochloric and hydrofluoric acids are absorbed within the water ice lattice at mole fractions maximizing below 0.00001 and 0.0001 in a variety of solid impurity studies. The absorption mechanism may be substitutional or interstitial, leading in either case to a weak permeation of stratospheric ices by the acids at equilibrium. Impurities could also inhabit grain boundaries, and the acid content of atmospheric ice crystals will then depend on details of their surface and internal microstructures. Limited evidence indicates similar properties for the absorption of HNO3. Water ice lattices saturated with acid cannot be a significant local reservoir for HCl in the polar stratosphere.

  19. An Effective Acid Combination for Enhanced Properties and Corrosion Control of Acidizing Sandstone Formation

    NASA Astrophysics Data System (ADS)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham

    2016-03-01

    To fulfill the demand of the world energy, more technologies to enhance the recovery of oil production are being developed. Sandstone acidizing has been introduced and it acts as one of the important means to increase oil and gas production. Sandstone acidizing operation generally uses acids, which create or enlarge the flow channels of formation around the wellbore. In sandstone matrix acidizing, acids are injected into the formation at a pressure below the formation fracturing pressure, in which the injected acids react with mineral particles that may restrict the flow of hydrocarbons. Most common combination is Hydrofluoric Acid - Hydrochloric with concentration (3% HF - 12% HCl) known as mud acid. But there are some problems associated with the use of mud acid i.e., corrosion, precipitation. In this paper several new combinations of acids were experimentally screened to identify the most effective combination. The combinations used consist of fluoboric, phosphoric, formic and hydrofluoric acids. Cores were allowed to react with these combinations and results are compared with the mud acid. The parameters, which are analyzed, are Improved Permeability Ratio, strength and mineralogy. The analysis showed that the new acid combination has the potential to be used in sandstone acidizing.

  20. UV laser activated digital etching of GaAs

    SciTech Connect

    Meguro, T.; Aoyagi, Y.

    1996-12-31

    The self-limited etching characteristics of digital etching employing an UV laser/Cl{sub 2}/GaAs system are presented. The self-limiting nature is the key mechanism and plays an important role in digital etching for obtaining etch rates independent of etching parameters. Surface processes based on photodissociation of physisorbed chlorine on GaAs with diffusion of negatively charged Cl into GaAs are also discussed.

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

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

    Coleman, Thomas P.; Buck, Peter D.

    1995-12-01

    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 controlled via a microprocessor- controlled etch system with a highly accurate parameter-metering system that ensures greater process control. Using design-of-experiment methodologies, a chrome plasma etch process (using OCG-895i) was developed. This work proves the feasibility of plasma etching chromium patterns on photomasks. The results show an etch that has excellent uniformity, is anisotropic, and has excellent edge quality. Also, resist selectivity is high for the etching of thin chrome films. SEM results show a significant reduction in the bias needed to achieve nominal CDs. As with many dry etch processes, loading and microloading effects (i.e., localized pattern density effect on etch rates) are a concern. Initial investigations of loading and microloading effects were conducted. Results suggest that due to the high anisotropy of the etch, microloading is not an issue. However, plate loading (or the amount of chrome removed) increases etch times and can result in radial etch patterns. Loading effects must be minimized or eliminated to optimize etch uniformity.

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

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1989-01-01

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

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

    SciTech Connect

    ZAIDI, SALEEM H

    2002-05-01

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

  5. Dry etched SiO2 Mask for HgCdTe Etching Process

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl2 plasmas, as a function of rf bias power or ion incident energy Ei, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on Ei: one is the roughening mode at low Ei < 200-300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing Ei, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher Ei, where the rms surface roughness decreases substantially with Ei down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on Ei were also observed in the etch rate versus √{Ei } curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing Ei were found to correspond to changes in the predominant ion flux from feed gas ions Clx+ to ionized etch products SiClx+ caused by the increased etch rates at increased Ei, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  7. Dry etched SiO2 Mask for HgCdTe Etching Process

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. Process capability of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Takai, Kosuke; Iida nee Sakurai, Noriko; Kamo, Takashi; Morikawa, Yasutaka; Hayashi, Naoya

    2015-10-01

    With shrinking pattern size at 0.33NA EUV lithography systems, mask 3D effects are expected to become stronger, such as horizontal/vertical shadowing, best focus shifts through pitch and pattern shift through focus. Etched multilayer EUV mask structures have been proposed in order to reduce mask 3D effects. It is estimated that etched multilayer type mask is also effective in reducing mask 3D effects at 0.33NA with lithographic simulation, and it is experimentally demonstrated with NXE3300 EUV Lithography system. We obtained cross-sectional TEM image of etched multilayer EUV mask pattern. It is observed that patterned multilayer width differs from pattern physical width. This means that effective reflecting width of etched multilayer pattern is smaller than pattern width measured by CD-SEM. In this work, we evaluate mask durability against both chemical and physical cleaning process to check the feasibility of etched multilayer EUV mask patterning against mask cleaning for 0.33NA EUV extension. As a result, effective width can be controlled by suitable cleaning chemicals because sidewall film works as a passivation film. And line and space pattern collapse is not detected by DUV mask pattern inspection tool after mask physical cleaning that includes both megasonic and binary spray steps with sufficient particle removal efficiency.

  9. 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.

  10. Pulsed plasma etching for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Economou, Demetre J.

    2014-07-01

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

  11. Patterning enhancement techniques by reactive ion etch

    NASA Astrophysics Data System (ADS)

    Honda, Masanobu; Yatsuda, Koichi

    2012-03-01

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

  12. Low radio frequency biased electron cyclotron resonance plasma etching

    NASA Astrophysics Data System (ADS)

    Samukawa, Seiji; Toyosato, Tomohiko; Wani, Etsuo

    1991-03-01

    A radio frequency (rf) biased electron cyclotron resonance (ECR) plasma etching technology has been developed to realize an efficient ion acceleration in high density and uniform ECR plasma for accurate Al-Si-Cu alloy film etching. In this technology, the substrate is located at the ECR position (875 G position) and the etching is carried out with a 400 kHz rf bias power. This Al-Si-Cu etching technology achieves a high etching rate (more than 5000 A/min), excellent etching uniformity (within ±5%), highly anisotropic etching, and Cu residue-free etching in only Cl2 gas plasma. These etching characteristics are accomplished by the combination of the dense and uniform ECR plasma generation at the ECR position with the efficient accelerated ion flux at the ECR position by using 400 kHz rf bias.

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

    PubMed

    Uşümez, Serdar; Orhan, Metin; Uşümez, Aslihan

    2002-12-01

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

  14. ICP Etching of SiC

    SciTech Connect

    Grow, J.M.; Lambers, E.S.; Ostling, M.; Pearton, S.J.; Ren, F.; Shul, R.J.; Wang, J.J.; Zetterling, C.-M.

    1999-02-04

    A number of different plasma chemistries, including NF{sub 3}/O{sub 2}, SF{sub 6}/O{sub 2}, SF{sub 6}/Ar, ICl, IBr, Cl{sub 2}/Ar, BCl{sub 3}/Ar and CH{sub 4}/H{sub 2}/Ar, have been investigated for dry etching of 6H and 3C-SiC in a Inductively Coupled Plasma tool. Rates above 2,000 {angstrom} cm{sup {minus}1} are found with fluorine-based chemistries at high ion currents. Surprisingly, Cl{sub 2}-based etching does not provide high rates, even though the potential etch products (SiCi{sub 4} and CCl{sub 4}) are volatile. Photoresist masks have poor selectivity over SiC in F{sub 2}-based plasmas under normal conditions, and ITO or Ni are preferred.

  15. Solderability enhancement of copper through chemical etching

    SciTech Connect

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

    1995-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

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

    PubMed

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

    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

  18. 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

  19. Purified water etching of native oxides on heteroepitaxial CdTe thin films

    NASA Astrophysics Data System (ADS)

    Meinander, Kristoffer; Carvalho, Jessica L.; Miki, Carley; Rideout, Joshua; Jovanovic, Stephen M.; Devenyi, Gabriel A.; Preston, John S.

    2014-12-01

    The etching of native oxides on compound semiconductors is an important step in the production of electronic and optoelectronic devices. Although it is known that the native oxide on CdTe can be etched through a rinsing in purified water, a deeper investigation into this process has not been done. Here we present results on both surface morphology changes and reaction rates for purified water etching of the native oxide on heteroepitaxial CdTe thin films, as studied by atomic force microscopy and x-ray photoelectron spectroscopy. Together with a characterization of both the structure and stoichiometry of the initial native oxide, we show how an altering of the pH-level of the etchant will affect the etching rates. If oxide regrowth was allowed, constant etching rates could be observed for all etchants, while a logarithmic decrease in oxide thickness was observed if regrowth was inhibited. Both acidic and basic etchants proved to be more efficient than neutral water.

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

    SciTech Connect

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

    2014-08-04

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Stráský, Josef; Havlíková, Jana; Bačáková, Lucie; Harcuba, Petr; Mhaede, Mansour; Janeček, Miloš

    2013-09-01

    Presented work aims at multi-method characterization of combined surface treatment of Ti-6Al-4V alloy for biomedical use. Surface treatment consists of consequent use of electric discharge machining (EDM), acid etching and shot peening. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. Acid etching by strong Kroll's reagent is capable of removing surface layer of transformed material created by EDM. Acid etching also creates partly nanostructured surface and significantly contributes to the enhanced proliferation of the bone cells. The cell growth could be positively affected by the superimposed bone-inspired structure of the surface with the morphological features in macro-, micro- and nano-range. Shot peening significantly improves poor fatigue performance after EDM. Final fatigue performance is comparable to benchmark electropolished material without any adverse surface effect. The proposed three-step surface treatment is a low-cost process capable of producing material that is applicable in orthopedics.

  3. Wettability investigating on the wet etching textured multicrystalline silicon wafer

    NASA Astrophysics Data System (ADS)

    Liu, Xiangju; Niu, Yuchao; Zhai, Tongguang; Ma, Yuying; Zhen, Yongtai; Ma, Xiaoyu; Gao, Ying

    2016-02-01

    In order to investigate the wettability properties of multicrystalline silicon (mc-Si), the different surface structures were fabricated on the as-cut p-type multi-wire slurry sawn mc-Si wafers, such as as-cut, polished and etched in various acid solutions. The contact angles and the XRD spectra of these samples were measured. It was noted that both the surface structures and the use of surfactant, such as Tween 80, made a stronger effect on wettability of the Si wafer. Due to the lipophilic groups of Tween 80 combined with the Si atoms while the hydrophilic groups of it were outward, a lipophilic surface of Si changed into a hydrophilic one and the rougher the surface, the stronger the hydrophily. Thus, it is feasible to add an appropriate surfactant into the etching solution during black-Si wafer fabrication for solar cells. In addition, different crystal plains of Si had different dangling bond density, so that their surface energies were different. A surface with higher surface energy could attract more water atoms and its wettability was better. However, the effect of crystal plain on the surface wettability was much weaker than surface morphology.

  4. Dynamic observation of electrochemical etching in silicon

    SciTech Connect

    Ross, F.M.; Searson, P.C.

    1995-03-01

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

  5. Dry etching of III-V nitrides

    SciTech Connect

    Pearton, S.J.; Shul, R.J.; McLane, G.F.; Constantine, C.

    1995-12-01

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

  6. Technique for etching monolayer and multilayer materials

    DOEpatents

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  7. 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.

  8. Multilayer Badges Indicate Depths Of Ion Sputter Etches

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Multilayer badges devised to provide rapid, in-place indications of ion sputter etch rates. Badges conceived for use in estimating ion erosion of molybdenum electrodes used in inert-gas ion thrustors. Concept adapted to measure ion erosion in industrial sputter etching processes used for manufacturing of magnetic, electronic, and optical devices. Badge etched when bombarded by energetic ions. Badge layers exposed using mask. Contrast between layers facilitates counting of layers to determine etch depth.

  9. Anodic etching of p-type cubic silicon carbide

    NASA Technical Reports Server (NTRS)

    Harris, G. L.; Fekade, K.; Wongchotigul, K.

    1992-01-01

    p-Type cubic silicon carbide was anodically etched using an electrolyte of HF:HCl:H2O. The etching depth was determined versus time with a fixed current density of 96.4 mA/sq cm. It was found that the etching was very smooth and very uniform. An etch rate of 22.7 nm/s was obtained in a 1:1:50 HF:HCl:H2O electrolyte.

  10. High index contrast polysiloxane waveguides fabricated by dry etching

    SciTech Connect

    Madden, S. J.; Zhang, M. Y.; Choi, D.-Y.; Luther-Davies, B.; Charters, R.

    2009-05-15

    The authors demonstrate the production of low loss enhanced index contrast waveguides by reactive ion etching of IPG trade mark sign polysiloxane thin films. The use of a silica mask and CHF{sub 3}/O{sub 2} etch gas led to large etch selectivity between the silica and IPG trade mark sign of >20 and etch rates of >100 nm/min. This work indicates that compact optical circuits could be successfully fabricated for telecommunication applications using polysiloxane films.

  11. Optimization of Track Etched Makrofol Etching Conditions for Short-term Exposure Duration

    NASA Astrophysics Data System (ADS)

    Moreno, V.; Font, Ll.

    Exposure time of nuclear track detectors at humid environments is normally limited to a few weeks because filter used to avoid humidity is not completely waterproof and, after several months, some parts of detector start to degrade. In other really extreme measurement conditions, like high aerosol content, high or low temperatures, etc., the exposure time also requires a reduction. Then detector detection limit becomes a problem, unless radon concentrations were high. In those cases where radon levels are not high enough a better detection efficiency is required. In our laboratory we use passive detectors based on the track etched Makrofol DE foil covered with aluminized Mylar and they are analyzed by means of an electrochemical etching. Our standard etching conditions allow analyzing detectors generally exposed for periods between three and six months. We have optimized our etching conditions to reduce the exposure time down to a month for common radon concentration values.

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

    DOEpatents

    Hankins, Dale E.

    1987-01-01

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

  13. New phase formation in titanium aluminide during chemical etching

    SciTech Connect

    Takasaki, Akito; Ojima, Kozo; Taneda, Youji . Dept. of Mathematics and Physics)

    1994-05-01

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

  14. 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.

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

    PubMed

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

    2012-12-01

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

  16. 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

  17. Novel strategy for the design of highly transparent ArF resists with excellent dry etch resistance

    NASA Astrophysics Data System (ADS)

    Zhao, Wenwei; Ohfuji, Takeshi; Sasago, Masaru; Tagawa, Seiichi

    1998-06-01

    To circumvent the difficulty in seeking a balance between dry etch resistance and the transparency at 193 nm in the design of a single-layer-resist for ArF lithography, a new strategy based on the de-coupling of these two criteria from each other is presented. The possibility of the de-coupling has been demonstrated by imparting dry etch resistance to resist matrix after the exposure step. Imparting of dry etch resistance can be achieved with the utilization of thermal- activated reactions during post exposure bake or plasma- activated reactions during etching. Specifically, copolymers containing acrylonitrile were synthesized and evaluated as a demonstration. Chemical reactions, especially cyclization reaction, in the copolymers upon heating were investigated. Intramolecular cyclization of the nitrile groups, which is electrophilic reagent catalyzed, starts at about 130 degree(s)C in a copolymer of acrylonitrile containing 50 mol% methacrylic acid. The reaction results in rigid ring structures with satisfying dry etch resistance. Dry etch resistance of the copolymer after thermal treatment was measured to be up to the same level of a poly(hydroxystyrene)-based commercial resist. Partially protection of the acid component by introducing tertiary- butyl ester groups provides new chemically amplified resist candidates. The materials based on terpolymers of acrylonitrile, tertiary-butyl methacrylate and methacrylic acid well satisfy the basic requirements for ArF resists with high transparency at 193 nm and excellent dry etch resistance after prolonged post exposure bake. Lithographic performance of the newly designed materials are currently under further assessments..

  18. Development of Wet-Etching Tools for Precision Optical Figuring

    SciTech Connect

    Rushford, M C; Dixit, S N; Hyde, R; Britten, J A; Nissen, J; Aasen, M; Toeppen, J; Hoaglan, C; Nelson, C; Summers, L; Thomas, I

    2004-01-27

    This FY03 final report on Wet Etch Figuring involves a 2D thermal tool. Its purpose is to flatten (0.3 to 1 mm thickness) sheets of glass faster thus cheaper than conventional sub aperture tools. An array of resistors on a circuit board was used to heat acid over the glass Optical Path Difference (OPD) thick spots and at times this heating extended over the most of the glass aperture. Where the acid is heated on the glass it dissolves faster. A self-referencing interferometer measured the glass thickness, its design taking advantage of the parallel nature and thinness of these glass sheets. This measurement is used in close loop control of the heating patterns of the circuit board thus glass and acid. Only the glass and acid were to be moved to make the tool logistically simple to use in mass production. A set of 4-circuit board, covering 80 x 80-cm aperture was ordered, but only one 40 x 40-cm board was put together and tested for this report. The interferometer measurement of glass OPD was slower than needed on some glass profiles. Sometimes the interference fringes were too fine to resolve which would alias the sign of the glass thickness profile. This also caused the phase unwrapping code (FLYNN) to struggle thus run slowly at times taking hours, for a 10 inch square area. We did extensive work to improve the speed of this code. We tried many different phase unwrapping codes. Eventually running (FLYNN) on a farm of networked computers. Most of the work reported here is therefore limited to a 10-inch square aperture. Researched into fabricating a better interferometer lens from Plexiglas so to have less of the scattered light issues of Fresnel lens groves near field scattering patterns, this set the Nyquest limit. There was also a problem with the initial concept of wetting the 1737 glass on its bottom side with acid. The wetted 1737 glass developed an Achromatic AR coating, spoiling the reflection needed to see glass thickness interference fringes. In response

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

    PubMed Central

    Zhang, Ying; Wang, Yong

    2012-01-01

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

  20. Chemically assisted ion beam etching of polycrystalline and (100)tungsten

    NASA Technical Reports Server (NTRS)

    Garner, Charles

    1987-01-01

    A chemically assisted ion-beam etching technique is described which employs an ion beam from an electron-bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 microns thick with good anisotropy and pattern definition over areas of 30 sq mm, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred-orientation etching, while polycrystalline tungsten films exhibit high etch rates. This technique can be used to pattern the dispenser cathode surfaces serving as electron emitters in traveling-wave tubes to a controlled porosity.

  1. Research on wet etching at MEMS torsion mirror optical switch

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Wang, Jifeng; Luo, Yuan

    2002-10-01

    Etching is a very important technique at MEMS micromachining. There are two kinds of etching processing, the one is wet etching and the other is dry etching. In this paper, wet selective etching with KOH and tetramethyl ammonium hydroxide (TMAH) etchants is researched in order to make a torsion mirror optical switch. The experiments results show that TMAH with superphosphate is more suitable at MEMS torsion mirror optical switch micromachining than KOH, and it also has good compatibility with IC processing. Also our experiments results show some different with other reported research data. More work will be done to improve the yield rate of MEMS optical switch.

  2. Effect of a functional monomer (MDP) on the enamel bond durability of single-step self-etch adhesives.

    PubMed

    Tsuchiya, Kenji; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsubota, Keishi; Tsujimoto, Akimasa; Berry, Thomas P; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The present study aimed to determine the effect of the functional monomer, 10-methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single-step self-etch adhesives through integrating fatigue testing and long-term water storage. An MDP-containing self-etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP-free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre-etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre-etching and for MF after 24 h of storage in distilled water, SE with pre-etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre-etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long-term water storage. PMID:26620762

  3. 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.

  4. 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.

  5. Photonic devices based on preferential etching.

    PubMed

    Bellini, Bob; Larchanché, Jean-François; Vilcot, Jean-Pierre; Decoster, Didier; Beccherelli, Romeo; d'Alessandro, Antonio

    2005-11-20

    We introduce a design concept of optical waveguides characterized by a practical and reproducible process based on preferential etching of crystalline silicon substrates. Low-loss waveguides, spot-size converters, and power dividers have been obtained with polymers. We have also aligned liquid crystals in the waveguides and demonstrated guided propagation. Therefore this technology is a suitable platform for soft-matter photonics and heterogeneous integration. PMID:16318190

  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. Assembly Methods for Etched Foil Regenerators

    NASA Astrophysics Data System (ADS)

    Mitchell, Matthew P.

    2004-06-01

    Etched foil appears to offer substantial advantages over other regenerator materials, especially for annular regenerators. However, assembly of etched foil regenerators has been difficult because etching regenerator patterns in foil is most satisfactorily accomplished using pieces too small for a complete, spiral-wrapped regenerator. Two techniques have been developed to deal with that problem: For spiral-wrapped regenerators, a new technique for joining pieces of foil using tabs has been successfully employed. The joints are no thicker than the parent material. The tabs substantially fill the holes into which they are locked, virtually eliminating any undesired leak path through the regenerator. The holes constitute breaks in the conductive path through the regenerator. A patent is pending. An alternate method is to insert pieces of foil in a cylindrical housing one at a time. An inflatable bladder presses each newly-inserted piece of foil against the previous layer until both edges slip past each other and contact the previously-installed piece. When the bladder is deflated, the natural springiness of the foil causes the cut edges to seek the wall and meet each other in a butt joint. A patent on the method has been issued; a patent on the resulting regenerator is pending.

  8. Sb (111) Abnormal Behavior under Ion Etching

    NASA Astrophysics Data System (ADS)

    Smirnov, A. A.; Bozhko, S. I.; Ionov, A. M.; Protasova, S. G.; Chekmazov, S. V.; Kapustin, A. A.

    Due to a strong spin-orbit interaction (SOI), the surface states of Sb (111) are similar to those for topological insulators (TI) Sugawara et al. (2006). The surface states are protected by time-reversal symmetry and energy dispersion is a linear function of momentum. Defects in crystal structure lead to a local break of the surface translational symmetry and can modify surface states. It is the primary reason to study defects of Sb crystal structure and their effect on the surface states dispersion. Etching of the Sb (111) surface using Ar+ ions is a common way to create defects both in a bulk and on the surface of the crystal. Sb (111) ion etching at room temperature reveals anomalous behavior of surface crystal structure. It results in formation of flat terraces of 2 nm in size. Investigation of electronic structure of the etched Sb (111) surface has demonstrated increase of density of states (DOS) at the Fermi level. The results are discussed in terms of local break of conditions of Peierls transition.

  9. Laser etching of polymer masked leadframes

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  10. Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes

    NASA Astrophysics Data System (ADS)

    Chaghi, R.; Cervera, C.; Aït-Kaci, H.; Grech, P.; Rodriguez, J. B.; Christol, P.

    2009-06-01

    In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current-voltage measurements. The zero-bias resistance area product R0A above 4 × 105 Ω cm2 at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.

  11. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    SciTech Connect

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  12. 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.

  13. Etching characteristics of LiNbO{sub 3} in reactive ion etching and inductively coupled plasma

    SciTech Connect

    Ren, Z.; Yu, S.; Heard, P. J.; Marshall, J. M.; Thomas, P. A.

    2008-02-01

    The etching characteristics of congruent LiNbO{sub 3} single crystals including doped LiNbO{sub 3} and proton-changed LiNbO{sub 3} have been studied in reactive ion etching (RIE) and inductively coupled plasma (ICP) etching tools, using different recipes of gas mixtures. The effects of parameters including working pressure, RIE power, and ICP power are investigated and analyzed by measurement of etching depth, selectivity, uniformity, etched surface state, and sidewall profile by means of focused ion beam etching, energy-dispersive x-ray analysis, secondary ion mass spectroscopy, scanning electron microscopy, and surface profilometry. The effects of a sample carrier wafer coating have also been investigated. Optimized processes with high etching rates, good mask selectivity, and a near-vertical profile have been achieved. Ridge waveguides on proton-exchanged LiNbO{sub 3} have been fabricated and optically measured.

  14. Comparison of Buffer Effect of Different Acids During Sandstone Acidizing

    NASA Astrophysics Data System (ADS)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham; Hamid, Mohamed Ali

    2015-04-01

    The most important concern of sandstone matrix acidizing is to increase the formation permeability by removing the silica particles. To accomplish this, the mud acid (HF: HCl) has been utilized successfully for many years to stimulate the sandstone formations, but still it has many complexities. This paper presents the results of laboratory investigations of different acid combinations (HF: HCl, HF: H3PO4 and HF: HCOOH). Hydrofluoric acid and fluoboric acid are used to dissolve clays and feldspar. Phosphoric and formic acids are added as a buffer to maintain the pH of the solution; also it allows the maximum penetration of acid into the core sample. Different tests have been performed on the core samples before and after the acidizing to do the comparative study on the buffer effect of these acids. The analysis consists of permeability, porosity, color change and pH value tests. There is more increase in permeability and porosity while less change in pH when phosphoric and formic acids were used compared to mud acid. From these results it has been found that the buffer effect of phosphoric acid and formic acid is better than hydrochloric acid.

  15. Improving UV laser damage threshold of fused silica optics by wet chemical etching technique

    NASA Astrophysics Data System (ADS)

    Ye, Hui; Li, Yaguo; Yuan, Zhigang; Wang, Jian; Xu, Qiao; Yang, Wei

    2015-07-01

    Fused silica is widely used in high-power laser systems because of its good optical performance and mechanical properties. However, laser damage initiation and growth induced by 355 nm laser illumination in optical elements have become a bottleneck in the development of high energy laser system. In order to improve the laser-induced damage threshold (LIDT), the fused silica optics were treated by two types of HF-based etchants: 1.7%wt. HF acid and buffer oxide etchant (BOE: the mixture of 0.4%wt. HF and 12%wt. NH4F), respectively, for varied etching time. Damage testing shows that both the etchants increase the damage threshold at a certain depth of material removal, but further removal of material lowers the LIDT markedly. The etching rates of both etchants keep steady in our processing procedure, ~58 μg/min and ~85 μg/min, respectively. The micro-surface roughness (RMS and PV) increases as etching time extends. The hardness (H) and Young's modulus (E) of the fused silica etched for diverse time, measured by nano-indenter, show no solid evidence that LIDT can be related to hardness or Young's modulus.

  16. Comparison of wet and dry chrome etching with the CORE-2564

    NASA Astrophysics Data System (ADS)

    Buck, Peter D.; Grenon, Brian J.

    1994-02-01

    Chrome masks have traditionally been wet etched in an acidic solution of cerric ammonium nitrate. The etchant is commonly sprayed on the mask while the mask is slowly rotated, using an APT-914 or equivalent processor. While this process is well-understood, relatively trouble- free and inexpensive, the isotropic nature of wet etching results in an undercut of the chrome relative to the resist etch mask of approximately equals 150 nm per edge. Compensation for the undercut, in order to maintain control of the mean critical dimension (CD), is done by adjusting the printed feature size such that the undercut grows the printed feature to the desired final size. This sizing can be performed by manipulating the computer aided design database, which can be expensive and time consuming. In this paper, we present a comparison of wet and dry chrome etch processes using plates printed with the CORE-2564 in OCG-895 i resist. The differences in CD performance and resolution are illustrated.

  17. Anisotropic Ta{sub 2}O{sub 5} waveguide etching using inductively coupled plasma etching

    SciTech Connect

    Muttalib, Muhammad Firdaus A. Chen, Ruiqi Y.; Pearce, Stuart J.; Charlton, Martin D. B.

    2014-07-01

    Smooth and vertical sidewall profiles are required to create low loss rib and ridge waveguides for integrated optical device and solid state laser applications. In this work, inductively coupled plasma (ICP) etching processes are developed to produce high quality low loss tantalum pentoxide (Ta{sub 2}O{sub 5}) waveguides. A mixture of C{sub 4}F{sub 8} and O{sub 2} gas are used in combination with chromium (Cr) hard mask for this purpose. In this paper, the authors make a detailed investigation of the etch process parameter window. Effects of process parameters such as ICP power, platen power, gas flow, and chamber pressure on etch rate and sidewall slope angle are investigated. Chamber pressure is found to be a particularly important factor, which can be used to tune the sidewall slope angle and so prevent undercut.

  18. NiCr etching in a reactive gas

    SciTech Connect

    Ritter, J.; Boucher, R.; Morgenroth, W.; Meyer, H. G.

    2007-05-15

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

  19. Ion-induced chlorination of titanium leading to enhanced etching

    SciTech Connect

    O'Brien, W.L.; Rhodin, T.N.; Rathbun, L.C.

    1988-10-15

    The ion-induced chemical etching of titanium with chlorine has been studied. Quartz crystal microbalance studies show that the ion beam etch rate of Ti is enhanced upon addition of molecular chlorine, whereas molecular chlorine does not etch Ti in the absence of ion stimulation. This is very similar to the etching behavior of silicon in the presence of argon stimulation and chlorine gas. The etching of titanium is compared to a generalized version of the ion-assisted chemical etching model first proposed by Winters and Coburn. In this model the ion beam either enhances or induces one of the following chemical etching steps: initial adsorption, product formation, or product removal. The ion beam effect on product formation was determined by x-ray photoemission spectroscopy after sample etching. Ion beam effects on product removal were studied by measuring product distributions using modulated ion beam and time-of-flight techniques. It is found that the energetic ions induce formation of a chemically altered surface containing TiCl/sub x/ compounds. It is the ion-induced formation of this altered surface which leads to enhanced etching. Discussion in terms of the general model provides a comparison of the ion-assisted chemical etching mechanisms of titanium to silicon.

  20. 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

  1. Particle reduction and control in EUV etching process

    NASA Astrophysics Data System (ADS)

    Jun, JeaYoung; Ha, TaeJoong; Kim, SangPyo; Yim, DongGyu

    2014-10-01

    As the device design rule shrinks, photomask manufacturers need to have advanced defect controllability during the ARC (Anti-Reflection Coating) and ABS (Absorber) etch in an EUV (extreme ultraviolet) mask. Therefore we studied etching techniques of EUV absorber film to find out the evasion method of particle generation. Usually, Particles are generated by plasma ignition step in etching process. When we use the standard etching process, ARC and ABS films are etched step by step. To reduce the particle generation, the number of ignition steps need to decrease. In this paper, we present the experimental results of in-situ EUV dry etching process technique for ARC and ABS, which reduces the defect level significantly. Analysis tools used for this study are as follows; TEM (for cross-sectional inspection) , SEM (for in-line monitoring ) and OES (for checking optical emission spectrum)

  2. Experiment and Results on Plasma Etching of SRF cavities

    SciTech Connect

    Upadhyay, Janardan; Im, Do; Peshl, J.; Vuskovic, Leposova; Popovic, Svetozar; Valente, Anne-Marie; Phillips, H. Lawrence

    2015-09-01

    The inner surfaces of SRF cavities are currently chemically treated (etched or electropolished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.

  3. Correlated crystallographic etching of graphene and nanoribbon formation

    NASA Astrophysics Data System (ADS)

    Johnson, Stephen; Hunley, D. Patrick; Stieha, Joseph; Sundararajan, Abhishek; Kar, Arunita; Johnson, A. T. Charlie; Strachan, Douglas

    2011-03-01

    Catalytic etching is a promising method for constructing crystallographically defined graphene structures such as nanoribbons. Catalytic etching experiments are performed and shown to contain significant correlation yielding crystallographic graphene nanoribbons. This correlation is investigated as a function of etching conditions and compared to simulations with possible sources discussed. Supported in part by NSF Award No. DMR-0805136, the Kentucky NSF EPSCoR program, the University of Kentucky Center for Advanced Materials, and the University of Kentucky Center for Nanoscale Science and Engineering.

  4. Etched-multilayer phase shifting masks for EUV lithography

    DOEpatents

    Chapman, Henry N.; Taylor, John S.

    2005-04-05

    A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.

  5. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanisms and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  6. A new back-etch for silicon devices

    SciTech Connect

    Malberti, P.; Ciappa, M.; Scacco, P.

    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.

  7. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  8. Photoinduced laser etching of a diamond surface

    SciTech Connect

    Kononenko, V V; Komlenok, M S; Pimenov, S M; Konov, V I

    2007-11-30

    Nongraphitising ablation of the surface of a natural diamond single crystal irradiated by nanosecond UV laser pulses is studied experimentally. For laser fluences below the diamond graphitisation threshold, extremely low diamond etching rates (less than 1nm/1000 pulses) are obtained and the term nanoablation is used just for this process. The dependence of the nanoablation rate on the laser fluence is studied for samples irradiated both in air and in oxygen-free atmosphere. The effect of external heating on the nanoablation rate is analysed and a photochemical mechanism is proposed for describing it. (interaction of laser radiation with matter. laser plasma)

  9. Influence of erbium, chromium-doped: Yttrium scandium-gallium-garnet laser etching and traditional etching systems on depth of resin penetration in enamel: A confocal laser scanning electron microscope study

    PubMed Central

    Vijayan, Vishal; Rajasigamani, K.; Karthik, K.; Maroli, Sasidharan; Chakkarayan, Jitesh; Haris, Mohamed

    2015-01-01

    Objective: This study was performed to assess the resin tag length penetration in enamel surface after bonding of brackets to identify which system was most efficient. Methodology: Our study was based on a more robust confocal microscopy for visualizing the resin tags in enamel. Totally, 100 extracted human first and second premolars have been selected for this study and were randomly divided into ten groups of 10 teeth each. In Group 1, the buccal enamel surface was etched with 37% phosphoric acid (3M ESPE), Group 2 with 37% phosphoric (Ultradent). In Groups 5, 6, and 7, erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser (Biolase) was used for etching the using following specifications: Group 5 (1.5 W/20 Hz, 15 s), Group 6 (2 W/10 Hz, 15 s), and Group 7 (2 W/20 Hz, 15 s). In Groups 8, 9, and 10, Er, Cr: YSGG laser (Biolase) using same specifications and additional to this step, conventional etching on the buccal enamel surface was etched with 37% (3M ESPE) after laser etching. In Groups 1, 5, 6, 7, 8, 9, and 10 3M Unitek Transbond XT primer was mixed with Rhodamine B dye (Sigma-Aldrich, Germany) to etched surface and then cured for 20 s. In Group 2, Ultradents bonding agent was mixed with Rhodamine B. In Group 3, 3M Unitek Transbond PLUS, Monrovia, USA, which was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Group 4, with self-etching primer (Ultradent-Peak SE, USA) was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Later (3M Unitek, Transbond XT, Monrovia USA) [Figure 1] was used to bond the modified Begg brackets (T. P. Orthodontics) in Groups 1, 3, 5, 6, 7, 8, 9, and 10. In Groups 2, 4 Ultradent-Peak LC Bond was used to bond the modified brackets. After curing brackets were debonded, and enamel depth penetration was assessed using confocal laser scanning microscope. Results: Group J had a mean maximum depth of penetration of 100.876 μm, and Group D was the least having a maximum value of 44.254 μm. Conclusions: Laser

  10. Fabrication of large periodic arrays of AlGaAs microdisks by laser-interference lithography and selective etching

    NASA Astrophysics Data System (ADS)

    Petter, K.; Kipp, T.; Heyn, Ch.; Heitmann, D.; Schuller, C.

    2002-07-01

    By laser-interference lithography, reactive-ion etching, and selective wet-chemical etching using a citric acid-based solution, we have fabricated large periodic arrays of AlGaAs microdisks with periods of 4 mum and disk diameters between 1.5 and 2 mum. The arrays are characterized by temperature-dependent photoluminescence spectroscopy. Taking into account the below-threshold absorption of the quantum wells inside the disks, we get disk quality factors close to the theoretical maximum value. We demonstrate that our technique allows one also to produce one-dimensionally or two-dimensionally coupled arrays of microdisks.

  11. Inductively coupled plasma etching of GaN

    SciTech Connect

    Shul, R.J.; McClellan, G.B.; Casalnuovo, S.A.; Rieger, D.J.; Pearton, S.J.; Constantine, C.; Barratt, C.; Karlicek, R.F. Jr.; Tran, C.; Schurman, M.

    1996-08-01

    Inductively coupled plasma (ICP) etch rates for GaN are reported as a function of plasma pressure, plasma chemistry, rf power, and ICP power. Using a Cl{sub 2}/H{sub 2}/Ar plasma chemistry, GaN etch rates as high as 6875 A/min are reported. The GaN surface morphology remains smooth over a wide range of plasma conditions as quantified using atomic force microscopy. Several etch conditions yield highly anisotropic profiles with smooth sidewalls. These results have direct application to the fabrication of group-III nitride etched laser facets. {copyright} {ital 1996 American Institute of Physics.}

  12. Modeling of the angular dependence of plasma etching

    SciTech Connect

    Guo Wei; Sawin, Herbert H.

    2009-11-15

    An understanding of the angular dependence of etching yield is essential to investigate the origins of sidewall roughness during plasma etching. In this article the angular dependence of polysilicon etching in Cl{sub 2} plasma was modeled as a combination of individual angular-dependent etching yields for ion-initiated processes including physical sputtering, ion-induced etching, vacancy generation, and removal. The modeled etching yield exhibited a maximum at {approx}60 degree sign off-normal ion angle at low flux ratio, indicative of physical sputtering. It transformed to the angular dependence of ion-induced etching with the increase in the neutral-to-ion flux ratio. Good agreement between the modeling and the experiments was achieved for various flux ratios and ion energies. The variation of etching yield in response to the ion angle was incorporated in the three-dimensional profile simulation and qualitative agreement was obtained. The surface composition was calculated and compared to x-ray photoelectron spectroscopy (XPS) analysis. The modeling indicated a Cl areal density of 3x10{sup 15} atoms/cm{sup 2} on the surface that is close to the value determined by the XPS analysis. The response of Cl fraction to ion energy and flux ratio was modeled and correlated with the etching yields. The complete mixing-layer kinetics model with the angular dependence effect will be used for quantitative surface roughening analysis using a profile simulator in future work.

  13. Molecular Dynamics Simulations Of Nanometer-Scale Feature Etch

    SciTech Connect

    Vegh, J. J.; Graves, D. B.

    2008-09-23

    Molecular dynamics (MD) simulations have been carried out to examine fundamental etch limitations. Beams of Ar{sup +}, Ar{sup +}/F and CF{sub x}{sup +} (x = 2,3) with 2 nm diameter cylindrical confinement were utilized to mimic 'perfect' masks for small feature etching in silicon. The holes formed during etch exhibit sidewall damage and passivation as a result of ion-induced mixing. The MD results predict a minimum hole diameter of {approx}5 nm after post-etch cleaning of the sidewall.

  14. TRAVIT: software tool to simulate dry etch in maskmaking

    NASA Astrophysics Data System (ADS)

    Babin, S.; Bay, K.; Okulovsky, S.

    2005-06-01

    A software tool, TRAVIT, has been developed to simulate dry etch in maskmaking. The software predicts the etch profile, etched critical dimensions (CDs), and CD-variation for any pattern of interest. The software also takes into account microloading effect that is pattern dependent and contributes to CD variation. Once CD variation is known, it can then be applied to correct the CD-error. Examples of simulations including variable ICP power, physical and chemical etch components, and optimization of a bias and CD variation are presented. Incorporating simulation into the maskmaking process can save cost and shorten the time to production.

  15. 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

  16. Use of super acids to digest chrysotile and amosite asbestos in simple mixtures or matrices found in building materials compositions

    SciTech Connect

    Sugama, T.; Petrakis, L.; Webster, R.P.

    1999-12-21

    A composition for converting asbestos-containing material to environmentally benign components is provided. The composition comprises a fluoro acid decomposing agent which can be applied to either amosite-containing thermal insulation or chrysotile-containing fire-proof material or to any asbestos-containing material which includes of chrysotile and amosite asbestos. The fluoro acid decomposing agent includes FP{sub 0}(OH){sub 2}, hexafluorophosphoric acid, a mixture of hydrofluoric and phosphoric acid and a mixture of hexafluorophosphoric acid and phosphoric acid. A method for converting asbestos-containing material to environmentally benign components is also provided.

  17. Masking Technique for Ion-Beam Sputter Etching

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Rutledge, S. K.

    1986-01-01

    Improved process for fabrication of integrated circuits developed. Technique utilizes simultaneous ion-beam sputter etching and carbon sputter deposition in conjunction with carbon sputter mask or organic mask decomposed to produce carbon-rich sputter-mask surface. Sputter etching process replenishes sputter mask with carbon to prevent premature mask loss.

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

    SciTech Connect

    Rucker, Victor C.; Shediac, Rene; Simmons, Blake A.; Havenstrite, Karen L.

    2007-08-07

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

  19. Laser etching: A new technology to identify Florida grapefruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laser labeling of fruits and vegetables is an alternative means to label produce. Low energy CO2 laser beam etches the surface showing the contrasting underlying layer. These etched surfaces can promote water loss and potentially allowing for pathogen entry. The long term effects of laser labeling o...

  20. 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.

  1. Evaluation of bond strength of orthodontic brackets without enamel etching

    PubMed Central

    Boruziniat, Alireza; Motaghi, Shiva; Moghaddas, Mohmmadjavad

    2015-01-01

    Background To compare the shear bond strength of brackets with and without enamel etching. Material and Methods In this study, 60 sound premolars were randomly divided into four different groups: 1- TXE group: Enamel etching+Transbond XT adhesive+ Transbond XT composite. 2- TXS group: Transbond plus self-etch adhesive+ Transbond XT composite. 3- PQ1E group: Enamel etching+ PQ1 adhesive+ Transbond XT composite. 4- PQ1 group: PQ1 adhesive+ Transbond XT composite. The shear bond strengths of brackets were evaluated using universal testing machine at cross head speed of 0.5 mm/min. The Adhesive Remnant Index (ARI) was also measured. One-way ANOVA, Tukey’s post hoc, Kruskal-wallis and Mann-Witney U test were used for data analysis. Results There was a significant difference between etched and unetched groups respect to SBS and ARI (p<0.05), however; no significant difference was observed between unetched group and self-etch adhesive group (p>> 0.05). The shear bond strength of PQ1 group was the least but in acceptable range and its ARI was less than other groups. Conclusions PQ1 adhesive can be used for bracket bonding without enamel etching with adequate bond strength and minimal ARI. Key words:Bracket, shear bond strength, filled-adhesive, self-etch adhesive. PMID:26535100

  2. Reactive ion etching of quartz and Pyrex for microelectronic applications

    NASA Astrophysics Data System (ADS)

    Zeze, D. A.; Forrest, R. D.; Carey, J. D.; Cox, D. C.; Robertson, I. D.; Weiss, B. L.; Silva, S. R. P.

    2002-10-01

    The reactive ion etching of quartz and Pyrex substrates was carried out using CF4/Ar and CF4/O2 gas mixtures in a combined radio frequency (rf)/microwave (μw) plasma. It was observed that the etch rate and the surface morphology of the etched regions depended on the gas mixture (CF4/Ar or CF4/O2), the relative concentration of CF4 in the gas mixture, the rf power (and the associated self-induced bias) and microwave power. An etch rate of 95 nm/min for quartz was achieved. For samples covered with a thin metal layer, ex situ high resolution scanning electron microscopy and atomic force microscopy imaging indicated that, during etching, surface roughness is produced on the surface beneath the thin metallic mask. Near vertical sidewalls with a taper angle greater than 80° and smooth etched surfaces at the nanometric scale were fabricated by carefully controlling the etching parameters and the masking technique. A simulation of the electrostatic field distribution was carried out to understand the etching process using these masks for the fabrication of high definition features.

  3. 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

  4. 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

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

    SciTech Connect

    Vogli, Evelina; Metzler, Dominik; Oehrlein, Gottlieb S.

    2013-06-24

    We describe controlled, self-limited etching of a polystyrene polymer using a composite etching cycle consisting of sequential deposition of a thin reactive layer from precursors produced from a polymer-coated electrode within the etching chamber, modification using O{sub 2} exposure, and subsequent low-pressure Ar plasma etching, which removes the oxygen-modified deposited reactive layer along with Almost-Equal-To 0.1 nm unmodified polymer. Deposition prevents net etching of the unmodified polymer during the etching step and enables self-limited etch rates of 0.1 nm/cycle.

  6. 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.

  7. Effects of mask imperfections on InP etching profiles

    SciTech Connect

    Huo, D.T.C.; Yan, M.F.; Wynn, J.D.; Wilt, D.P. )

    1990-01-01

    The authors have demonstrated that the quality of etch masks has a significant effect on the InP etching profiles. In particular, the authors have shown that mask imperfections can cause defective etching profiles, such as vertical sidewalls and extra mask undercutting in InP. The authors also discovered that the geometry of these defective profiles is determined by the orientation of the substrate relative to the direction of the mask imperfections. Along a {l angle}110{r angle} line mask defect, the downward etching process changes the {l angle}110{r angle} v-grooves to vertical sidewalls without extra undercutting. For v-grooves aligned along the {l angle}110{r angle} direction, defects on the mask give a significant extra undercutting without changing the etching profile.

  8. 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.

  9. Software to simulate dry etch in photomask fabrication

    NASA Astrophysics Data System (ADS)

    Babin, Sergey; Bay, Konstantin; Okulovsky, Sergey

    2004-12-01

    Dry etch in maskmaking is one of the major contributors to variation of critical dimensions (CD) which is caused primarily by the microloading and macroloading effects. CD variation during etch depends on the type of pattern involved. It would be highly desirable to run a pattern through the software to predict CD variation due to dry etch and decide if the variation is within the prescribed tolerance or if the pattern needs additional correction, and to what degree. In this paper, a dry etch simulation tool TRAVIT is introduced that is capable of simulating etch profile, CD, and CD errors. Using a set of desired process conditions, the software runs the simulation for the pattern of interest that helps to optimize sidewall, bias, and CD variation. Incorporating simulation into the maskmaking process can save cost and shorten the time to production.

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

    DOEpatents

    Ashby, Carol I. H.; Dishman, James L.

    1987-01-01

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

  11. 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

  12. Development and characterization of multilevel metal interconnection etch process

    NASA Astrophysics Data System (ADS)

    Dang, Kim

    1997-08-01

    A more robust chlorine chemistry based reactive ion etch (RIE) process was developed, characterized and optimized to anisotropically etch the interconnecting metal layers for use in the fabrication of CMOS and BiCMOS IC devices, using the Lam 4600 single wafer etcher. The titanium nitride and titanium silicide buried layer, used in the metal 1 structure, present unique constraints on etch selectivity to the underlying film. The process must clear metal stringers with minimal lateral etching of the aluminum during the tiN/Ti etch and overetch steps. The new optimized process meets all requirements imposed by advanced technologies, such as vertical metal sidewalls, wide process latitude, tight CD control, minimal of TEOS oxide underlayer, less sensitivity to photoresist pattern, excellent reliability and reproducibility, and lower level of polymer (reaction by- product) build-up in reactor chamber which could lead to metal corrosion and cluster defects.

  13. Atomic precision etch using a low-electron temperature plasma

    NASA Astrophysics Data System (ADS)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2016-03-01

    Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

  14. Study of 193-nm resist degradation under various etch chemistries

    NASA Astrophysics Data System (ADS)

    Bazin, Arnaud; May, Michael; Pargon, Erwine; Mortini, Benedicte; Joubert, Olivier

    2007-03-01

    The effectivity of 193nm photoresists as dry etch masks is becoming more and more critical as the size of integrated devices shrinks. 193nm resists are known to be much less resistant to dry etching than 248nm resists based on a poly(hydroxystyrene) polymer backbone. The decrease in the resist film budget implies a better etch resistance to use single layer 193nm photoresists for the 65nm node and beyond. In spite of significant improvements made in the past decade regarding the etch resistance of photoresists, much of the fundamental chemistry and physics that could explain the behaviour of these materials has to be better understood. Such knowledge is necessary in order to propose materials and etch processes for the next technology nodes (45nm and below). In this paper, we report our studies on the etch behaviour of different 193nm resist materials as a function of etch chemistry. In a first step, we focus our attention on the interactions between photoresists and the reactive species of a plasma during a dry etch step. Etch experiments were carried out in a DPS (Decoupled Plasma Source) high density chamber. The gas chemistry in particular was changed to check the role of the plasma reactive species on the resist. O II, Cl II, CF 4, HBr and Ar gas were used. Etch rates and chemical modifications of different materials were quantified by ellipsometry, Fourier Transformed Infrared Spectroscopy (FTIR), and X-Ray Photoelectrons Spectroscopy (XPS). We evaluated different materials including 248nm model polymer backbones (pure PHS or functionalized PHS), and 193nm model polymers (PMMA and acrylate polymers) or resist formulations. Besides the influence of resist chemistry, the impact of plasma parameters was addressed.

  15. In-situ diagnostics and characterization of etch by-product deposition on chamber walls during halogen etching of silicon

    NASA Astrophysics Data System (ADS)

    Rastgar, Neema; Sriraman, Saravanapriyan; Marsh, Ricky; Paterson, Alex

    2014-10-01

    Plasma etching is a critical technology for nanoelectronics fabrication, but the use of a vacuum chamber limits the number of in-situ, real-time diagnostics measurements that can be performed during an etch process. Byproduct deposition on chamber walls during etching can affect the run-to-run performance of an etch process if there is build-up or change of wall characteristics with time. Knowledge of chamber wall evolution and the composition of wall-deposited films are critical to understanding the performance of plasma etch processes, and an in-situ diagnostics measurement is useful for monitoring the chamber walls in real time. We report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to perform in-situ diagnostics of a vacuum chamber's walls during plasma etching. Using ATR-FTIR, we are able to monitor the relative thickness and makeup of chamber wall deposits in real time. We then use this information to develop a chamber wall cleaning process in order to maintain reproducible etching conditions from wafer to wafer. In particular, we report mid-IR (4000-650 cm-1) absorption spectra of chamber wall-deposited silicon byproducts formed during halogen etching of silicon wafers.

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

    SciTech Connect

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

    1993-06-01

    Nonuniform etching is a serious problem in plasma processing of semiconductor materials and has important consequences in the quality and yield of microelectronic components. In many plasmas, etching occurs at a faster rate near the periphery of the wafer, resulting in nonuniform removal of specific materials over the wafer surface. This research was to investigate in situ optical diagnostic techniques for monitoring etch uniformity during plasma processing of microelectronic components. We measured 2-D images of atomic chlorine at 726 nm in a chlorine-helium plasma during plasma etching of polysilicon in a parallel-plate plasma etching reactor. The 3-D distribution of atomic chlorine was determined by Abel inversion of the plasma image. The experimental results showed that the chlorine atomic emission intensity is at a maximum near the outer radius of the plasma and decreases toward the center. Likewise, the actual etch rate, as determined by profilometry on the processed wafer, was approximately 20% greater near the edge of the wafer than at its center. There was a direct correlation between the atomic chlorine emission intensity and the etch rate of polysilicon over the wafer surface. Based on these analyses, 3-D imaging would be a useful diagnostic technique for in situ monitoring of etch uniformity on wafers.

  17. Organic analysis of the returned lunar sample.

    PubMed

    Abell, P I; Draffan, G H; Eglinton, G; Hayes, J M; Maxwell, J R; Pillinger, C T

    1970-01-30

    Lunar fines have been examined for organic compounds by crushing, programmed heating, hydrofluoric acid etching, and solvent extraction. Products were examined by mass spectroscopy. A variety of small organic molecules, including methane and other hydrocarbons, accompanied the release of the rare gases when the sample was heated in a stepwise fashion to 900 degrees C under vacuum. Methane is more abundant (abundance on the order of 1 part per million) than argon in the matrix-entrapped gases liberated by hydrofluoric acid etching of lunar fines. Methane is also present in a dark portion of the gas-rich meteorite Kapoeta. PMID:17781581

  18. CBr4-based in-situ etching of GaAs, assisted with TMAl and TMGa

    NASA Astrophysics Data System (ADS)

    Della Casa, Pietro; Maaßdorf, Andre; Zeimer, Ute; Weyers, Markus

    2016-01-01

    In-situ etching of GaAs with CBr4 in metalorganic vapor phase epitaxy has been investigated at different temperatures using in-situ reflectivity to measure the etch rates. Deep (150 nm) etching of epitaxially-grown GaAs leads to the development of etch pits on the surface, corresponding to the emerging points of threading dislocations. Addition of trimethylgallium (TMGa) leads to a linear superposition of growth and etching. Trimethylaluminium (TMAl) added in moderate quantity enhances the etch rate and inhibits the development of etch pits. A model description for the enhanced etch rate is presented.

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

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    This work investigates the isotropic etching properties in inductively coupled plasma (ICP) etcher for microneedle arrays fabrication. The effects of process variables including powers, gas and pressure on needle structure generation are characterized by factorial design of experiment (DOE). The experimental responses of vertical etching depth, lateral etching length, ratio of vertical etching depth to lateral etching length and photoresist etching rate are reported. The relevance of the etching variables is also presented. The obtained etching behaviours for microneedle structure generation will be applied to develop recipes to fabricate microneedles in designed dimensions.

  20. Energy dispersive X-ray spectroscopy analysis of Si sidewall surface etched by deep-reactive ion etching

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Nishioka, Kunio; Sato, Mina

    2016-06-01

    We investigated the composition of a passivation film on a sidewall etched by deep-reactive ion etching (RIE) using SF6/O2 and C4F8 plasma, by energy-dispersive X-ray (EDX) spectroscopy. It was found that the compositions of carbon and fluorine in the passivation film on the etched sidewall depend on the width and depth of the etched trench. It is important to understand both the plasma behavior and the passivation film composition to carry out fabrication by deep-RIE. We consider that these results of the EDX analysis of an etched sidewall will be useful for understanding plasma behavior in order to optimize the process conditions of deep-RIE.

  1. Direct Visualization of Etching Trajectories in Metal-Assisted Chemical Etching of Si by the Chemical Oxidation of Porous Sidewalls.

    PubMed

    Yoon, Sung-Soo; Khang, Dahl-Young

    2015-09-29

    We demonstrate a simple method for the visualization of trajectories traced by noble metal nanoparticles during metal-assisted chemical etching (MaCE) of Si. The nanoporous Si layer formed around drilled pores is converted into SiO2 by simple chemical oxidation. Etch removal of the remaining Si using alkali hydroxide leaves SiO2 nanostructures that are the exact replica of those drilled pores or etching trajectories. The differences in etching characteristics between Ag and Au have been investigated using the proposed visualization method. The shape and chemical stability of metal nanoparticles used for MaCE have been found to be critical in determining etching paths. The proposed method would be very helpful in studying the fundamental mechanism of MaCE as well as in micro/nanostructuring of the Si surface for various applications. This approach can also be used for the generation of straight or helical SiO2 nanotubes. PMID:26352208

  2. Role of nitrogen in the downstream etching of silicon nitride

    SciTech Connect

    Blain, M.G.; Meisenheimer, T.L.; Stevens, J.E.

    1996-07-01

    Chemical downstream etching of silicon nitride (Si{sub 3}N{sub 4}) requires the addition of nitrogen to the discharge for obtaining efficient etch rates. A 10{percent} addition of N{sub 2} to a CF{sub 4}/O{sub 2} discharge (CF{sub 4}/O{sub 2} = 1.2, 0.525 Torr) causes a factor of 6 increase in the Si{sub 3}N{sub 4} etch rate and a 8{percent} decrease in the silicon dioxide etch rate. The result is selectivities approaching 9:1. Importantly, the conversion of CF{sub 4} to F and F-containing reactive species by the discharge decreases or remains constant as nitrogen is added to the discharge mix, indicating that the etching reaction is not limited by delivery of these species to the substrate. By measuring the amount of NO and NO{sub 2} in the etch chamber, it is found that the NO concentration increases by a factor of 6 as N{sub 2} is added, while the amount of NO{sub 2} remains small and constant. The NO signal is significantly reduced during nitride etching compared to the signal observed during a discharge with an empty etch chamber, implying that the increase in Si{sub 3}N{sub 4} etch rate is related to the formation of NO in the discharge. This view is consistent with the observation that an NF{sub 3} plasma in a quartz discharge tube results in a nitride etch rate which is a factor of 2 higher than for the same discharge in a sapphire tube. The conclusion is that the oxygen liberated by erosion of the quartz tube allows the formation of NO. That NO is a key Si{sub 3}N{sub 4} etch reactant was confirmed by performing a series of experiments in which N{sub 2}, NO, NO{sub 2}, and N{sub 2}O were injected into the discharge and then downstream in the reaction chamber during a CF{sub 4}/O{sub 2} discharge. Nitride etch rates increased significantly upon injection of NO into both discharge and etch chamber as compared to injection of the other N{sub {ital x}}O{sub {ital y}} species. {copyright} {ital 1996 American Vacuum Society}

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

    DOEpatents

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  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. UV-Photoassisted Etching of GaN in KOH

    SciTech Connect

    Abernathy, C.R.; Auh, K.H.; Cho, H.; Donovan, S.M.; Han, J.; Lambers, E.S.; Pearton, S.J.; Ren F.; Shul, R.J.

    1998-11-12

    The etch rate of GaN under W-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n - 3x 10^12Gcm-3) GaN are 2 1000 .min-l. The etching is diffusion limited under our conditions with an activation energy of - 0.8kCal.mol-1. The etched surfaces are rough, but retain their stoichiometry. PEC etching is found to selectively reveal grain boundaries in GaN under low light illumination conditions. At high lamp powers the rates increase with sample temperature and the application of bias to the PEC cell, while they go through a maximum with KOH solution molarity. The etching is diffusion-limited, producing rough surface morphologies that are suitable in a limited number of device fabrication steps. The surfaces however appear to remain relatively close to their stoichiometric composition.

  6. Porous silicon formation during Au-catalyzed etching

    SciTech Connect

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

    2014-04-28

    The formation of “black” nano-textured Si during the Au-catalyzed wet-chemical etch process was investigated with respect to photovoltaic applications. Cross-sectional scanning electron microscopy (SEM) images recorded at different stages of the etch process exhibit an evolution of a two-layer structure, consisting of cone-like Si hillocks covered with a nano-porous Si (np-Si) layer. Optical measurements confirm the presence of a np-Si phase which appears after the first ∼10 s of the etch process and continuously increases with the etch time. Furthermore, the etch process was investigated on Si substrates with different doping levels (∼0.01–100 Ω cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 Ω cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of “black” Si on various Si substrates, which is of significant interest for photovoltaic applications.

  7. 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

  8. Toward a durable superhydrophobic aluminum surface by etching and ZnO nanoparticle deposition.

    PubMed

    Rezayi, Toktam; Entezari, Mohammad H

    2016-02-01

    Fabrication of suitable roughness is a fundamental step for acquiring superhydrophobic surfaces. For this purpose, a deposition of ZnO nanoparticles on Al surface was carried out by simple immersion and ultrasound approaches. Then, surface energy reduction was performed using stearic acid (STA) ethanol solution for both methods. The results demonstrated that ultrasound would lead to more stable superhydrophobic Al surfaces (STA-ZnO-Al-U) in comparison with simple immersion method (STA-ZnO-Al-I). Besides, etching in HCl solution in another sample was carried out before ZnO deposition for acquiring more mechanically stable superhydrophobic surface. The potentiodynamic measurements demonstrate that etching in HCl solution under ultrasound leads to superhydrophobic surface (STA-ZnO-Al(E)-U). This sample shows remarkable decrease in corrosion current density (icorr) and long-term stability improvement versus immersion in NaCl solution (3.5%) in comparison with the sample prepared without etching (STA-ZnO-Al-U). Scanning electron micrograph (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed a more condense and further particle deposition on Al substrate when ultrasound was applied in the system. The crystallite evaluation of deposited ZnO nanoparticles was carried out using X-ray diffractometer (XRD). Finally, for STA grafting verification on Al surface, Fourier transform infrared in conjunction with attenuated total reflection (FTIR-ATR) was used as a proper technique. PMID:26513735

  9. Manganese-tuned chemical etching of a platinum-copper nanocatalyst with platinum-rich surfaces

    NASA Astrophysics Data System (ADS)

    Huang, Y. Y.; Zhao, T. S.; Zhao, G.; Yan, X. H.; Xu, K.

    2016-02-01

    This work presents a modified chemical etching strategy to fabricate binary metal nanocatalysts with large active areas. The strategy employs PtCu alloy particles with Pt-rich outer layers as the precursor and manganese species to manipulate the acid leaching processes. X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy techniques are used to analyze the catalyst structures and the tuning mechanism of manganese species during etching. It is found that the introduction of manganese species allows more Pt active sites to be formed onto the catalyst surface after etching, possibly due to reduction in the number of Pt atoms enclosed inside particles. The electrochemically active surface area of the synthetic MnA-PtCu/C catalyst increases by 90% relative to commercial Pt/C catalyst. As a result of the increase in active areas and the additional promotion effects by Cu, the MnA-PtCu/C catalyst reveals a methanol oxidation activity 1.7 and 4.0 times higher than that of the synthetic PtCu/C and commercial Pt/C catalysts, respectively.

  10. Ultrasensitive Visual Sensing of Molybdate Based on Enzymatic-like Etching of Gold Nanorods.

    PubMed

    Zhang, Zhiyang; Chen, Zhaopeng; Chen, Lingxin

    2015-08-25

    Here, we have developed a novel approach to the visual detection of molybdate with high sensitivity and selectivity in aqueous media based on the combination of catalytic formation of iodine and iodine-mediated etching of gold nanorods. In weak acid solution, like peroxidase, molybdate can catalyze the reaction between H2O2 and I(-) to produce I2, a moderate oxidant, which then etches gold nanorods preferentially along the longitudinal direction in the presence of hexadecyltrimethylammonium bromide. The etching results in the longitudinal localized surface plasmon resonance extinction peak shifts to short wavelength, accompanied by a color change from blue to red. Under optimal conditions, this sensor exhibits good sensitivity with a detection limit of 1.0 nM. The approach is highlighted by its high selectivity and tolerance to interference, which enables the sensor to detect molybdate directly in real samples, such as tap water, drinking water, and seawater. In addition, perhaps the proposed sensing strategy can be also used for other targets that can selectively regulate the formation of I2 under given conditions. PMID:26226196

  11. Electrochemical etching of a shape memory alloy using new electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Mineta, Takashi

    2004-01-01

    In this paper we present the electrochemical etching characteristics of a shape memory alloy (SMA) using new electrolytes of inorganic salt in alcohol, in comparison with conventional H2SO4-methanol solution. It has become apparent that pattern etching of SMA sheets can be carried out in electrolyte solutions using LiCl and NH4Cl. Especially, in the case of 1 mol l-1 LiCl-ethanol, good etching properties such as a controllable low etch rate of about 3.5 µm min-1, high etch factor (etching depth/side etching width) of 1.5, uniform etching depth and smooth etched surface can be obtained. Throughout etching can be carried out by using a back-side dummy metal of Ni or Cu. This etching technique has been applied to the micromachining of SMA sheet for fabrication of microactuators.

  12. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2006-06-27

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  13. Metal-assisted chemical etch porous silicon formation method

    DOEpatents

    Li, Xiuling; Bohn, Paul W.; Sweedler, Jonathan V.

    2004-09-14

    A thin discontinuous layer of metal such as Au, Pt, or Au/Pd is deposited on a silicon surface. The surface is then etched in a solution including HF and an oxidant for a brief period, as little as a couple seconds to one hour. A preferred oxidant is H.sub.2 O.sub.2. Morphology and light emitting properties of porous silicon can be selectively controlled as a function of the type of metal deposited, Si doping type, silicon doping level, and/or etch time. Electrical assistance is unnecessary during the chemical etching of the invention, which may be conducted in the presence or absence of illumination.

  14. In situ etching using a novel precursor of tertiarybutylchloride (TBCl)

    NASA Astrophysics Data System (ADS)

    Kondow, Masahiko; Shi, Binqiang; Tu, Charles W.

    2000-02-01

    We investigated systematically chemical beam etching of GaAs, GaInP and AlInP using a novel precursor, tertiarybutylchloride (TBCl). Because TBCl is not corrosive to the growth system and has long-term stability at room temperature, it is a promising alternative to AsCl 3 or AsBr 3 from the viewpoint of safety. Layer-by-layer etching was achieved as evidenced by intensity oscillations in reflection high-energy electron diffraction. While a slightly higher substrate temperature around 550°C is necessary, pre-cracked TBCl may be applicable in in situ etching for III-V semiconductor device fabrication.

  15. Laser etching of metals in neutral salt solutions

    NASA Astrophysics Data System (ADS)

    Datta, M.; Romankiw, L. T.; Vigliotti, D. R.; von Gutfeld, R. J.

    1987-12-01

    We report new findings that relate to rapid maskless laser etching of steel and stainless steel in neutral solutions of sodium chloride, sodium nitrate, and potassium sulfate. Etch rates have been determined as a function of laser power, laser on-time, and solution concentration. The morphology of laser-etched holes obtained in these solutions was compared with holes obtained in pure water. Results indicate that some controlled melting occurs under certain laser conditions in addition to the metal dissolution process induced by the locally intense heat of the laser beam.

  16. Structural and magnetic etch damage in CoFeB

    SciTech Connect

    Krayer, L.; Lau, J. W.; Kirby, B. J.

    2014-05-07

    A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

  17. Optical properties of micromachined polysilicon reflective surfaces with etching holes

    NASA Astrophysics Data System (ADS)

    Zou, Jun; Byrne, Colin; Liu, Chang; Brady, David J.

    1998-08-01

    MUMPS (Multi-User MEMS Process) is receiving increasingly wide use in micro optics. We have investigated the optical properties of the polysilicon reflective surface in a typical MUMPS chip within the visible light spectrum. The effect of etching holes on the reflected laser beam is studied. The reflectivity and diffraction patterns at five different wavelengths have been measured. The optical properties of the polysilicon reflective surface are greatly affected by the surface roughness, the etching holes, as well as the material. The etching holes contribute to diffraction and reduction of reflectivity. This study provides a basis for optimal design of micromachined free-space optical systems.

  18. CDU improvement technology of etching pattern using photo lithography

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  19. Selectively-etched nanochannel electrophoretic and electrochemical devices

    SciTech Connect

    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.

  20. Etching of mercuric iodide in cation iodide solutions

    NASA Astrophysics Data System (ADS)

    Ponpon, J. P.; Amann, M.

    2006-07-01

    The surface properties of mercuric iodide after etching in various cation iodide solutions have been investigated in terms of dissolution rate, morphology, electrical properties and reaction with water vapour. No significant differences have been observed in the etching rates. However, dissolution of HgI 2 in NH 4I, NaI, KI or RbI leaves the surface more or less covered with a residual iodo mercurate compound whose electrical properties and stability with regard to humidity may noticeably influence the behaviour of mercuric iodide devices. The smallest effect has been observed for etching in NaI.

  1. Rapid recipe formulation for plasma etching of new materials

    NASA Astrophysics Data System (ADS)

    Chopra, Meghali; Zhang, Zizhuo; Ekerdt, John; Bonnecaze, Roger T.

    2016-03-01

    A fast and inexpensive scheme for etch rate prediction using flexible continuum models and Bayesian statistics is demonstrated. Bulk etch rates of MgO are predicted using a steady-state model with volume-averaged plasma parameters and classical Langmuir surface kinetics. Plasma particle and surface kinetics are modeled within a global plasma framework using single component Metropolis Hastings methods and limited data. The accuracy of these predictions is evaluated with synthetic and experimental etch rate data for magnesium oxide in an ICP-RIE system. This approach is compared and superior to factorial models generated from JMP, a software package frequently employed for recipe creation and optimization.

  2. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    PubMed

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process. PMID:26635279

  3. Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl{sub 2} ion beam assisted etching

    SciTech Connect

    Anglin, Kevin Goodhue, William D.; Swint, Reuel B.; Porter, Jeanne

    2015-03-15

    A deeply etched, anisotropic 45° and 90° mirror technology is developed for Al{sub x}Ga{sub 1−x}As heterostructures using a Cl{sub 2} ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si{sub 3}N{sub 4}-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar{sup +} ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.

  4. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time. PMID:26754938

  5. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  6. Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

    PubMed

    Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

    2014-02-01

    The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding. PMID:24372961

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

    PubMed Central

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

    2012-01-01

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

  8. Network flow model analysis of the impact of chlorofluorocarbon phaseout on acid-grade fluorspar. Information circular/1994

    SciTech Connect

    Slatnick, J.A.; Fulton, R.B.

    1994-12-31

    Chlorofluorocarbons (CFC`s) are being phased out and eventually banned under extensive international agreements because the chlorine in CFC`s is thought to deplete the Earth`s ozone layer. As a result, the fluorspar mining industry, which is the source of fluorine in fluorocarbons through intermediate hydrofluoric acid, is being affected. Concern for this impact has led the U.S. Bureau of Mines to employ its capabilities to analyze various scenarios in the evolution of CFC replacements and substitutes to determine their effect on fluorspar mining. This report utilizes a network flow model to examine the effects of proposed replacements for CFC`s, in terms of fluorine content, on fluorspar operations worldwide and on hydrofluoric acid plants in North America and Europe.

  9. Integrated reactive ion etching to pattern cross-linked hydrophilic polymer structures for protein immobilization

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Parijat; Strickland, Aaron D.; Kim, Il; Malliaras, George G.; Batt, Carl A.

    2007-04-01

    Patterning of cross-linked hydrophilic polymer features using reactive ion etching (RIE) capable of covalently immobilizing proteins has been achieved. Projection photolithography was used to pattern photoresist to create micromolds. Vapor phase molecular self-assembly of polymerizable monolayer in molds allowed covalent binding of hydrogel on surface during free-radical polymerization. Excess hydrogel blanket film was consumed with oxygen RIE resulting into hydrogel pattern of 1μm size aligned to prefabricated silicon oxide structures. Proteins were finally coupled through their primary amine groups selectively to acid functionalized hydrogel features through stable amide linkages using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride and N-hydroxysulfosuccinimide.

  10. Ion orbits in plasma etching of semiconductors

    SciTech Connect

    Madziwa-Nussinov, Tsitsi G.; Arnush, Donald; Chen, Francis F.

    2008-01-15

    Fabrication of high-speed semiconductor circuits depends on etching submicron trenches and holes with straight walls, guided by sheath accelerated ions, which strike the substrate at a normal angle. Electrons accumulate at the nonconductive entrance of each trench, charging it negatively and preventing the penetration of electrons to the bottom of the trench. This 'electron shading' effect causes an ion charge at the bottom, which is well known to cause damage to thin oxide layers. In addition, the deflection of ions by electric fields in the trench can cause deformation of the trench shape. To study this effect, the ion orbits are computed self-consistently with their charging of the trench walls. It is found that (a) the orbits depend only on the electric fields at the entrance and are sensitive to changes in the shape of the photoresist layer there; (b) there is an 'ion shading' effect that protects part of the wall; and (c) the number of ions striking the wall is too small to cause any deformation thereof.

  11. Automated process control for plasma etching

    NASA Astrophysics Data System (ADS)

    McGeown, Margaret; Arshak, Khalil I.; Murphy, Eamonn

    1992-06-01

    This paper discusses the development and implementation of a rule-based system which assists in providing automated process control for plasma etching. The heart of the system is to establish a correspondence between a particular data pattern -- sensor or data signals -- and one or more modes of failure, i.e., a data-driven monitoring approach. The objective of this rule based system, PLETCHSY, is to create a program combining statistical process control (SPC) and fault diagnosis to help control a manufacturing process which varies over time. This can be achieved by building a process control system (PCS) with the following characteristics. A facility to monitor the performance of the process by obtaining and analyzing the data relating to the appropriate process variables. Process sensor/status signals are input into an SPC module. If trends are present, the SPC module outputs the last seven control points, a pattern which is represented by either regression or scoring. The pattern is passed to the rule-based module. When the rule-based system recognizes a pattern, it starts the diagnostic process using the pattern. If the process is considered to be going out of control, advice is provided about actions which should be taken to bring the process back into control.

  12. Effect of Postoperative Bleaching on Microleakage of Etch-and-Rinse and Self-etch Adhesives

    PubMed Central

    Mortazavi, Vajihesadat; Fathi, Mohammadhossein; Soltani, Fereidon

    2011-01-01

    Background: Bleaching the discoloured teeth may affect the tooth/composite interface. The aim of this in vitro experimental study was to evaluate the effect of vital tooth bleaching on microleakage of existent class V composite resin restorations bonded with three dental bonding agents. Methods: Class V cavities were prepared on buccal surfaces of 72 intact, extracted human anterior teeth with gingival margins in dentin and occlusal margins in enamel, and randomly divided into 3 groups. Cavities in the three groups were treated with Scotch bond Multi-Purpose, a total etch system and Prompt L-Pop and iBond, two self-etch adhesives. All teeth were restored with Z250 resin composite material and thermo-cycled. Each group was equally divided into the control and the bleached subgroups (n = 12). The bleached subgroups were bleached with 15% carbamide peroxide gel for 8 hours a day for 15 days. Microleakage scores were evaluated on the incisal and cervical walls. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Bonferroni post-hoc tests (α = 0.05). Results: Bleaching with carbamide peroxide gel significantly increased the microleakage of composite restorations in Prompt L-Pop group at dentinal walls (P = 0.001). Bleaching had no effect on microleakage of restorations in the Scotch bond Multi-Purpose and iBond groups. Conclusion: Vital tooth bleaching with carbamide peroxide gel has an adverse effect on marginal seal of dentinal walls of existent composite resin restorations bonded with prompt L-Pop self-etch adhesive. PMID:22132010

  13. Chemical etching for automatic processing of integrated circuits

    NASA Technical Reports Server (NTRS)

    Kennedy, B. W.

    1981-01-01

    Chemical etching for automatic processing of integrated circuits is discussed. The wafer carrier and loading from a receiving air track into automatic furnaces and unloading onto a sending air track are included.

  14. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, Robert J.; Mayer, Steven T.; Tarte, Lisa A.

    1996-01-01

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment.

  15. 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.

  16. 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.

  17. Summary of Chalcogenide Glass Processing: Wet-Etching and Photolithography

    SciTech Connect

    Riley, Brian J.; Sundaram, S. K.; Johnson, Bradley R.; Saraf, Laxmikant V.

    2006-12-01

    This report describes a study designed to explore the different properties of two different chalcogenide materials, As2S3 and As24S38Se38, when subjected to photolithographic wet-etching techniques. Chalcogenide glasses are made by combining chalcogen elements S, Se, and Te with Group IV and/or V elements. The etchant was selected from the literature and was composed of sodium hydroxide, isopropyl alcohol, and deionized water and the types of chalcogenide glass for study were As2S3 and As24S38Se38. The main goals here were to obtain a single variable etch rate curve of etch depth per time versus NaOH overall solution concentration in M and to see the difference in etch rate between a given etchant when used on the different chalcogenide stoichiometries. Upon completion of these two goals, future studies will begin to explore creating complex, integrated photonic devices via these methods.

  18. 1. Photocopy of an early etching (Original in collection of ...

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

    1. Photocopy of an early etching (Original in collection of the Historical Society of Montana) BROADWAY AND JACKSON ELEVATIONS - Second Masonic Temple, Broadway & Jackson Streets, Helena, Lewis and Clark County, MT

  19. Novel Surface Reaction Model in Dry-Etching Process Simulator

    NASA Astrophysics Data System (ADS)

    Misaka, Akio; Harafuji, Kenji; Kubota, Masafumi; Nomura, Noboru

    1992-12-01

    A new surface reaction model has been presented to simulate topological evolutions by taking into account the existence of adsorbed radicals on the substrate surface. The model treats the etching rate as a function of the coverage ratio by adsorbed radicals on the surface. Based on the model, a two-dimensional topography simulator has been developed. The simulator is applied to silicon-dioxide trench etchings made by hydrofluorocarbon gases. First, micro-loading effects in an important ion-assisted etching process are studied. It is confirmed that the micro-loading effect is due to the shortage of supplied active radicals inside the trench structure. Secondly, the competitive process between etching and deposition is examined. The side-wall protection phenomena resulting from the process are well simulated.

  20. Analysis of machining characteristics in electrochemical etching using laser masking

    NASA Astrophysics Data System (ADS)

    Shin, Hong Shik; Chung, Do Kwan; Park, Min Soo; Chu, Chong Nam

    2011-12-01

    Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.

  1. 153. Copy of Louis Rosenberg Etching (original in the Tower ...

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

    153. Copy of Louis Rosenberg Etching (original in the Tower City Development Office, Cleveland, Ohio) TERMINAL TOWER UNDER CONSTRUCTION, PUBLIC SQUARE ELEVATION, VIEW NORTHWEST TO SOUTHEAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

  2. 158. Copy of Louis Rosenberg Etching (original in the Tower ...

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

    158. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) TERMINAL TOWER UNDER CONSTRUCTION, PUBLIC SQUARE FACADE, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

  3. Origin of electrical signals for plasma etching endpoint detection

    SciTech Connect

    Sobolewski, Mark A.

    2011-11-14

    Electrical signals are used for endpoint detection in plasma etching, but the origin of the electrical changes observed at endpoint is not known. They may be caused by changes in the gas-phase densities of etch products and reactants or by changes in substrate surface properties such as photoemitted or ion-induced electron yield. To investigate these effects, experiments were performed in an inductively coupled, rf-biased reactor, during CF{sub 4}/Ar etches of SiO{sub 2} films on Si wafers. The rf bias impedance was measured vs. time during etching, simultaneous with Langmuir probe measurements. At endpoint, a decrease in impedance coincided with increases in ion current and electron energy. The data, analyzed by a numerical model of the discharge, indicate that changes in electron emission yield were relatively insignificant or entirely absent. Thus the impedance change is not a surface effect but is, instead, predominantly or entirely a gas-phase phenomenon.

  4. In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study

    PubMed Central

    Nagpal, Rajni; Manuja, Naveen; Tyagi, Shashi Prabha; Singh, Udai Pratap

    2011-01-01

    Aim: To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin–dentin interfacial ultrastructure under scanning electron microscope (SEM). Materials and Methods: 100 extracted human premolars were divided into two groups for different adhesives (Clearfil S3 and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin–dentin interface. Results: At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin–dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied. Conclusions: In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage. PMID:22025829

  5. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chemical etching and milling subcategory. 413.60 Section 413.60 Protection of Environment ENVIRONMENTAL... Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling... chemical milling or etching of ferrous or nonferrous materials....

  6. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... chemical etching and milling subcategory. 413.60 Section 413.60 Protection of Environment ENVIRONMENTAL... Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling... chemical milling or etching of ferrous or nonferrous materials....

  7. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... chemical etching and milling subcategory. 413.60 Section 413.60 Protection of Environment ENVIRONMENTAL... Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling... chemical milling or etching of ferrous or nonferrous materials....

  8. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... chemical etching and milling subcategory. 413.60 Section 413.60 Protection of Environment ENVIRONMENTAL... Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling... chemical milling or etching of ferrous or nonferrous materials....

  9. 40 CFR 413.60 - Applicability: Description of the chemical etching and milling subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... chemical etching and milling subcategory. 413.60 Section 413.60 Protection of Environment ENVIRONMENTAL... Etching and Milling Subcategory § 413.60 Applicability: Description of the chemical etching and milling... chemical milling or etching of ferrous or nonferrous materials....

  10. Advantages of p++ polysilicon etch stop layer versus p++ silicon

    NASA Astrophysics Data System (ADS)

    Charavel, Remy; Laconte, Jean; Raskin, Jean Pierre

    2003-04-01

    Boron highly doped silicon is now widely used as etch stop layer in MicroElectroMechanical Systems (MEMS) devices fabrication. The present paper shows the advantages of replacing the p++ Si etch stop layer by a p++ polysilicon layer. The etch rate of Tetramethylammoniunhydroxide (TMAH) is measured for LPCVD polysilicon and silicon doped with Boron at concentrations from 8.1018 up to 4.1020 atoms/cm3 which is the Boron solubility limit into Si. TMAH etch being often used during back-end process, selectivity to aluminium is usually needed. The etch selectivity of various TMAH solutions for p++ Si, p++ Poly and aluminium have been measured, from 25 % to 5 % TMAH pure and mixed with silicon powder and ammonium persulfate. Contrarily to silicon, polysilicon is etched isotropically in TMAH solution which constitutes a great advantage when cavities with vertical walls have to be opened. Although the polysilicon etch rate is higher than the silicon one, the selectivity (doped/undoped) is the same for the both materials, allowing identical uses. Another great advantage of polysilicon is that it can be deposited at any process step and does not require clever epitaxy steps or wafer bonding as for silicon. The surface roughness of the etched Poly region is considerably decreased with TMAH mixed with silicon powder and ammonium persulfate mixture compared to pure 25 % TMAH solution. The definition of buried masks in polysilicon layer through Boron implant is the main foreseen application. The p++ Poly buried mask brings solutions for the fabrication of self-aligned double gate MOS, microfluidic or optical networks in MEMS field.

  11. Selective chemical etching of iron-doped lithium niobate

    SciTech Connect

    Alekseeva, Z.E.; Vorob'eva, L.B.; Evlanova, N.F.

    1987-01-01

    Addition of the dopant changed the way in which the lithium niobate crystal etched. As a result, nonpolar slices clearly showed microdomain etch figures that enabled determination of surface sign as well as <0110> and <0001> directions on the (2110) planes. Mechanical treatment was shown to be one of the reasons for microdomain destruction at the surface layer. The thickness of the damaged layer may be determined by the width of the edge zone displaying a high microdomain density at the (0001) plane.

  12. Characterization and Control of Etch Processes Using Multiple Metrologies

    NASA Astrophysics Data System (ADS)

    Bushman, Scott; Celii, Francis; Martin, Scott; Tristan, Luis

    2005-09-01

    The integration of embedded ferroelectric random access memory (FRAM) into a standard CMOS flow requires significant control and characterization of the etch process. Current qualification and control of the etch process for the TiAlN hardmask and Ir/PZT/Ir capacitor film stack relies on several metrologies to evaluate performance (etch rate, critical dimension, sidewall angle, etc). Profilometry is currently used for monitoring hardmask etch rate, but is fraught with difficulties such as low throughput and low reproducibility. Here we compare options for determining hardmask etch rate, including Atomic Force Microscopy (AFM), profilometry, and scatterometry. Wafers with a range of film stacks were generated to test each measurement technique's robustness in etch rate determination. A robust, precise, short cycle time, fully automated process monitor of etch rate is required to make qualification of the etch process manufacturable. Scatterometry is a non-destructive optical metrology based on the analysis of light scattered from a periodic sample. It is a faster technique than either profilometry or AFM because of the optical nature of the measurement, and provides measurements of patterned grating structures. However, a detailed film model is required to estimate parameters of interest. The scatterometry model for this investigation includes four adjustable parameters: TiAlN material index of refraction, thickness, linewidth and sidewall angle. The results show good agreement between the scatterometry measurements and the AFM across the range of step-heights available on the wafers. In addition, the practical aspects of the method, such as the modeling time and estimation of material parameters required to generate the signature library as well as measurement speed are presented.

  13. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    SciTech Connect

    Wang, Yufeng; Zeng, Yongbin Qu, Ningsong; Zhu, Di

    2015-07-15

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained.

  14. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    DOEpatents

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  15. Evaluating the shear bond strength of enamel and dentin with or without etching: A comparative study between dimethacrylate-based and silorane-based adhesives

    PubMed Central

    Hajizadeh, Hila; Nasseh, Atefeh; Rahmanpour, Naim

    2015-01-01

    Background Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching. Material and Methods 40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- Filtek P90 composite and Silorane adhesive. Each group divided into two subgroups: with or without additional etching. For additional etching, 37% acid phosphoric was applied before bonding procedure. A cylinder of the composite was bonded to the surface. After 24 hours storage and 500 thermo cycling between 5-55°C, shear bond strength was assessed with the cross head speed of 0.5 mm/min. Then, bonded surfaces were observed under stereomicroscope to determine the failure mode. Data were analyzed with two-way ANOVA and Fischer exact test. Results Shear bond strength of Filtek P60 composite was significantly higher than Filtek P90 composite both in enamel and dentin surfaces (P<0.05). However, additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites (P>0.05). There was no interaction between composite type and additional etching (P>0.05). Failure pattern was mainly adhesive and no significant correlation was found between failure and composite type or additional etching (P>0.05). Conclusions Shear bond strength of methacrylate-based composite was significantly higher than silorane-based composite both in enamel and dentin surfaces and additional etching had no significant effect on shear bond strength in enamel or dentin for

  16. Etching of germanium-tin using ammonia peroxide mixture

    SciTech Connect

    Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia; Zhang, Zheng; Pan, Jisheng; Tok, Eng-Soon

    2015-12-28

    The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

  17. 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.

  18. Vapor etching of nuclear tracks in dielectric materials

    DOEpatents

    Musket, Ronald G.; Porter, John D.; Yoshiyama, James M.; Contolini, Robert J.

    2000-01-01

    A process involving vapor etching of nuclear tracks in dielectric materials for creating high aspect ratio (i.e., length much greater than diameter), isolated cylindrical holes in dielectric materials that have been exposed to high-energy atomic particles. The process includes cleaning the surface of the tracked material and exposing the cleaned surface to a vapor of a suitable etchant. Independent control of the temperatures of the vapor and the tracked materials provide the means to vary separately the etch rates for the latent track region and the non-tracked material. As a rule, the tracked regions etch at a greater rate than the non-tracked regions. In addition, the vapor-etched holes can be enlarged and smoothed by subsequent dipping in a liquid etchant. The 20-1000 nm diameter holes resulting from the vapor etching process can be useful as molds for electroplating nanometer-sized filaments, etching gate cavities for deposition of nano-cones, developing high-aspect ratio holes in trackable resists, and as filters for a variety of molecular-sized particles in virtually any liquid or gas by selecting the dielectric material that is compatible with the liquid or gas of interest.

  19. Etching of photoresist with an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    West, Andrew; van der Schans, Marc; Xu, Cigang; Gans, Timo; Cooke, Mike; Wagenaars, Erik

    2014-10-01

    Low-pressure oxygen plasmas are commonly used in semiconductor industry for removing photoresist from the surface of processed wafers; a process known as plasma ashing or plasma stripping. The possible use of atmospheric-pressure plasmas instead of low-pressure ones for plasma ashing is attractive from the point of view of reduction in equipment costs and processing time. We present investigations of photoresist etching with an atmospheric-pressure plasma jet (APPJ) in helium gas with oxygen admixtures driven by radio-frequency power. In these experiments, the neutral, radical rich effluent of the APPJ is used for etching, avoiding direct contact between the active plasma and the sensitive wafer, while maintaining a high etch rate. Photoresist etch rates and etch quality are measured for a range of plasma operating parameters such as power input, driving frequency, flow rate and wafer temperature. Etch rates of up to 10 micron/min were achieved with modest input power (45 W) and gas flow rate (10 slm). Fourier Transform Infrared (FTIR) spectroscopy showed that the quality of the photoresist removal was comparable to traditional plasma ashing techniques. This work was supported by the UK Engineering and Physical Sciences Research Council Grant EP/K018388/1.

  20. Low damage, highly anisotropic dry etching of SiC

    SciTech Connect

    Wang, J.J.; Hong, J.; Lambers, E.S.; Pearton, S.J.; Ren, F.; Ostling, M.; Zetterling, C.M.; Grow, J.M.; Shul, R.J.

    1998-03-01

    A parametric study of the etching characteristics of 6H p{sup +} and n{sup +} SiC and thin film SiC{sub 0.5}N{sub 0.5} in Inductively Coupled Plasma NF{sub 3}/O{sub 2} and NF{sub 3}/Ar discharges has been performed. The etch rates in both chemistries increase monotonically with NF{sub 3} percentage and rf chuck power. The etch rates go through a maximum with increasing ICP source power, which is explained by a trade-off between the increasing ion flux and the decreasing ion energy. The anisotropy of the etched features is also a function of ion flux, ion energy and atomic fluorine neutral concentration. Indium-tin-oxide (ITO) masks display relatively good etch selectivity over SiC (maximum of {approximately} 70:1), while photoresist etches more rapidly than SiC. The surface roughness of SiC is essentially independent of plasma composition for NF3/O2 discharges, while extensive surface degradation occurs for SiCN under high NF{sub 3}:O{sub 2} conditions.