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1

Initial pits for electrochemical etching in hydrofluoric acid  

Microsoft Academic Search

This paper reports on a characterization of structures fabricated by electrochemical etching in hydrofluoric acid (HF) using different types of initial pits. An initial pit has been thought to require a sharp tip in order to collect electronic holes generated by illumination. Therefore, the initial pits have been formed by etching in a KOH solution, which suffers from crystal orientation

H Ohji; P. J French; S Izuo; K Tsutsumi

2000-01-01

2

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

Microsoft Academic Search

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

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

2009-01-01

3

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

Microsoft Academic Search

The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses 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

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

2009-01-01

4

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

PubMed

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. PMID:20652125

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

2009-01-01

5

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

6

HYDROFLUORIC ACID Safety Office  

E-print Network

acids like Sulfuric and Hydrochloric. Hydrofluoric Acid is an acid like no other. It is so potentHYDROFLUORIC ACID SAFETY Safety Office University ofTennessee Space Institute Tullahoma, TN #12;What is Hydrofluoric Acid ? Hydrofluoric acid is a "weak" inorganic acid. Primarily used

Davis, Lloyd M.

7

The microstructures of perthitic alkali feldspars revealed by hydrofluoric acid etching  

NASA Astrophysics Data System (ADS)

Etching of alkali feldspar cleavage fragments with hydrofluoric acid vapor, followed by study of the surfaces by scanning electron microscopy (SEM), is a simple and rapid technique for characterizing the microtextures of crypto- and microperthites. This technique has a number of advantages over conventional transmission electron microscopy (TEM) including ease of sample preparation and the large areas of crystals which can be imaged. Alkali feldspars studied by the method can yield important information on the cooling history of igneous and metamorphic rocks, fluid-feldspar interactions and the morphology and microstructures of albite exsolution lamellae. Some of these applications are illustrated by examples of etched crypto- and micro-perthites from the Klokken layered syenite, south Greenland and the Shap granite, north-west England.

Waldron, K.; Lee, M. R.; Parsons, I.

1994-04-01

8

Release of oxides of nitrogen in etching Zr + 1% Nb tubes in a mixture of nitric and hydrofluoric acids  

Microsoft Academic Search

Toxic oxides of nitrogen NO\\/sub x\\/ are released on etching fuel-pin tubes made of zirconium alloys, which adversely effect the working conditions and produce air pollution. In this paper, the authors examine the effects of some technological parameters on the release of these oxides during zirconium-alloy tube etching in a mixture of nitric and hydrofluoric acids, and they also examine

A. S. Polyakov; Z. Sh. Nikuradze

1987-01-01

9

Release of oxides of nitrogen in etching Zr + 1% Nb tubes in a mixture of nitric and hydrofluoric acids  

SciTech Connect

Toxic oxides of nitrogen NO/sub x/ are released on etching fuel-pin tubes made of zirconium alloys, which adversely effect the working conditions and produce air pollution. In this paper, the authors examine the effects of some technological parameters on the release of these oxides during zirconium-alloy tube etching in a mixture of nitric and hydrofluoric acids, and they also examine ways of reducing the yield of NO/sub x/ during the etching. The experiments were performed with a thermostatic teflon reactor. The region that was examined and the variation intervals are shown. The authors used experiment planning with the scheme for a 2/sup 5-1/ fractional factor experiment (FFE). A planning matrix for the 2/sup 5-1/ FFE and the measurement results are presented. It is shown that the release of the NO/sub x/ directly into the gas and the accumulation in the solution vary considerably with the etching conditions. The regression equations and the ranking diagram presented here provide scope for reducing the release of oxides of nitrogen during etching zirconium-alloy tubes.

Polyakov, A.S.; Nikuradze, Z.Sh.

1987-01-01

10

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

PubMed Central

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

STEINHAUSER, Henrique Caballero; TURSSI, Ceclia Pedroso; FRANA, Fabiana Mantovani Gomes; do AMARAL, Flvia Lucisano Botelho; BASTING, Roberta Tarkany

2014-01-01

11

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

12

Geochemistry of Hydrofluoric Acid in Kaolinitic Soils  

Microsoft Academic Search

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

2004-01-01

13

Geochemistry of Hydrofluoric Acid in Kaolinitic Soils  

SciTech Connect

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

DENHAM, MILES

2004-05-11

14

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

Microsoft Academic Search

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

Matthew G

2009-01-01

15

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

DOEpatents

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

Hankins, Matthew G. (Albuquerque, NM)

2009-10-06

16

Vapor Hydrofluoric Acid Sacrificial Release Technique for Micro Electro Mechanical Systems Using Labware  

Microsoft Academic Search

We have developed a novel technique of sacrificial layer etching for micro electro mechanical systems (MEMS). Our technique uses vapor of hydrofluoric acid (HF) to etch sacrificial silicon oxide and to make freestanding silicon microstructures. The advantages of this technique are: (1) no subsequent water rinse is needed, (2) freestanding silicon microstructures can be successfully released without sticking to the

Yamato Fukuta; Hiroyuki Fujita; Hiroshi Toshiyoshi

2003-01-01

17

[Hydrofluoric acid injuries: pathogenesis and treatment].  

PubMed

On the basis of two case histories, the most recent literature concerning hydrofluoric acid injuries is reviewed with particular attention to the pathogenesis and the therapeutic possibilities. It is concluded that washing with water is the primary and most important treatment. Depending upon the extent of the injury, surface treatment with 2.5% calcium gluconate solution or gel may then be employed and/or infiltration treatment with a 5-10% calcium solution. Possibly combined with local analgesia and hyaluronic acid. Intravenous or intra-arterial infusion of calcium compounds and surgical excision may be considered as specialist treatment. PMID:2360278

Trap, R; Christensen, I

1990-05-28

18

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

E-print Network

Glass-ceramic Flexural Strength after Hydrofluoric Acid and Unfilled Resin Treatment Sumana one of the most effective methods for achieving durable resin bond to glass-ceramics. Nonetheless, HF acid etching effect on glass-based ceramics strength remains uncertain and only a few contradictory

Zhou, Yaoqi

19

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

20

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

21

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

22

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

23

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

24

Hydration structure in dilute hydrofluoric acid.  

PubMed

We have performed the multistate empirical valence bond (MS-EVB) molecular dynamics simulations of a dilute hydrofluoric acid solution at ambient temperature to study the hydration structure associated with its weak acidity. The developed MS-EVB model showed reasonable agreement with experimental and previous ab initio molecular dynamics and reference interaction site model self-consistent field simulations for the free energy and structural properties. The local tetrahedral and translational order parameters around the fluorine atom significantly increase in the transition and product states of the HF dissociation reaction. This indicates that the angular and translational rearrangements of the hydrogen-bond topology are necessary especially around the fluorine atom. At the transition state of the proton transfer, the tetrahedral order parameters are very large, whereas the translational order parameters are not. This suggests that for the proton transfer to occur the large angular rearrangements of the hydrogen-bond topology are more necessary than the translational ones. PMID:21210669

Joutsuka, Tatsuya; Ando, Koji

2011-02-10

25

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

Code of Federal Regulations, 2012 CFR

...Substances 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products with...significant new uses are: (i) Release to water. Requirements...

2012-07-01

26

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

Code of Federal Regulations, 2013 CFR

...Substances 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products with...significant new uses are: (i) Release to water. Requirements...

2013-07-01

27

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

Code of Federal Regulations, 2010 CFR

...Substances 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products with...significant new uses are: (i) Release to water. Requirements...

2010-07-01

28

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

Code of Federal Regulations, 2014 CFR

...Substances 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products with...significant new uses are: (i) Release to water. Requirements...

2014-07-01

29

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

Code of Federal Regulations, 2011 CFR

...Substances 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products with...significant new uses are: (i) Release to water. Requirements...

2011-07-01

30

Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1  

Microsoft Academic Search

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

Osborne

2000-01-01

31

Basics of Etching technology Wet etching  

E-print Network

Type A" from Transene Co., Inc. is a mixture of phosphoric acid, acetic acid and nitric acid. Etch Rate (Hydrofluoric acid + Nitric acid + Acetic acid) Base: ·KOHetch ·NaOH etch ·EDP (Ethylene Diamine Pyrocatechol Phosphoric Acid 55A/min (BOE dip first to remove oxynitride layer), etches silicon dioxide at 10 ?

Wang, Deli

32

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

E-print Network

Hydrofluoric Acid Policy Procedure: 5.08 Created: 7/2007 Version: 2.0 Revised: 9/2014 Environmental with hydrofluoric acid (HF), a highly hazardous chemical. It outlines safe work practices and response in case Hydrofluoric Acid (HF) is an inorganic acid which is derived from dissolving hydrogen fluoride in water. HF

Jia, Songtao

33

Process support conditions for dissolving metallic plutonium in a mixture of nitric and hydrofluoric acids  

Microsoft Academic Search

The process of dissolving metallic plutonium is based on a method that uses a mixture of nitric and hydrofluoric acids. The choice of this method is cited in comparison primarily with the method of dissolving Pu in hydrochloric acid solutions [1]. Dissolution is done in mixtures of 412 moles\\/liter of nitric acid and 0.20.4 mole\\/liter of hydrofluoric acid with boiling

B. S. Zakharkin; V. P. Varykhanov; V. S. Kucherenko; L. N. Solovyeva

2000-01-01

34

Process support conditions for dissolving metallic plutonium in a mixture of nitric and hydrofluoric acids  

Microsoft Academic Search

The process of dissolving metallic plutonium is based on a method that uses a mixture of nitric and hydrofluoric acids. The choice of this method is cited in comparison primarily with the method of dissolving Pu in hydrochloric acid solutions [1]. Dissolution is done in mixtures of 4-12 moles\\/liter of nitric acid and 0.2-0.4 mole\\/liter of hydrofluoric acid with boiling

B. S. Zakharkin; V. P. Varykhanov; V. S. Kucherenko; L. N. Solov'yeva

2000-01-01

35

Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid.  

PubMed

Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns and bridges. The present study evaluated the shear bond strength of metal orthodontic brackets to the feldspathic porcelain surfaces following conditioning by different powers of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and hydrofluoric acid as a conventional method. Seventy-two glazed porcelain samples were prepared and randomly attributed to six equal groups of 12. In the conventional hydrofluoric (HF) group, the specimens were etched by 9.6% hydrofluoric acid for 4min. In laser groups, samples were conditioned by 0.75-, 1-, 1.25-, 1.5-, and 2-W Nd:YAG laser for 10s. Metal brackets were bonded to porcelain samples and after being stored in distilled water for 24h, they were subjected to thermocycling for 500cycles. The debonding was carried out by a Zwick testing machine. The data were statistically analyzed by ANOVA and Tamhane multiple comparisons tests. The mean SD of the shear bond strength in the laser group 0.75, 1, 1.25, 1.5, and 2W and HF group was 2.2??0.9, 4.2??1.1, 4.9??2.4, 7??1.7, 9.6??2.7, and 9.4??2.5, respectively. Together with the increased power of laser, the mean shear bond strength was increased continuously and no significant differences were found between the HF group and the laser groups with power of 1.5 or 2W. Also, there was no significant difference between all test groups in ARI scores. There was no significant difference between bond strength of laser groups with power of 1.5 and 2W and HF-etched group. So, Nd:YAG laser with appropriate parameters can be used as an alternative method for porcelain etching. PMID:24142046

Hosseini, Mohammad Hashem; Sobouti, Farhad; Etemadi, Ardavan; Chiniforush, Nasim; Shariati, Mahsa

2015-02-01

36

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

Microsoft Academic Search

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

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

2001-01-01

37

Hydrofluoric Acid Corrosion Study of High-Alloy Materials  

SciTech Connect

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

Osborne, P.E.

2002-09-11

38

Observation of hydrofluoric acid burns on osseous tissues by means of terahertz spectroscopic imaging.  

PubMed

Terahertz technologies have gained great amount of attention for biomedical imaging and tissue analysis. In this study, we utilize terahertz imaging to study the effects of hydrofluoric acid on both compact bone tissue and cartilage. We compare the differences observed in the exposure for formalin fixed and raw, dried, tissue as well as those resulting from a change in hydrofluoric (HF) concentration. Measurements are performed with THz-TDS, and a variety of spectroscopic-based image reconstruction techniques are utilized to develop contrast in the features of interest. PMID:25055307

Baughman, William E; Yokus, Hamdullah; Balci, Soner; Wilbert, David Shawn; Kung, Patrick; Kim, Seongsin Margaret

2013-07-01

39

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

Microsoft Academic Search

The Molten Salt Reactor Experiment (MSRE) remediation requires that almost 40 kg of uranium hexafluoride (UF) be converted to uranium oxide (UO). In the process of this conversion, six moles of hydrofluoric acid (HF) are produced for each mole of UF converted. The entire conversion process can be summarized by the following reaction: UF + 3HO UO + 6HF.

Osborne

2000-01-01

40

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

Microsoft Academic Search

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

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

2000-01-01

41

Acute Health Effects in a Community after a Release of Hydrofluoric Acid  

Microsoft Academic Search

Approximately 3000 persons were evacuated from a Texas community after 24036 kg (53000 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

Jessie S. Wing; Lee M. Sanderson; Jean D. Brender; Dennis M. Perrotta; Richard A. Beauchamp

1991-01-01

42

Frequency estimates for transport-related hydrofluoric and sulfuric acid release scenarios  

Microsoft Academic Search

An analysis was performed to predict the frequency of release associated with transportation scenarios for four refineries and a chemical plant in the South Coast Basin using hydrofluoric acid (HF) in the alkylation process\\/chemical process. The analysis considers two settings. The first is the set of ongoing HF transportation scenarios, and the second is a projected set of HF and

Subodh R. Medhekar; Willard C. Gekler; Dennis C. Bley

1993-01-01

43

Regional Intravenous Infusion of Calcium Gluconate for Hydrofluoric Acid Burns of the Upper Extremity  

Microsoft Academic Search

Study objective: To describe regional intravenous infusion of calcium gluconate as a therapy for hydrofluoric acid (HF) burns of the forearm, hand, or digits. Methods: This study describes seven patients with HF burns. Calcium gluconate, 10 mL of 10% solution with 30 to 40 mL normal saline solution, was injected intravenously into the affected limb using a Bier block technique.

Andis Graudins; Michael J Burns; Cynthia K Aaron

1997-01-01

44

Neutralization method for a hydrofluoric acid release. [Use of lime\\/water slurry  

Microsoft Academic Search

A laboratory investigation of methods for neutralizing a release at the hydrofluoric acid tank farm at the Portsmouth Gaseous Diffusion Plant has revealed that the best neutralization method incorporates the use of a lime\\/water slurry. In this method, settling of suspended solids in the liquid is enhanced by the application of sodium dodecyl sulfate, which causes immediate flocculation and settling.

D. L. Williams; L. E. Deacon

1976-01-01

45

New Acid Etched Titanium Dental Implant Surface  

Microsoft Academic Search

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

Gintaras Juodzbalys; Marija Sapragoniene; Ann Wennerberg

46

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

PubMed

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

Ayotte, Patrick; Plessis, Sylvain; Marchand, Patrick

2008-08-28

47

Determination of 5-methylcytosine by acid hydrolysis of DNA with hydrofluoric acid.  

PubMed

Quantitation of 5-methylcytosine in DNA after acid hydrolysis has been inaccurate because deamination of cytosine and 5-methylcytosine occurs during the hydrolysis procedure. There is little information in the literature regarding the use of hydrofluoric acid (HF) for DNA hydrolysis and we have therefore undertaken a systematic study of this process. The deoxyribonucleotides of cytosine and 5-methylcytosine were shown not to undergo detectable levels of deamination during prolonged periods (up to 24 h) at 80 degrees C in 48% HF. Kinetic studies show that the release of purine and pyrimidine bases was complete by 4 h under these conditions. Analysis of the 5-methylcytosine content of DNA from various tissues gave levels that were very close to the values reported in the literature. This method is ideally suited for the determination of the overall cytosine methylation levels in DNA. PMID:3442330

Catania, J; Keenan, B C; Margison, G P; Fairweather, D S

1987-12-01

48

Hydrofluoric acid and anhydrous ammonia spills evaporation\\/air dispersion modeling and exposure assessment  

Microsoft Academic Search

This report provides an assessment of the air dispersion and human exposure to toxic airborne chemical concentrations resulting from potential spill scenarios involving a volatile liquid--hydrofluoric acid (HF) and a liquified gas--anhydrous ammonia (NH3). The HF spill was evaluated both as a ground-level area source and a stack release from within a building. The NH3 spill was only evaluated as

1990-01-01

49

An Effective Approach for Restraining Galvanic Corrosion of Polycrystalline Silicon by Hydrofluoric-Acid-Based Solutions  

Microsoft Academic Search

This paper presents an effective method to restrain galvanic corrosion of polycrystalline silicon (polysilicon) that is electrically coupled with noble metals of microelectromechanical systems (MEMS) devices by hydrofluoric-acid (HF)-based solu- tions. A titanium (Ti) redox sacrificial layer is added on the noble-metal layer and then covered by photoresist. Benefiting from the lower electrochemical potential of Ti than that of polysilicon

Yunfei Liu; Jing Xie; Mingliang Zhang; Jinling Yang; Fuhua Yang

2011-01-01

50

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

PubMed

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

Nicoletti, Giovanni; Pellegatta, Tommaso

2014-01-01

51

Frequency estimates for transport-related hydrofluoric and sulfuric acid release scenarios  

SciTech Connect

An analysis was performed to predict the frequency of release associated with transportation scenarios for four refineries and a chemical plant in the South Coast Basin using hydrofluoric acid (HF) in the alkylation process/chemical process. The analysis considers two settings. The first is the set of ongoing HF transportation scenarios, and the second is a projected set of HF and sulfuric acid transportation scenarios if the HF alkylation units of the refineries are replaced by sulfuric acid alkylation units. 5 refs., 9 figs., 10 tabs.

Medhekar, S.R.; Gekler, W.C.; Bley, D.C. (PLG, Inc., Newport Beach, CA (United States))

1993-07-01

52

In situ optical measurements of hydrofluoric acid aerosols  

SciTech Connect

HF aerosol measurements were obtained in a specially developed flow chamber with a cross-section of 8 {times} 16 feet, and approximately 140 feet long. The primary objective was to determine the extent of HF aerosol mist formation in a potential accidental release of HF. A newly developed in situ optical instrument (PCSV-P) was used to obtain on-line measurements of the aerosol. A total of 86 usable aerosol data sets were obtained during the test period. As many as 10 data sets were acquired for an 11 minute duration HF release. Briefly summarizing the results, the PCSV-P measured predominately submicron aerosols at the exit of the sharp-edged orifice. The aerosol then grew to larger particles at the outlet of the flow chamber. This result points to the formation of an aerosol through vaporization-condensation as opposed to a conventional shear spray. Temperature, humidity, release pressure, radial position in the plume, and type of acid did not appear to have an significant effect in the measured size distributions for the range of conditions investigated. 7 refs., 23 figs., 2 tabs.

Holve, D.J.; Harvill, T.L.; Schatz, K.W.; Koopman, R.P. (INSITEC, San Ramon, CA (USA); Mobil Research and Development Corp., Princeton, NJ (USA); Lawrence Livermore National Lab., CA (USA))

1989-09-01

53

Limited efficacy of calcium and magnesium in a porcine model of hydrofluoric acid ingestion  

Microsoft Academic Search

ObjectiveThis investigation evaluated the effectiveness of calcium and magnesium in treating oral hydrofluoric acid (HF) poisoning.\\u000a \\u000a \\u000a \\u000a MethodsThe controlled laboratory investigation used anesthetized pigs. Subjects received HF via NG tube, titrated to abolish electrocardiographic\\u000a abnormalities. The untreated group received saline infusion. The treatment group received serial injections of calcium chloride\\u000a (CaCl2) and magnesium chloride (MgCl2). A third group received oral infusions

Jason A. Coffey; Kori L. Brewer; Robert Carroll; John Bradfield; William J. Meggs

2007-01-01

54

Production of lunar oxygen, iron, magnesium, and silicon by aqueous hydrofluoric acid leaching  

NASA Astrophysics Data System (ADS)

Aqueous hydrofluoric acid (HF) processing of lunar regolith offers the versatile options of lunar iron and oxygen production by room temperature electrolysis as well as the extraction of electronic grade silicon and lunar magnesium. All the above products are derived from distillates (SiF4), leachates (Fe and 02), and residues (Mg) of a single leaching operation done on unbeneficiated soil. Water and all reagents can be recovered by well documented reactions involving evaporations, volatilizations, and vaporizations at temperatures under 500C that are well suited to the lunar environment.

Agosto, William N.

55

Anisotropic Vapor HF etching of silicon dioxide for Si microstructure release  

E-print Network

and vapor phase hydrofluoric acid. The etch rate ratio between implanted and unimplanted silicon dioxide is more than 150 in vapor hydrofluoric acid (VHF). This feature is of interest to greatly reduceAnisotropic Vapor HF etching of silicon dioxide for Si microstructure release Vikram Passia , Ulf

Paris-Sud XI, Université de

56

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

57

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

SciTech Connect

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

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

1987-07-01

58

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

E-print Network

amounts of water on the contaminated area thoroughly for at least 5 minutes. During this, have someone the contaminated clothing and continue again with the running water from the safety shower. 4) Using gloves (toHydrofluoric Acid (HF) Instructions The CEPSR Clean Room supplies one pound bottles of aqueous HF

Kim, Philip

59

Carbon and nitrogen isotope composition of bulk soils, particle-size fractions and organic material after treatment with hydrofluoric acid  

Microsoft Academic Search

Summary Soils and sediments contain only small amounts oforganic matter, and large concentrations ofpara- magnetic metals can give poor solid-state nuclear magnetic resonance (NMR) spectra oforganic matter. Pretreatment of samples with hydrofluoric acid (HF) dissolves significant proportions of the mineral matrix and extracts paramagnetic elements. We investigated the effects of 10% HF treatment on the stable isotope content ofcarbon (C)

G. G LEIXNER

2005-01-01

60

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

SciTech Connect

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

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

2008-07-01

61

Hydrofluoric acid burn resulting from ignition of gas from a compressed air duster.  

PubMed

A young female suffered burns to her hand after the ignition of gas from a compressed air duster. After debridement and dressing, the patient continued to have pain out of proportion to injury that was refractory to intravenous morphine. The material safety data sheet revealed that the chemical used was 1,1-difluoroethane. High temperatures can cause decompensation to form hydrofluoric acid. Calcium gluconate gel was applied topically to the patient's burns, which caused prompt and complete relief of her pain. A review of different compressed air duster products revealed that the main ingredient in each was a halogenated hydrocarbon. Although not considered flammable, all products have warnings regarding the possibility of ignition under various circumstances. Ignition of the gas in compressed air cleaners not only can cause flame burns, it can also cause chemical damage from exposure to hydrogen and fluoride ions. Prompt recognition and treatment is necessary to prevent severe injury. PMID:14501419

Foster, Kevin N; Jones, LouAnn; Caruso, Daniel M

2003-01-01

62

Fabrication of Micro-Grooves in Silicon Carbide Using Femtosecond Laser Irradiation and Acid Etching  

NASA Astrophysics Data System (ADS)

A simple method using an 800-nm femtosecond laser and chemical selective etching is developed for fabrication of high-aspect-ratio grooves in silicon carbide. Micro grooves with an aspect ratio of approximately 40 are obtained. The morphology and chemical compositions of the grooves are analyzed using a scanning electronic microscope equipped with an energy dispersive x-ray spectroscopy. The formation mechanism of SiC grooves is attributed to the chemical reactions of the laser induced structural changes with a mixed solution of hydrofluoric acid and nitric acid. In addition, the effects of laser irradiation parameters on the aspect ratio of the grooves are investigated.

Khuat, Vanthanh; Ma, Yun-Can; Si, Jin-Hai; Chen, Tao; Chen, Feng; Hou, Xun

2014-03-01

63

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

PubMed

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 . Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed. PMID:25389749

De Sio, Stphanie M; Wilson, Richard E

2014-12-01

64

Arsenic contamination of coarse-grained and nanostructured nitinol surfaces induced by chemical treatment in hydrofluoric acid.  

PubMed

XPS measurements of coarse-grained and nanostructured nitinol (Ni(50.2)Ti(49.8)) before and after chemical treatment in hydrofluoric acid (40% HF, 1 min) are presented. The nanostructured state, providing the excellent mechanical properties of nitinol, is achieved by severe plastic deformation. The near-surface layers of nitinol were studied by XPS depth profiling. According to the obtained results, a chemical treatment in hydrofluoric acid reduces the thickness of the protective TiO(2) oxide layer and induces a nickel release from the nitinol surface and an arsenic contamination, and can therefore not be recommended as conditioning to increase the roughness of NiTi-implants. A detailed evaluation of the resulting toxicological risks is given. PMID:22807469

Korotin, D M; Bartkowski, S; Kurmaev, E Z; Borchers, C; Mller, M; Neumann, M; Gunderov, D V; Valiev, R Z; Cholakh, S O

2012-10-01

65

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

Microsoft Academic Search

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

Karen M. Steel; John W. Patrick

2004-01-01

66

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

SciTech Connect

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

Hui Tian; Charles Reece; Michael Kelley; Sean Corcoran

2008-02-12

67

Influence of solution volume on the dissolution rate of silicon dioxide in hydrofluoric Acid.  

PubMed

Experimental data and modeling of the dissolution of various Si/SiO2 thermal coatings in different volumes of hydrofluoric acid (HF) are reported. The rates of SiO2 -film dissolution, measured by means of various electrochemical techniques, and alteration in HF activity depend on the thickness of the film coating. Despite the small volumes (0.6-1.2 mL) of the HF solution, an effect of SiO2 -coating thickness on the dissolution rate was detected. To explain alterations detected in HF activity after SiO2 dissolution, spectroscopic analyses (NMR and FTIR) of the chemical composition of the solutions were conducted. This is associated with a modification in the chemical composition of the HF solution, which results in either the formation of an oxidized species in solution or the precipitation of dissolution products. HF2 (-) accumulation in the HF solution, owing to SiO2 dissolution was identified as the source of the chemical alteration. PMID:25399799

Shvartsev, Boris; Gelman, Danny; Komissarov, Ilia; Epshtein, Alon; Starosvetsky, David; Ein-Eli, Yair

2015-02-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

69

Hydrofluoric acid and anhydrous ammonia spills evaporation/air dispersion modeling and exposure assessment  

SciTech Connect

This report provides an assessment of the air dispersion and human exposure to toxic airborne chemical concentrations resulting from potential spill scenarios involving a volatile liquid--hydrofluoric acid (HF) and a liquified gas--anhydrous ammonia (NH3). The HF spill was evaluated both as a ground-level area source and a stack release from within a building. The NH3 spill was only evaluated as a ground-level area source. Critical receptors for exposure assessment were located downwind at 100 m, the nearest public highway, and the nearest site boundary. In addition, worker exposure inside a building after an indoor spill of HF was evaluated. The evaporation computer code SPILLS was used to determine time-variable emission (evaporation) rates for input into the air dispersion model INPUFF. First order kinetic models were used to evaluate the buildup and decay of the indoor HF spill using both steady state and SPILLS time-variable emission rates. Air concentrations were plotted as a function of time to determine the time intervals that receptor concentrations exceeded the TLV, IDLH, and 10,000*TLV levels. 7 refs., 12 figs., 5 tabs.

Abbott, M.L.

1990-04-01

70

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

71

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

PubMed

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. PMID:2039270

Wing, J S; Brender, J D; Sanderson, L M; Perrotta, D M; Beauchamp, R A

1991-01-01

72

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

SciTech Connect

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

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

1991-05-01

73

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

PubMed

Chemical acid etching alone of the titanium implant surface have the potential to greatly enhance osseointegration without adding particulate matter (e.g. TPS or hydroxyapatite) or embedding surface contaminants (e.g. grit particles). The aims of the present study were to evaluate any differences between the machined and dual acid etching implants with the removal torque as well as topographic analysis. A total of 40 custom-made, screw-shaped, commercially pure titanium implants with length of 5 mm and an outer diameter of 3.75 mm were divided into 4 groups, 10 screws in each, and chemical modification of the titanium implant surfaces were achieved using HF and HCl/H(2)SO(4) dual acid etching. The first exposure was to hydrofluoric acid and the second was to a combination of hydrochloric acid and sulfuric acid. The tibia metaphysics was exposed by incisions through the skin, fascia, and periosteum. One implant of each group was inserted in every rabbit, 2 in each proximal tibia metaphysics. Every rabbit received 3 implants with acid etched surfaces and 1 implant with a machined surface. Twelve weeks post-surgically, 7 rabbits were sacrificed, Subsequently, the leg was stabilized and the implant was removed under reverse torque rotation with a digital torque gauge (Mark-10 Corporation, USA) (Fig. 1). Twelve weeks after implant placement, the removal torque mean values were the dual acid etched implants (24%HF+HCl/H(2)SO(4), group C) required a higher average force (34.7 Ncm), than the machined surface implants (group A) (p=0.045) (Mann-Whiteney test). Scanning electron micrographs of acid etching of the titanium surface created an even distribution of very small (1-2 microm) peaks and valleys, while machining of the titanium surface created typical microscopically grooved surface characteristics. Nonetheless, there was no difference in surface topography between each acid etched implant groups. Therefore, chemically acid etching implant surfaces have higher strengths of osseointegration than machined implant surfaces. There is less correlation between removal torque and the difference in HF volume%. PMID:12809791

Cho, Sung-Am; Park, Kyung-Tae

2003-09-01

74

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

PubMed Central

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

2012-01-01

75

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

PubMed

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

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

2012-01-01

76

Laboratory-scale fracture conductivity created by acid etching  

E-print Network

to field conditions and enables analysis of etching pattern and rock strength. A systematic experimental study that covered a variety of formations, acid types, and acid contact times was conducted. An acid fracture conductivity correlation was developed...

Pournik, Maysam

2009-05-15

77

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

PubMed Central

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

Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

2013-01-01

78

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

E-print Network

, and leather. · HF reacts with glass, concrete and other silicon bearing materials to produce SiF4. HF etches glass and should not be stored in glass containers. · HF reacts with carbonates, cyanides, and sulfates to produce toxic gases. · HF reacts with common metals to release H2 which can become a fire hazard. · Adding

79

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

SciTech Connect

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

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

2014-06-16

80

In vitro degradation behavior and biocompatibility of Mg-Nd-Zn-Zr alloy by hydrofluoric acid treatment.  

PubMed

In this paper, Mg-Nd-Zn-Zr alloy (denoted as JDBM) coated with hydrofluoric acid (HF) chemical conversion film (MgF2) was researched as a potential biodegradable cardiovascular stent material. The microstructures, in vitro degradation and biocompatibility were investigated. The field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) showed that a compact MgF2 film was formed on the surface of JDBM. The corrosion rate decreased in artificial plasma from 0.337 to 0.253 mmy(-1) and the electrochemical measurement demonstrated that the corrosion resistance of JDBM alloy could be obviously improved due to the protective MgF2 film on the surface of the substrate. Meanwhile, the hemolysis ratio of JDBM decreased from 52.0% to 10.1% and the cytotoxicity met the requirement of cellular application after HF treatment. In addition, JDBM and MgF2 film showed good anti-platelet adhesion, which is a very favorable property for implant material in contact with blood directly. PMID:25428068

Mao, Lin; Yuan, Guangyin; Niu, Jialin; Zong, Yang; Ding, Wenjiang

2013-01-01

81

Dry release for surface micromachining with HF vapor-phase etching  

Microsoft Academic Search

A new method for dry etching of silicon dioxide for surface micromachining is presented to obtain very compliant polysilicon microstructures with negligible stiction problem and to greatly simplify the overall releasing procedure as well. By etching the sacrificial silicon dioxide with hydrofluoric acid (HF) vapor instead of conventional aqueous HF solution, the need for subsequent rinsing and an elaborate drying

Yong-Il Lee; K.-H. Park; J. Lee; C.-S. Lee; H. J. Yoo; C.-J. Kim; Y.-S. Yoon

1997-01-01

82

Orthodontic bonding to acid- or laser-etched prebleached enamel  

PubMed Central

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

Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

2013-01-01

83

Using hydrofluoric acid for morphological investigations of Zoanthids (Cnidaria: Anthozoa): a critical assessment of methodology and necessity.  

PubMed

Zoanthids comprise an order of benthic, generally colonial cnidarians, which can usually be distinguished from other hexacorallians by embedded sand and detritus in their mesoglea to help strengthen their structure. These animals are becoming increasingly important research subjects in biochemistry and other research fields. Their inclusion of both calcium and silica results in the need for both decalcification and desilification for internal morphological examinations. Since the methodology of hydrofluoric acid (HF) desilification has rarely been documented in zoanthids, histological surveys for zoanthid taxonomy have often been abandoned and their taxonomy is often problematic. Recent investigations utilizing molecular methods have brought a clearer understanding of zoanthid diversity, but standardization of HF treatments are still needed to provide a link between molecular and more traditional techniques, and to properly examine specimens for which molecular methods may not be an option (e.g., formalin-preserved specimens, etc.). Here, we use both "straight" HF and, for the first time with zoanthids, buffered HF (BHF) treatments at different treatment lengths (1-48h) on polyps from three different species of zoanthids for histological examination. Section conditions were judged based on the presence/absence of embedded detritus, drag marks, and tissue condition. Results show that the BHF treatment resulted in slightly better tissue conditions for all specimens, and suggest that desilification works well regardless of treatment time for species with smaller (polyp diameter <0.5cm), less heavily encrusted polyps. Desilification of heavily encrusted Palythoa mutuki polyps were still problematic, with at least 24h treatment needed. To aid future research, we provide guidelines for HF treatments of zoanthid specimens. PMID:20063029

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

2010-10-01

84

Copper-assisted, anti-reflection etching of silicon surfaces  

DOEpatents

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.

Toor, Fatima; Branz, Howard

2014-08-26

85

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

PubMed Central

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.

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

2014-01-01

86

HYDROFLUORIC ACID SCRUBBER SYSTEMS  

SciTech Connect

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.

PANESKO JV; MERRITT HD

2011-05-18

87

HYDROFLUORIC ACID SCRUBBER SYSTEMS  

Microsoft Academic Search

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

PANESKO JV; MERRITT HD

2011-01-01

88

Improvement in etching rate for epilayer lift-off with surfactant  

NASA Astrophysics Data System (ADS)

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 ?m / 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.

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

2013-03-01

89

Optimum Atomic Spacing for AlAs Etching in GaAs Epitaxial Lift-Off Technology  

Microsoft Academic Search

With respect to GaAs epitaxial lift-off technology, we report here the optimum atomic spacing (5-10 nm) needed to etch off the AlAs release layer that is sandwiched between two GaAs epitaxial layers. The AlAs etching rate in hydrofluoric acid based solutions was monitored as a function of release layer thickness. We found a sudden quenching in the etching rate, approximately

Kota S. R. Koteswara Rao; Takeshi Katayama; Shin Yokoyama; Masataka Hirose

2000-01-01

90

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

SciTech Connect

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

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

2011-06-01

91

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

PubMed

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

Donaldson, E M

1970-07-01

92

Free-standing AlxGa1-xAs heterostructures by gas-phase etching of germanium  

E-print Network

As layer is selectively removed through immersion in an aqueous hydrofluoric HF acid solution. This process the etch to full release, this technique may be used to realize heterogeneous integration of disparateAs by employing a buffered citric-acid solution, though this etchant requires a minimum of 10%­12% aluminum

93

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

PubMed Central

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

Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

2014-01-01

94

Biomimetic Remineralization of Resin-bonded Acid-etched Dentin  

PubMed Central

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

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

2009-01-01

95

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

Microsoft Academic Search

The electro-osmotic flow limit of detection and separation efficiency of glass channels machined using abrasive jet micromachining (AJM) were measured and compared with those for channels machined using conventional wet etching with hydrofluoric acid. It was found that the electro-osmotic mobility in AJM channels was similar to that in wet-etched channels, ?4 10?4 cm2 V?1 s?1 for 20 m

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

2012-01-01

96

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

NASA Astrophysics Data System (ADS)

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

Padmanabhan Ramalekshmi Thanu, Dinesh

97

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

PubMed Central

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

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

2014-01-01

98

A single process for building capacitive pressure sensors and timing references with precise control of released area using lateral etch stop  

Microsoft Academic Search

In this paper, we present a capacitive absolute pressure sensor co-fabricated with a MEMS resonator using an improved epitaxial polysilicon encapsulation process. The process features insensitivity to timed hydrofluoric acid etch variation when releasing structures via sacrificial silicon dioxide. Moreover, the process enables fabrication of structures to drive\\/sense in both lateral (x, y) and vertical (z) directions, providing a powerful

Chia-Fang Chiang; Andrew B. Graham; Gary J. O'Brien; Thomas W. Kenny

2012-01-01

99

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

PubMed

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

Pinheiro Moreira, Pedro Augusto Franco; de Koning, Maurice

2013-10-31

100

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

SciTech Connect

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

Despotopulos, J D; Sudowe, R

2012-02-21

101

Nanoparticle-based etching of silicon surfaces  

DOEpatents

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

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

2011-12-13

102

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

Microsoft Academic Search

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

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

2008-01-01

103

Galvanic etching for sensor fabrication  

NASA Astrophysics Data System (ADS)

This paper describes the application of a novel etch-stop technique, based on galvanic element formation, to the fabrication of micromechanical sensors. The theory of operation in tetramethyl ammonium hydroxide (TMAH) and hydrofluoric acid (HF) solutions is discussed, together with the main limitations. A number of devices are presented. These include a piezoresistive pressure sensor made with a galvanic etch stop in a 25% TMAH solution at 80 C and the contactless fabrication in similar solutions of a vibration sensor based on free-standing crystalline silicon beams. The thickness definition and uniformity were found to be poorer with the cantilever than with the membrane type sensors. Oxygen in the solution was used to provide the cell current, which was therefore rather low. This resulted in a low package density of the sensor elements on the wafer. Free-standing thick polysilicon structures were also formed with a galvanic etch-stop technique in HF solutions. The selectivity of this process, and the thickness definition and uniformity were good. In these solutions, the cell current could be easily increased by adding other strong oxidizing agents, such as hydrogen peroxide. Therefore, high package densities could be achieved in these solutions.

Ashruf, C. M. A.; French, P. J.; Sarro, P. M.; Kazinczi, R.; Xia, X. H.; Kelly, J. J.

2000-12-01

104

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

PubMed

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

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

2012-03-01

105

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

PubMed Central

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-?m-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. PMID:17105173

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

2007-01-01

106

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

PubMed

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

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

2003-11-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

109

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

PubMed Central

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

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

2013-01-01

110

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

PubMed

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

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

2013-02-01

111

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

PubMed Central

A carbon dioxide laser operating at the highly absorbed wavelength of 9.3?m with a pulse duration of 1015?s is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 510 seconds. PMID:23539418

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

2012-01-01

112

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

PubMed

Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37C 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 (20.11.8 MPa) and acid+laser (15.63.5 MPa) groups were significantly higher than those for laser+acid (15.63.5 MPa), laser etching (14.13.4 MPa) and control (8.12.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching. PMID:23875083

Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

2013-01-01

113

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

PubMed Central

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 37C 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 (20.11.8 MPa) and acid+laser (15.63.5 MPa) groups were significantly higher than those for laser+acid (15.63.5 MPa), laser etching (14.13.4 MPa) and control (8.12.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching. PMID:23875083

Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

2013-01-01

114

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

DOEpatents

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

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

1991-06-11

115

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

DOEpatents

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.

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

1991-01-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

117

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

118

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

PubMed Central

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

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

2014-01-01

119

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

PubMed Central

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

Alsulaimani, Fahad F.

2014-01-01

120

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

PubMed Central

The dependence of the etch mechanism of lithographically seeded macropores in low-doped p-type silicon on water and hydrofluoric acid (HF) concentrations has been investigated. Using different HF concentrations (prepared from 48 and 73?wt.% HF) in organic electrolytes, the pore morphologies of etched samples have been related to in situ impedance spectra (IS) obtained by Fast Fourier Transform (FFT) technique. It will be shown that most of the data can be fitted with a simple equivalent circuit model. The model predicts that the HF concentration is responsible for the net silicon dissolution rate, while the dissolution rate selectivity at the pore tips and walls that ultimately enables pore etching depends on the water content. The quality of the pores increases with decreasing water content in HF/organic electrolytes. PMID:22716663

2012-01-01

121

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

PubMed

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

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

2013-05-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

123

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

PubMed

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

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

2006-04-19

124

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

PubMed

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

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

2014-01-01

125

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

PubMed Central

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

2014-01-01

126

Comparative evaluation of retentive properties of acid etched resin bonded fixed partial dentures  

PubMed Central

Background Little consensus exist in suitable tooth preparation design and alloy pre-treatment methods for improving the retention of resin bonded fixed partial dentures (RBFPDs). Methods An in-vitro experiment was done with four designs. Group A: standard form, B: wings and proximal slices, C: wings, proximal slice and grooves, D: wings, proximal slice, grooves and occlusal coverage. Alloys were subjected to pre-treatment procedures like Group I: control, II: sand blasting, III: electro etching, IV: tin plating. Debonding forces of the castings were recorded in a universal testing machine and results were analyzed by student's t test. Results Group B, C and D showed higher debonding forces compared to A. However, there were no significant differences in mean force values among Groups B, C and D. Group II, III and IV with different alloy pre-treatment methods demonstrated higher values against control. Inter group variations among Group II, III and IV were not significant. Conclusion Tooth preparation with adequate surface extensions and pre-treatment procedures of casting alloys are two parameters that play important role in determining the retentive features of RBFPDs. Different types of tooth preparation designs and alloy pre-treatment methods exert almost similar influence in increasing the retention of acid etched RBFPDs. PMID:24623948

Arora, Vimal; Sharma, M.C.; Dwivedi, Ravi

2013-01-01

127

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

PubMed

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

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

2008-09-01

128

Water spray mitigation of hydrofluoric acid releases  

Microsoft Academic Search

Two series of tests were conducted in flow chambers to assess the effectiveness of water spray in mitigating releases of Hydrogen Fluoride (HF). Bench scale experiments identified key variables for testing in a larger facility. The larger scale field tests have demonstrated that HF releases can be mitigated with water and have also quantified the impact of numerous design variables

K. W. Schatz; R. P. Koopman

1989-01-01

129

Porous siliconformation and etching process for use in silicon micromachining  

DOEpatents

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

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

1991-01-01

130

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

PubMed

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

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

2014-09-15

131

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

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

132

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

133

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

PubMed

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. PMID:25489862

Chen, Chia-Yun; Wong, Ching-Ping

2014-12-18

134

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

NASA Astrophysics Data System (ADS)

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

Costescu, Ruxandra M.

2011-10-01

135

Pulpal response to adhesive resin systems applied to acid-etched vital dentin: damp versus dry primer application.  

PubMed

A number of studies have reported that acid etching of dentin is toxic to the cells of the odontoblastic layer and dental pulp. Other studies report that pulpal inflammation is a consequence of bacterial microleakage. The purpose of this study was to observe the degree of pulpal healing after pretreatment of vital dentin prior to placement of All-Bond and Scotch-bond 2 composite resin adhesives. Zinc oxide-eugenol cement and an acidic cement were employed as controls. One hundred twelve Class V nonexposed cavity preparations were placed throughout the dentitions of five healthy adult rhesus monkeys and observed at 3, 25, and 80 days. Various dentinal pretreatment procedures were employed. The All-Bond Universal primer system was placed on air-dried vital dentin in 23 cavities and on damp vital dentin in 27 cavities. Scotchbond 2 was placed as per manufacturer's instructions. All treatment procedures, materials, and times were represented in all animals. Placement of silicate cement resulted in the most severe pulpal responses at all time periods. Stained bacterial profiles in the remaining dentin on the axial walls of inflamed control pulps were associated with severe pulpal inflammation. These results indicate that acid etching of vital dentin does not impair pulpal healing in deep Class V cavities. PMID:8058899

White, K C; Cox, C F; Kanka, J; Dixon, D L; Farmer, J B; Snuggs, H M

1994-04-01

136

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

PubMed

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

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

2014-01-01

137

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

PubMed

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

Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; Castillo-Oyage, R; Garca, A; Albaladejo, A

2014-05-01

138

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

PubMed Central

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

CAO, BINRUI; QIU, PENGHE; MAO, CHUANBIN

2013-01-01

139

Mesoporous iron oxide nanoparticles prepared by polyacrylic acid etching and their application in gene delivery to mesenchymal stem cells.  

PubMed

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

Cao, Binrui; Qiu, Penghe; Mao, Chuanbin

2013-09-01

140

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

PubMed Central

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

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

2014-01-01

141

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

PubMed

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

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

2014-01-01

142

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

E-print Network

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

Oeth, Cassandra V

2013-11-25

143

Apparatus For Etching Or Depositing A Desired Profile Onto A Surface  

DOEpatents

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

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

2004-05-25

144

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

145

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

E-print Network

are assigned a conductivity because of small-scale roughness features using a correlation obtained from laboratory measurements of acid fracture conductivity as a function of closure stress. The overall conductivity of the fracture is then obtained...

Deng, Jiayao

2011-02-22

146

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

PubMed Central

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

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

2012-01-01

147

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

PubMed

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

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

2012-09-26

148

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

NASA Astrophysics Data System (ADS)

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+-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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05949b

Chen, Chia-Yun; Wong, Ching-Ping

2014-12-01

149

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

PubMed Central

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 37C 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

Foroutan, Tahereh; Ayoubian, Nader

2013-01-01

150

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

PubMed Central

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

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

2013-01-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

152

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

PubMed Central

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

2014-01-01

153

Early loading of sandblasted and acid-etched (SLA) implants: a prospective split-mouth comparative study.  

PubMed

Sandblasted and acid-etched (SLA) implants were recently introduced to reduce the healing period between surgery and prosthesis. In this split-mouth study, SLA implants were compared to titanium plasma-sprayed (TPS) implants under loaded conditions one year after placement in 32 healthy patients, with comparable bilateral edentulous sites and no discrepancies in the opposing dentition. The surgical procedure was performed by the same operator and was identical at 68 SLA (test) and 68 TPS (control) sites. Tapping was never performed and primary stability was always achieved. Abutment connection was carried out at 35 Ncm 6 weeks postsurgery for test sites and 12 weeks for the controls, by the same dentist blind to the type of surface of the implant. In 4 of the 68 test sites the implant rotated slightly, patients reported minor pain and connection was not completed. Provisional restoration was fabricated and a new tightening was performed after six weeks. Similar gold-ceramic restorations were cemented on the same type of solid abutments on both sites. No implant was lost. Clinical measures and radiographic changes were recorded by the same operator, blind to the type of surface of the implant, 1 year post surgery. No significant differences were found with respect to presence of plaque (24% vs. 27%), bleeding on probing (24% vs. 31%), mean pocket depth (3.3 mm vs. 2.9 mm) or mean marginal bone loss (0.65 mm vs. 0.77 mm). The results suggest that SLA implants are suitable for early loading at 6 weeks. Limited implant spinning may occasionally be found but, if properly handled, it produces no detrimental effect on the clinical outcome. PMID:11737100

Roccuzzo, M; Bunino, M; Prioglio, F; Bianchi, S D

2001-12-01

154

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

PubMed Central

Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (??=?0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2?=?0.726, p<0.0001 for the smooth surface; R2?=?0.405, p?=?0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections. PMID:24671257

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

2014-01-01

155

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

PubMed

Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (??=?0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2?=?0.726, p<0.0001 for the smooth surface; R2?=?0.405, p?=?0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections. PMID:24671257

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

2014-01-01

156

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

PubMed

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

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

2010-11-01

157

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

PubMed Central

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the KruskalWallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 10.004)mm3, (0.0530.002)mm3, (0.003 60.001)mm3 and (0.005 90.002)mm3 respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.313.8)m, (594.517.12)m, (543.115.33)m and (910.726.2)m respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA. PMID:23306857

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

2012-01-01

158

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

PubMed

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 10.004)mm(3), (0.0530.002)mm(3), (0.003 60.001)mm(3) and (0.005 90.002)mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.313.8)m, (594.517.12)m, (543.115.33)m and (910.726.2)m respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA. PMID:23306857

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

2012-12-01

159

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

160

vwDepartment of Geoscience Hydrofluoric Acid Policy  

E-print Network

.) The following protective clothing must be worn: inner gloves outer gloves lab coat liquid resistant apron disposal. After neutralization (with limestone chips or shell chips), the remaining residue to be sent be showered immediately under an emergency shower. Contaminated clothing should be removed as rapidly

Habib, Ayman

161

Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid  

SciTech Connect

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

Timothy M. Swager

2005-03-17

162

In situ optical measurements of hydrofluoric acid aerosols  

Microsoft Academic Search

HF aerosol measurements were obtained in a specially developed flow chamber with a cross-section of 8 16 feet, and approximately 140 feet long. The primary objective was to determine the extent of HF aerosol mist formation in a potential accidental release of HF. A newly developed in situ optical instrument (PCSV-P) was used to obtain on-line measurements of the

D. J. Holve; T. L. Harvill; K. W. Schatz; R. P. Koopman; NJ Princeton

1989-01-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

164

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

PubMed

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, 5-55C), 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 (?=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 (12.561.73 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 highest bond strength. PMID:24809541

Samimi, P; Mortazavi, V; Salamat, F

2014-01-01

165

Process for etching mixed metal oxides  

DOEpatents

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

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

1994-01-01

166

Process for etching mixed metal oxides  

DOEpatents

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

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

1994-10-18

167

Anion effects on the electrochemical regeneration of Ce(IV) in nitric acid used for etching chromium.  

PubMed

The anion impurities such as SO4(2-), Cl(-), and Cr2O7(2-) commonly present in the spent (hazardous) Cr-etch solutions from color filter manufacturing processes may influence the solutions' regeneration by the electrooxidation of Ce(III) to Ce(IV). This study, therefore, investigated the effects of these anions on Ce(III)/Ce(IV) redox reactions at glassy carbon in HNO3. In cyclic voltammetric tests, the presence of SO4(2-) decreased the formal potential but increased the peak potential separation (Delta Ep) of Ce(III)/Ce(IV) couple, and lowered the peak current for Ce(IV) reduction whereas Cl(-) did not change the formal potential and Delta Ep, but the peaks for Cl(-) and Ce(III) oxidation partially overlapped. Cr2O7(2-) slightly lowered the peak current for Ce(III) oxidation but significantly decreased that for Ce(IV) reduction. The Tafel slope for Ce(III) oxidation was approximately 65mVdecade(-1) in the absence of anion impurities. Increasing SO4(2-), Cl(-), or Cr2O7(2-) in solution raised the Tafel slope. The Ce(III)/Ce(IV) equilibrium potential decreased with the increase of SO4(2-) or Cl(-) but was hardly influenced by Cr2O7(2-) addition. These observations from individual anion species together well explained the anions' co-effect (kinetic hindrance) on the Ce(III) oxidation in HNO3, revealing that these anions are unfavorable for the electrooxidation of Ce(III) in the spent Cr-etch solutions. PMID:17765399

Chen, Te-San; Yeh, Kuei-Jyum C; Huang, Kuo-Lin

2008-04-15

168

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

169

Phase Transitions Vol. 77, Nos. 12, JanuaryFebruary 2004, pp. 131137  

E-print Network

silane in the gas phase. Etching these particles with mixtures of hydrofluoric acid (HF) and nitric acid of silicon nanoparticles can be reduced by etching them in mixtures of hydrofluoric acid (HF) and nitric acid SILICON NANOPARTICLES BY PHOTOTHERMAL AEROSOL SYNTHESIS FOLLOWED BY ACID ETCHING X. LI, Y. HE, S

Swihart, Mark T.

170

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

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=100?s for Enamel and Energy=80mJ,Frequency=10Hz, Pulse duration=100?s 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 37c 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 restorations.

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

2013-01-01

171

Chromium Etching Revised: 2009-12-15  

E-print Network

ammonium nitrate (NH4 )2 [Ce(NO3 )6 ]. Perchloric acid is a very strong acid and therefore almost ammonium nitrate. Ceric ammonium nitrate itself is a very strong oxidizer. The following chemical equation summarizes the mechanism of chromium etching with per- chloric acid and ceric ammonium nitrate: 3 Ce(NH4 )2

Yoo, S. J. Ben

172

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

PubMed Central

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

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

2014-01-01

173

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

PubMed

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

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

2014-01-01

174

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

PubMed Central

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

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

2011-01-01

175

Anisotropic etching of silicon  

Microsoft Academic Search

Anisotropic etching of silicon has become an important technology in silicon semiconductor processing during the past ten years. It will continue to gain stature and acceptance as standard processing technology in the next few years. Anisotropic etching of

K. E. Bean

1978-01-01

176

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

E-print Network

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

Agarwal, Amit Kumar

2013-01-14

177

Etch pits on caprolactam  

NASA Astrophysics Data System (ADS)

As an extension of the results on the morphology, we investigated the defect structure of solution-grown caprolactam crystals by means of slight etching in cyclohexane and subsequent microscopic observation of the resulting etch pits on the 200, 110, and faces. In case of the face (which is a cleavage plane), we confirmed that the etch pits are formed around dislocation lines by performing an "etch-and-match" experiment. Information is obtained on morphology and density of etch pits, the presence of grain boundaries, as well as qualitative information on the inclination of the dislocation lines.

van der Heijden, A. E. D. M.; Geertman, R. M.

1992-09-01

178

Ion beam enhanced etching of LiNbO 3  

NASA Astrophysics Data System (ADS)

Single crystals of z- and x-cut LiNbO 3 were irradiated at room temperature and 15 K using He +- and Ar +-ions with energies of 40 and 350 keV and ion fluences between 5 10 12 and 5 10 16 cm -2. The damage formation investigated with Rutherford backscattering spectrometry (RBS) channeling analysis depends on the irradiation temperature as well as the ion species. For instance, He +-irradiation of z-cut material at 300 K provokes complete amorphization at 2.0 dpa (displacements per target atom). In contrast, 0.4 dpa is sufficient to amorphize the LiNbO 3 in the case of Ar +-irradiation. Irradiation at 15 K reduces the number of displacements per atom necessary for amorphization. To study the etching behavior, 400 nm thick amorphous layers were generated via multiple irradiation with He +- and Ar +-ions of different energies and fluences. Etching was performed in a 3.6% hydrofluoric (HF) solution at 40 C. Although the etching rate of the perfect crystal is negligible, that of the amorphized regions amounts to 80 nm min -1. The influence of the ion species, the fluence, the irradiation temperature and subsequent thermal treatment on damage and etching of LiNbO 3 are discussed.

Schrempel, F.; Gischkat, Th.; Hartung, H.; Kley, E.-B.; Wesch, W.

2006-09-01

179

Sputtered gold mask for deep chemical etching of silicon  

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

180

Enhancement of cladding modes couplings in tilted Bragg gratings owing to cladding etching  

Microsoft Academic Search

We analyze the evolution of the cladding modes couplings in tilted fiber Bragg gratings when the fiber diameter and the refractive index of the surrounding medium are modified. To decrease the fiber diameter, we make use of hydrofluoric acid and to modify the external refractive index, we use a set of index oils. We also investigate a new way to

C. Caucheteur; K. Chah; F. Lhomme; M. Debliquy; D. Lahem; M. Blondel; P. Megret

2005-01-01

181

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

PubMed Central

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

Shahabi, Sima; Chiniforush, Nasim; Juybanpoor, Nasrin

2013-01-01

182

Graphene Oxidation: Thickness-Dependent Etching and  

E-print Network

Graphene Oxidation: Thickness-Dependent Etching and Strong Chemical Doping Li Liu,,,§ Sunmin Ryu oxide" made by mineral acid attack. Graphene is a zero-gap semimetal whose electronic band structure- and multiple-layer graphene regions are present simultaneously in a single sample (Figure 1); thus, oxidation

183

Excimer Laser Etching  

SciTech Connect

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.

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

2008-04-01

184

The Etch Process  

NSDL National Science Digital Library

This website includes an animation which shows the plasma etching of silicon dioxide. In this type of plasma etching process, a chlorine gas and argon gas mixture is used. The chlorine gas neutral charge molecules bond with the surface silicon dioxide molecules and create silicon chloride molecule. Through the bombardment of the plasma charged Argon molecules the silicon chloride molecules are released from the surface layer. The etch continues till the exposed silicon dioxide material is removed. Objective: Describe in detail the etch process. This simulation is from Module 047 of the Process and Equipment II of the MATEC Module Library (MML). You can find this animation under the heading "Process & Equipment II." To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtml

185

Effect of using self-etching primer for bonding orthodontic brackets.  

PubMed

Questions over the use of self-etching primers with composite resin adhesives in the bonding of orthodontic brackets remain unsolved. In addition, there are no previous reports on the efficacy of self-etching primers with resin-modified glass ionomer cements for bonding orthodontic brackets in orthodontic dentistry. The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of four protocols: (1) a composite resin adhesive used with 40% phosphoric acid, (2) the same composite resin used with Megabond self-etching primer, (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. The appearance of the tooth surfaces after acid etching or priming was observed with a field-emission scanning electron microscope (FE-SEM). When used with resin-modified glass ionomer cement, Megabond self-etching primer gave no significantly different shear bond strength compared with polyacrylic acid etching. But when used with composite resin adhesive, Megabond self-etching primer gave significantly lower shear bond strength than phosphoric acid etching. However, the shear bond strength of orthodontic brackets bonded with composite resin adhesive after Megabond priming was almost the same as that of brackets bonded with resin-modified glass ionomer cement after polyacrylic acid etching. FE-SEM observation revealed that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching. Megabond self-etching primer may be a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement for minimizing the amount of enamel loss. PMID:12518948

Yamada, Rieko; Hayakawa, Tohru; Kasai, Kazutaka

2002-12-01

186

Encapsulation and release of rifampicin using poly(vinyl pyrrolidone)-poly(methacrylic acid) polyelectrolyte capsules  

Microsoft Academic Search

Poly(vinyl pyrrolidone) and poly(methacrylic acid) multilayer capsules based on hydrogen bonding have been prepared by the layer-by-layer approach and used to encapsulate and release rifampicin, an anti-tuberculosis drug. Removal of silica core using a buffer of ammonium fluoride and hydrofluoric acid at about pH 3 was found to produce better capsules than hydrofluoric acid alone. An eight-layered capsule had a

K. N. Anil Kumar; S. Basu Ray; V. Nagaraja; Ashok M. Raichur

2009-01-01

187

Inverse Metal-Assisted Chemical Etching Produces Smooth High Aspect Ratio InP Nanostructures.  

PubMed

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

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

2015-01-14

188

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

PubMed Central

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.

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

2015-01-01

189

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

PubMed

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

Ekstrand, K; Ruyter, I E

1987-09-01

190

Etching fission tracks in zircons  

USGS Publications Warehouse

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

Naeser, C.W.

1969-01-01

191

Fabrication of a Molecular Self-Assembled Monolayer Diode Using  

E-print Network

with acetone, and a wet etch of diluted hydrofluoric (HF) acid was used to etch the oxide, exposing the bottom, and then the mold released. The same mold was used in over 50 imprints, with no observable damage or loss

192

Aluminum (Al) Etch Instructions The CEPSR cleanroom stores Aluminum Etchant Type A, a pre-made product used for  

E-print Network

Aluminum (Al) Etch Instructions The CEPSR cleanroom stores Aluminum Etchant Type A, a pre-made product used for removing or etching away aluminum. This etchant is stored inside the acid or corrosive a specific thickness of aluminum that is desired. Note: Once the bottle is empty or you find that it's etch

Kim, Philip

193

Containment of nitric acid solutions of Plutonium-238  

NASA Astrophysics Data System (ADS)

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

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

1999-01-01

194

Containment of Nitric Acid Solutions of Plutonium-238  

SciTech Connect

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

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

1999-01-31

195

ISOTROPIC ETCHING OF 111 SCS FOR WAFER-SCALE MANUFACTURING OF PERFECTLY HEMISPHERICAL SILICON MOLDS  

E-print Network

are XeF2 and HF-Nitric acid etching. XeF2 is a gas phase etch, in which the XeF2 sublimates at room as a buffer gas. HNA, which is typically a combination of HF and Nitric acid diluted by Acetic acid or water, makes use of the oxidizing properties of Nitric acid in combination with the SiO2 consuming properties

Afshari, Ehsan

196

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

PubMed

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

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

2012-04-01

197

Selective Etching of Semiconductor Glassivation  

NASA Technical Reports Server (NTRS)

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

Casper, N.

1982-01-01

198

Etching technology for chromatography microchannels  

Microsoft Academic Search

Half-circular channels, to be used for gas chromatography, were etched isotropically using a mixture of HF, HNO3 and H2O. Two wafers with half-circular channels were bonded on top of each other to yield channels with a circular cross-section. During etching the so-called loading effect was encountered: the etch rate depends on the local structure density. To solve this, extra structures

R. W. Tjerkstra; M. de Boer; E. Berenschot; J. G. E. Gardeniers; A. van den Berg; M. C. Elwenspoek

1997-01-01

199

Mechanism of copper deposition on silicon from dilute hydrofluoric acid solution  

SciTech Connect

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

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

1997-08-01

200

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

Microsoft Academic Search

FEM3 is a three-dimensional computer model that was designed to simulate the atmospheric dispersion of heavier-than-air gas releases. Recently a phase-change submodel based on local thermodynamic equilibrium has been implemented to treat vapor-liquid transition of the dispersed material. A preliminary evaluation of the phase-change submodel was performed by using data obtained from two recently conducted series of field experiments, namely,

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

1987-01-01

201

Wet Etching in Nanofabrication  

NSDL National Science Digital Library

This lab, presented by the National Nanotechnology Infrastructure Network, students will "help students understand how chemical reactions are used to create the specific shapes on surfaces of crystalline materials, which make up functional components within electronics." The wet etching process is used to create computer chips, and through this simulated lab, students will have a chance to explore the same process using different materials. Included in this lab are:Student Worksheet #1,Student Worksheet #2,Student worksheet 1 with answers,Student worksheet 2 with answers, andTeacher guide.

202

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

203

AUTOETCH PLASMA ETCHING SYSTEM OPERATING PROCEDURES  

E-print Network

Introduction The basic function of the Auto Etch is to etch wafers using a plasma dry etch process. Two systems an initialization routine erasing recipe and parameters programmed information and asking that a wafer cleanout

Yoo, S. J. Ben

204

Etch your name into Bobcat  

E-print Network

Etch your name into Bobcat History... Take advantage of this special opportunity to leave an enduring memento on a personalized brick in the Bobcat Plaza. Select from one of four sizes with prices starting at only $100. "Etch your name into Bobcat History" by completing the attached form today

205

MEMS Pressure Sensor Backside Etch  

NSDL National Science Digital Library

This animation, created by Southwest Center for Microsystems Education (SCME), " illustrates the anisotropic etch on the backside of a silicon wafer. The chamber formed as a result of this etch is used as the reference chamber for a micro-pressure sensor." Viewers can find supporting Learning Modules and activities from the SCME website under Educational Materials.

2014-07-21

206

ZERODUR: bending strength data for etched surfaces  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

207

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

E-print Network

; Fe; Pb; Ni; NiO, Ni2O3; Sn; SnO2; Ti; Zn Hydrofluoric Acid (HF): GaAs; Ni; SiO2; Ti Nitric Acid (HNO3 : hydrofluoric acid (49%, aq) HNO3 : nitric acid (70%, aq) H2SO4 : sulfuric acid (96%, aq) H3PO4 : phosphoricAcetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In

Garmestani, Hamid

208

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

PubMed Central

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

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

2012-01-01

209

Bond strength with various etching times on young permanent teeth  

SciTech Connect

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

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

1991-07-01

210

Submicron patterned metal hole etching  

DOEpatents

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

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

2000-01-01

211

Recent advances in defect-selective etching of GaN  

NASA Astrophysics Data System (ADS)

In this communication two defect-selective etching methods for GaN are evaluated and critically compared: (i) orthodox etching in molten bases (KOH-NaOH eutectic denoted E) and in hot H 2SO 4/H 3PO 4 acids (denoted HH etching) and (ii) photoelectrochemical (PEC) etching in aqueous KOH solutions. The parameters of etching are given for different type of materials, i.e. bulk crystals and epitaxial layers, for both Ga- and N-polar {0 0 0 1} surfaces. It is shown that molten bases are effective in revealing nano-pipes, inversion domains (IDs) and some dislocations, but the optimal etching parameters depend on the type of material, type and density of defects and polarity. Both orthodox etchants that result in the formation of pits on dislocations are also suitable for revealing micro-defects in heavily Mg-doped GaN single crystals but instead of pits, protruding etch features are formed. The reliability and limitations of these etching methods in revealing defects are demonstrated by means of transmission electron microscopy (TEM) calibration and by the selective formation of etch pits on dislocations introduced by indentation. Comparison with PEC etching, newly developed for GaN, is briefly discussed.

Weyher, J. L.; Brown, P. D.; Rouvire, J. L.; Wosinski, T.; Zauner, A. R. A.; Grzegory, I.

2000-03-01

212

Decontamination of metals using chemical etching  

DOEpatents

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

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

1980-01-01

213

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

PubMed

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

Haller, Bernd

2013-10-01

214

MOS Gate Etching Using an Advanced Magnetron Etching System  

NASA Astrophysics Data System (ADS)

A new type of magnetron etching system, RAMRIE, has been developed. Its characteristics for poly-Si gate etching with Cl2 has been investigated as a function of RF power and etching pressure in comparison with those for RIE whose structure and operating conditions are the same as those of RAMRIE. It was found that the profile of etched poly-Si is determined only by the etch selectivity of poly-Si to SiO2 (SSiO) and that the pattern profile changes from an overhung shape to an undercut shape with increasing SSiO for both systems. Good anisotropy was obtained with RAMRIE when SSiO is about 20, which is two times as large as that with RIE. Under this condition, a 0.2 ?m gate pattern was successfully delineated with RAMRIE. The characteristics of MOS capacitors prepared with RAMRIE and RIE have also been studied, but no etching-induced damage has been observed.

Noda, Shuichi; Nishikawa, Satoshi; Ohno, Seigo

1989-11-01

215

Etching with electron beam generated plasmas  

Microsoft Academic Search

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

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

2004-01-01

216

Etching and Growth of GaAs  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

217

Copper (Cu) Etch Instructions The CEPSR Clean Room stores Copper Etchant NT CE100, a pre-made product used for  

E-print Network

Copper (Cu) Etch Instructions The CEPSR Clean Room stores Copper Etchant NT CE100, a pre-made product used for removing or etching away copper. This etchant is stored inside the acid or corrosive waste disposal bottle (labeled Copper Etch Waste), the waste bottles are located below the wet bench

Kim, Philip

218

Etching Of Semiconductor Wafer Edges  

DOEpatents

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

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

2003-12-09

219

Northern Arabia Etched Terrain  

NASA Technical Reports Server (NTRS)

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

2002-01-01

220

State of the art etch-and-rinse adhesives  

PubMed Central

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

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

2013-01-01

221

Controlled pulse-etching with xenon difluoride  

Microsoft Academic Search

A gas-phase, room-temperature, plasmaless isotropic etching system has been used for bulk and thin film silicon etching. A computer controlled multi-chambered etcher is used to provide precisely metered pulses of xenon difluoride (XeF2) gas to the etch chamber. Etch rates as high as 15 microns per minute have been observed. The etch appears to have infinite selectivity to many common

Patrick B. Chu; Jeffrey T. Chen; Richard Yeht; Gisela Lin; Jeff C. P. Huang; B. A. Warneke; S. J. Pister

1997-01-01

222

Wet Chemical Etching Survey of III-Nitrides  

SciTech Connect

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

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

1999-02-04

223

Transparentization of Tunnel-Etched Al Foil by Anodic Oxidation  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

224

X-ray photoelectron spectroscopy of etched ZnSe  

NASA Astrophysics Data System (ADS)

To produce longitudinal ZnSe laser structures the GaAs substrate must be removed from the MBE grown layers. When an aqueous solution of sulfuric acid and hydrogen peroxide was used for this purpose, a red film was left on the surface of the ZnSe. X-ray photoelectron spectroscopy was used to examine the wafers before etching, after etching and after etching followed by heating in vacuum or in an argon atmosphere. The as-polished surface contained Se in two different chemical states: ZnSe and Se oxide. The etch predominantly removed the Zn leaving a red Se-rich surface with mostly Se-Se bonding. The Zn Auger parameter decreased toward that of the oxide. The etched surface could be restored to ZnSe by heating in vacuum but not in an argon atmosphere. The one heated in the argon showed the Se Auger parameter approaching that of ZnSe while the Zn Auger parameter increased past that of ZnSe toward metallic Zn.

McGee, T. F.; Cornelissen, H. J.

1989-01-01

225

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

E-print Network

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

Bookhagen, Bodo

226

Top-Down Nanomanufacturing: Etching Process  

NSDL National Science Digital Library

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

2011-09-22

227

Materials Modification in Nanotechnology: Advanced Etch Systems  

NSDL National Science Digital Library

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

2010-03-17

228

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

PubMed Central

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

2012-01-01

229

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

PubMed Central

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

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

230

Etch Processes for Microsystems - Part I  

NSDL National Science Digital Library

This YouTube video, created bySouthwest Center for Microsystems Education (SCME), provides an introduction to etch processes used in microsystems. The lecture runs for 15:26 seconds and covers "types of etch processes used to fabrication micro-sized devices with an emphasis on the wet etch processes." More information on microsystems and etch processes can be found on the SCME website.

231

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

E-print Network

Influence of chlorine on etched sidewalls in chemically assisted ion beam etching with SU-8 as mask etch mask in a chemically assisted ion beam etching (CAIBE) system. The effect of the chlorine gas flow angle about 1.5 deg by Lincoln et al.2 In the RIBE of GaAs with chlorine (Cl2), ion beam sputtering

Fainman, Yeshaiahu

232

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

PubMed

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

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

2013-11-01

233

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

DOEpatents

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

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

1981-01-01

234

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

E-print Network

Transene Co., Inc. is a mixture of phosphoric acid, acetic acid and nitric acid. Etch Rate is about 1 min ­ Hot Phos #12;4 Acid: ·HNA (Hydrofluoric acid + Nitric acid + Acetic acid) Base: ·KOHetch ·NaOH etch/min ·165°C Phosphoric Acid 55A/min (BOE dip first to remove oxynitride layer), etches silicon dioxide at 10

Wang, Deli

235

Transfer and characterization of silicon nanomembrane based photonic devices on flexible polyimide substrate  

E-print Network

nanomembrane is obtained by immersing the SOI wafer into hydrofluoric (HF) acid solution. The HF solution selectively etches the buried oxide away and releases the silicon nanomembrane from the SOI wafer.

Texas at Austin, University of

236

Effects of epitaxial lift-off on interface recombination and laser cooling in GaInP/GaAs heterostructures  

E-print Network

layer between the device and substrate; this layer is removed using a hydrofluoric acid etch.2 We show, which can be semi-insulating GaAs. Heterostructure lift-off is accomplished by growing an AlAs release

Sheik-Bahae, Mansoor

237

440 Phys. Chem. Chem. Phys., 2013, 15, 440--443 This journal is c the Owner Societies 2013 Cite this: Phys. Chem. Chem. Phys.,  

E-print Network

-type) are secured in a Teflon etch cell filled with a 1 : 3 hydrofluoric acid and ethanol mixture. A nanoporous Si process, and then released from Si wafers and transferred to flexible and conductive substrates

Cui, Yi

238

In situ X-ray photoelectron spectroscopy study of gas cluster ion beam etching of FeCo film  

NASA Astrophysics Data System (ADS)

FeCo films of the type used in spin transfer torque magnetoresistive random access memory were etched by gas cluster ion beam (GCIB) irradiation with acetic acid vapor and characterized by in situ X-ray photoelectron spectroscopy. After 20 keV O2-GCIB irradiation with acetic acid vapor, etching depth enhancement (10.7) was observed compared with the results without acetic acid vapor. The etching model of FeCo can be described as follows: (1) FeCo oxide formation with O2-GCIB irradiation, (2) acetic acid adsorption on FeCo oxide, (3) reactions between FeCo oxide and acetic acid, and (4) the desorption of volatile compounds by local and transient heating owing to O2-GCIB bombardment. Cross-sectional transmission electron microscopy, transmission electron diffraction analysis, and electron energy loss spectroscopy results showed no significant etching damage or oxidation of FeCo films after etching by O2-GCIB irradiation with acetic acid vapor. Therefore, the low-damage etching of FeCo can be performed by O2-GCIB irradiation with acetic acid vapor.

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

2014-01-01

239

Influence of laser etching on enamel and dentin bond strength of Silorane System Adhesive.  

PubMed

The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p?acid treatment in dentin groups (p?etched and non-etched groups in enamel and dentin (p?>?0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p?>?0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive. PMID:23912781

Ustunkol, Ildem; Yazici, A Ruya; Gorucu, Jale; Dayangac, Berrin

2013-08-01

240

Control over the permeation of silica nanoshells by surface-protected etching with water.  

PubMed

We demonstrate a water-based etching strategy for converting solid silica shells into porous ones with controllable permeability. It overcomes the challenges of the alkaline-based surface-protected etching process that we previously developed for the production of porous and hollow silica nanostructures. Mild etching around the boiling point of water partially breaks the imperfectly condensed silica network and forms soluble monosilicic acid, eventually producing mesoscale pores in the silica structures. With the surface protection from poly(vinyl pyrrolidone) (PVP), it is possible to maintain the overall shape of the silica structures while at the same time to create porosity inside. By using bulky PVP molecules which only protect the near-surface region, we are able to completely remove the interior silica and produce hollow particles. Because the etching is mild and controllable, this process is particularly useful for treating small silica particles or core-shell particles with very thin silica shells for which the alkaline-based etching method has been difficult to control. We demonstrated the precise control of the permeation of the chemical species through the porous silica shells by using a model reaction which involves the etching of Ag encapsulated inside Ag@SiO(2) by a halocarbon. It is expected that the water-based surface-protected etching method can be conveniently extended to the production of various porous silica shells containing functional materials whose diffusion to outside and/or reaction with outside species can be easily controlled. PMID:20571704

Hu, Yongxing; Zhang, Qiao; Goebl, James; Zhang, Tierui; Yin, Yadong

2010-10-14

241

Laser-driven fusion etching process  

DOEpatents

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

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

1989-01-01

242

Laser-driven fusion etching process  

DOEpatents

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

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

1987-08-25

243

Etching method for photoresists or polymers  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

244

Etching of glass microchips with supercritical water.  

PubMed

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

Karsek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, Frantiek

2015-01-01

245

Defect-related emission characteristics of nonpolar m-plane GaN revealed by selective etching  

NASA Astrophysics Data System (ADS)

A comprehensive study of the morphology and luminescence characteristics of nonpolar m-plane GaN etched in hot acids was presented. It was found that many four-sided pyramidal pits were distributed on the etched GaN surface with the long side perpendicular to the [1 1 2 0] direction, corresponding to the threading dislocations. When compared to the as-grown GaN, DAP emission intensity and its LO-phonon coupling phenomenon in the etched GaN were greatly attenuated, whereas the intensity of BSF-related band almost kept constant due to its immunity to chemical etching. Especially, a new PSF-related emission at 3.32 eV emerged in CL spectra of etched GaN. Simultaneously, partial relaxation of compressive stress happened for the etched GaN epilayer according to the red shift of NBE emission in photoluminescence (PL) and E2(high) phonon peak in the Raman spectra. Contrary, the DAP peak in etched GaN was blueshifted, likely due to the reduced impurity level fluctuation by etching. In addition, the different behaviors were discussed for NBE and defect-related transitions in the etched GaN, characterized by excitation power- and temperature-dependent PL.

Wei, T. B.; Yang, J. K.; Hu, Q.; Duan, R. F.; Huo, Z. Q.; Wang, J. X.; Zeng, Y. P.; Wang, G. H.; Li, J. M.

2011-01-01

246

Etching methodologies in ?111?-oriented silicon wafers  

Microsoft Academic Search

New methodologies in anisotropic wet-chemical etching of ?111?-oriented silicon, allowing useful process designs combined with smart mask-to-crystal-orientation-alignment are presented in this paper. The described methods yield smooth surfaces as well as high-quality plan-parallel beams and membranes. With a combination of pre-etching and wall passivation, structures can be etched at different depths in a wafer. Designs, using the ?111?-crystal orientation, supplemented

R. Edwin Oosterbroek; J. W. Berenschot; H. V. Jansen; A. J. Nijdam; G. Pandraud; A. van den Berg; M. C. Elwenspoek

2000-01-01

247

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

SciTech Connect

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

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

2008-01-09

248

Effect of clearfil protect bond and transbond plus self-etch primer on shear bond strength of orthodontic brackets  

PubMed Central

Background: The aim of this study was to evaluate the shear bond strength of an antimicrobial and fluoride-releasing self-etch primer (clearfil protect bond) and compare it with transbond plus self-etch primer and conventional acid etching and priming system. Materials and Methods: Forty-eight extracted human premolars were divided randomly to three groups. In group 1, the teeth were bonded with conventional acid etching and priming method. In group 2, the teeth were bonded with clearfil protect bond self-etch primer, and transbond plus self-etch primer was used to bond the teeth in group 3. The samples were stored in 37C distilled water and thermocycled. Then, the SBS of the sample was evaluated with Zwick testing machine. Descriptive statistics and the analysis of variances (ANOVA) and Tukey's test and Kruskal-Wallis were used to analyze the data. Results: The results of the ANOVA showed that the mean of group 3 was significantly lower than that of other groups. Most of the sample showed a pattern of failure within the adhesive resin. Conclusion: The shear bond strength of clearfil protect bond and transbond plus self-etch primer was enough for bonding the orthodontic brackets. The mode of failure of bonded brackets with these two self-etch primers is safe for enamel. PMID:23372605

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

2011-01-01

249

Advanced plasma etch technologies for nanopatterning  

NASA Astrophysics Data System (ADS)

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

Wise, Rich

2012-03-01

250

Dry etching technologies for reflective multilayer  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

251

Etching Magnetic Tunnel Junction with Metal Etchers  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

252

Method for dry etching of transition metals  

DOEpatents

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

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

1998-01-01

253

Etching radical controlled gas chopped deep reactive ion etching  

DOEpatents

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

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

254

Gallium nitride nanowires by maskless hot phosphoric wet etching  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

255

Self-etching increases matrix metalloproteinase expression in the dentin-pulp complex.  

PubMed

In adhesive restorations, one major problem is hybrid layer degradation. At present, this deterioration is explained by the activation of the endogenous matrix metalloproteinases (MMPs) present in dentin due to the acidic property of adhesive systems. We hypothesized that self-etching adhesive should also stimulate the expression of MMPs in odontoblasts. In cultured tooth slices, we evaluated the changes in MMP-2 and proMMP-9 expression in the dentin-pulp complex after self-etching adhesive treatment on dentin cavities in immunochemistry and by zymography. The treatment resulted in increased MMP-2 expression in odontoblasts, as shown by immunohistochemistry. Zymography showed increased proMMP-9 and MMP-2 in dentin under self-etching treatment when pulp was present. These results showed that self-etching adhesive stimulates the secretion of MMPs from the dentin-pulp complex and, more precisely, by odontoblasts, suggesting that odontoblasts participate in hybrid layer degradation. PMID:19131322

Lehmann, N; Debret, R; Romas, A; Magloire, H; Degrange, M; Bleicher, F; Sommer, P; Seux, D

2009-01-01

256

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

PubMed

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

Greil, Stefanie M; Schpke, Andreas; Rappich, Jrg

2012-08-27

257

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

E-print Network

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

Melendez Castillo, Maria Georgina

2009-06-02

258

Etching with electron beam generated plasmas  

SciTech Connect

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.

Leonhardt, D.; Walton, S.G.; Muratore, C.; Fernsler, R.F.; Meger, R.A. [U.S. Naval Research Laboratory, Plasma Physics Division, Washington, DC 20375 (United States)

2004-11-01

259

Plastic deformation magnetic assembly of out-of-plane structures using vapour phase hydrofluoric (HF) acid release  

Microsoft Academic Search

We report on the fabrication of out-of-plane microstructures using plastic deformation magnetic assembly (PDMA) and vapour phase HF release process. A 0.5?m thin silicon oxide (SiO2) layer deposited on blank silicon has been implemented as a sacrificial layer. A nickel film, 0.5?m thick, deposited on top of the SiO2 layer acts as the seed layer for the electrodeposition of a

P. Argyrakis; R. Cheung

2009-01-01

260

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

E-print Network

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

Diaz, Jaime O. (Jaime Oscar Diaz Villamil)

2010-01-01

261

Etch-a-Sketch Nanoelectronics  

NASA Astrophysics Data System (ADS)

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

Levy, Jeremy

2009-10-01

262

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

SciTech Connect

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

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

2002-04-08

263

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

NASA Astrophysics Data System (ADS)

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vaporliquidsolid grown InAs nanowires with embedded InP segments of 1060 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap.

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

2014-11-01

264

User Name & ID (Print): PI (subject to change): User Signature & Date  

E-print Network

Etch HNA Hydrochloric Acid (HCl) Hydrofluoric Acid (HF) Hydrogen Peroxide Nitric Acid PAN Phosphoric Acid Piranha Potassium Hydroxide RCA1 (Base) RCA2 (Acid) SulphoNitric Sulphuric Acid Breadth of Hazards to change): User email: Acetic Acid, Glacial Ammonium Fluoride Ammonium Hydroxide Aqua Regia Buffered Oxide

Yoo, S. J. Ben

265

Reactive ion etching of gallium nitride films  

NASA Astrophysics Data System (ADS)

Reactive ion etching (RIE) was performed on gallium nitride (GaN) films grown by electron cyclotron resonance (ECR) plasma assisted molecular beam epitaxy (MBE). Etching was carried out using trifluoromethane (CHF3) and chloropentafluoroethane (C2ClF5) plasmas with Ar gas. A conventional rf plasma discharge RIE system without ECR or Ar ion gun was used. The effects of chamber pressure, plasma power, and gas flow rate on the etch rates were investigated. The etch rate increased linearly with the ratio of plasma power to chamber pressure. The etching rate varied between 60 and 500/min, with plasma power of 100 to 500W, chamber pressure of 60 to 300 mTorr, and gas flow rate of 20 to 50 seem. Single crystalline GaN films on sapphire showed a slightly lower etch rate than domain-structured GaN films on GaAs. The surface morphology quality after etching was examined by atomic force microscopy and scanning electron microscopy.

Lee, Heon; Oberman, David B.; Harris, James S.

1996-05-01

266

Galvanic etch stop for Si in KOH  

NASA Astrophysics Data System (ADS)

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

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

2004-08-01

267

Oxide formation during etching of gallium arsenide  

Microsoft Academic Search

Characterisation of n-type GaAs, etched in a 5:1:1 mixture of H2SO4:H2O2:H2O, was performed using X-ray photoelectron spectroscopy (XPS) and electrochemical AC impedance. Quantitative XPS analysis of GaAs indicated that the as-received wafers had a gallium-rich native oxide which was not affected by solvent degreasing treatments. Subsequent, oxidative etching formed a thinner arsenic-rich oxide. It is suggested that etching causes initial

D. Ghidaoui; S. B. Lyon; G. E. Thompson; J. Walton

2002-01-01

268

Dry etching method for compound semiconductors  

DOEpatents

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

Shul, R.J.; Constantine, C.

1997-04-29

269

Method of sputter etching a surface  

DOEpatents

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

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

1984-01-01

270

Method of sputter etching a surface  

DOEpatents

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

Henager, C.H. Jr.

1984-02-14

271

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

PubMed Central

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

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

2014-01-01

272

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 ...

273

Generalized Data Correlations for Extinguishment Times and Acid Concentrations in Fire Tests with Fluorinated Suppression Agents  

Microsoft Academic Search

Correlations have been developed to predict the extinguishment time and peak hydrofluoric acid concentration for fires suppressed with heptatluoropropane (FM-200), trifluoromethane (FE-13), and perfluorobutane (CEA-410), as well as bromotnfluoromethane (Halon 1301). The extinguishment time correlations are ofthe form t, \\/ td = f, (Q*, C \\/ C,) where t, is the extinguishment time, td is the discharge time, Q' is

Robert Zalosh; Scott Heyworth

274

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

DOEpatents

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

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

1992-01-01

275

Inductively Coupled Plasma Etching of Silicon Using Solid Iodine as an Etching Gas Source  

NASA Astrophysics Data System (ADS)

We investigated the Si dry etching process by inductively coupled plasma (ICP) using solid I2 as an etching gas source. A vertical etching profile and a smooth etched surface, which satisfy the requirements for optical device fabrication, were obtained at a relatively higher substrate temperature. The etching rate of Si was approximately 90 nm/min at 1 Pa and at an ICP/bias RF power of 300/100 W. The I2 plasma etching technique is a very simple C-, CF-, and H-free process. In addition, we believe that this proposed process is useful for fabricating Si-based optical devices, such as photonic crystals, narrow optical waveguides, and micro-electro-mechanical systems (MEMS).

Matsutani, Akihiro; Ohtsuki, Hideo; Koyama, Fumio

2011-06-01

276

A simplified etching technique to improve the adhesion of fiber post  

PubMed Central

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

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

2014-01-01

277

Method for anisotropic etching in the manufacture of semiconductor devices  

DOEpatents

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

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

1993-01-01

278

Method for anisotropic etching in the manufacture of semiconductor devices  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

279

Revelation of stepped dislocations in amethyst crystals by hydrothermal etching  

Microsoft Academic Search

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

M. S. Josut; M. A. IrryncHrN

280

Oxidative etching of cleaved synthetic diamond {1 1 1} surfaces  

Microsoft Academic Search

In this study, three commonly used methods for oxidative etching of diamond {111} faces are compared: gas phase etching using `dry' oxygen, gas phase etching using an oxygen\\/water vapour mixture and liquid etching in molten potassium nitrate. The synthetic diamond surfaces are prepared by cleavage. The morphology of the surfaces is studied using atomic force microscopy and the kinetics of

F. K. de Theije; E. van Veenendaal; W. J. P. van Enckevort; E. Vlieg

2001-01-01

281

Effect of etching and chemomechanical polishing on the surface quality of polycrystalline ZnSe  

Microsoft Academic Search

We examine the etching and chemomechanical polishing of zinc selenide with the use of aqueous solutions of inorganic acids\\u000a and bases of different concentrations. The results are used to develop a procedure for chemomechanical polishing of polycrystalline\\u000a zinc selenide.

O. V. Timofeev; E. Yu. Vilkova

2010-01-01

282

Chemical etching of ZnSe crystals  

NASA Astrophysics Data System (ADS)

Our report describes a newly developed chemical etchant suitable for producing mirror-like ZnSe surfaces. A mirror surface without any scratch obtained through lapping and polishing was produced by etching in a KMnO4(100 mg)/ H2SO4(10 ml)/H2O(40 ml) solution. The etching rate of ZnSe used in this case was about 1 um/min. The etchant could be applied to crystals with (lll)A, (lll)B, and (100) faces and the etching rate similar for each face. The value of the full width at half maximum in the x-ray rocking curve decreased by half after etching with the KMnO4-system etchant.

Tamura, Hitoshi; Okuno, Yasuo; Kato, Hiroyuki

1994-08-01

283

Epoxy bond and stop etch fabrication method  

DOEpatents

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

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

2000-01-01

284

Investigation of Nitride Morphology After Self-Aligned Contact Etch  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

285

Plasma/Neutral-Beam Etching Apparatus  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

286

Dynamic transition in etching with poisoning  

NASA Astrophysics Data System (ADS)

We study a lattice model for etching of a crystalline solid including the deposition of a poisoning species. The model considers normal and lateral erosion of the columns of the solid by a flux of etching particles and the blocking effects of impurities formed at the surface. As the probability p of formation of this poisoning species increases, the etching rate decreases and a continuous transition to a pinned phase is observed. The transition is in the directed percolation (DP) class, with the fraction of the exposed columns as the order parameter. This interpretation is consistent with a mapping of the interface problem in d+1 dimensions onto a d-dimensional contact process, and is confirmed by numerical results in d=1 and d=2. In the etching phase, the interface width scales with Kardar-Parisi-Zhang (KPZ) exponents, and shows a crossover from the critical DP behavior (Wt) to KPZ near the critical point, at etching times of the order of (pc-p)-??. Anomalous roughening is observed at criticality, with the roughness exponent related to DP exponents as ?c=??/??>1. The main differences from previously studied DP transitions in growth models and isotropic percolation transitions in etching models are discussed. Investigations in real systems are suggested.

Aaro Reis, F. D.

2003-10-01

287

Dynamic transition in etching with poisoning.  

PubMed

We study a lattice model for etching of a crystalline solid including the deposition of a poisoning species. The model considers normal and lateral erosion of the columns of the solid by a flux of etching particles and the blocking effects of impurities formed at the surface. As the probability p of formation of this poisoning species increases, the etching rate decreases and a continuous transition to a pinned phase is observed. The transition is in the directed percolation (DP) class, with the fraction of the exposed columns as the order parameter. This interpretation is consistent with a mapping of the interface problem in d+1 dimensions onto a d-dimensional contact process, and is confirmed by numerical results in d=1 and d=2. In the etching phase, the interface width scales with Kardar-Parisi-Zhang (KPZ) exponents, and shows a crossover from the critical DP behavior (W approximately t) to KPZ near the critical point, at etching times of the order of (pc-p)(-nu(||)). Anomalous roughening is observed at criticality, with the roughness exponent related to DP exponents as alphac=nu(||)/nu(perpendicular)>1. The main differences from previously studied DP transitions in growth models and isotropic percolation transitions in etching models are discussed. Investigations in real systems are suggested. PMID:14682948

Aaro Reis, F D A

2003-10-01

288

UV laser activated digital etching of GaAs  

SciTech Connect

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.

Meguro, T.; Aoyagi, Y. [RIKEN, Wako, Saitama (Japan). Inst. of Physical and Chemical Research

1996-12-31

289

Plasma etching of proton-exchanged lithium niobate  

Microsoft Academic Search

Plasma etching of lithium niobate with fluorine gases is limited by the redeposition LiF. This results in a low etch rate and nonvertically etched walls. Etching of proton-exchanged lithium niobate can prevent the LiF deposition to a large extent because of the greatly reduced lithium concentration in lithium niobate. We performed different inductively coupled plasma etching processes using SF or

H. Hu; A. P. Milenin; R. B. Wehrspohn; H. Hermann; W. Sohler

2006-01-01

290

The electronic structure of anodized and etched aluminum alloy surfaces  

NASA Astrophysics Data System (ADS)

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

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

1988-11-01

291

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

PubMed

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

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

2002-12-01

292

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

NASA Astrophysics Data System (ADS)

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

Yongliang, Li; Qiuxia, Xu

2010-03-01

293

Digital projection photochemical etching defines gray-scale features.  

PubMed

We demonstrate a maskless photochemical etching method that is capable of performing one-step etching of multi-level structures. This method uses a digital projector to focus an image onto the sample and define the etching pattern. By combining digital projection photochemical etching with diffraction phase microscopy, etch heights can be measured in situ in a non-destructive manner. This method is single shot, eliminating the need for expensive gray-scale masks or laser scanning methods. The etch rate is studied as a function of the wavelength and irradiance of the projected light. A lateral etch resolution of 2 ?m is demonstrated by etching selected portions of the USAF-1951 target. Micropillars, multi-level plateaus, and an Archimedean spiral are etched, each in a single processing step, to illustrate the unique capabilities. PMID:23736607

Edwards, Chris; Wang, Kaiyuan; Zhou, Renjie; Bhaduri, Basanta; Popescu, Gabriel; Goddard, Lynford L

2013-06-01

294

Geometric characteristics of silicon cavities etched in EDP  

NASA Astrophysics Data System (ADS)

Etching characteristics of hexagonal and triangular cavities on a lang1 1 1rang-oriented silicon wafer in the etchant of ethylene diamine, pyrocatechol and water (EDP/EPW) were investigated. The patterns are aligned to keep the sides perpendicular to lang1 1 0rang crystal orientations, in order that the sidewalls of cavities are parallel to {1 1 0} crystalline planes. RIE-ICP etching is used to define the depth of the triangular and hexagonal cavities, and EDP etching is followed for different etching times. The final self-etch-stop profiles of cavities are determined by the dimension of mask patterns and the depth of cavities in the wafer. The etching process of the hexagon and triangle cavities is modeled, based on the crystal structure and wet etching principle. The results of etched cavities confirm the condition to determine the final etching profiles.

Ju, Hui; Ohta, Takayuki; Ito, Masafumi; Sasaki, Minoru; Hane, Kazuhiro; Hori, Masaru

2007-05-01

295

Microleakage of Resin-Modified Glass Ionomer Restorations With Selective Enamel Etching.  

PubMed

SUMMARY Aim : Bonding of resin-modified glass ionomers to enamel is an important quality, especially when saliva contamination is inevitable. This study evaluated if microleakage of a resin-modified glass ionomer improves with selective enamel etching, with or without saliva contamination. Methods : Class V cavities with the occlusal margin in enamel and the gingival margin on the root were prepared in extracted human permanent teeth and filled with a resin-modified glass ionomer using an acidic primer according to the manufacturer's recommendation or with an additional selective enamel etching step. Preparations were contaminated with saliva before primer application or before restoration placement (n=10). Restored teeth were thermocycled between 5C and 55C for 1000 cycles, stained with basic fuchsin, and sectioned. Microleakage distance was measured and analyzed with analysis of variance followed by Duncan post hoc test at a significance level of 0.05. Results : Enamel microleakage was highest when saliva contamination occurred before the placement of resin-modified glass ionomer. Microleakage distances were significantly reduced in the selective etching groups regardless of saliva contamination. However, selective etching of enamel increased microleakage in cementum. The increase in cementum leakage was significantly higher when saliva contamination occurred before restoration placement. Conclusion : Selective etching reduces enamel microleakage of a resin-modified glass ionomer even with saliva contamination, but it may increase microleakage at the cementum. The severity of microleakage is affected by the timing of saliva contamination. PMID:24502752

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

2014-02-01

296

Purified water etching of native oxides on heteroepitaxial CdTe thin films  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

297

ICP Etching of SiC  

SciTech Connect

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.

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

298

Practical applications of backside silicon etching  

SciTech Connect

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

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

1995-12-31

299

Environmentally benign semiconductor processing for dielectric etch  

NASA Astrophysics Data System (ADS)

Semiconductor processing requires intensive usage of chemicals, electricity, and water. Such intensive resource usage leaves a large impact on the environment. For instance, in Silicon Valley, the semiconductor industry is responsible for 80% of the hazardous waste sites contaminated enough to require government assistance. Research on environmentally benign semiconductor processing is needed to reduce the environmental impact of the semiconductor industry. The focus of this dissertation is on the environmental impact of one aspect of semiconductor processing: patterning of dielectric materials. Plasma etching of silicon dioxide emits perfluorocarbons (PFCs) gases, like C2F6 and CF4, into the atmosphere. These gases are super global warming/greenhouse gases because of their extremely long atmospheric lifetimes and excellent infrared absorption properties. We developed the first inductively coupled plasma (ICP) abatement device for destroying PFCs downstream of a plasma etcher. Destruction efficiencies of 99% and 94% can be obtained for the above mentioned PFCs, by using O 2 as an additive gas. Our results have lead to extensive modeling in academia as well as commercialization of the ICP abatement system. Dielectric patterning of hi-k materials for future device technology brings different environment challenges. The uncertainty of the hi-k material selection and the patterning method need to be addressed. We have evaluated the environmental impact of three different dielectric patterning methods (plasma etch, wet etch and chemical-mechanical polishing), as well as, the transistor device performances associated with the patterning methods. Plasma etching was found to be the most environmentally benign patterning method, which also gives the best device performance. However, the environmental concern for plasma etching is the possibility of cross-contamination from low volatility etch by-products. Therefore, mass transfer in a plasma etcher for a promising hi-k dielectric material, ZrO2, was studied. A novel cross-contamination sampling technique was developed, along with a mass transfer model.

Liao, Marci Yi-Ting

300

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

301

Chemical etching of ZnSe crystals  

Microsoft Academic Search

Our report describes a newly developed chemical etchant suitable for producing mirror-like ZnSe surfaces. A mirror surface\\u000a without any scratch obtained through lapping and polishing was produced by etching in a KMnO4(100 mg)\\/ H2SO4(10 ml)\\/H2O(40 ml) solution. The etching rate of ZnSe used in this case was about 1 um\\/min. The etchant could be applied to crystals\\u000a with (lll)A, (lll)B,

Hitoshi Tamura; Yasuo Okuno; Hiroyuki Kato

1994-01-01

302

EPA study on HF acid could spell trouble for refiners  

Microsoft Academic Search

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

Lobsenz

1993-01-01

303

Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites  

Microsoft Academic Search

This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group).

X. F. Meng; K. Yoshida; N. Gu

2010-01-01

304

Stress focusing for controlled fracture in microelectromechanical systems Matthew A. Meitl,a  

E-print Network

set to 110 °C. After etching, exposure to concentrated hydrofluoric acid 7 min removes the etch mask structures fix the otherwise released compo- nents in their original positions until the point of transfer rinsing with water and drying with nitrogen, the released beams sag and contact the underlying silicon

Rogers, John A.

305

A diffusion and reaction related model of the epitaxial lift-off process  

Microsoft Academic Search

In the present work a so-called diffusion and reaction related model (DR model) is derived based on the notion that the overall etch rate in the epitaxial lift-off (ELO) process is determined both by the diffusion rate of hydrofluoric acid to the etch front and its subsequent reaction rate in the process. In contrast to the model that was previously

A. T. J. van Niftrik; J. J. Schermer; G. J. Bauhuis; P. Mulder; P. K. Larsen; J. J. Kelly

2007-01-01

306

Characterization of wide-band-gap semiconductors (GaN, SiC) by defect-selective etching and complementary methods  

NASA Astrophysics Data System (ADS)

Two defect-selective etching approaches used for revealing and analysis of defects in wide-band-gap semiconductors (GaN, SiC) are described in detail: (i) orthodox etching in molten salts (KOH, NaOH) and hot acids (H 2SO 4,H 3PO 4) and (ii) electroless photo-etching (photoelectrochemical or PEC) in aqueous solutions of KOH. Characteristic features of these two techniques, their reliability and limitation in revealing different types of defects (dislocations, stacking faults, micro-defects and electrically active chemical non-homogeneities) will be discussed. Examples of the use of both etching approaches to reveal defects in bulk and epitaxial layers of different crystallographic orientation are given. Numerous references to previous work on calibration of the etch features by means of TEM, X-ray diffraction, Raman and PL methods are cited.

Weyher, J. L.

2006-10-01

307

High-density plasma etching of compound semiconductors  

Microsoft Academic Search

Inductively coupled plasma (ICP) etching of GaAs, GaP, and InP is reported as a function of plasma chemistry, chamber pressure, rf power, and source power. Etches were characterized in terms of rate and anisotropy using scanning electron microscopy, and root-mean-square surface roughness using atomic force microscopy. ICP etch rates were compared to electron cyclotron resonance etch rates for Cl\\/Ar, Cl\\/N,

R. J. Shul; G. B. McClellan; R. D. Briggs; D. J. Rieger; S. J. Pearton; C. R. Abernathy; J. W. Lee; C. Constantine; C. Barratt

1997-01-01

308

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

PubMed Central

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

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

2014-01-01

309

Wafer Backside Anisotropic Wet Etching of Silicon  

NSDL National Science Digital Library

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

2014-07-30

310

Anisotropic Etching, Silicon Crystal Orientation, and MEMS  

NSDL National Science Digital Library

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

Lopez, Fabian

2012-12-31

311

Etch Profile Simulation Using Level Set Methods  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

312

Dry etch processes for the fabrication of EUV masks  

Microsoft Academic Search

The absorber and buffer etching is a crucial step in the manufacture of EUV masks due to the stringent CD and reflectance requirements. Plasma etching of Cr layers, usually applied as an absorber for conventional masks, induces a resolution-limiting line width reduction. Therefore, new absorber materials for extreme ultraviolet lithography (EUVL) masks have to be evaluated. We investigated the etching

F. Letzkus; J. Butschke; M. Irmscher; F. M. Kamm; C. Koepernik; J. Mathuni; J. Rau; G. Ruhl

2004-01-01

313

CR-39 track etching and blow-up method  

DOEpatents

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

Hankins, Dale E. (Livermore, CA)

1987-01-01

314

Plasma etch chemistry of aluminum and aluminum alloy films  

Microsoft Academic Search

The chemistry occurring in glow discharges used to etch aluminum and aluminum alloy films is examined and is related to recurring problms such as initiation and reproducibility of etching, polymer or residue formation, photoresist degradation, aluminum corrosion, and safety aspects. The relative effects of different etch gases on these problems is discussed in light of aluminum surface chemistry and gas-phase

Dennis W. Hess

1982-01-01

315

Oxidative etching of cleaved synthetic diamond {1 1 1} surfaces  

NASA Astrophysics Data System (ADS)

In this study, three commonly used methods for oxidative etching of diamond {1 1 1} faces are compared: gas phase etching using `dry' oxygen, gas phase etching using an oxygen/water vapour mixture and liquid etching in molten potassium nitrate. The synthetic diamond surfaces are prepared by cleavage. The morphology of the surfaces is studied using atomic force microscopy and the kinetics of the reactions is determined by measuring the decrease in thickness of the diamond. The atomic arrangement of the {1 1 1} surfaces etched in oxygen/water is studied using surface X-ray diffraction. Upon dry oxygen etching, the {1 1 1} faces are roughened and become morphologically unstable. This observation conflicts with standard theory, which predicts {1 1 1} to be a stable F-face that should etch via a layer mechanism. A possible explanation for this is chemical roughening. The addition of water vapour to the oxygen has a dramatic effect on the etching mechanism of the {1 1 1} faces. Now etching proceeds via a layer mechanism involving monoatomic steps. Shallow etch pits are formed, of which the slope increases for increasing etching temperature. Surface X-ray diffraction experiments show that the surface is -OH terminated. For potassium nitrate etching, the {1 1 1} face etches also via a layer mechanism and triangular etch pits with rounded corners are formed, having point or flat bottoms. This etching technique appears to be the best method to reveal different types of defects ending on diamond {1 1 1} surfaces.

de Theije, F. K.; van Veenendaal, E.; van Enckevort, W. J. P.; Vlieg, E.

2001-10-01

316

Modeling Wet Chemical Etching of Surface Flaws on Fused Silica  

SciTech Connect

Fluoride-based wet chemical etching of fused silica optical components is useful to open up surface fractures for diagnostic purposes, to create surface topology, and as a possible mitigation technique to remove damaged material. To optimize the usefulness of etching , it is important to understand how the morphology of etched features changes as a function of the amount of material removed. In this study, we present two geometric etch models that describe the surface topology evolution as a function of the amount etched. The first model, referred to as the finite-difference etch model, represents the surface as an array of points in space where at each time-step the points move normal to the local surface. The second model, referred to as the surface area-volume model, more globally describes the surface evolution relating the volume of material removed to the exposed surface area. These etch models predict growth and coalescence of surface fractures such as those observed on scratches and ground surfaces. For typical surface fractures, simulations show that the transverse growth of the cracks at long etch times scales with the square root of etch time or the net material removed in agreement with experiment. The finite-difference etch model has also been applied to more complex structures such as the etching of a CO{sub 2} laser-mitigated laser damage site. The results indicate that etching has little effect on the initial morphology of this site implying little change in downstream scatter and modulation characteristics upon exposure to subsequent high fluence laser light. In the second part of the study, the geometric etch model is expanded to include fluid dynamics and mass transport. This later model serves as a foundation for understanding related processes such as the possibility of redeposition of etch reaction products during the etching, rinsing or drying processes.

Feit, M D; Suratwala, T I; Wong, L L; Steele, W A; Miller, P E; Bude, J D

2009-10-28

317

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

NASA Technical Reports Server (NTRS)

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.

Garner, Charles

1987-01-01

318

ICP etching of GaAs via hole contacts  

SciTech Connect

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

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

1996-09-01

319

Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes  

NASA Astrophysics Data System (ADS)

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 ? 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.

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

2009-06-01

320

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

SciTech Connect

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 probability of damage initiation at 12 J/cm{sup 2} of an ensemble of scratches decreased from {approx}100 mm{sup -1} of scratch length to {approx}0.001 mm{sup -1}.

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

321

Acid inhibition of CRA`s: A review  

SciTech Connect

This paper will review the brief history in the literature of the inhibition of corrosion resistant alloys (CRA`s) in acidic stimulation fluids. This review primarily discusses the problems associated with inhibiting 13% Cr and 22% Cr duplex steels in hydrochloric (HCI) and hydrochloric-hydrofluoric (HCl-HF) acid systems using low alloy inhibitors and the successes achieved using high alloy inhibitors. Other areas briefly discussed are the repassivation of 13% Cr and 22% Cr, effect on nickel-based alloys and use of organic acids.

Walker, M.L.; Cassidy, J.M.; Lancaster, K.R.; McCoy, T.H. [Halliburton Energy Services, Duncan, OK (United States)

1994-12-31

322

Mars: South polar pits and etched terrain  

NASA Technical Reports Server (NTRS)

Martian south polar pits and etched terrain attest to alternating episodes of eolian deposition and erosion. Sometimes the south polar area has served as a sump for the accumulation of airborne debris and associated particles of frozen volatiles. At other times, the wind patterns or wind effectiveness change, and the atmosphere begins to remove the blanket of material it has earlier spread over the south polar region.

Sharp, R. P.

1973-01-01

323

Capability of etched multilayer EUV mask fabrication  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

324

Etching of moldavities under natural conditions  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

325

Shapes of agglomerates in plasma etching reactors  

SciTech Connect

Dust particle contamination of wafers in reactive ion etching (RIE) plasma tools is a continuing concern in the microelectronics industry. It is common to find that particles collected on surfaces or downstream of the etch chamber are agglomerates of smaller monodisperse spherical particles. The shapes of the agglomerates vary from compact, high fractal dimension structures to filamentary, low fractal dimension structures. These shapes are important with respect to the transport of particles in RIE tools under the influence electrostatic and ion drag forces, and the possible generation of polarization forces. A molecular dynamics simulation has been developed to investigate the shapes of agglomerates in plasma etching reactors. We find that filamentary, low fractal dimension structures are generally produced by smaller ({lt}100s nm) particles in low powered plasmas where the kinetic energy of primary particles is insufficient to overcome the larger Coulomb repulsion of a compact agglomerate. This is analogous to the diffusive regime in neutral agglomeration. Large particles in high powered plasmas generally produce compact agglomerates of high fractal dimension, analogous to ballistic agglomeration of neutrals. {copyright} {ital 1997 American Institute of Physics.}

Huang, F.Y.; Kushner, M.J. [University of Illinois, Department of Electrical and Computer Engineering, 1406 West Green Street, Urbana, Illinois 61801 (United States)] [University of Illinois, Department of Electrical and Computer Engineering, 1406 West Green Street, Urbana, Illinois 61801 (United States)

1997-05-01

326

Improving aluminum nitride plasma etch process for MEMS applications  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

327

Fabrication of Three-Dimensional Cu Coaxial Cable Using Porous Silicon Technology  

Microsoft Academic Search

This paper presents the fabrication of a three-dimensional Cu coaxial cable with a thick oxidized porous silicon (OPS) layer for application of microwave and RF integrated circuit technology. The structure was fabricated by hydrofluoric acid, nitric acid, acetic acid (HNA) etching, followed by the OPS process, electroplating and photoresist (PR) reflow. The return loss of the Cu coaxial cable on

Duk-Soo Eun; Jang-Kyoo Shin; Jong-Hyun Lee

2004-01-01

328

Extreme ultraviolet lithography mask etch study and overview  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

329

Plasma etching of proton-exchanged lithium niobate  

SciTech Connect

Plasma etching of lithium niobate with fluorine gases is limited by the redeposition LiF. This results in a low etch rate and nonvertically etched walls. Etching of proton-exchanged lithium niobate can prevent the LiF deposition to a large extent because of the greatly reduced lithium concentration in lithium niobate. We performed different inductively coupled plasma etching processes using SF{sub 6} or CHF{sub 3}/Ar on proton-exchanged lithium niobate. Negligible underetching and nearly vertically etched walls on proton-exchanged lithium niobate samples were obtained by CHF{sub 3}/Ar gas at chamber pressure of 6 mTorr and 130 V dc bias.

Hu, H.; Milenin, A.P.; Wehrspohn, R.B.; Hermann, H.; Sohler, W. [Department of Physics, University of Paderborn, D-33095 Paderborn (Germany); Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Department of Physics, University of Paderborn, D-33095 Paderborn (Germany)

2006-07-15

330

Photonic crystals of titanium dioxide fabricated by swift heavy ions  

Microsoft Academic Search

We have developed a method of fabricating nano-micro-structures in a rutile TiO2 single crystal using swift heavy-ion irradiation that takes advantage of the good etching selectivity induced by ion irradiation. The areas into which ions heavier than Cl and accelerated with MeV-order high energy had been irradiated were readily etched by 20% hydrofluoric acid. By comparison, etching was not observed

Koichi Awazu; Makoto Fujimaki; Yoshimichi Ohki; Tetsuro Komatsubara

2005-01-01

331

Electroluminescence (EL) from photo-chemically etched silicon  

Microsoft Academic Search

Visible luminescence from Si-based materials has been investigated to develop new opto-electronic devices on a Si wafer. In this report, we propose a photo-chemical etching method in order to form a luminescent layer on a Si wafer. A comparison between electroluminescence (EL) and photoluminescence (PL) from the photo-chemically etched silicon is discussed. In the photo-chemical etching method, a Si wafer

Naokatsu Yamamoto; Atsushi Sumiya; Hiroshi Takai

2000-01-01

332

Photo-enhanced chemical wet etching of GaN  

Microsoft Academic Search

In this paper, we report a photo-enhanced chemical etch rate study on two GaN samples of differing structural and electrical quality as a function of the KOH or H3PO4 etch solution molarity. The etch rate of KOH was observed to be higher than that of H3PO4. This was found to be result from the effects of surface band bending, and

C. H. Ko; Y. K. Su; S. J. Chang; W. H. Lan; Jim Webb; M. C. Tu; Y. T. Cherng

2002-01-01

333

Improvement of sidewall roughness in deep silicon etching  

Microsoft Academic Search

The recently developed High Aspect Ratio Si Etch (HARSE) process is widely used for applications requiring silicon structures\\u000a with high aspect ratios. This process relies on the alternation of sidewall passivation and silicon etching phases and enables\\u000a the obtainment of high silicon etch rates and highly anisotropic profiles. This paper reports an innovative approach to improve\\u000a the sidewall roughness through

M. Chabloz; Y. Sakai; T. Matsuura; K. Tsutsumi

2000-01-01

334

Laser etching of glass substrates by 1064 nm laser irradiation  

Microsoft Academic Search

Glass substrates are transparent to 1064nm laser irradiation and cannot be etched directly by 1064nm pulsed laser. By placing\\u000a the glass substrate in contact with copper sulphate (CuSO4) solution and irradiating 1064nm laser light through the glass, etching of the glass is observed on the downside of the\\u000a glass, the contact side with the copper sulphate solution. The etching mechanism

Z. Q. Huang; M. H. Hong; T. B. M. Do; Q. Y. Lin

2008-01-01

335

Ion beam sputter etching and deposition of fluoropolymers  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

336

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

PubMed

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

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

2007-07-01

337

Plasma etching characteristics of sputtered MoSi2 films  

NASA Astrophysics Data System (ADS)

Plasma etching of sputtered MoSi2 films using CF4/O2 mixtures was studied in a barrel-type reactor. The etch rate in pure CF4 was very low (?100 /min) and insensitive to applied power. The addition of a small percentage (<10%) of O2 dramatically increased the etch rate. For CF4/4% O2, and etch rate of 920 /min was measured at 100 W. A near-linear etch rate dependence on rf power was observed, indicating that the controlling factor is the generation rate of etching radicals. For CF4/8% O2, the etch rate nearly doubled and showed saturation at high rf power, indicating the increased role of the surface reaction rate. Postdeposition anneal results in a 10-20% decrease in etch rate. An etch rate selectivity of 14-22 for MoSi2 vs SiO2 and of 2-3 for doped poly-Si vs MoSi2 were measured.

Chow, T. P.; Steckl, A. J.

1980-09-01

338

Anisotropic etching of Al by a directed Cl2 flux  

NASA Technical Reports Server (NTRS)

A new Al etching technique is described that uses an ion beam from a Kaufman ion source and a directed Cl2 flux. The ion beam is used primarily to remove the native oxide and to allow the Cl2 to spontaneously react with the Al film forming volatile Al2Cl6. By controlling both the flux equivalent pressure of Cl2 and the ion beam current, this etching technique makes possible the anisotropic etching of Al with etch rates from 100 nm/min to nearly 10 microns/min with a high degree of selectivity.

Efremow, N. N.; Geis, M. W.; Mountain, R. W.; Lincoln, G. A.; Randall, J. N.

1986-01-01

339

Advanced plasma etching processes for dielectric materials in VLSI technology  

NASA Astrophysics Data System (ADS)

Manufacturable plasma etching processes for dielectric materials have played an important role in the Integrated Circuits (IC) industry in recent decades. Dielectric materials such as SiO2 and SiN are widely used to electrically isolate the active device regions (like the gate, source and drain from the first level of metallic interconnects) and to isolate different metallic interconnect levels from each other. However, development of new state-of-the-art etching processes is urgently needed for higher aspect ratio (oxide depth/hole diameter---6:1) in Very Large Scale Integrated (VLSI) circuits technology. The smaller features can provide greater packing density of devices on a single chip and greater number of chips on a single wafer. This dissertation focuses on understanding and optimizing of several key aspects of etching processes for dielectric materials. The challenges are how to get higher selectivity of oxide/Si for contact and oxide/TiN for vias; tight Critical Dimension (CD) control; wide process margin (enough over-etch); uniformity and repeatability. By exploring all of the parameters for the plasma etch process, the key variables are found and studied extensively. The parameters investigated here are Power, Pressure, Gas ratio, and Temperature. In particular, the novel gases such as C4F8, C5F8, and C4F6 were studied in order to meet the requirements of the design rules. We also studied CF4 that is used frequently for dielectric material etching in the industry. Advanced etch equipment was used for the above applications: the medium-density plasma tools (like Magnet-Enhanced Reactive Ion Etching (MERIE) tool) and the high-density plasma tools. By applying the Design of Experiments (DOE) method, we found the key factors needed to predict the trend of the etch process (such as how to increase the etch rates, selectivity, etc.; and how to control the stability of the etch process). We used JMP software to analyze the DOE data. The characterization of the etch processes included measurement of the etch rates, etch profiles, etch depth, top-down images, selectivity and etch margin. The cross-section images were taken on the Hitachi S-4500 Scanning Electron Microscope (SEM, Tokyo, Japan) tool.

Wang, Juan Juan

340

Release-etch modeling for complex surface micromachined structures  

SciTech Connect

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

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

1996-10-01

341

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

PubMed Central

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, Coltne/Whaledent) and a dual-cure composite (Paracore, Coltne/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.

Bortolotto, Tissiana; Roig, Miguel; Krejci, Ivo

2014-01-01

342

Reactive ion etching (RIE) technique for application in crystalline silicon solar cells  

SciTech Connect

Saw damage removal (SDR) and texturing by conventional wet chemical processes with alkali solution etch about 20 micron of silicon wafer on both sides, resulting in thin wafers with which solar cell processing is difficult. Reactive ion etching (RIE) for silicon surface texturing is very effective in reducing surface reflectance of thin crystalline silicon wafers by trapping the light of longer wavelength. High efficiency solar cells were fabricated during this study using optimized RIE. Saw damage removal (SDR) with acidic mixture followed by RIE-texturing showed the decrease in silicon loss by {proportional_to}67% and {proportional_to}70% compared to conventional SDR and texturing by alkaline solution. Also, the crystalline silicon solar cells fabricated by using RIE-texturing showed conversion efficiency as high as 16.7% and 16.1% compared with 16.2%, which was obtained in the case of the cell fabricated with SDR and texturing with NaOH solution. (author)

Yoo, Jinsu [Photovoltaic Research Center, Korea Institute of Energy Research, 102 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea)

2010-04-15

343

Surface-enhanced Raman spectroscopy on transparent fume-etched ITO-glass surface  

NASA Astrophysics Data System (ADS)

This work reports a simple yet highly efficient method to fabricate transparent substrates for surface enhanced Raman scattering (SERS) application. Our technique is based on a fume etching process for commercial ITO-glass (ITO film on glass substrate) with atmospheric fume of hydrochloric acid (HCl). Surface analyses suggested that the spontaneously evaporated HCl molecules chemically reacted with ITO and formed island-like nanostructures. The topography of the ITO surface can be tuned to optimize the SERS efficiency by adjusting the etching parameters. On-line SERS spectra of the R6G solution concentration variation were also obtained to study the adsorption behavior of R6G on ITO surface. This convenient, simple, and low-cost method of making transparent SERS-active substrates potentially opens a way toward rapid, nondestructive and quantitative bioanalysis, particularly in microfluidics.

Yang, Yimin; Long, Kailing; Kong, Fan; Fan, Jiyang; Qiu, Teng

2014-08-01

344

Three-dimensional etching of silicon substrates using a modified deep reactive ion etching technique  

NASA Astrophysics Data System (ADS)

We report realization of highly featured three-dimensional micro- and nano-structures on silicon substrates with a single masking layer using a hydrogen-assisted deep reactive ion etching process. Three gases of oxygen, hydrogen and SF6 are used in a sequential passivation and etching process to achieve high aspect ratio features. By controlling the flows of these gases and the power and timing of each subsequence, it is possible to achieve desired deep vertical etching with controlled underetching and recovery, yielding three-dimensional features directly on silicon substrates. Etch rates up to 0.75 m min-1 have been obtained with a low plasma power density of 1 W cm-2. Also features with a controllable underetching with more than 8 m in sidewall recession have been achieved. The three-dimensional structures can be used as a mold for polymers as well as a holding substrate for projection display applications where an electro-chromic material (WO3) has been used.

Azimi, S.; Sandoughsaz, A.; Amirsolaimani, B.; Naghsh-Nilchi, J.; Mohajerzadeh, S.

2011-07-01

345

Chemical etching of bovine serum albumin-protected Au25 nanoclusters for label-free and separation-free detection of cysteamine.  

PubMed

This study describes a novel Au nanocluster-based fluorescent sensor for label-free, separation-free and selective detection of cysteamine (CSH). The sensing mechanism is based on CSH etching-induced fluorescence quenching of the bovine serum albumin-protected Au25 nanoclusters (BSAGNCs). A series of characterizations is carried out towards a better understanding of the CSH-induced fluorescence quenching of the BSAGNCs. It is found that CSH can etch the Au25 nanoclusters, exhibiting the potent etching activity. Other thiol-containing compounds such as glutathione and cysteine and other 19 natural amino acids do not interfere with such CSH-induced etching process. The decreases in fluorescence intensity of the BSAGNCs allow sensitive detection of free CSH in the range of 500-10,000nM. The detection limit for CSH is 150nM (S/N=3). The spiked human serum samples can be analyzed with satisfactory results. PMID:25460897

Shu, Tong; Su, Lei; Wang, Jianxing; Li, Chenzhong; Zhang, Xueji

2015-04-15

346

Organic analysis of the returned lunar sample.  

PubMed

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

Abell, P I; Draffan, G H; Eglinton, G; Hayes, J M; Maxwell, J R; Pillinger, C T

1970-01-30

347

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

348

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

349

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

350

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

351

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

352

A Two-level Prediction Model for Deep Reactive Ion Etch (DRIE)  

E-print Network

We contribute a quantitative and systematic model to capture etch non-uniformity in deep reactive ion etch of microelectromechanical systems (MEMS) devices. Deep reactive ion etch is commonly used in MEMS fabrication where ...

Taylor, Hayden K.

353

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

SciTech Connect

We describe controlled, self-limited etching of a polystyrene polymer using a composite etching cycle consisting of sequential deposition of a thin reactive layer from precursors produced from a polymer-coated electrode within the etching chamber, modification using O{sub 2} exposure, and subsequent low-pressure Ar plasma etching, which removes the oxygen-modified deposited reactive layer along with Almost-Equal-To 0.1 nm unmodified polymer. Deposition prevents net etching of the unmodified polymer during the etching step and enables self-limited etch rates of 0.1 nm/cycle.

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

2013-06-24

354

Deep-etched fused silica gratings and applications  

NASA Astrophysics Data System (ADS)

Deep-etched fused silica grating is a kind of high density phase gratings whose surface are etched into an optimized depth for achieving a series of novel functions, such as high efficient diffraction at the -1 order, polarizing beam splitting, 1x2, 1x3 beam splitting, etc.. Since deep-etched fused silica grating is made of pure dielectric material of fused silica, so it has a high laser damage threshold for high power laser applications. We fabricated the polarizing beam splitter of the fused silica grating and realized the even and odd modes for analysis of fused silica grating. We gave the generalized equations for describing the performance of polarizing beam splitting and high efficient diffraction at the -1 order. We gave the analytic equation of 1x3 diffraction, which is impossible to obtain with the previous rigorously coupled wave method. For fabrication of deep-etched fused silica gratings, holographic recording, lithographic technique, and inductively coupled plasma etching are used to make the deep-etched gratings. Deep-etched gratings have a variety of practical applications. It can be used for demultiplexing optical signals in DWDM optical fiber communications. It can also be used as a pulse compressor of femtosecond or picosecond laser pulses. It can also be used as polarizing beam splitter, high efficient diffraction for spectrometer, etc.. Deep-etched fused silica gratings have a bright future for practical applications.

Zhou, Changhe

2010-11-01

355

PATTERN DENSITY BASED PREDICTION FOR DEEP REACTIVE ION ETCH (DRIE)  

E-print Network

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

Boning, Duane S.

356

Reactive ion etched substrates and methods of making and using  

DOEpatents

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

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

2007-08-07

357

Wet-Chemical Etching Revised: 2012-02-11  

E-print Network

. These pyramids are realised on c-Si solar cells for the purpose of reflection minimization. (110)-orientated? Gladly we send you one or more posters for free (only valid for Europe)! Just send us a short e). HNO3 -free HF etches do not attack Si. The SiO2 etch rate is determined by the HF-concentra- tion

Yoo, S. J. Ben

358

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...

359

Sacrificial wafer bonding for planarization after very deep etching  

Microsoft Academic Search

A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for resist spinning and layer patterning as well as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a wafer bond step followed by an etch back. Results of polymer bonding followed by

Vincent L. Spiering; J. W. Berenschot; Miko Elwenspoek; Jan H. J. Fluitman

1995-01-01

360

Environmental photostability of SF6-etched silicon nanocrystals  

NASA Astrophysics Data System (ADS)

We report on the long-term environmental stability of the photoluminescent (PL) properties of silicon nanocrystals (SiNCs). We prepared sulfur hexafluoride (SF6) etched SiNCs in a two-stage plasma reactor and investigated their PL stability against UV irradiation in air. Unlike SiNCs with hydrogen-passivated surfaces, the SF6-etched SiNCs exhibit no photobleaching upon extended UV irradiation despite surface oxidation. Furthermore, the PL quantum yield also remains stable upon heating the SF6-etched SiNCs up to 160?C. The observed thermal and UV stability of SF6-etched SiNCs combined with their PL quantum yields of up to 50% make them attractive candidates for UV downshifting to enhance the efficiency of solar cells. Electron paramagnetic spin resonance indicates that the SF6-etched SiNCs have a lowered density of defect states, both as-formed and after room temperature oxidation in air.

Liptak, R. W.; Yang, J.; Kramer, N. J.; Kortshagen, U.; Campbell, S. A.

2012-10-01

361

Etching Technologies in NLD (magnetic Neutral Loop Discharge) Plasma  

NASA Astrophysics Data System (ADS)

NLD (magnetic Neutral Loop Discharge) plasma has two major characteristic features that high density one is generated at the lower pressure than 1 Pa and is controllable by changing the magnetic coil current. Utilizing this feature, ionic etching should be carried out at the lower pressure than 1 Pa for chemical reactive substrates, for example, organic materials or ArF photo resists, because ionic etching is low selective and low reactive. In Si etching process, the NLD plasma is utilized by employing sputter/etching method, which is scheduled cyclic. The NLD plasma is very stable for abrupt changing of the process pressure. This is brought on by weakly magnetized plasma. When PTFE (Poly Tetra-Fluoro-Ethylene) is used as a sputter target, deep etching of 180 ?m is achieved for 7 ?m pattern with aspect ratio of 25.7.

Hayashi, Toshio; Morikawa, Yasuhiro

362

High rate ECR etching of III-V nitride materials  

SciTech Connect

The III-V nitride compound semiconductors are attracting considerable attention for blue and ultraviolet light emitting diodes (LEDs) and lasers as well as high temperature electronics due to their wide band gaps and high dielectric constants. The recent progress observed in the growth of these materials has not been matched by progress in processing techniques to fabricate more highly sophisticated devices. Patterning these materials has been especially difficult due to the relatively inert chemical nature of the group-III nitrides. The authors review dry etch techniques which have been used to pattern these materials including electron cyclotron resonance (ECR), reactive ion etch (RIE), and chemically assisted ion beam etching (CAIBE). ECR etch rates greater than 3,800 {angstrom}/min for InN, 3,500 {angstrom}/min for GaN, and 1,170 A/min for AlN are reported. Etch anisotropy, surface morphology, and near-surface stoichiometry will be discussed.

Shul, R.J.; Howard, A.J.; Kilcoyne, S.P. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J.; Abernathy, C.R.; Vartuli, C.B. [Univ. of Florida, Gainesville, FL (United States); Barnes, P.A.; Bozack, M.J. [Auburn Univ., AL (United States)

1994-12-31

363

Etching Patterns in SrTiO3 Crystals  

NASA Astrophysics Data System (ADS)

We will discuss patterns which we have etched into single crystals of the perovskite SrTiO_3, and the degree of control which we have been able to excercise over this patterning. The nucleation of etch pits at screw dislocations on the surface plays a major role in this sort of processing, and therefore the degree to which these crystals are annealed prior to etching is of some importance. Of course, the choice and concentration of etchant also determines the degree to which the etch may be planar. While such concerns are not unique to SrTiO_3, we will discuss our experience with this system, and will systematically detail methodologies for controllable exploitation of our observations. By largely following earlier work on the fundamentals of etching in silicon, we hope to enhance the ability to create meaningful structures in SrTiO_3.

Spalding, G. C.; Murphy, W. L.; Davidsmeier, T.

1998-03-01

364

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

PubMed Central

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

Abinaya; Karthikeyan; Sarvanan; Vikram, Raj

2014-01-01

365

Optimization of graphene dry etching conditions via combined microscopic and spectroscopic analysis  

NASA Astrophysics Data System (ADS)

Single-layer graphene structures and devices are commonly defined using reactive ion etching and plasma etching with O2 or Ar as the gaseous etchants. Although optical microscopy and Raman spectroscopy are widely used to determine the appropriate duration of dry etching, additional characterization with atomic force microscopy (AFM) reveals that residual graphene and/or etching byproducts persist beyond the point where the aforementioned methods suggest complete graphene etching. Recognizing that incomplete etching may have deleterious effects on devices and/or downstream processing, AFM characterization is used here to determine optimal etching conditions that eliminate graphene dry etching residues.

Prado, Mariana C.; Jariwala, Deep; Marks, Tobin J.; Hersam, Mark C.

2013-05-01

366

Optimization of graphene dry etching conditions via combined microscopic and spectroscopic analysis  

SciTech Connect

Single-layer graphene structures and devices are commonly defined using reactive ion etching and plasma etching with O{sub 2} or Ar as the gaseous etchants. Although optical microscopy and Raman spectroscopy are widely used to determine the appropriate duration of dry etching, additional characterization with atomic force microscopy (AFM) reveals that residual graphene and/or etching byproducts persist beyond the point where the aforementioned methods suggest complete graphene etching. Recognizing that incomplete etching may have deleterious effects on devices and/or downstream processing, AFM characterization is used here to determine optimal etching conditions that eliminate graphene dry etching residues.

Prado, Mariana C. [Departamento de Fisica, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte (Brazil)] [Departamento de Fisica, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte (Brazil); Jariwala, Deep [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)] [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Marks, Tobin J.; Hersam, Mark C. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States) [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)

2013-05-13

367

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

PubMed Central

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

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

2013-01-01

368

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

PubMed Central

Continuous etching of aggressive all-in-one adhesives occurs in wet dentin tubules after polymerization of the adhesives. This study challenged the hypothesis that unpolymerized acidic monomers from an aggressive all-in-one self-etching adhesive continue to etch beyond dentin hybrid layers. Dentin surfaces bonded with Adper Prompt L-Pop were sectioned into 0.3-mm-thick slabs. Some of the slabs were stored in water (pH 6.8) or glycine buffer (pH 11.1) for six weeks and then examined by CLSM, SEM, and TEM. The rest were immersed in a biomimetic remineralizing medium for up to 4 months. Morphologic analysis indicated no difference in demineralization thickness between the two 6-week storage groups. However, increased permeability and loss of integrity occurred along the base of the hybrid layers in the glycine buffer group, but not in the water storage group. These findings were also confirmed by the results of biomimetic remineralization along the bases of those hybrid layers. PMID:20200420

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

2010-01-01

369

Self-etch bonding agent beneath sealant: Bond strength for laser-irradiated enamel  

PubMed Central

Objectives: This study evaluated the in vitro shear bond strength (SBS) of a resin-based pit-and-fissure sealant (Fluroshield [F], Dentsply/Caulk) associated with either an etch-and-rinse (Adper Single Bond 2 [SB], 3M/ESPE) or a two-step self-etch adhesive system (Adper SE Plus [SE], 3M/ESPE) on Er: YAG laser-irradiated enamel. Materials and Methods: Seventeen sound third molar crowns were embedded in acrylic resin, and the mesialdistal enamel surfaces were flattened. The enamel sites were irradiated with a 2.94-?m wavelength Er: YAG laser (120 mJ, 4 Hz, noncontact mode/17 mm, 20 s). The specimens were randomly assigned to three groups according to the bonding technique: I - 37% phosphoric acid etching + SB + F; II - SE + F and III - F applied to acid-etched enamel, without an intermediate layer of bonding agent. In all of the groups, a 3-mm diameter enamel-bonding site was demarcated and the sealant cylinders were bonded. After 24 hours in distilled water, the shear bond strength was tested at a crosshead speed of 0.5 mm/minute. The data were analyzed by one-way ANOVA and Tukey's test. The debonded specimens were examined with a stereomicroscope to assess the failure modes. Results: The mean SBS values in MPa were I = 6.39 (1.44); II = 9.50 (2.79); and III = 5.26 (1.82). No statistically significant differences were observed between groups I and III; SE/F presented a significantly higher SBS than that of the other groups (P = 0.001). With regard to the failure mode, groups I (65%) and II (75%) presented adhesive failures, while group III showed 50% adhesive failure. Cohesive failure did not occur. Conclusion: The application of the two-step self-etch bonding agent (Adper SE Plus) beneath the resin pit-and-fissure sealant placement resulted in a significantly higher bond strength for the Er:YAG laser-irradiated enamel. PMID:24926208

Borsatto, Maria Cristina; Giuntini, Jackelline de Lemes; Contente, Marta Maria Martins Giamatei; Gomes-Silva, Jaciara Miranda; Torres, Carolina Paes; Galo, Rodrigo

2013-01-01

370

Porous silicon formation during Au-catalyzed etching  

SciTech Connect

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 (?0.01100 ? cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 ? cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of black Si on various Si substrates, which is of significant interest for photovoltaic applications.

Algasinger, Michael; Bernt, Maximilian; Koynov, Svetoslav; Stutzmann, Martin [Walter Schottky Institut, Technische Universitt Mnchen, 85748 Garching (Germany)

2014-04-28

371

UV-Photoassisted Etching of GaN in KOH  

SciTech Connect

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.

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

372

Scalloping minimization in deep Si etching on Unaxis DSE tools  

NASA Astrophysics Data System (ADS)

Sidewall smoothness is often a critical requirement for many MEMS devices, such as microfludic devices, chemical, biological and optical transducers, while fast silicon etch rate is another. For such applications, the time division multiplex (TDM) etch processes, so-called "Bosch" processes are widely employed. However, in the conventional TDM processes, rough sidewalls result due to scallop formation. To date, the amplitude of the scalloping has been directly linked to the silicon etch rate. At Unaxis USA Inc., we have developed a proprietary fast gas switching technique that is effective for scalloping minimization in deep silicon etching processes. In this technique, process cycle times can be reduced from several seconds to as little as a fraction of second. Scallop amplitudes can be reduced with shorter process cycles. More importantly, as the scallop amplitude is progressively reduced, the silicon etch rate can be maintained relatively constant at high values. An optimized experiment has shown that at etch rate in excess of 7 ?m/min, scallops with length of 116 nm and depth of 35 nm were obtained. The fast gas switching approach offers an ideal manufacturing solution for MEMS applications where extremely smooth sidewall and fast etch rate are crucial.

Lai, Shouliang; Johnson, Dave J.; Westerman, Russ J.; Nolan, John J.; Purser, David; Devre, Mike

2003-01-01

373

Dry etching technologies for the advanced binary film  

NASA Astrophysics Data System (ADS)

ABF (Advanced Binary Film) developed by Hoya as a photomask for 32 (nm) and larger specifications provides excellent resistance to both mask cleaning and 193 (nm) excimer laser and thereby helps extend the lifetime of the mask itself compared to conventional photomasks and consequently reduces the semiconductor manufacturing cost [1,2,3]. Because ABF uses Ta-based films, which are different from Cr film or MoSi films commonly used for photomask, a new process is required for its etching technology. A patterning technology for ABF was established to perform the dry etching process for Ta-based films by using the knowledge gained from absorption layer etching for EUV mask that required the same Ta-film etching process [4]. Using the mask etching system ARES, which is manufactured by Shibaura Mechatronics, and its optimized etching process, a favorable CD (Critical Dimension) uniformity, a CD linearity and other etching characteristics were obtained in ABF patterning. Those results are reported here.

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

2011-11-01

374

Targeted sacrificial layer etching for MEMS release using microfluidic channels  

NASA Astrophysics Data System (ADS)

A microfluidics based targeted etchant delivery and masking approach to wet etching has been used to control the etch progression of a MEMS sacrificial layer during the release of silicon nitride (SiNx) microbeams. A reusable 3-input open-channel polydimethylsiloxane (PDMS) microfluidic cassette was used to form a dynamically controllable fluid etch mask to control the location of the etchant during the wet release process. In contrast conventional release techniques which use solid masking and homogeneous etching environments, microfluidic devices can utilise laminar flows to generate heterogeneous etching conditions which can be controlled in real-time by altering the composition and flow rates of the fluids passing through specific inlets. The fluid nature of the heterogeneous flow can be used to target etch specific areas of sacrificial material or conversely, dynamically mask specific areas both above and below suspend structures. As a result of this control, structures with anchor geometries not achievable using conventional release techniques were created. Not only does this method require small volumes of etchant fluid, it is also suitable for use on samples which may be sensitive to the chemical and/or physical rigors of photolithographic patterning, such as porous silicon. Microfluidic based release etching, using dynamically controlled fluid masks, provides a valuable addition to the suite of microchannel based fabrication techniques.

Cheah, Ben C.; Keating, Adrian J.; Dell, John M.

2013-12-01

375

ELSEVIER InorganicaChimicaActa240 (1995) 109-115 Crystal growth in aqueous hydrofluoric acid and (HF)x" pyridine  

E-print Network

and (HF)x" pyridine solutions: syntheses and crystal structures of [Ni (H20) 6]2÷ [MF6] 2- (M =Ti, Zr, HfCI6.6H20 crystallizes in space group R3 with the nickel and tin atoms, coordinated by water and chloride, respec- tively, arranged in nearly regular octahedra. Ray et al. described the crystal structures

Poeppelmeier, Kenneth R.

376

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

E-print Network

with a trauma pad or gauze. Skin: When possible grab another user to help you dress the wound in the gowning area, however when necessary you may dress your wounds in the cleanroom. Gauze and trauma pads

Woodall, Jerry M.

377

Integrated reactive ion etching to pattern cross-linked hydrophilic polymer structures for protein immobilization  

NASA Astrophysics Data System (ADS)

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 1?m 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.

Bhatnagar, Parijat; Strickland, Aaron D.; Kim, Il; Malliaras, George G.; Batt, Carl A.

2007-04-01

378

Crystallographic Polarity and Etching Behavior of ZnSe  

Microsoft Academic Search

The crystallographic polarity of ZnSe has been identified uniquely by employing X-ray diffraction techniques. The X-ray identification has been correlated with the etch-pit figures formed on the (111)Zn and (\\\\bar{1}\\\\bar{1}\\\\bar{1}) Se surfaces. When etched with the K2Cr2O7-H2SO4 solution, the (111) surface is highly polished, while the (\\\\bar{1}\\\\bar{1}\\\\bar{1}) surface forms triangular pyramidal shaped pits with positive orientation. Subsequently etched with the

Atsuko Ebina; Kiyomitsu Asano; Tadashi Takahashi

1977-01-01

379

Parametric study on the solderability of etched PWB copper  

SciTech Connect

The rapid advancement of interconnect technology has resulted in a more engineered approach to designing and fabricating printed wiring board (PWB) surface features. Recent research at Sandia National Laboratories has demonstrated the importance of surface roughness on solder flow. This paper describes how chemical etching was used to enhance the solderability of surfaces that were normally difficult to wet. The effects of circuit geometry, etch concentration, and etching time on solder flow are discussed. Surface roughness and solder flow data are presented. The results clearly demonstrate the importance of surface roughness on the solderability of fine PWB surface mount features.

Hosking, F.M.; Stevenson, J.O.; Hernandez, C.L.

1996-10-01

380

Etching of mercuric iodide in cation iodide solutions  

NASA Astrophysics Data System (ADS)

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.

Ponpon, J. P.; Amann, M.

2006-07-01

381

Structural and magnetic etch damage in CoFeB  

SciTech Connect

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.

Krayer, L. [Physics Department, University of California, San Diego, California 92093 (United States); Electrical and Computer Engineering Department, University of Maryland, College Park, Maryland 20742 (United States); Lau, J. W. [Materials Science and Engineering Division, NIST, Gaithersburg, Maryland 20899 (United States); Kirby, B. J., E-mail: brian.kirby@nist.gov [Center for Neutron Research, NIST, Gaithersburg, Maryland 20899 (United States)

2014-05-07

382

Selective protection of polymeric materials from effects of chemical etching  

SciTech Connect

A photolithographic method for treating an article formed of polymeric material comprises subjecting portions of a surface of the polymeric article to ionizing radiation; and then subjecting the surface to chemical etching. The ionizing radiation treatment according to the present invention minimizes the effect of the subsequent chemical etching treatment. Thus, selective protection from the effects of chemical etching can be easily provided. The present invention has particular applicability to articles formed of fluorocarbons, such as PTFE. The ionizing radiation employed in the method may comprise Mg(k{alpha}) x-rays or low-energy electrons. 10 figs.

Martinez, R.J.; Rye, R.R.

1989-03-29

383

New silicon architectures by gold-assisted chemical etching.  

PubMed

Silicon nanowires (SiNWs) were produced by nanosphere lithography and metal assisted chemical etching. The combination of these methods allows the morphology and organization control of Si NWs on a large area. From the investigation of major parameters affecting the etching such as doping type, doping concentration of the substrate, we demonstrate the formation of new Si architectures consisting of organized Si NW arrays formed on a micro/mesoporous silicon layer with different thickness. These investigations will allow us to better understand the mechanism of Si etching to enable a wide range of applications such as molecular sensing, and for thermoelectric and photovoltaic devices. PMID:21882843

Mikhael, Bechelany; Elise, Berodier; Xavier, Maeder; Sebastian, Schmitt; Johann, Michler; Laetitia, Philippe

2011-10-01

384

CDU improvement technology of etching pattern using photo lithography  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

385

Selectively-etched nanochannel electrophoretic and electrochemical devices  

DOEpatents

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.

Surh, Michael P. (Livermore, CA); Wilson, William D. (Pleasanton, CA); Barbee, Jr., Troy W. (Palo Alto, CA); Lane, Stephen M. (Oakland, CA)

2006-06-27

386

Photo-enhanced chemical etched GaN LED on silicon substrate  

Microsoft Academic Search

In this study, GaN LEDs grown with an intermediate DBR on a Si substrate were chemically etched by 3M KOH solution under UV light illumination. After 60min of KOH etching, the hexagonal etch pits and randomized embossments were clearly imaged by SEM and AFM. The etch pits were generated at the threading dislocations, which are common for lattice mismatched growth

Hong-Yeol Kim; Michael A. Mastro; Jennifer Hite; Charles R. Eddy; Jihyun Kim

2011-01-01

387

Etching of silicon in alkaline solutions: a critical look at the {111} minimum  

Microsoft Academic Search

Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In this technology, etching through masks is used for fast and reproducible shaping of micromechanical structures. The etch rates Image depend mainly on composition and temperature of the etchant. In a plot of etch rate versus orientation, there is always a

A. J. Nijdam; Suchtelen van J; J. W. Berenschot; J. G. E. Gardeniers; M. C. Elwenspoek

1999-01-01

388

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

NASA Astrophysics Data System (ADS)

We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I-, Br-) in HF/HNO3/CH3COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br-, I-..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.

Abbadie, A.; Hamaide, G.; Mariolle, D.; Chaupin, M.; Brunier, F.; Martinez, E.; Mhli, J.

2012-03-01

389

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

SciTech Connect

We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I{sup -}, Br{sup -}...) in HF/HNO{sub 3}/CH{sub 3}COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br{sup -}, I{sup -}..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.

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

2012-03-15

390

Removal of field and embedded metal by spin spray etching  

DOEpatents

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.

Contolini, R.J.; Mayer, S.T.; Tarte, L.A.

1996-01-23

391

Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene  

E-print Network

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

Campos, Leonardo

392

Etching Technology Using Ozone for Chemically Stable Polymer in MEMS  

NASA Astrophysics Data System (ADS)

We have developed the etching technology using an ozone solution for chemically stable polymers such as polyimide, SU-8 and BCB, which are often used for MEMS, and a carbonized resist. Conventionally, these polymers are difficult to remove by O2 plasma and organic solutions. In this study, the etching experiments of these chemically stable polymers were carried out using an acetic solution of ozone. The residues after the etching of the polymers were evaluated with surface profiler, scanning electron microscope and X-ray photoelectron spectroscopy. It was demonstrated that the acetic solution of ozone can etch and remove these polymers without residue. The developed method can remove not only organic polymers but also polymers containing inorganic materials, and is safe and easy.

Yanagida, Hideaki; Yoshida, Shinya; Esashi, Masayoshi; Tanaka, Shuji

393

Removal of field and embedded metal by spin spray etching  

DOEpatents

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.

Contolini, Robert J. (Pleasanton, CA); Mayer, Steven T. (San Leandro, CA); Tarte, Lisa A. (Livermore, CA)

1996-01-01

394

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

395

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

PubMed Central

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

Hpkes, Jrgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

2012-01-01

396

Hydrolytic Stability of Self-etch Adhesives Bonded to Dentin  

Microsoft Academic Search

Functional monomers chemically interact with hydroxyapatite that remains within submicron hybrid layers produced by mild self-etch adhesives. The functional monomer 10-MDP interacts most intensively with hydroxyapatite, and its calcium salt appeared most hydrolytically stable, as compared with 4-MET and phenyl-P. We investigated the hypothesis that additional chemical interaction of self-etch adhesives improves bond stability. The micro-tensile bond strength (?TBS) of

S. Inoue; K. Koshiro; Y. Yoshida; J. De Munck; K. Nagakane; K. Suzuki; H. Sano; B. Van Meerbeek

2005-01-01

397

Visible luminescence from photo-chemically etched silicon  

Microsoft Academic Search

A new photo-chemical etching method using H2O2 as an oxidant was proposed to form a luminescence layer on a Si wafer. A single crystalline n-type Si wafer (100) having resisitivity of 3545 ? cm was photo-chemically etched in a mixture of HF and H2O2 (HF:H2O2=6:1), and HeNe laser (633 nm) was irradiated onto the wafer surface through the solution for

Naokatsu Yamamoto; Hiroshi Takai

2000-01-01

398

Laser-induced chemical etching of silicon in chlorine atmosphere  

Microsoft Academic Search

Laser-induced chemical etching of single-crystalline (100) Si in Cl2 atmosphere has been investigated for continuous Ar+ and Kr+ laser irradiation at around 351 nm, and at 457.9, 488.0, 514.5, and 647.1 nm. For laser irradiances below 105 W\\/cm2 the etching mechanism is non-thermal, and is based on photo-generated electron-hole pairs within the Si surface and Cl atoms produced within the

P. Mogyorsi; K. Piglmayer; R. Kullmer; D. Buerle

1988-01-01

399

Cure rate and dry etch patterning of thermoset polymers  

NASA Astrophysics Data System (ADS)

High quality thermoset polymer solutions are available from several commercial suppliers. These are suitable for forming thin films for optical waveguides because of their high transmission, suitable refractive indices and thickness uniformity of films obtained by spinning solutions on a substrate such as silicon. The solution's viscosity and the spinning speed determine the thickness of resulting films. The plasma etch rate was examined for trenches (of the order of 1 ?m depth, suitable for photonic waveguide fabrication) formed in such films from a relatively high viscose polymer solution (UV15 from Master Bond). The cross-link density of the polymer is dependent on its curing process, that is, the exposure to ultra-violet light radiation and heat. The curing process can have a profound affect on the etch rate. Different paths were taken in the curing and etching process of the spun polymer film in order to examine the relation between the cross-link density and the polymer etching process. We examine the polymer films using FTIR to qualitatively measure the cross-link density and DSC for changes in the glass transition temperature (Tg). FTIR is used to show if chemical changes occur for different levels of curing. Determining Tg is important because this will show how it changes with the baking step. We have observed that for films with low Tg, the plasma etch process can cause the polymer surface to flow and hence wrinkle. Post-curing at higher temperatures increases Tg. By choosing appropriate curing steps, Tg and the etch rate can be optimized to obtain an optimum etch rate and preserve the smooth polymer surface during etching.

Montoya, Maria-Jose; Simon, Darren; Holland, Anthony S.; Shanks, Robert

2005-02-01

400

Etched-angled-facet superluminescent diodes for improved mode locking  

NASA Astrophysics Data System (ADS)

When conventional superluminescent diodes are mode locked in an external cavity to mitigate nonlinearities and dispersion, the residual reflectivity at the diode's facet creates a detrimental compound cavity. This compound cavity modulates the spectrum of the round trip gain, and this modulation strongly hinders the complete locking of modes. Such lasers produce longer pulses, pulses with undesirable temporal structure or multiple pulses. Prior work has shown some success with using etched angled facets to divert the modal reflection away from the waveguide. In this dissertation, a new microfabrication process is developed to produce superluminescent diodes with the combination of low facet reflectivity, bias-controlled saturable absorption and CW operation without noticeable degradation. An improved etching process reduces the roughness of the angled facet to reduce reflectivity due to backscattering. The process uses reactive ion etching (RIE) to pattern the silicon dioxide etch mask, and chemically assisted ion beam etching (CAIBE) to pattern the aluminum gallium arsenide (AlGaAs) epitaxial structure. The smoothness of the etched facets correlates with etching conditions. As measured by atomic force microscopy, the facets are as smooth as 4 nm R.M.S. The reflectivity of these angled facets is on the order of 10-5, inferred from measurements of CW superluminescence spectra. This low reflectivity is broadband. Passive mode locking of these diodes in a simple external cavity produces single pulses of 4 ps duration (without compression). The mode-locked optical spectra are smooth and symmetric, with a full width of 2.4 nm to 3.0 nm. The laser operation exhibits bistability with respect to both the absorber bias and the gain current. The operation is repeatable. In the present devices, the pulse widths and spectral widths are limited only by the insufficient length of the saturable absorber section, 30 ?m. The very low reflectivity of the etched angled facet allows for good mode locking with a very simple cavity and simple DC bias.

Pesarcik, Scott Frederick

1998-10-01

401

Auger electron spectroscopy study of reactive ion etched silicon carbide  

Microsoft Academic Search

Reactive ion etching (RIE) of bulk 4H-SiC based on CHF3O2 plasma was studied by varying the rf power and process pressure. The elements on the etched surface and the surface roughness were characterized by Auger electron spectroscopy and atomic force microscopy, respectively. It was found that the surface roughening is mainly caused by Al contamination and C rich layer (C

J. H. Xia; Rusli; S. F. Choy; R. Gopalakrishan; C. C. Tin; J. Ahn; S. F. Yoon

2006-01-01

402

Zigzag structures obtained by anisotropic etching of macroporous silicon  

NASA Astrophysics Data System (ADS)

High-aspect-ratio structures with thin corrugated walls have been obtained by processing of macroporous silicon with a trigonal lattice in anisotropic etchants. For this purpose, a pattern of seeding etch pits with a certain orientation relative to crystallographic axes is created prior to electrochemical etching and a solution of definite composition for treating macropores is used after anodizing. The possibility of using zigzag structures as anodes in lithium-ion batteries is discussed.

Chernienko, A. V.; Astrova, E. V.; Zharova, Yu. A.

2013-11-01

403

Revealing obliterated engraved marks on high strength aluminium alloy (AA7010) surfaces by etching technique.  

PubMed

Restoration of obliterated engraved marks on high strength Al-Zn-Mg-Cu alloy (AA7010) surfaces by etching technique was studied. The alloy surfaces were mechanically engraved with some identification marks using "Gravograph". The marks were then erased by removing the metal to different levels up to and below the depth of engraving. Five metallographic reagents were tested on the obliterated surfaces by etching. The following two methods (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH were found to be quite effective to reveal the obliterated marks. These two procedures were also able to show effectively the marks obliterated by over-engraving and centre punching. Of the two techniques immersion in phosphoric acid provided more contrast. Interestingly, alternate swabbing of 60% HCl and 40% NaOH presented itself to be the common reagent for restoration on pure aluminium as well as its alloy surfaces. This is evident from our own current experiments and those of earlier researchers [G. Peeler, S. Gutowski, H. Wrobel, G. Dower, The restoration of impressed characters on aluminium alloy motor cycle frames, J. Forensic Ident. 58 (1) (2008) 27-32; M. Izhar M. Baharum, R. Kuppuswamy, A.A. Rahman, Restoration of engraved marks on aluminium surfaces by etching technique, Forensic Sci. Int. 177 (2008) 221-227]. The findings have assumed importance as engines and chassis of cars and frames of firearms are currently made of high strength aluminium alloys and recovery on these surfaces by current methods is not satisfactory. PMID:20022189

Bong, Yeu Uei; Kuppuswamy, R

2010-02-25

404

Etching of silicon surfaces using atmospheric plasma jets  

NASA Astrophysics Data System (ADS)

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.

Paetzelt, H.; Bhm, G.; Arnold, Th

2015-04-01

405

Low damage, highly anisotropic dry etching of SiC  

SciTech Connect

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.

Wang, J.J.; Hong, J.; Lambers, E.S.; Pearton, S.J.; Ren, F. [Univ. of Florida, Gainesville, FL (United States); Ostling, M.; Zetterling, C.M. [Royal Inst. of Tech., Kista (Sweden); Grow, J.M. [New Jersey Inst. of Tech., Newark, NJ (United States); Shul, R.J. [Sandia National Labs., Albuquerque, NM (United States)

1998-03-01

406

Vapor etching of nuclear tracks in dielectric materials  

DOEpatents

A process involving vapor etching of nuclear tracks in dielectric materials for creating high aspect ratio (i.e., length much greater than diameter), isolated cylindrical holes in dielectric materials that have been exposed to high-energy atomic particles. The process includes cleaning the surface of the tracked material and exposing the cleaned surface to a vapor of a suitable etchant. Independent control of the temperatures of the vapor and the tracked materials provide the means to vary separately the etch rates for the latent track region and the non-tracked material. As a rule, the tracked regions etch at a greater rate than the non-tracked regions. In addition, the vapor-etched holes can be enlarged and smoothed by subsequent dipping in a liquid etchant. The 20-1000 nm diameter holes resulting from the vapor etching process can be useful as molds for electroplating nanometer-sized filaments, etching gate cavities for deposition of nano-cones, developing high-aspect ratio holes in trackable resists, and as filters for a variety of molecular-sized particles in virtually any liquid or gas by selecting the dielectric material that is compatible with the liquid or gas of interest.

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

2000-01-01

407

Laser etching technique using bubble jet impact for glass substrates  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to propose a new laser etching technique using bubble jet impact for glass substrates. An Nd:YAG laser is applied to the backside of the substrate which is partially submerged in water. A metal plate is placed below the glass substrate. The metal vaporizes the water and generates a turbulent bubble flow. The bubble nozzle is proposed to enhance the impact of the bubble jet. The glass surface will first be softened, and then expelled by the shock wave resulting from the jet impact. The phenomena of bubble nucleation, growth, collapse, and jet impact were studied in this paper. The formation of the etching cavity can be divided into three types: double-petal, triple-petal, and four-petal. The etching pits expanded and combined to form a complete cavity. The needed laser power does not exceed 5 W. The proposed laser etching method was successfully demonstrated for etching a cavity of 5-20 m in depth and 50-250 m in diameter. The bubble jet of the small nozzle diameter is well concentrated, creating a strong jet impact on the glass surface. A greater nozzle depth can enhance the impact of the bubble jet. The proposed etching technique has great potential to provide an improved solution for the micro-machining of glass.

Weng, Tsu-Shien; Tsai, Chwan-Huei

2014-12-01

408

Optimization of (100)-Si TMAH etching for uncooled infrared detector  

NASA Astrophysics Data System (ADS)

The influences of concentration of the Tetra-methyl ammonium hydroxide (TMAH) solution together with oxidizer additions were studied in order to optimize the anisotropic silicon etching in the development of a fabrication process for Ba0.65Sr0.35TiO3 (BST) pyroelectric thin film infrared detectors. The detector active element was consisted of capacitance NiCr/BST/Pt and the thin silicon suspending membrane. The later one was formed by bulk anisotropically etching of the (100)-Si wafer. Both solution concentration and oxidizing agent were tuned in order to obtain an optimum etching process. Some improvements such as higher etch rate and lower surface roughness have been obtained by the addition of ammonium peroxide sulfate ((NH4)S2O8) as oxidizing agent under different conditions. The examination of etching speed and surface topography were performed by step surface profiler and scanned electronic microscopy. Furthermore, a simple approach was developed to fabric BST pyroelectric thin film detector based on the optimized TMAH etching parameters. A BST thin film capacitance was formed on a thin silicon membrane, where high sensitivity D* of 9.4107cmHz1/2/W was measured.

Shuai, Y.; Wu, C. G.; Zhang, W. L.; Li, Y. R.; Liu, X. Z.; Zhu, J.

2009-07-01

409

The grand challenges of plasma etching: a manufacturing perspective  

NASA Astrophysics Data System (ADS)

Plasma etching has been enabling nano-electronic fabrication since the 1980s; during this time, transistor size has shrunk by nearly two orders of magnitude, starting at 1.0 m in the mid 80s to ?0.01 m today. The manufacturing of these devices requires overcoming a series of challenges, ranging from continuous innovation on device integration to extend Moore's law to breaking tradeoffs on the perennial challenge of aspect ratio-dependent etching. In this paper, we will review four key areas in etch manufacturing: uniformity, defects, surface precision and sticky/non-volatile etch materials. In the uniformity section, we will discuss the challenges for microscopic uniformity, such as localized feature dimension variations; macroscopic uniformity, such as performance at the extreme edge of the wafer; and repeatable uniformity, meaning wafer-to-wafer, lot-to-lot and chamber-to-chamber performance. While defect management is successful with in situ plasma cleans, one must be cognizant of the choice of clean chemistry. In surface precision, we look at the approach of atomic layer etching and how it can be successful in a manufacturing environment. Finally, in the non-volatile material section, we review technology drivers for DRAM (dynamic random access memory) and NAND flash memory in the microelectronics Si industry, with focus on the utilization of such materials and what it means to etch equipment manufacturers.

Lee, Chris G. N.; Kanarik, Keren J.; Gottscho, Richard A.

2014-07-01

410

SPENT ACID RECOVERY USING DIFFUSION DIALYSIS  

EPA Science Inventory

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

411

Influences of temperature and etching voltage on the surface morphology of photo-electro-chemical etching for silicon microchannel arrays  

NASA Astrophysics Data System (ADS)

The application fields of high aspect ratio Si microchannel arrays have increased considerably, for example, Si microchannel plates, MEMS devices and so on. By the method of photo-electrochemical etching (PEC), Si microchannel arrays are prepared using n-Si wafer covered by anti-corrosion layers and initiation array pits. The dark current intensity curve of an n-type silicon wafer was presented in aqueous HF. The relationship among temperature, etching voltage and carrier transportation was presented. The influences of temperature and etching voltage on the surface morphology of silicon microchannel arrays were researched. The perfect Si microchannel arrays structure with the pore depth of 297 ?m, the pore size of 3 ?m and the aspect ratio of 99 was obtained by the method of reducing etching voltage gradually.

Zhang, Yao; Duanmu, Qingduo; Yu, Feng-yuan; Liang, Yong-zhao; Chai, Jin; Wang, Guo-zheng; Yang, Ji-kai

2013-08-01

412

Microtensile bond strength of etch-and-rinse and self-etch adhesives to artificially created carious dentin.  

PubMed

This article evaluates a pH-cycling model for simulation of caries-affected and caries-infected dentin (CAD and CID, respectively) surfaces, by comparing the bond strength of an etch-and-rinse and a self-etch adhesive system. For both adhesives, bonding to sound dentin (SD) showed that the microtensile bond strength (?TBS) values of SD, CAD, and CID were SD > CAD > CID (P < 0.05). Knoop microhardness number mean values followed the same trend. Adhesive systems were not able to totally penetrate into CAD and CID, forming more irregular resin-dentin interdiffusion zones and atypical resin tags than SD. The tested in vitro pH-cycling caries model allowed the evaluation of specific dentin substrate alterations in response to ?TBS. The type of dentin and its histological structure played an important role in etch-and-rinse and self-etch bonding, as lower ?TBS values were attained in CAD and CID. PMID:24784516

Erhardt, Maria Carolina Guilherme; Lobo, Maristela Maia; Goulart, Marcelo; Coelho-de-Souza, Fabio Herrmann; Valentino, Thiago Assuncao; Pisani-Proenca, Jatyr; Conceicao, Ewerton Nocchi; Pimenta, Luiz Andre Freire

2014-01-01

413

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

414

Split-it!: from litho etch litho etch to self-aligned double patterning decomposition  

NASA Astrophysics Data System (ADS)

Double Patterning (DP) is still the most viable lithography option for sub-22nm nodes. The two main types of DP are Litho Etch Litho Etch (LELE) and Self-Aligned Double Patterning (SADP). Of those two, SADP has the advantage of lower sensitivity to overlay error. However SADP imposes a lot of restrictions on the layout. One of the ways to do SADP decomposition is to use an LELE decomposer while prohibiting stitches, and to generate mandrel and trim masks from LELE masks using some Boolean characterization equations. In this paper, we propose an SADP decomposer based on an LELE decomposer that is used to decide which target polygons are mandrel and which are non-mandrel. However the core of the LELE decomposer has been made SADP-aware, such that it gives less priority to pairs of polygons separated by spacing values that are prohibited by SADP. Then, a mandrel and trim masks generator uses the LELE decomposer output and produces the final mandrel and trim masks. Experimental results show that adding SADPawareness to the core of the decomposer has decreased the average number of coloring conflicts by 38%. The proposed decomposer is faster than the previous SADP decomposition approaches that use Integer Linear Programming (ILP) and Satisfiability (SAT).

Badr, Yasmine A.; Wassal, Amr G.; Hammouda, Sherif

2012-11-01

415

A randomized control clinical trial of fissure sealant retention: Self etch adhesive versus total etch adhesive  

PubMed Central

Context: There are limited studies on comparison of Total etch (TE) and Self etch (SE) adhesive for placement of sealants. Aims: The aim of the study was to compare the retention of fissure sealants placed using TE adhesive to those sealants placed using SE (seventh generation) adhesive. Settings and Design: The study was conducted in the dental section, Aga Khan University Hospital. This study was a randomized single blinded trial with a split mouth design. Materials and Methods: The study included 37 patients, 101 teeth were included in both study groups. The intervention arm was treated with SE Adhesive (Adper Easy One, 3M ESPE, US). Control arm received TE adhesive (Adper Single Bond 2, 3M ESPE, US) before sealant application. The patients were followed after 6 months for assessment of sealant retention. Statistical analysis used: Interexaminer agreement for outcome assessment was assessed by Kappa Statistics and outcome in intervention group was assessed by McNemar's test. Results: Ninety-one pairs of molar (90%) were reevaluated for sealant retention. Complete retention was 56% in TE arm and 28% in SE arm with an odds ratio (OR) of 3.7. Conclusions: Sealants applied with TE adhesives show higher rate of complete sealant retention than SE adhesive. PMID:25657521

Aman, Nadia; Khan, Farhan Reza; Salim, Aisha; Farid, Huma

2015-01-01

416

Etching and forward transfer of fused silica in solid-phase by femtosecond laser-induced solid etching (LISE)  

NASA Astrophysics Data System (ADS)

We present a femtosecond laser-based technique for etching and forward transfer of bulk transparent materials in solid-phase. Femtosecond laser pulses with ?=800nm were focused through a fused silica block onto an absorbing thin film of Cr. A constraining Si wafer was pressed into tight contact with the Cr film to prevent lift-off of the film. A combination of the high temperature and pressure of the Cr, and compressive stress from the Si, resulted in etching of smooth features from the fused silica by cracking. Unlike in conventional ablative or chemical etching, the silica was removed from the bulk as single solid-phase pieces which could be collected on the Si. Using this so-called laser-induced solid etching (LISE) technique, 1-2 ?m deep pits and channels have been produced in the silica surface, and corresponding dots and lines deposited on the Si. The threshold fluence for etching was found to be ?0.4J/cm with ?130fs duration pulses. The morphology of the etched features are investigated as functions of fluence and exposure to multiple pulses.

Banks, David P.; Kaur, Kamal S.; Eason, Robert W.

2009-07-01

417

Measuring the refractive indices of conjugated polymer films with Bragg grating outcouplers  

E-print Network

, the waveguided photo- luminescence is scattered by the grating. The refractive index is determined by measuring10­PPV), which has the chemical structure shown in Fig. 1 a . The substrates for our studies were beams ( 325 nm), developing the resist, and etching the SiO2 in 50:1 hydrofluoric acid HF . The gratings

McGehee, Michael

418

Monocrystalline silicon carbide nanoelectromechanical systems Y. T. Yang, K. L. Ekinci, X. M. H. Huang, L. M. Schiavone, and M. L. Roukesa)  

E-print Network

electromechanical resonators from single-crystal 3C-SiC layers grown epitaxially upon Si substrates. A surface by timed etching in aque- ous hydrofluoric acid solutions.6 Single crystal 3C-SiC sur- face micromachined for publication 15 November 2000 SiC is an extremely promising material for nanoelectromechanical systems given

Roukes, Michael L.

419

Hall effect and transmission electron microscopy of epitaxial MnSi thin films  

E-print Network

were done on pattern Hall bars with gold wire leads attached with indium solder. The samples were prepared by photolithographic patterning using SPR220 3.0 photoresist and were either wet-etched with a 45:35:15 acetic:nitric:hydrofluoric acid mixture...

Meynell, S. A.; Wilson, M. N.; Loudon, J. C.; Spitzig, A.; Rybakov, F. N.; Johnson, M. B.; Monchesky, T. L.

2014-12-22

420

Vapor phase release of silicon nanostructures for optomechanics application  

Microsoft Academic Search

Suspended silicon based nanostructures for optomechanic applications have been successfully fabricated using the Hydrofluoric acid (HF) vapor phase etching technique. In this paper, we demonstrate the fabrication of parallel silicon waveguides with a cross section of 250nm x 220nm, and photonic crystal nanobeam cavities with an air gap as small as 50nm between these released structures. The waveguides have been

Parag B. Deotare; Mughees Khan; Marko Loncar

2009-01-01

421

Robust polyazobenzene microcapsules with photoresponsive pore channels and tunable release profiles  

Microsoft Academic Search

Monodisperse silica particles coated with azobenzene polymer (PAzo) shell were synthesized through distillation precipitation polymerization. Robust PAzo microcapsules were obtained after selective removal of the silica templates by hydrofluoric acid (HF) etching. These PAzo microcapsules, confirmed by transmission electron microscopy (TEM) investigation, had excellent reversible photoisomerization with transformation between trans and cis isomers under ultraviolet (UV) and visible lights. Due

Xiaotao Wang; Yingkui Yang; Yonggui Liao; Zhifang Yang; Man Jiang; Xiaolin Xie

422

Supplementary Information: Synchronization of Micromechanical Oscillators Using Light  

E-print Network

in buffered hydrofluoric acid (6 : 1) for an isotropic etch of the SiO2 in between the disks and the substrate and the residual chrome is lift-off afterwards. In order to release the structure, the device is immersed

McEuen, Paul L.

423

Organic Analysis of the Returned Lunar Sample  

Microsoft Academic Search

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

Paul I. Abell; G. H. Draffan; Geoffrey Eglinton; John M. Hayes; James R. Maxwell; Colin T. Pillinger

1970-01-01

424

An analytical study of two-dimensional buckling of thin films on compliant substrates  

E-print Network

by photolithographic processing and etching of the top silicon. Next, the buried SiO2 layer is removed by hydrofluoric acid to yield membranes that rest on, but are not bonded to, the underlying wafer. The lateral temperature released the thermally induced prestrain, thereby causing the PDMS to relax back to its unstrained

Rogers, John A.

425

A full wafer dicing free dry release process for MEMS devices  

Microsoft Academic Search

This paper presents a full wafer, dicing free, dry release process using hydrofluoric acid (HF) vapour phase etching (VPE) for MEMS sensors and actuators fabricated using silicon on insulator (SOI) wafers. It is particularly beneficial to MEMS sensors whose performance benefits from a large proof mass, for example accelerometers and gyroscopes. Such a fabrication method was first proposed by Overstolz

I. Sari; I. Zeimpekis; M. Kraft

2010-01-01

426

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

E-print Network

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

Wang, Zhong L.

427

A Tobacco Etch Virus Protease with Increased Substrate Tolerance at the P1' position  

PubMed Central

Site-specific proteases are important tools for in vitro and in vivo cleavage of proteins. They are widely used for diverse applications, like protein purification, assessment of proteinprotein interactions or regulation of protein localization, abundance or activity. Here, we report the development of a procedure to select protease variants with altered specificity based on the well-established Saccharomyces cerevisiae adenine auxotrophy-dependent red/white colony assay. We applied this method on the tobacco etch virus (TEV) protease to obtain a protease variant with altered substrate specificity at the P1 Position. In vivo experiments with tester substrates showed that the mutated TEV protease still efficiently recognizes the sequence ENLYFQ, but has almost lost all bias for the amino acid at the P1 Position. Thus, we generated a site-specific protease for synthetic approaches requiring in vivo generation of proteins or peptides with a specific N-terminal amino acid. PMID:23826349

Renicke, Christian; Spadaccini, Roberta; Taxis, Christof

2013-01-01

428

Study on the formation of dodecagonal pyramid on nitrogen polar GaN surface etched by hot H3PO4  

NASA Astrophysics Data System (ADS)

Hot phosphor acid (H3PO4) etching is presented to form a roughened surface with dodecagonal pyramids on laser lift-off N face GaN grown by metalorganic chemical vapor deposition. A detailed analysis of time evolution of surface morphology is described as a function of etching temperature. The activation energy of the H3PO4 etching process is 1.25 eV, indicating the process is reaction-limited scheme. And it is found that the oblique angle between the facets and the base plane increases as the temperature increases. Thermodynamics and kinetics related factors of the formation mechanism of the dodecagonal pyramid are also discussed. The light output power of a vertical injection light-emitting-diode (LED) with proper roughened surface shows about 2.5 fold increase compared with that of LED without roughened surface.

Qi, S. L.; Chen, Z. Z.; Fang, H.; Sun, Y. J.; Sang, L. W.; Yang, X. L.; Zhao, L. B.; Tian, P. F.; Deng, J. J.; Tao, Y. B.; Yu, T. J.; Qin, Z. X.; Zhang, G. Y.

2009-08-01

429

Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint  

SciTech Connect

We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated at grains boundaries, and may short circuit the device if the CdTe is too thin. The etching process facilitates the Cu diffusion and results in thicker conductive layers. The existence of this inhomogeneous conductive layer directly affects the current transport and is probably the reason for needing thick CdTe in these devices.

Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M.; Metzger, W. K.; Li, X.; Al-Jassim, M. M.

2006-05-01

430

Scanning electron microscopy of the root surface texture of extracted periodontally diseased teeth following various etching and chelating regimens.  

PubMed

Scanning electron microscopy of root surfaces that had been ultrasonically scaled and subjected to various conditioning regimens revealed the presence of two distinct types of cracks: extensive cracks, presumed to have been caused by drying before and during sputter-coating procedures; and smaller cracks that reflected the pattern of the irregular underlying dentin. Both etching and chelating agents appear to cause demineralization of the interfacial layer between cementum and dentin, causing a "peeling off" of cementum and exposure of the underlying dentin. The results suggest that burnishing the scaled root surface with either saline or any of the etching or chelating agents for at least 10 seconds, followed by soaking the cementum in 8% ethylenediaminetetraacetic acid for about 40 seconds, achieved a root surface that might be regarded as optimal for regeneration of periodontal tissues. PMID:9663095

Bergenholtz, A; Babay, N

1998-04-01

431

Efficient Polymer Solar Cells Fabricated on Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate)-Etched Old Indium Tin Oxide Substrates  

SciTech Connect

In organic electronic devices, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are the most common transparent electrode and anodic buffer layer materials, respectively. A widespread concern is that PEDOT:PSS is acidic and etches ITO. We show that this issue is not serious: only a few nanometers of ITO are etched in typical device processing conditions and storage thereafter; conductivity losses are affordable; and optical transmission gains further offset these losses. Organic photovoltaic (OPV) devices fabricated on old ITO (with PEDOT:PSS history) were similar or higher in efficiency than devices on fresh ITO. Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b?]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

Elshobaki, Moneim [Mansoura University; Anderegg, James [Ames Laboratory; Chaudhary, Sumit [Ames Laboratory

2014-08-13

432

Efficient polymer solar cells fabricated on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-etched old indium tin oxide substrates.  

PubMed

In organic electronic devices, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are the most common transparent electrode and anodic buffer layer materials, respectively. A widespread concern is that PEDOT:PSS is acidic and etches ITO. We show that this issue is not serious: only a few nanometers of ITO are etched in typical device processing conditions and storage thereafter; conductivity losses are affordable; and optical transmission gains further offset these losses. Organic photovoltaic (OPV) devices fabricated on old ITO (with PEDOT:PSS history) were similar or higher in efficiency than devices on fresh ITO. Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

Elshobaki, Moneim; Anderegg, James; Chaudhary, Sumit

2014-08-13

433

Dry etching performance of advanced EUV mask blanks  

NASA Astrophysics Data System (ADS)

Mask defectivity is often highlighted as one of the barriers to a manufacturable EUV solution. As EUV lithography matures, other components of mask making also emerge as key focus areas in the industry: critical dimension (CD) control, film variability, selectivity, and profile tolerance. Mask materials and specifications continue to evolve to meet the unique challenges of EUV lithography, creating the need for etch capabilities that can keep pace with the latest developments. In this study, the performance of a new EUV mask etch system will be evaluated using a variety of mask blanks to determine the relative performance of each blank type. Etch contributions to mean to target (MTT), CDU, linearity, selectivity, capping layer uniformity, line edge roughness (LER), and profile quality will be characterized to determine tool performance. The new system will also be used to demonstrate multilayer etching capabilities, important for opaque frame and alternating phase shift applications. A comprehensive summary of the etch performance of various EUV films and the readiness for manufacturing applications will be provided.

Whang, John; Chandrachood, Madhavi; Gallagher, Emily; Faure, Tom; Grimbergen, Michael; Crawford, Shaun; Yu, Keven; Leung, T. Y. B.; Wistrom, Richard; Sabharwal, Amitabh; Chen, Jeff; Wu, Banqiu

2011-11-01

434

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

NASA Technical Reports Server (NTRS)

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

Nguyen, Hung D.

1999-01-01

435

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

SciTech Connect

Current theories of CVD growth on (100) diamond are unable to account for the numerous experimental observations of slow-growing, locally smooth (100)(2x1) films. In this paper they use quantum mechanical calculations of diamond surface thermochemistry and atomic-scale kinetic Monte Carlo simulations of deposition to investigate the efficacy of preferential etching as a mechanism that can help to reconcile this discrepancy. This etching mechanism allows for the removal of undercoordinated carbon atoms from the diamond surface. In the absence of etching, simulated growth on the (100)(2x1) surface is faster than growth on the (110) and (111) surfaces, and the (100) surface is atomically rough. When etching is included in the simulations, the (100) growth rates decrease to values near those observed experimentally, while the rates of growth on the other surfaces remain largely unaffected and similar to those observed experimentally. In addition, the etching mechanism promotes the growth of smooth (100) surface regions in agreement with numerous scanning probe studies.

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

1999-08-02

436

Fabrication of polymer nanowires via maskless O2 plasma etching  

NASA Astrophysics Data System (ADS)

In this paper, we introduce a simple fabrication technique which can pattern high-aspect-ratio polymer nanowire structures of photoresist films by using a maskless one-step oxygen plasma etching process. When carbon-based photoresist materials on silicon substrates are etched by oxygen plasma in a metallic etching chamber, nanoparticles such as antimony, aluminum, fluorine, silicon or their compound materials are self-generated and densely occupy the photoresist polymer surface. Such self-masking effects result in the formation of high-aspect-ratio vertical nanowire arrays of the polymer in the reactive ion etching mode without the necessity of any artificial etch mask. Nanowires fabricated by this technique have a diameter of less than 50 nm and an aspect ratio greater than 20. When such nanowires are fabricated on lithographically pre-patterned photoresist films, hierarchical and hybrid nanostructures of polymer are also conveniently attained. This simple and high-throughput fabrication technique for polymer nanostructures should pave the way to a wide range of applications such as in sensors, energy storage, optical devices and microfluidics systems.

Du, Ke; Wathuthanthri, Ishan; Liu, Yuyang; Kang, Yong Tae; Choi, Chang-Hwan

2014-04-01

437

The dissolution of stearic ACID. I. The B modification in octane  

NASA Astrophysics Data System (ADS)

For the B modification of stearic acid, the dissolution kinetics and macroscopic etch figures were observed during the dissolution into octane at 17C. The dissolution seems to be a quadratic function of subsaturation, the kinetics is higher than for growth. The spreading velocity of the borders of the etch pits varies linearly with subsaturation. The etch pit density of approximately 0.6 10 4 cm -2 and the slopes of the borders of the pits of 5 to 7 were found to be nearly independent of subsaturation. The results are discussed in terms of the current theories for dissolution and etching.

Beckmann, Wolfgang

1987-05-01

438

Triangle pore arrays fabricated on Si (111) substrate by sphere lithography combined with metal-assisted chemical etching and anisotropic chemical etching  

PubMed Central

The morphological change of silicon macropore arrays formed by metal-assisted chemical etching using shape-controlled Au thin film arrays was investigated during anisotropic chemical etching in tetramethylammonium hydroxide (TMAH) aqueous solution. After the deposition of Au as the etching catalyst on (111) silicon through a honeycomb mask prepared by sphere lithography, the specimens were etched in a mixed solution of HF and H2O2 at room temperature, resulting in the formation of ordered macropores in silicon along the [111] direction, which is not achievable by conventional chemical etching without a catalyst. In the anisotropic etching in TMAH, the macropores changed from being circular to being hexagonal and finally to being triangular, owing to the difference in etching rate between the crystal planes. PMID:22812920

2012-01-01

439

Method of plasma etching Ga-based compound semiconductors  

DOEpatents

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

Qiu, Weibin; Goddard, Lynford L.

2012-12-25

440

Method of plasma etching GA-based compound semiconductors  

DOEpatents

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

Qiu, Weibin; Goddard, Lynford L.

2013-01-01

441

Fabrication of sub-15?nm aluminum wires by controlled etching  

SciTech Connect

We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15?nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; Markovi?, N. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); McQueen, T. M. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2014-04-28

442

Fabrication of sub-15 nm aluminum wires by controlled etching  

NASA Astrophysics Data System (ADS)

We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Markovi?, N.

2014-04-01

443

Catalytic subsurface etching of nanoscale channels in graphite.  

PubMed

Catalytic hydrogenation of graphite has recently attracted renewed attention as a route for nanopatterning of graphene and to produce graphene nanoribbons. These reports show that metallic nanoparticles etch the surface layers of graphite or graphene anisotropically along the crystallographic zig-zag 11-20 or armchair 10-10 directions. The etching direction can be influenced by external magnetic fields or the supporting substrate. Here we report the subsurface etching of highly oriented pyrolytic graphite by Ni nanoparticles, to form a network of tunnels, as seen by scanning electron microscopy and scanning tunnelling microscopy. In this new nanoporous form of graphite, the top layers bend inward on top of the tunnels, whereas their local density of states remains fundamentally unchanged. Engineered nanoporous tunnel networks in graphite allow for further chemical modification and may find applications in various fields and in fundamental science research. PMID:23340419

Lukas, Maya; Meded, Velimir; Vijayaraghavan, Aravind; Song, Li; Ajayan, Pulickel M; Fink, Karin; Wenzel, Wolfgang; Krupke, Ralph

2013-01-01

444

Characteristics of silicon etching by silicon chloride ions  

SciTech Connect

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

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

2013-05-15

445

Method and apparatus for spatially uniform electropolishing and electrolytic etching  

DOEpatents

In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed. 6 figs.

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

1992-03-17

446

Investigation of plasma etch induced damage in compound semiconductor devices  

SciTech Connect

We have investigated the electrical performance of mesa-isolated GaAs [ital pn]-junction diodes to determine the plasma-induced damage effects from reactive ion and reactive ion beam etching (RIBE). A variety of plasma chemistries (SiCl[sub 4], BCl[sub 3], BCl[sub 3]/Cl[sub 2], and Cl[sub 2]) and ion energies ranging from 100 to 400 eV were studied. We have observed that many of the reactive ion etching BCl[sub 3]/Cl[sub 2] plasmas and RIBE Cl[sub 2] plasmas yield diodes with low reverse-bias currents that are comparable to the electrical characteristics of wet-chemical-etched devices. The reverse-bias leakage currents are independent of surface morphology and sidewall profiles.

Shul, R.J.; Lovejoy, M.L.; Hetherington, D.L.; Rieger, D.J.; Vawter, G.A.; Klem, J.F. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)); Melloch, M.R. (School of Electrical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States))

1994-07-01

447

Plasma etching of superconducting Niobium tips for scanning tunneling microscopy  

NASA Astrophysics Data System (ADS)

We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 ?m diameter are dry etched in an SF6 plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100), and Nb(100), as well as a doped topological insulator Bi2Se3 at temperatures ranging from 30 mK to 9 K.

Roychowdhury, A.; Dana, R.; Dreyer, M.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.

2014-07-01

448

Wetting and energetics in nanoparticle etching of graphene  

E-print Network

Molten metallic nanoparticles have recently been used to construct graphene nanostructures with crystallographic edges. The mechanism by which this happens, however, remains unclear. Here, we present a simple model that explains how a droplet can etch graphene. Two factors possibly contribute to this process: a difference between the equilibrium wettability of graphene and the substrate that supports it, or the large surface energy associated with the graphene edge. We calculate the etching velocities due to either of these factors and make testable predictions for evaluating the significance of each in graphene etching. This model is general and can be applied to other materials systems as well. As an example, we show how our model can be used to extend a current theory of droplet motion on binary semiconductor surfaces.

Sujit S. Datta

2010-08-12

449

Study of etching rate uniformity in SRF cavities  

SciTech Connect

Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in the gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and chlorine concentration in the Argon/Chlorine gas mixtures.

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

2012-07-01

450

A Reactive-Ion Etch for Patterning Piezoelectric Thin Film  

NASA Technical Reports Server (NTRS)

Reactive-ion etching (RIE) under conditions described below has been found to be a suitable means for patterning piezoelectric thin films made from such materials as PbZr(1-x)Ti(x)O3 or Ba(x)Sr(1.x)TiO3. In the original application for which this particular RIE process was developed, PbZr(1-x)Ti(x)O3 films 0.5 microns thick are to be sandwiched between Pt electrode layers 0.1 microns thick and Ir electrode layers 0.1 microns thick to form piezoelectric capacitor structures. Such structures are typical of piezoelectric actu