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1

Fabrication of free standing structure using single step electrochemical etching in hydrofluoric acid  

Microsoft Academic Search

This paper presents a new technique of micromachining using single step electrochemical etching in hydrofluoric acid (HF). The electrochemical etching in HF is known as a technique for porous silicon formation. This etching technique is applied to fabricate 3-D structures in single crystal silicon by a combination of anisotropic and isotropic modes. The diameter of the pore, or the width

H. Ohji; P. J. Trimp; P. J. French

1999-01-01

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 10 nm, there were two etching\\u000a regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds\\u000a as expected and one

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

2009-01-01

3

Weakening of soda-lime glass by particle impact during hydrofluoric acid etching  

SciTech Connect

During etching of soda-lime glass in hydrofluoric acid solutions, insoluble reaction products can collect in the acid solution or deposit on the glass surface. In this study it is shown that impact of these insoluble reaction products on the etching surfaces can cause strength degradation. The insoluble reaction products are characterized by scanning electron microscopy, wet chemical, X-ray diffraction, and surface area analyses.

Roach, D.H.; Cooper, A.R.

1986-07-01

4

The microstructures of perthitic alkali feldspars revealed by hydrofluoric acid etching  

Microsoft Academic Search

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

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

1994-01-01

5

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

PubMed Central

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

2009-01-01

6

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

7

Comparison of microleakage on one composite etched with phosphoric acid or a combination of phosphoric and hydrofluoric acids and bonded with several different systems  

Microsoft Academic Search

Statement of problem. There are no data available on whether or to what extent hydrofluoric acid affects the marginal integrity of dentin-bonded composite restorations when it is used instead of phosphoric acid in the total-etch technique. Purpose. This in vitro study examined the etching effects of phosphoric acid versus a combination of phosphoric and hydrofluoric acid by evaluation of microleakage

Susanne Szep; Nicole Langner; Silja Bayer; Diana Börnichen; Christoph Schulz; Thomas Gerhardt; Anette Schriever; Joachim Becker; Detlef Heidemann

2003-01-01

8

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

PubMed

Stainless steel wire has been widely used as the substrate of solid-phase microextraction (SPME) fibers to overcome the shortcomings of conventional silica fibers such as fragility, by many researchers. However, in previous reports various sorbent coatings are always required in conjunction with the stainless steel wire for SPME. In this work, we report the bare stainless steel wire for SPME without the need for any additional coatings taking advantage of its high mechanical and thermal stability. To evaluate the performance of stainless steel wire for SPME, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, chlorobenzene, n-propylbenzene, aniline, phenol, n-hexane, n-octane, n-decane, n-undecane, n-dodecane, chloroform, trichloroethylene, n-octanol, and butanol were tested as analytes. Although the stainless steel wire had almost no extraction capability toward the tested analytes before etching, it did exhibit high affinity to the tested PAHs after etching with hydrofluoric acid. The etched stainless steel wire gave a much bigger enhancement factor (2541-3981) for the PAHs than the other analytes studied (< or = 515). Etching with hydrofluoric acid produced a porous and flower-like structure with Fe(2)O(3), FeF(3), Cr(2)O(3), and CrF(2) on the surface of the stainless steel wire, giving high affinity to the PAHs due to cation-pi interaction. On the basis of the high selectivity of the etched stainless steel wire for PAHs, a new SPME method was developed for gas chromatography with flame ionization detection to determine PAHs with the detection limits of 0.24-0.63 microg L(-1). The precision for six replicate extractions using one SPME fiber ranged from 2.9% to 5.3%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.3-8.8%. One etched stainless steel wire can stand over 250 cycles of SPME without significant loss of extraction efficiency. The developed etched stainless steel wire is very stable, highly selective, and reproducible for the SPME of PAHs. PMID:19445486

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

2009-06-15

9

Corrosion Behavior of Nickel Alloys in Wet Hydrofluoric Acid  

Microsoft Academic Search

Hydrofluoric acid is a water solution of hydrogen fluoride (HF). Hydrofluoric acid is used widely in diverse types of industrial applications; traditionally, it is used in pickling solutions in the metal industry, in the fabrication of chlorofluorocarbon compounds, as an alkylation agent for gasoline and as an etching agent in the industry of glass. In recent years, hydrofluoric acid has

Rebak

2004-01-01

10

[Hydrofluoric acid poisoning: case report].  

PubMed

Hydrofluoric acid is a highly dangerous substance with industrial and domestically appliances. Clinical manifestations of poisoning depend on exposure mechanism, acid concentration and exposed tissue penetrability. Gastrointestinal tract symptoms do not correlate with injury severity. Patients with history of hydrofluoric acid ingestion should undergo an endoscopy of the upper gastrointestinal tract. Intoxication requires immediate intervention because systemic toxicity can take place. We present a 5 year old girl who accidentally swallowed 5 ml of 20% hydrofluoric acid. We performed gastrointestinal tract endoscopy post ingestion, which revealed erythematous esophagus and stomach with erosive lesions. Two months later, same study was performed and revealed esophagus and stomach normal mucous membrane. PMID:23381711

Cortina, Tatiana Judith; Ferrero, Hilario Andrés

11

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

PubMed

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

Ahmad, Muthanna; Grime, Geoffrey W

2013-02-07

12

Hydrofluoric acid dermal exposure.  

PubMed

A retrospective review of 237 consecutive cases of dermal exposure to dilute (6-11%) hydrofluoric acid (HF)- containing rust stain remover consumer products reported to the Rocky Mountain Poison and Drug Center during 1986 was done to evaluate the toxicity of these agents and the efficacy of topical treatment with calcium gluconate gel. In 148 cases (62%), failure to follow manufacturers' recommended safety procedures was the likely cause of exposure. 219 patients developed the following symptoms: dermal swelling, redness, or both (131, 55%); blistering (12, 5%); black discoloration under fingernails (12, 5%); or pain without reported dermal changes (64, 27%). Local complications were noted in 7 cases (3%) (infection, 4 cases; fingertip dermal necrosis, 3 cases). No systemic toxicity was noted. 116 patients (49%) received treatment with topical calcium gluconate gel; 53 were followed until complete resolution of symptoms. There appeared to be a relationship between earlier initial gel application and more rapid resolution of signs and symptoms. Some degree of dermal injury may be quite common following exposure to dilute (6-11%) HF-containing rust stain remover consumer products. Failure to follow manufacturers' recommended safety procedures may be responsible for many exposures. Treatment with topical calcium gluconate gel may be effective, and more rapid resolution of signs and symptoms may occur with earlier initiation of this therapy. PMID:2741315

el Saadi, M S; Hall, A H; Hall, P K; Riggs, B S; Augenstein, W L; Rumack, B H

1989-06-01

13

Electrowetting Lens Employing Hemispherical Cavity Formed by Hydrofluoric Acid, Nitric Acid, and Acetic Acid Etching of Silicon  

NASA Astrophysics Data System (ADS)

We demonstrate the design of an electrowetting lens employing a high-aspect-ratio hemispherical lens cavity and its micro-electro-mechanical-system (MEMS) fabrication process in this study. Our preliminary simulation results showed that the physical and electrical durability of the lens can be improved by the mitigation of stresses on the insulator at the hemispherical cavity. High-aspect-ratio hemispherical cavities with various diameters and very smooth sidewall surfaces were uniformly fabricated on a silicon wafer by a sophisticated isotropic wet etching technique. Moreover, we experimentally investigated the optical properties of the MEMS-based electrowetting lens with the proposed cavity. Two immiscible liquids in the proposed lens cavity were electrostatically controlled with negligible optical distortion and low focal-length hysteresis due to the fully axis-symmetrical geometry and smooth sidewall of the cavity.

Lee, June Kyoo; Choi, Ju Chan; Jang, Won Ick; Kim, Hak-Rin; Kong, Seong Ho

2012-06-01

14

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...MANUFACTURING POINT SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415...Applicability; description of the hydrofluoric acid production subcategory....

2010-07-01

15

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...MANUFACTURING POINT SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415...Applicability; description of the hydrofluoric acid production subcategory....

2009-07-01

16

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

17

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

NASA Astrophysics Data System (ADS)

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

Cho, I. H.; Kim, D. H.; Noh, D. Y.

2006-07-01

18

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

SciTech Connect

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

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

2006-07-31

19

In vitro dentinal surface reaction of 9.5% buffered hydrofluoric acid in repair of ceramic restorations: A scanning electron microscopic investigation  

Microsoft Academic Search

Statement of Problem: Fracture of porcelain is a relatively common clinical misfortune. Recent research has indicated that strong bonds can be formed between composite and dental porcelain. Porcelain surfaces are etched with hydrofluoric acid and treated with silane coupling agents before composite application. The question is how exposed dentin may react to etching with hydrofluoric acid. Purpose: This investigation examined

Susanne Szep; Thomas Gerhardt; Hans-Werner Gockel; Manfred Ruppel; Ditmar Metzeltin; Detlef Heidemann

2000-01-01

20

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Hydrofluoric acid, reaction products with heptane...Substances § 721.4385 Hydrofluoric acid, reaction products with heptane...chemical substance identified as a hydrofluoric acid, reaction products...

2009-07-01

21

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products with heptane...Substances § 721.4385 Hydrofluoric acid, reaction products with heptane...chemical substance identified as a hydrofluoric acid, reaction products...

2010-07-01

22

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Hydrofluoric acid, reaction products with octane...Substances § 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products...

2009-07-01

23

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products with octane...Substances § 721.4461 Hydrofluoric acid, reaction products with octane...identified generically as a hydrofluoric acid, reaction products...

2010-07-01

24

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

25

Vibrational spectra of niobium and tantalum complexes in hydrofluoric acid  

Microsoft Academic Search

Niobium and tantalum compounds are widely used in special materials as well as in the electrolytic production of the metals and of alloys and metallic coatings. One method of making niobium and tantalum fluorides and oxyfluorides is precipitation from solution in hydrofluoric acid. Here the authors examine the Raman and IR spectra of hydrofluoric acid containing these elements over wide

D. V. Tsikaeva; S. D. Nikitina; A. I. Agulyanskii; V. T. Kalinnikov

1987-01-01

26

Characterization of polishing induced defects and hydrofluoric acid passivation effect in ZnO  

NASA Astrophysics Data System (ADS)

We used depth-resolved cathodoluminescence spectroscopy and transient photovoltage spectroscopy (T-SPS) measurements to study the spatial distributions and densities of native point defects in bulk ZnO samples subjected to mechanical polishing and how the defects change with hydrofluoric acid (HF) etching. Mechanical polishing produces Zn vacancy-related defects that deplete free carriers at depths extending to 300-500 nm, while HF etching removes/passivates these defects as well as bulk oxygen vacancy-related defects, restoring the charge carriers below the etched surface. T-SPS defect density changes with polishing/etching correlate closely with deep level transient spectroscopy densities, demonstrating the applicability of T-SPS as a non-contact quantitative defect density measurement technique.

Zhang, Zhichun; Quemener, V.; Lin, C.-H.; Svensson, B. G.; Brillson, L. J.

2013-08-01

27

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

28

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

29

Hydrofluoric acid burn: latent period was key factor  

SciTech Connect

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

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

1987-07-01

30

Urine, serum and hair monitoring of hydrofluoric acid workers  

Microsoft Academic Search

Summary To define the relationship between fluoride (F) concentration in the serum, urine and hair of workers and the concentration of hydrofluoric acid (HF) in the work environment, pre- and postshift serum and urine samples of 142 HF exposed workers and 237 unexposed workers were examined. Hair specimens were also collected for the determination of F. To determine whether external

Koichi Kono; Yasuhisa Yoshida; Misuzu Watanabe; Yukio Orita; Tomotaro Dote; Yasumori Bessho

1993-01-01

31

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

NASA Astrophysics Data System (ADS)

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

Chen, Danti; Xiao, Hongdi; Han, Jung

2012-09-01

32

Design criteria for matrix stimulation with hydrochloric hydrofluoric acid  

Microsoft Academic Search

Matrix stimulation with hydrochloric-hydrofluoric acid mixtures is a successful technique for improving well performance. However, little is known about this complex stimulation mechanism. A high-pressure, high-temperature acid permeameter constructed to investigate the reaction of HCl-HF on sandstone cores at reservoir conditions is providing new insight into the reservoir and treatment variables that control the acidization process. Though reservoir conditions cannot

J. T. Farley; V. Schoettle; B. M. Miller

1969-01-01

33

Evaluation of optimal reuse system for hydrofluoric acid wastewater.  

PubMed

The treatment of hydrofluoric acid (HF) wastewater has been an important environmental issue in recent years due to the extensive use of hydrofluoric acid in the chemical and electronics industries, such as semiconductor manufacturers. Coagulation/precipitation and ion exchange technologies have been used to treat HF wastewater, but these conventional methods are ineffective in removing organics, salts, and fluorides, limiting its reuse for water quality and economic feasibility. One promising alternative is reverse osmosis (RO) after lime treatment. Based on pilot-scale experiment using real HF wastewater discharged from semiconductor facility, the spiral wound module equipped with polyamide membranes has shown excellent flux and chemical cleaning cycles. Our results suggest that coagulation/precipitation and spiral wound RO constitute the optimal combination to reuse HF wastewater. PMID:23009792

Won, Chan-Hee; Choi, Jeongyun; Chung, Jinwook

2012-08-10

34

Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1  

Microsoft Academic Search

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

Osborne

2000-01-01

35

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

NASA Astrophysics Data System (ADS)

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

Yamamoto, Hideki; Sumoge, Iwao

2011-03-01

36

The restoration of serial numbers on vehicle glass using hydrofluoric acid.  

PubMed

Very little research has been carried out investigating techniques for the restoration of obliterated serial numbers on vehicle glass. A study into the effectiveness of hydrofluoric (HF) acid, a known etchant for glass, has been performed. Character sequences previously etched into panes of vehicle glass were sanded to varying depths and attempts were made to restore the sequences by polishing and using a range of concentrations of HF acid. A concentration of 30% HF acid gave at least a 50% restoration of the sequence if up to approximately 30 ?m of glass had been removed during obliteration. Recovery improves if less glass is removed, but not if the concentration of the acid is increased. It appears that removal of glass below the level of the original characters makes subsequent restoration using this technique impossible. PMID:23597735

Miller, Ruben J

2013-03-08

37

Hydrofluoric acid-resistant composite window and method for its fabrication  

DOEpatents

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

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

1985-07-18

38

Dissolution of (Th,U)O sub 2 in Nitric Acid - Hydrofluoric Acid Solutions.  

National Technical Information Service (NTIS)

The dissolution of mixed thorium-uranium oxide fuel in nitric acid/hydrofluoric acid mixtures was studied to assist the design of equipment and procedures for reprocessing. The dissolution rate was found to depend upon the acid concentrations and the temp...

R. W. Dyck R. Taylor D. G. Boase

1977-01-01

39

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

Microsoft Academic Search

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor–liquid equilibrium\\u000a for acid aqueous solutions and acid mixtures. The vapor–liquid equilibrium of hydrofluoric acid + salt systems (fluorite,\\u000a potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed\\u000a a salting-out effect on the vapor–liquid equilibrium of

Hideki Yamamoto; Iwao Sumoge

2011-01-01

40

Dissolution of Plutonium Oxide in Nitric Acid at High Hydrofluoric Acid Concentrations.  

National Technical Information Service (NTIS)

The dissolution of plutonium dioxide in nitirc acid (HNO sub 3 ) at high hydrofluoric acid (HF) concentrations has been investigated. Dissolution rate curves were obtained using 12M HNO sub 3 and HF at concentrations varying from 0.05 to 1.0 molar. The di...

A. R. Kazanjian J. R. Stevens

1984-01-01

41

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

Microsoft Academic Search

During the post-processing of silicon (Si) microsystems in hydrofluoric acid (HF)-based solutions, a galvanic couple is formed between the Si (anode) and metallic overlayers (cathode), such as gold (Au). Electrochemical etching (corrosion) of the exposed Si results in a porous silicon (PS) film and substantial degradation of mechanical and electrical properties occur. Focused ion beam milling (FIB) of micro-scale silicon-on-insulator

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

2010-01-01

42

Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1  

SciTech Connect

The conversion of the uranium hexafluoride (UF{sub 6}) 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{sub 2}, AlF{sub 3}, and MgF{sub 2}). Tests have been performed to identify the best media to use for trapping the HF. These tests are described in this report. The first series of tests evaluated 37 trapping materials using a 6 wt % solution of HF. The solution was pumped through a 3.8-cm-diam column at a slow rate, and samples were taken in 100-mL batches until it was determined that the media could no longer neutralize the solution. Each bed volume of media was evaluated for its retention of fluoride and for its plugging problems. Mixtures of calcium hydroxide and blast furnace slag (BFS) with high Surface areas (18-30 mesh) performed the best. A mixture of 80 wt % calcium hydroxide and 20 wt % BFS was capable of loading 0.134 g HF per cubic centimeter (cm{sup 3}) of media. Other media that performed well were (a) mixtures of calcium hydroxide and portland cement and (b) pure calcium hydroxide. The second series of tests evaluated media using a 33 wt % HF solution. The best performing media from the first series and some new ones were tested. A 2.54-cm-diam, clear, polyvinyl chloride pipe was used as the column, and solution was introduced to different types or sizes of media using slugs from a pipette or constant flow of {approx}10.7 mL/min from a metering pump. The transparent PVC allowed for observation of acid-media interaction and provided a glimpse into how the media and cartridge were performing in this highly corrosive environment. Results from the second series of tests showed that many of the best performing media from the first series of tests would not do well under the more concentrated solutions of HF. Plugging and vigorous reactions were common in the second series, and calcium hydroxide-based media was ruled out due to its disintegration at any size (1.25-cm diam to 30 mesh). The best performing media was mid-sized (4-18 mesh) soda and lime (soda lime). This media not only stood up well in the HF solution, but it also had great neutralization capability, effectively neutralizing up to {approx}0.5 g HF/cm{sup 3} of media. It is expected that a cartridge of this sorbent will be capable of handling approximately seven batches of HF from the uranium conversion.

Osborne, P.E.

2000-09-14

43

Influence of Fluorine on the Conductivity and Oxidation of Silicon Nanomembranes after Hydrofluoric Acid Treatment  

NASA Astrophysics Data System (ADS)

After immersion in hydrofluoric acid, the sheet resistance of a 220-nm-thick silicon nanomembrane, measured in dry air by van der Pauw method, drops around two orders of magnitude initially, then increases and reaches the level of a sample with a native oxide surface in about one month. The surface component and oxidation rate are also characterized by x-ray photo electronic spectroscopy measurement. Fluorine is found to play a significant role in improving conductivity and has no apparent influence on the oxidation rate after hydrofluoric acid treatment.

Zhao, Xiang-Fu; Han, Ping; Zhang, Rong; Zheng, You-Dou

2011-08-01

44

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

Microsoft Academic Search

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

Joshua G. Alters

45

PREVENTION POSSIBILITIES OF STRESS CORROSION CRACKING OF MONEL 400 IN HYDROFLUORIC ACID  

Microsoft Academic Search

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

R. Kumar; U. K. Chatterjee

46

Corrosion of High-Alloy Materials in Aqueous Hydrofluoric Acid Environments  

Microsoft Academic Search

A series of immersion tests for eight high-alloy materials was performed in a variety of hydrofluoric acid (HF) environments. Solution strengths of 0.05%, 1%, 10%, 24%, and 48% HF were examined at 24 C, 50 C, and 76 C. Coupons of each alloy were exposed fully immersed in solution and partially exposed in the aerated vapor above each solution. In

S. J. Pawel

1994-01-01

47

Anchoring metal nanoparticles on hydrofluoric acid treated multiwalled carbon nanotubes as stable electrocatalysts  

Microsoft Academic Search

We attempted the treatment of multiwalled carbon nanotubes (MWCNTs) in hydrofluoric acid (HF) aqueous solution for depositing Pt nanoparticles as catalysts for methanol oxidation for the first time. The preliminary results revealed that the Pt nanoparticles could be well dispersed on HF treated MWCNTs and gave enhanced activity and stability for methanol oxidation. As demonstrated in this study, the Pt

Yongliang Li; Feng Ping Hu; Xin Wang; Pei Kang Shen

2008-01-01

48

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

SciTech Connect

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.

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

2000-08-01

49

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

50

Fabrication of high-aspect-ratio grooves in silicon using femtosecond laser irradiation and oxygen-dependent acid etching.  

PubMed

We demonstrated a new method to fabricate micron-sized grooves with high aspect ratios in silicon wafers by combining femtosecond laser irradiation and oxygen-dependent acid etching. Femtosecond laser was employed to induce structure changes and incorporate oxygen into silicon, and then materials in oxygen-containing regions were etched by hydrofluoric acid (HF) solution to form grooves. The etching could be attributed to the reaction between HF and silicon oxides formed by femtosecond laser irradiation. The dependences of the aspect ratios of grooves on the laser fluence and the scanning velocity were also investigated. PMID:23938517

Pan, An; Si, Jinhai; Chen, Tao; Ma, Yuncan; Chen, Feng; Hou, Xun

2013-07-15

51

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

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

52

Influence of Fluorine on the Conductivity and Oxidation of Silicon Nanomembranes after Hydrofluoric Acid Treatment  

Microsoft Academic Search

After immersion in hydrofluoric acid, the sheet resistance of a 220-nm-thick silicon nanomembrane, measured in dry air by van der Pauw method, drops around two orders of magnitude initially, then increases and reaches the level of a sample with a native oxide surface in about one month. The surface component and oxidation rate are also characterized by x-ray photo electronic

Xiang-Fu Zhao; Ping Han; Rong Zhang; You-Dou Zheng

2011-01-01

53

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

SciTech Connect

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

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

1984-06-15

54

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

National Technical Information Service (NTIS)

When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0(sub 3)) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution ann...

B. C. Norby

1992-01-01

55

The effect of de-ionized water rinsing after immersion in hydrofluoric acid on the electrical conductivity of silicon nanomembranes  

Microsoft Academic Search

Electrical conductivity of 28 and 220-nm thick silicon membranes was measured by the van der Pauw method in dry air (relative humidity <5%) at room temperature (around 20°C). Immediately after hydrofluoric acid immersion the conductivity increases several orders of magnitude because of surface-induced band bending; it then drops and reaches the level of samples with a native oxide surface in

Xiang-Fu Zhao; Ping Han; Qiang Guo

56

Corrosion of high-alloy materials in aqueous hydrofluoric acid environments  

SciTech Connect

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

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

1994-12-01

57

Efficacy of hexafluorine for emergent decontamination of hydrofluoric acid eye and skin splashes.  

PubMed

Hexafluorine is an amphoteric, hypertonic, polyvalent compound for decontaminating hydrofluoric acid (HF) eye and skin splashes. In a German metallurgy facility during the period of 1994-1998, all eye or skin splashes with 40% HF alone or with a 6% HF/15% HNO3 mixture were initially decontaminated with Hexafluorine within 2 min following the splash at the accident site by the victims themselves or co-workers who witnessed the accident. Eleven workers using 40% HF or a 6% HF/15% HNO3 mixture sustained eye (2 cases) or skin (10 cases) splashes (1 combined) during 1994-1998. Hexafluorine was used within 2 min, and a second Hexafluorine decontamination was done on arrival at the plant infirmary. No further medical or surgical treatment was needed, no workers developed chemical burns, and none lost work time. These II cases demonstrate the efficacy of Hexafluorine in decontaminating HF or combined HF/HNO3 splashes. PMID:11577928

Mathieu, L; Nehles, J; Blomet, J; Hall, A H

2001-10-01

58

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

60

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

National Technical Information Service (NTIS)

At concentrations below 60%, wet hydrofluoric acid (HF) is extremely corrosive to steels, stainless steels and reactive metals, such as titanium, zirconium, and tantalum. In fact, only a few metallic materials will withstand wet HF at temperatures above a...

P. Crook N. S. Meck R. B. Rebak

2006-01-01

61

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; Müller, M; Neumann, M; Gunderov, D V; Valiev, R Z; Cholakh, S O

2012-07-18

62

Technetium(VII) extraction by a primary amine and technetium(VII) coprecipitation with ammonium diuranate in hydrofluoric acid solution  

Microsoft Academic Search

The separation of technetium(VII) from uranium(VI) has beeen studied through experiments on the coprecipitation of Tc(VII) with ammonium diuranate precipitate, and in the extraction of Tc(VII) from an aqueous hydrofluoric acid solution using a primary amine (Primene JMT) as an extractant dissolved inn-heptane. The extraction of Tc(VII) reached a quantitative level after several repetitions of the extraction procedure. Also, the

K. Ito; Y. Akai-Imoto

1994-01-01

63

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

64

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

2012-06-27

65

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.

2012-01-01

66

Laser micromachined and acid-etched Fabry-Perot cavities in silica fibres  

NASA Astrophysics Data System (ADS)

This paper reports on two techniques for creating Fabry-Perot cavities in conventional single- and multi-mode optical fibres. The authors have reported previously on the design and fabrication of extrinsic fibre Fabry-Perot interferometric multi-functional sensors. Here, the authors report on two novel techniques for creating intrinsic fibre optic sensors based on the Fabry-Perot etalon. The first technique involved the use of hydrofluoric acid to preferentially etch the core of the optical fibre. This technique is simple to carry out and provides a cost-effective means for manufacturing intrinsic fibre Fabry-Perot sensors. In the second technique, a 157 nm excimer laser along with a custom-designed beam delivery system was used to ablate (micro-machine) near-paralleled walled cavities through the diameter of the optical fibre (outer diameter of 125 ?m). The paper details the experimental methodology and the associated instrumentation for the two techniques. The acid etched and laser ablated cavities were characterised using a 3-D surface profiler, optical and scanning electron microscopy. The feasibility of using these cavities as intrinsic fibre Fabry-Perot strain sensors is demonstrated. This was achieved by surface-mounting the acid etched cavities on to composite tensile test specimens. The output from the optical fibre devices was compared with surface-mounted electrical resistance strain gauges.

Machavaram, V. R.; Tuck, C. J.; Teagle, M. C.; Badcock, R. A.; Fernando, G. F.

2006-01-01

67

The effect of hydrofluoric acid treatment of titanium and titanium dioxide surface on primary human osteoblasts.  

PubMed

OBJECTIVE: The aim of the study was to investigate solely the effect of fluoride on the surface chemistry of polycrystalline ceramic titanium dioxide (TiO2 ) and metallic titanium (Ti) and its effect on proliferation and differentiation of primary human osteoblasts (NHO). MATERIALS AND METHODS: The NHO cells were exposed to fluoride-modified and unmodified samples for 1, 3, 7, 14 and 21 days. The fluoride effect on the mRNA expression was quantified and measured. The secretion of cytokines and interleukins in the cell culture medium was measured by Luminex, gene expression by RT-PCR, and compared with untreated controls. The effect on cell growth after 1 and 3 days in culture was measured using [(3) H]-thymidine incorporation. Fluoride release was measured using an ion-selective electrode. The surfaces were examined by X-ray photoelectron spectroscopy and profilometry. RESULTS: The fluoride release study detected that fluoride content easily washed off in TiO2 coins when compared with Ti coins. No increase in cell proliferation was found among fluoride-modified TiO2 surfaces compared with controls, except for washed Ti coins with fluoride modification. The cell differentiation with regard to gene expression showed no significant differences in both fluoride-modified and unmodified samples and less effect on protein release for all groups. CONCLUSIONS: The fluoride from hydrofluoric acid treatment on Ti and TiO2 surfaces gave no specific effect on primary human osteoblast cells. The study indicates that the released fluoride is not the unique factor for the bioactivity of Ti and TiO2 surfaces. PMID:23551563

Pham, Maria H; Landin, Maria A; Tiainen, Hanna; Reseland, Janne E; Ellingsen, Jan Eirik; Haugen, Håvard J

2013-04-01

68

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

SciTech Connect

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

Osborne, P.E.

2000-08-03

69

High-quality fiber fabrication in buffered hydrofluoric acid solution with ultrasonic agitation.  

PubMed

An etching method for preparing high-quality fiber-optic sensors using a buffered etchant with ultrasonic agitation is proposed. The effects of etching conditions on the etch rate and surface morphology of the etched fibers are investigated. The effect of surface roughness is discussed on the fibers' optical properties. Linear etching behavior and a smooth fiber surface can be repeatedly obtained by adjusting the ultrasonic power and etchant pH. The fibers' spectral quality is improved as the ratio of the pit depth to size decreases, and the fibers with smooth surfaces are more sensitive to a bacterial suspension than those with rough surfaces. PMID:23458795

Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Wang, Yongzhong; Chen, Rong

2013-03-01

70

Enlargement of diatom frustules pores by hydrofluoric acid etching at room temperature  

Microsoft Academic Search

Based on the fact that SiO2 can dissolve in HF solution, three kinds of diatom frustules were treated with 1% HF solution at room temperature. Given\\u000a the proper reaction times (0–2 h for the diatoms Coscinodiscus and Navicula, and 0–3 h for the diatom Melosira), the size of the pores on the frustules gradually increased and the structures of the frustules remained.

Deyuan ZhangYu; Yu Wang; Wenqiang Zhang; Junfeng Pan; Jun Cai

2011-01-01

71

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

72

Should acid etching be performed prior to nonvital bleaching?  

PubMed

This study sought to measure the microtensile bond strength of a nanofilled composite resin to human dentin after phosphoric acid etching followed by nonvital bleaching. Scanning electron microscopy was used to analyze fracture modes. Twenty extracted sound human maxillary premolars were prepared for Class I defects and assigned randomly to 4 groups (n = 5): Group 1 (control group) samples were unbleached and had no previous acid etching; Group 2 samples were bleached only, Group 3 samples were acid-etched for 15 seconds prior to bleaching, and Group 4 samples were acid-etched for 30 seconds prior to bleaching. There were no statistically significant differences of bond strength values among Groups 1-3; however, the mean values of Group 4 were statistically lower compared with the other groups. PMID:24064163

Batalha-Silva, Silvana; Arcari, Gilberto Muller; Monteiro, Sylvio

73

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

PubMed

Auto-degradation of collagen matrices occurs in resin-infiltrated dentine by the slow action of host-derived matrix metalloproteinases. As phosphoric acid-etching inactivates these endogenous enzymes, it is puzzling how hybrid layers created by simplified etch-and-rinse adhesives can degrade in vivo. This study tested the null hypothesis that there are no differences in the relative proteolytic activities of mineralised dentine, acid-etched dentine, and etch-and-rinse adhesive-treated acid-etched dentine. Powdered dentine prepared from extracted human teeth was treated with 17% EDTA, 10% phosphoric acid, or with five simplified etch-and-rinse adhesives that were applied to 10% phosphoric acid-etched dentine. The gelatinolytic activity of the dentine powder was assayed using fluorescein-labelled gelatine. TEM examination of the air-dried, treated dentine powder was performed to confirm the presence of remnant mineralised dentine after acid-etching. 17% EDTA significantly reduced the relative proteolytic activity (73.2%) of the untreated mineralised dentine powder (control), while 10% phosphoric acid-etched dentine exhibited the highest reduction (98.1%). Treating the acid-etched dentine powder with any of the five simplified etch-and-rinse adhesives resulted in the reactivation of the proteolytic activity, with a significant negative linear correlation (P<0.05) between the increases in fluorescence and the corresponding pH values of the adhesives. It is concluded that simplified etch-and-rinse adhesives can reactivate endogenous enzymatic activities in dentine that are previously inactivated by phosphoric acid-etching. The amount of enzyme reactivated may even exceed the original quantity present in untreated mineralised dentine. This provides an explanation for the degradation of hybrid layers after acid-etched dentine matrices are infiltrated with these adhesives. PMID:16687171

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

2006-05-09

74

Orthodontic bonding to acid- or laser-etched prebleached enamel  

PubMed Central

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

Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

2013-01-01

75

The etching of natural alpha-recoil tracks in mica with an argon RF-plasma discharge and their imaging via atomic force microscopy  

Microsoft Academic Search

The conventional technique used to reveal the natural alpha-recoil tracks, as well as other nuclear tracks, in muscovite mica is to etch the mica sheets in a concentrated hydrofluoric (HF) acid solution. However, because of the fast etching along the basal plane of the mica when using HF acid, the recoil-disturbed regions are commonly enlarged laterally so that it is

Norman M. D. Brown; Zhi Hui Liu

1996-01-01

76

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

Microsoft Academic Search

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

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

2006-01-01

77

Influence of previous acid etching on interface morphology and bond strength of self-etching adhesive to cavosurface enamel  

PubMed Central

Objectives: The aim of this study was to evaluate the (1) bond strength of a etch-and-rinse and self-etching adhesive systems to cavosurface enamel, (2) influence of the previous acid etching with phosphoric acid 35% to the self-etching adhesive application on bond strength values, and (3) analysis of the cavosurface enamel morphology submitted to different types of conditioning, with the use of a scanning electronic microscope (SEM). Methods: Twenty four human third molars were sectioned on mesio-distal direction, resulting in two slices. The specimens were ground flat with 600-grit aluminum oxide papers, and were randomly divided into three groups: Group 1 (etch-and-rinse adhesive system (control group)), Group 2 (self-etching adhesive), and Group 3 (self-etching adhesive with previous 35% phosphoric acid-etching for 15 s). Four cylinders (0.75 mm of diameter, 1 mm height) were confectioned prior to the microshear test. Four samples for each group were prepared according the cavosurface enamel treatment and were analyzed in an SEM. Results: Group 3 had the highest values on bond strength to cavosurface enamel compared to the other two groups, which presented statistically similar values. The performance of acid etching before the application of the self-etching adhesive results in an etching pattern that is different than the other groups, favoring the adhesion to the cavosurface enamel. Conclusions: Acid etching increases the bond strength values of the self-etching adhesive to cavosurface enamel, promoting a conditioning pattern that favors the adhesion to this substrate.

Lima, Adriano Fonseca; da Silva, Vinicius Brito; Soares, Giulliana Panfiglio; Marchi, Giselle Maria; Baggio Aguiar, Flavio Henrique; Lovadino, Jose Roberto

2012-01-01

78

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

79

Extractive Recovery of Tantalum(V) and Niobium(V) with Octanol from Hydrofluoric Acid Solutions Containing Large Amounts of Titanium(IV)  

Microsoft Academic Search

Extractive recovery with n-octanol of tantalum(V) and niobium(V) from hydrofluoric acid solutions containing large amounts of titanium (up to 2-3 M) was studied. The conditions were found for separation of tantalum(V) and niobium(V) from titanium(IV), allowing recovery of 95.7 and 84.1% of tantalum and niobium fluoride complexes, respectively, in one extraction cycle, with 2.6% recovery of titanium.

V. G. Maiorov; A. I. Nikolaev; L. I. Sklokin; I. V. Baklanova

2001-01-01

80

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

Microsoft Academic Search

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

W. L. Baun

1981-01-01

81

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

Microsoft Academic Search

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

Terri Deegan; Greg Hughes

1998-01-01

82

Etching characteristics of high-purity aluminum in hydrochloric acid solutions  

Microsoft Academic Search

We investigated the effects of additives to the etching solution of 1M hydrochloric acid on the electrochemical etching behavior for aluminum electrolytic capacitors, using scanning and transmission electron microscopy, and AC impedance spectroscopy. For the addition of 1M sulfuric acid or 5% ethylene glycol to the hydrochloric acid solution, the distribution of etch tunnels was more uniform with high density

Han-Jun Oh; Jong-Ho Lee; Hong-Joo Ahn; Yongsoo Jeong; No-Jin Park; Seong-Su Kim; Choong-Soo Chi

2007-01-01

83

THE CORROSION OF MONEL AND 70-30 CUPRONICKEL IN HYDROFLUORIC ACID  

Microsoft Academic Search

Monel is shown to be suitable for the handling of 1O to 70% HF at 14O ; deg F and for handling 38 and 48% acid at boiling; cupronickel also is useful ; over part of this range. Elimination of Oâ is necessary to achieve maximum ; corrosion resistance. Some accelerated interface attack was noted for 70-30 ; cupronickel. Welding

W. J. Braun; F. W. Fink; G. L. Ericson

1957-01-01

84

Effect of acid concentration and current density on DC etching of aluminum electrolytic capacitor foil  

Microsoft Academic Search

This work studies the effects of acid concentration and current density on etching morphology, microstructure and static capacity\\u000a of the aluminum foils used in high-voltage electrolytic capacitors. The behavior associated with electrochemical etching was\\u000a investigated with a potentiostat. The aluminum etching type of DC etching is greatly influenced by the etching potential.\\u000a The static capacity increased to 0.65 uF\\/cm2 with

Chiu Yi Hung; Ou Bin Lung; Lee Yuoh Lien

2007-01-01

85

Effects of hydrofluoric acid and anodised micro and micro/nano surface implants on early osseointegration in rats.  

PubMed

Our aim was to evaluate the effects of hydrofluoric acid and anodised micro and micro/nano surface implants on bony ingrowth in the earliest stage of implantation in rats. Sixty cylindrical screwed titanium alloy implants with machined, micro, and hierarchical hybrid micro/nano surfaces (n=20 in each group) were inserted into the distal femurs of 30 female Sprague-Dawley rats. In vivo microcomputed tomography (micro CT) was used to assess microarchitectural changes in the bone around the implants 2 weeks after implantation. All the animals were then killed and the femurs with implants harvested for histological analysis and pull-out testing. Micro CT analysis showed that the trabecular thickness and the bone:volume ratio (bone volume:total volume) (BV:TV) increased significantly in the micro/nano group compared with the other two groups, while the trabecular separation decreased significantly in the micro/nano group compared with the machined group. The mean (SD) bone-implant contacts (%) were 38.94 (9.48), 41.67 (8.71), and 51.49 (12.49) in the machined, micro, and micro/nano groups, respectively. The maximum pull-out forces (N) were 64.95 (6.11), 71.45 (7.15), and 81.90 (13.1), respectively. Both bone-implant contacts and maximum pull-out forces were significantly higher in the micro/nano group, but there was no significant difference between the micro group and the machined group. These data indicate that the hierarchical hybrid micro/nano surface of the implant can promote osseointegration in the earliest stage of implantation, and may be a promising option for further clinical use. PMID:22257706

Li, Yongfeng; Gao, Yuan; Shao, Bo; Xiao, Jianrui; Hu, Kaijin; Kong, Liang

2012-01-17

86

Silicon vertical microstructure fabrication by catalytic etching  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

87

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

88

Variation in the Pattern of Acid Etching of Human Dental Enamel Examined by Scanning Electron Microscopy  

Microsoft Academic Search

This study has shown that the exposure of human dental enamel to acid solutions in vitro produces three basic etching patterns. In the most common, called type 1 etching pattern, prism core material was preferentially removed leaving the prism peripheres relatively intact. In the second, type 2 etching pattern, the reverse pattern was observed. The peripheral regions of prisms were

L. M. Silverstone; C. A. Saxton; I. L. Dogon; O. Fejerskov

1975-01-01

89

An evaluation of the capacitance of aluminum electrolytic capacitor foils A.C. etched in hydrochloric acid electrolytes  

Microsoft Academic Search

The electrochemical alternating current (A.C.) etching of aluminum foils in 1N hydrochloric acid electrolyte solutions under various current frequencies, electric current capacity and current densities is evaluated by using the etched morphology, the electrostatic capacitance and the weight loss. The etched pit size decreases with an increasing etching frequency. The etched depth and the etchability increase with increasing current capacity.

2004-01-01

90

Biomimetic Remineralization of Resin-bonded Acid-etched Dentin  

PubMed Central

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

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

2009-01-01

91

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

PubMed

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

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

2010-02-11

92

Microstructuring of lithium niobate using differential etch-rate between inverted and non-inverted ferroelectric domains  

Microsoft Academic Search

Single crystal samples of lithium niobate have been spatially patterned with photoresist, and subsequently domain inverted using electric field poling, to produce a range of two dimensional spatial domain structures. Differential etching has subsequently been carried out using mixtures of hydrofluoric and nitric acids, at a range of temperatures between room temperature and the boiling point. The structures produced show

Ian E Barry; Graeme W Ross; Peter G. R Smith; Robert W Eason; Gary Cook

1998-01-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

94

Effects of Dipping in an Aqueous Hydrofluoric Acid Solution before Oxidation on Minority Carrier Lifetimes in p-Type Silicon Wafers  

NASA Astrophysics Data System (ADS)

A scanning photon microscope is successfully applied to measure ac surface photovoltages which correspond to apparent minority carrier lifetimes (?PCD) measured by the microwave-detected photoconductive decay (?-PCD) method, using oxidized p-type silicon wafers pre-treated with or without dipping in an aqueous hydrofluoric acid (HF) solution. The dipping in HF solution causes a larger fixed oxide charge, resulting in a strongly inverted layer beneath the oxide. This situation gives longer ?PCD than the bulk lifetime (?PV) by an ac photovoltaic method, while if the fixed oxide charge is small, ?PCD gives an apparently smaller lifetime than ?PV, implying that ?PCD is influenced by the surface charge state or the surface potential. Hence, the process diagnosis by lifetime requires the measurements by both surface photovoltages and the ?-PCD method.

Shimizu, Hirofumi; Honma, Noriaki; Munakata, Chusuke

1989-05-01

95

Photothermal radiometric quantitative detection of the different degrees of demineralization of dental enamel by acid etching  

NASA Astrophysics Data System (ADS)

Photothermal radiometric (FD-PTR or PTR) signals from human teeth have been used toward detecting an artificial surface demineralization. The aim of the study is to characterize PTR signals by using controlled mineral loss from human enamel to mimic surface and subsurface dental caries. At a fixed modulation frequency, an Ar+ ion laser was used as a light source to scan across the tooth surface, and an MCT infrared detector was used for measuring the PTR signals. Several human molar teeth were etched using 37% phosphoric acid etching gel and scanned across the etched region at 30 Hz. PTR amplitude from the etched region shows that the signal decreases with increasing etching time. The PTR phase also shows the same behavior with the amplitude and better contrast between different etching times. The PTR technique could thus be used to detect early surface demineralization and may give the examiner quantitative information of the degree of demineralization in dental caries.

Jeon, R. J.; Phan, T. D. T.; Wu, A.; Kulkarni, G.; Abrams, S. H.; Mandelis, A.

2005-06-01

96

Formation of three-dimensional microstructures by electrochemical etching of silicon  

NASA Astrophysics Data System (ADS)

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

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

2001-09-01

97

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

NASA Astrophysics Data System (ADS)

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

Padmanabhan Ramalekshmi Thanu, Dinesh

98

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

99

Etching of tungsten and tungsten silicide films by chlorine atoms  

SciTech Connect

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

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

1988-08-01

100

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

PubMed

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

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

2013-09-27

101

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

PubMed

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

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

2010-12-06

102

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

SciTech Connect

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

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

2006-12-04

103

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

104

Grafting of acrylic acid on etched latent tracks induced by swift heavy ions on polypropylene films  

NASA Astrophysics Data System (ADS)

In order to continue with a systematic study that include different polymers and monomers, the residual active sites produced by heavy ion beams, that remain after the etching process, were used to start the grafting process. To produce tracks, foils of polypropylene (PP) were irradiated with 208Pb of 25.62 MeV/n. Then, these were etched and grafted with acrylic acid (AA) monomers. Experimental curves of grafting yield as a function of grafting time with the etching time as a parameter were measured. Also, the grating yield as a function of the fluence and etching time was obtained. In addition, the permeation of solutions, with different pH, through PP grafted foils was measured.

Mazzei, R.; Fernández, A.; García Bermúdez, G.; Torres, A.; Gutierrez, M. C.; Magni, M.; Celma, G.; Tadey, D.

2008-06-01

105

Acid and Alkaline Etching of Sandblasted Zirconia Implants: A Histomorphometric Study in Miniature Pigs.  

PubMed

BACKGROUND: Zirconia (ZrO2 ) has received interest as a dental material; however, little information is available on the impact of surface modifications on the osseointegration of zirconia implants. PURPOSE: The aim of the present study was to determine the effect of acid or alkaline etching of sandblasted ZrO2 implants on bone apposition in vivo. METHODS: Cylindrical ZrO2 implants with two circumferential grooves were placed in the maxilla of 12 miniature pigs. Biopsies were harvested after 1, 2, 4, and 8 weeks of healing. Undecalcified toluidine blue-stained ground sections were produced. The bone-to-implant contact, the bone area, and the presence of multinucleated giant cells were determined by histomorphometry. An uncorrected explorative statistical analysis was performed. RESULTS: Acid etching but not alkaline etching of sandblasted ZrO2 implants caused more bone-to-implant contact than sandblasted ZrO2 implants. The bone area was unaffected by the surface modifications. Acid and alkaline etching both increased the formation of multinucleated giant cells at the implant surface. CONCLUSIONS: This study provides a scientific basis to further investigate the impact of acid etching of sandblasted ZrO2 implants on osseointegration and the role of multinucleated giant cells in this process. PMID:23574426

Saulacic, Nikola; Erdösi, Robert; Bosshardt, Dieter D; Gruber, Reinhard; Buser, Daniel

2013-04-01

106

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

107

Fabrication of wall array by electrochemical etching of n-type silicon  

NASA Astrophysics Data System (ADS)

Electrochemical etching of patterned n-type silicon in hydrofluoric acid (HF) solution has been employed as a useful micromachining technique. In this paper, 4 um pitch regular wall array structures with high aspect ratio (larger than 20) were fabricated in n-typed silicon with back side illuminating. Differing from common hole array's fabrication, undesired formation of separated pores along the trench bottom becomes a serious problem in the wall array's fabrication. By adjusting the etching current density, we have successfully suppressed this phenomenon. A theoretical analysis of the formation mechanism of wall array will also be discussed in this paper.

Zhao, Zhigang; Bai, Caili; Guo, Jinchuan; Niu, Hanben

2008-03-01

108

Roughness induced dynamic changes of wettability of acid etched titanium implant modifications  

Microsoft Academic Search

Dynamic contact angle analysis (DCA) was used to investigate time-dependent wettability changes of sandblasted and acid-etched commercially pure (cp) titanium (Ti) implant modifications during their initial contact with aqueous systems compared to a macrostructured reference surface. Surface topography was analyzed by scanning electron microscopy and by contact stylus profilometry. The microstructured Ti surfaces were found to be initially extremely hydrophobic.

F. Rupp; L. Scheideler; D. Rehbein; D. Axmann; J. Geis-Gerstorfer

2004-01-01

109

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

PubMed

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

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

2011-02-19

110

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

111

Determination of fluorochemical surfactants in acid etch baths by ion chromatography with on-line matrix elimination  

Microsoft Academic Search

Fluorochemical surfactants are added to acid etching solutions to ensure good wetting of the wafer surface. Methods were developed to determine the fluorochemical surfactant FC-93 in an etch bath composed of HF–ammonium fluoride (1:6) and the fluorochemical surfactant FC-95 in an etch bath containing concentrated HF, HCl and HNO3. On-line matrix elimination was accomplished on a polymeric reversed-phase column followed

Mark Laikhtman; Jeffrey S Rohrer

1998-01-01

112

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

113

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

Microsoft Academic Search

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

Gen Kato; Nobuo Nakabayashi

1998-01-01

114

Dynamic etching tests aid fracture-acidizing treatment design  

SciTech Connect

Satisfactory stimulation of oil- and gas-bearing formations by fracture acidizing depends on development of adequate fracture conductivity in the hydraulically induced fracture. The created fracture conductivity is a result of the reaction of the injected acid with the fracture face. This paper describes a laboratory core-testing procedure to evaluate the feasibility of an acid treatment and to allow optimization of several treatment parameters. Applications to treatment design for formations that typically are difficult to stimulate by fracture acidizing are given.

Anderson, M.S.; Fredrickson, S.E. (Halliburton Services (US))

1989-11-01

115

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

PubMed

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

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

2013-01-15

116

Pinhole-free Pyrex glass etching using HF-H2SO4 mixed acid and its applications for a PDMS microflow system  

Microsoft Academic Search

Useful Pyrex glass etching method using HF and H2SO4 mixed acid was studied. To realize the etching behaviors of constant etch rate, high masks durability, small under cut and pinhole free, optimum composition of HF-H2SO4 system was found out. Pinhole-free etching, constant etching rate of 0.5 ?m\\/min and smooth surface of less than 4.6 nm was obtained at 0.8vol% HF

Takahiro Arakawa; Y. Sato; Taro Ueno; Takashi Funatsu; Shuichi Shoji

2005-01-01

117

Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel  

PubMed Central

Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel.

Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

2010-01-01

118

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

NASA Astrophysics Data System (ADS)

Micro extrinsic fiber-optic Fabry-Perot interferometers (MEFPI) are fabricated by chemically etching Er-doped fiber and then splicing the etched fiber to a single-mode fiber, for the first time to our knowledge. By using the mixture of Hydrochloric (HCl) acid and Hydrofluoric (HF) acid as etching solution, a cavity length of up to ~27 ?m and a maximum fringe contrast of ~24dB are obtained. Experimental results show that the MEFPI is insensitive to temperature change but highly sensitive to strain, with temperature and strain sensitivities of ~0.65 pm/°C and 3.15 pm/ ??, respectively. Such type of MEFPI sensors based on the etched Er-doped fiber is compact, cost-effective and especially suitable for mass production, offering great potential for a wide range of applications.

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

2009-10-01

119

Characterization of deep wet etching of glass  

NASA Astrophysics Data System (ADS)

This paper presents a characterization of wet etching of glass in HF-based solutions with a focus on etching rate, masking layers and quality of the generated surface. The first important factor that affects the deep wet etching process is the glass composition. The presence of oxides such as CaO, MgO or Al2O3 that give insoluble products after reaction with HF can generate rough surface and modify the etching rate. A second factor that influences especially the etch rate is the annealing process (560°C / 6 hours in N2 environment). For annealed glass samples an increase of the etch rate with 50-60% was achieved. Another important factor is the concentration of the HF solution. For deep wet etching of Pyrex glass in hydrofluoric acid solution, different masking layers such as Cr/Au, PECVD amorphous silicon, LPCVD polysilicon and silicon carbide are analyzed. Detailed studies show that the stress in the masking layer is a critical factor for deep wet etching of glass. A low value of compressive stress is recommended. High value of tensile stress in the masking layer (200-300 MPa) can be an important factor in the generation of the pinholes. Another factor is the surface hydrophilicity. A hydrophobic surface of the masking layer will prevent the etching solution from flowing through the deposition defects (micro/nano channels or cracks) and the generation of pinholes is reduced. The stress gradient in the masking layer can also be an important factor in generation of the notching defects on the edges. Using these considerations a special multilayer masks Cr/Au/Photoresist (AZ7220) and amorphous silicon/silicon carbide/Photoresist were fabricated for deep wet etching of a 500 ?m and 1mm-thick respectively Pyrex glass wafers. In both cases the etching was performed through wafer. From our knowledge these are the best results reported in the literature. The quality of the generated surface is another important factor in the fabrication process. We notice that the roughness of generated surface can be significantly improved by adding HCl in HF solution (the optimal ratio between HF (49%) and HCl (37%) was 10/1).

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

2006-12-01

120

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

PubMed Central

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

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

2010-01-01

121

Note: Electrochemical etching of silver tips in concentrated sulfuric acid  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

122

Nitric–phosphoric acid etching effects on the surface chemical composition of CdTe thin film  

Microsoft Academic Search

Nitric–phosphoric (NP) acid etching has been regarded as one of the most effective methods for the formation of low resistance back contact with the metal electrode in CdTe based photovoltaic cells. We studied CdTe back surfaces and the changes with time of exposure to NP acid with x-ray photoelectron spectroscopy (XPS), and atomic force microscopy. Strong etching dependence on the

Irfan Irfan; Wei Xia; Hao Lin; Huanjun Ding; Ching W. Tang; Yongli Gao

2009-01-01

123

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

124

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

PubMed Central

A carbon dioxide laser operating at the highly absorbed wavelength of 9.3?m with a pulse duration of 10–15?s is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 5–10 seconds.

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

2012-01-01

125

Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography  

NASA Astrophysics Data System (ADS)

A carbon dioxide laser operating at the highly absorbed wavelength of 9.3?m with a pulse duration of 10-15?s is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 5-10 seconds.

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

2012-02-01

126

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

SciTech Connect

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

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

1999-04-02

127

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

128

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

PubMed

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

Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

2013-05-30

129

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

130

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

131

Effect of citric acid on microstructure and electrochemical characteristics of high voltage anodized alumina film formed on etched Al Foils  

Microsoft Academic Search

Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid+citric acid mixed solution. The microstructure and crystallinity of the resulting anodized film were examined by TEM and XRD. The special capacitance, resistance and withstanding voltage of the film were explored with electrochemical impedance spectroscopy

Chao-lei BAN; Ye-dong HE; Xin SHAO

2011-01-01

132

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

133

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

USGS Publications Warehouse

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

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

1996-01-01

134

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

PubMed Central

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

2012-01-01

135

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

NASA Astrophysics Data System (ADS)

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.

Ossei-Wusu, Emmanuel; Carstensen, Jürgen; Föll, Helmut

2012-06-01

136

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

NASA Astrophysics Data System (ADS)

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

Nagarah, John M.; Wagenaar, Daniel A.

2012-03-01

137

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

Microsoft Academic Search

Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na2SiF6 having 98.2% purity was considered

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

2009-01-01

138

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

Microsoft Academic Search

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

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

1996-01-01

139

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

NASA Astrophysics Data System (ADS)

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

Wang, Elmer; Zhao, Yang

2013-09-01

140

Maskless fabrication of concave microlens arrays on silica glasses by a femtosecond-laser-enhanced local wet etching method.  

PubMed

A simple and efficient technique for large-area manufacturing of concave microlens arrays (MLAs) on silica glasses with femtosecond (fs)-laser-enhanced chemical wet etching is demonstrated. By means of fs laser in situ irradiations followed by the hydrofluoric acid etching process, large area close-packed rectangular and hexagonal concave MLAs with diameters less than a hundred of micrometers are fabricated within a few hours. The fabricated MLAs exhibit excellent surface quality and uniformity. In contrast to the classic thermal reflow process, the presented technique is a maskless process and allows the flexible control of the size, shape and the packing pattern of the MLAs by adjusting the parameters such as the pulse energy, the number of shots and etching time. PMID:20940925

Chen, Feng; Liu, Hewei; Yang, Qing; Wang, Xianhua; Hou, Cong; Bian, Hao; Liang, Weiwei; Si, Jinhai; Hou, Xun

2010-09-13

141

Photometric determination of nitric acid in spent etching solutions from the production of filament lamps  

SciTech Connect

The etching of molybdenum cores in the production of tungsten spirals for filament lamps leads to solutions which contain, besides molybdenum (up to 10%) and traces of tungsten, large quantities of unreacted nitric and sulfuric acids. These solutions cannot be analyzed following the earlier procedure for the determination of mixtures of nitric and sulfuric acids because they are strongly colored which makes titration difficult and because the proposed titrant, lead nitrate, precipitates molybdates and tungstates. The proposed method (Leute's method) has the following drawbacks: the use of ferro iron as the indicator does not give clear equivalence points in the titration and when the solution is boiled, in accordance with this procedure, the complex itself is decomposed and iron(II) is oxidized. The procedure developed by the authors in this paper eliminates the boiling and thus eliminates oxidation of iron(II) with oxygen from the air. The color of the solutions obtained is stable for 48 h which allows the authors to determine photometrically the concentration of nitric acid.

Kochetkova, T.M.; Sazonova, N.N.

1986-11-01

142

Polymeric protective coatings for MEMS wet-etch processes  

NASA Astrophysics Data System (ADS)

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

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

2004-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

144

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

PubMed Central

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

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

2010-01-01

145

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

PubMed

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

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

2008-01-01

146

The Use of an Intermediate Resin in the Acid-etch Procedure: Retentive Strength, Microleakage, and Failure Mode Analysis  

Microsoft Academic Search

Three composite resin systems, one conventional (Concise) and two microfilled (IsoPast and Silar), used with and without an intermediate resin (Concise Enamel Bond), were evaluated with and without thermal stress for in vitro retentive strength and sealing ability to acid-etched human enamel.All three materials yielded significantly different shear strength values. The use of an intermediate resin significantly improved both the

A. P. Prevost; J. L. Fuller; L. C. Peterson

1982-01-01

147

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

148

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

NASA Astrophysics Data System (ADS)

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

Cabon, J. Y.

2002-03-01

149

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

SciTech Connect

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

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

1999-12-07

150

The effect on the tensile bond strength of orthodontic brackets of titanium tetrafluoride (TiF 4) application after acid etching  

Microsoft Academic Search

Titanium tetrafluoride (TiF4) was applied to acid-etched enamel surfaces to study the effect on surface structure and tensile bond strength of orthodontic brackets. Three groups of 20 premolars each were compared in debonding tests. Group l received a 1% and Group ll received a 4% topical TiF4 treatment after acid etching. Group lIl served as control, that is, no fluoride

Tamer Büyükyilmaz; Bjørn Øgaard; Sverre Dahm

1995-01-01

151

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

152

Effect of Temperature and Time on Etching Rate of Tin Oxide Thin Films  

Microsoft Academic Search

Etching processes and characterization of transparent conducting Tin Oxide thin film grown by sputtering on glass substrate was conducted. The samples were cleaned before etching process. 0.35 M-Oxalic acid were selected as etching solvent. Temperature and etching time are two crucial parameter affecting etching rate and etching quality. Etching Thickness and etching rate were determined by optical technique. The results

Chokchai Kahattha; Wisanu Pecharapa

153

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

Microsoft Academic Search

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

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

2000-01-01

154

Fabrication of Sub10 nm Planar Nanofluidic Channels Through Native Oxide Etch and Anodic Wafer Bonding  

Microsoft Academic Search

A simple, multiple-hydrofluoric (HF)-dip process is developed and characterized to etch native silicon-dioxide (SiO2) to obtain shallow silicon trenches. The room-temperature SiO2 grow-etch-grow process yields an etch rate of ~ 1 nm\\/HF-dip with atomically smooth trench surface. Low-temperature, low-voltage anodic bonding yields sub-10 nm deep planar nanochannels with aspect ratios as small as 0.002.

Chunrong Song; Pingshan Wang

2010-01-01

155

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

PubMed

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

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

2013-05-01

156

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

PubMed Central

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

Kukiattrakoon, Boonlert; Thammasitboon, Kewalin

2012-01-01

157

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

PubMed

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

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

2013-03-13

158

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

SciTech Connect

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

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

2012-02-01

159

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.

CAO, BINRUI; QIU, PENGHE; MAO, CHUANBIN

2013-01-01

160

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. Microsc. Res. Tech. 76:936-941, 2013. © 2013 Wiley Periodicals, Inc. PMID:23913581

Cao, Binrui; Qiu, Penghe; Mao, Chuanbin

2013-07-30

161

Porous silicon formation 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 theron 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%. 1 fig.

Guilinger, T.R.; Kelly, M.J.; Martin, S.B. Jr.; Stevenson, J.O.; Tsao, S.S.

1990-02-12

162

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

163

Effect of Highly Concentrated Ozone on the Etching Properties of Preoxide Films on Si(100)  

NASA Astrophysics Data System (ADS)

We have investigated the effect of ozone on already existing silicon oxide films as preoxide on Si(100). The use of highly concentrated ozone (25 vol%) at atmospheric pressure has made it possible to modify a native oxide film on Si(100) at 350°C, resulting in upgraded film quality and reduced thickness of structural transition layers. This was shown by the change of an etching rate by hydrofluoric acid (HF) solution of the oxide film exposed to ozone. However, the exposure of ozone to Si(100) at 350°C with an already existing thermally grown oxide film caused no change in the distribution of transition layers in the oxide. This contrast suggests the possibility of upgrading the properties of a preoxide film without structural transition layers at the appropriate substrate temperature.

Nakamura, Ken; Ichimura, Shingo; Kurokawa, Akira; Koike, Kunihiko

2002-07-01

164

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

PubMed Central

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

2011-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

167

Influence of calcium hydroxide dressing and acid etching on the push-out bond strengths of three luting resins to root canal dentin.  

PubMed

OBJECTIVES: This study aims to investigate the effects of calcium hydroxide (Ca(OH)2) dressing in root canals and the effects of subsequent acid etching on the adhesion of luting resins to root canals. MATERIALS AND METHODS: Root specimens were prepared from extracted human permanent molars. Specimen canals were (1) filled with etch-and-rinse (Nexus® third generation (NX3)) and two self-adhesive (RelyX Unicem, Maxcem Elite) luting resins, respectively; (2) dressed with Ca(OH)2 before Ca(OH)2 removal and luting resin filling; (3) dressed with Ca(OH)2 before Ca(OH)2 removal and post-cementation; or (4) treated as described in item (2) except that the canals were further etched with phosphoric acid before luting resin filling. Push-out bond strengths were measured and analyzed using one-way analysis of variance, and Fisher's multiple comparison tests provided a follow-up comparison among these four canal treatments. Attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to analyze the specimen surfaces. RESULTS: Ca(OH)2 dressing adversely affected the bond strengths to canal dentin of the three luting resins tested. Acid etching did not increase the bond strengths. Infrared analysis revealed that Ca(OH)2 dressing caused no structural changes on the dentin surface. XPS and SEM analyses revealed Ca(OH)2 remnants as the ultimate chemical cause leading to the decrease in bond strength. CONCLUSIONS: The bond strength of luting resin to dentin was affected by Ca(OH)2 dressing. Acid etching treatment could not increase the bond strength. CLINICAL RELEVANCE: Adhesion of the fiber post to the root canal wall may be compromised after Ca(OH)2 dressing. An effective method for complete removal of Ca(OH)2 dressing or increase of bond strength for luting resin needs to be developed. PMID:23686133

Lee, Bor-Shiunn; Lin, Yu-Chen; Chen, Sing-Fu; Chen, Shu-Yu; Chang, Che-Chen

2013-05-18

168

The effect on shear bond strength of different antimicrobial agents after acid etching.  

PubMed

The aim of the present study was to determine whether the application of different primers containing antibacterial agents (Micro Prime, Seal&Protect, and Gluma Desensitizer) can affect the shear bond strength (SBS) of an orthodontic resin composite. Seventy-two crowns of extracted lower human incisors were mounted in acrylic resin leaving the buccal surface of the crowns parallel to the base of the moulds. The teeth were randomly distributed into three experimental and one control group, each containing 18 teeth. In each experimental group, the primers were applied to the etched enamel surfaces. In the control group, no antibacterial primer was used. An orthodontic composite resin was applied to the surface into cylindrical-shaped plastic matrices after application of an orthodontic adhesive primer (Transbond XT). For shear bond testing, a stubby-shaped force transducer apparatus (Ultradent) was applied at a crosshead speed of 1 mm/minute to each specimen at the interface between the tooth and the composite until failure occurred. A Kruskal-Wallis one-way ANOVA and a Mann-Whitney U-test with a Bonferroni adjustment were used for statistical analysis. There was no significant difference between Seal&Protect (27.98 +/- 8.73 MPa) and the control (35.15 +/- 7.85 MPa) (P > 0.05). However, Gluma (21.61 +/- 7.96 MPa) and Micro Prime (14.89 +/- 5.55 MPa) caused a decrease in bond strength (P < 0.05). No statistically significant difference was observed between Seal&Protect and Gluma (P > 0.05). As triclosan containing Seal&Protect did not cause a significant decrease in bond strength, it can potentially be used under an orthodontic resin composite to obtain an antibacterial effect. However, further in vivo studies are required. PMID:16135539

Malkoc, Siddik; Demir, Abdullah; Sengun, Abdulkadir; Ozer, Fusun

2005-08-31

169

Effect of phosphoric acid concentration on wet-bonding to etched dentin  

Microsoft Academic Search

Objective. This study was conducted to investigate the influence of phosphoric acid (H3PO4) demineralization of dentin during smear layer removal prior to dentin bonding.Methods. Bovine dentin was pre-treated with either 10 wt% or 35 wt% phosphoric acid for 30 s. Substrates were then rinsed and either kept moist or air-dried before a light-cured bonding system was applied. The adhesive system

Gen Kato; Nobuo Nakabayashi

1996-01-01

170

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

NASA Astrophysics Data System (ADS)

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

Geringer, Jean; Demanget, Nicolas; Pellier, Julie

2013-10-01

171

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

2012-08-31

172

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

PubMed

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

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

2010-10-01

173

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

PubMed Central

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

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

2013-01-01

174

Ultrasonic recovery of copper and iron through the simultaneous utilization of Printed Circuit Boards (PCB) spent acid etching solution and PCB waste sludge.  

PubMed

A method was developed to recover the copper and iron from Printed Circuit Boards (PCB) manufacturing generated spent acid etching solution and waste sludge with ultrasonic energy at laboratory scale. It demonstrated that copper-containing PCB spent etching solution could be utilized as a leaching solution to leach copper from copper contained PCB waste sludge. It also indicated that lime could be used as an alkaline precipitating agent in this method to precipitate iron from the mixture of acidic PCB spent etching solution and waste sludge. This method provided an effective technique for the recovery of copper and iron through simultaneous use of PCB spent acid solution and waste sludge. The leaching rates of copper and iron enhanced with ultrasound energy were reached at 93.76% and 2.07% respectively and effectively separated copper from iron. Followed by applying lime to precipitate copper from the mixture of leachate and rinsing water produced by the copper and iron separation, about 99.99% and 1.29% of soluble copper and calcium were settled as the solids respectively. Furthermore the settled copper could be made as commercial rate copper. The process performance parameters studied were pH, ultrasonic power, and temperature. This method provided a simple and reliable technique to recover copper and iron from waste streams generated by PCB manufacturing, and would significantly reduce the cost of chemicals used in the recovery. PMID:20932641

Huang, Zhiyuan; Xie, Fengchun; Ma, Yang

2010-09-16

175

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

176

Etch-Pitting Characteristics of High-Purity Molybdenum.  

National Technical Information Service (NTIS)

The etch-pitting behavior of single and polycrystalline molybdenum was examined using various etching solutions and prior heat treatments. Murakami's solution, Wolff's solution, oxalic acid and sulphuric acid in methanol are found effective on planes in a...

H. L. Prekel A. Lawley

1965-01-01

177

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

178

Method for acidizing siliceous formations  

SciTech Connect

A method is described for treating a subterranean formation surrounding a wellbore which comprises injecting into the formation an aqueous acidizing solution. The aqueous acidizing solution contains hydrofluoric acid and excess fluoride. The excess fluoride is present in an amount greater than the amount of fluoride stoichiometrically required to form hydrofluoric acid, and thereafter fluids are produced from the wellbore.

Lamb, W.J.; Kunze, K.R.

1987-03-10

179

State of the art etch-and-rinse adhesives  

Microsoft Academic Search

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

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

2011-01-01

180

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 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal–Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm3, (0.053±0.002) mm3, (0.003 6±0.001) mm3 and (0.005 9±0.002) mm3 respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

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

2012-01-01

181

Laser-controlled chemical etching of aluminum  

NASA Astrophysics Data System (ADS)

A new technique is described for high-spatial-resolution (less than 2-micron linewidth) etching of Al thin films. The process is based upon moderate local heating by a tightly focused Ar(+) laser beam to activate an etching reaction in mixtures of phosphoric acid, nitric acid, and potassium dichromate. By chemically biasing the reaction near its passive/active transition, the laser can enhance the reaction rate by more than six orders of magnitude. The etching mechanism has been studied by etch-rate measurements, ellipsometry, and Auger spectroscopy, and is ascribed to a competition between the formation of soluble aluminum phosphates and insoluble aluminum oxides.

Tsao, J. Y.; Ehrlich, D. J.

1983-07-01

182

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

Microsoft Academic Search

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

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

2010-01-01

183

Effect of acid etching and different Er:YAG laser procedures on microleakage of three different fissure sealants in primary teeth after aging.  

PubMed

The purpose of this study was to evaluate the effects of different surface conditioning procedures on microleakage and unfilled area proportions of three fissure sealants(Aegis, Helioseal and Helioseal F) in primary molar teeth. One hundred and fifty teeth were randomly divided into five main groups according to surface conditioning procedures. Main groups were; acid-etching(Group A); laser 3.75 W(Group B) and 5 W(Group D); acid-etching combined with laser 3.75 W(Group C) and 5 W(Group E). Samples were aged by thermocycling and water bath. Afterwards, they were immersed in basic fuchsin solution for 24 h and bucco-lingual sections were obtained from each tooth. Digital images were taken using a stereo-microscope and the microleakage and unfilled area proportions were assessed by using a software system. Consequently, Aegis FS containing amorphous calcium phosphate was found to exhibit the lowest microleakage in all surface conditioning procedures. Unfilled areas were not detected in Groups C and E of all FSs. PMID:23903636

Unal, Murat; Hubbezoglu, Ihsan; Zan, Recai; Kapdan, Arife; Hurmuzlu, Feridun

2013-01-01

184

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

PubMed

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

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

2011-08-26

185

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

186

Microstructure etching and carbon analysis techniques  

SciTech Connect

The purpose of this program was to investigate etching methods and carbon content analytical techniques for characterizing alloy 690 tubing material. Results from initial etching investigations were used to direct further study towards those techniques which exhibited the greatest potential for providing quick, accurate, and reliable methods for assessing potential SCC performance by microstructural characterization. Follow-up investigations of selected methods provided additional evidence of the effectiveness and reproducibility of the selected etches when used by a variety of investigators. The carbon content results were used to assess the need for improved analytical methods to enable meeting the tight carbon limits required by current specifications. The program identified the bromine methanol etch, followed by examination using a scanning electron microscope, as the most suitable alloy 690 etch. However, the need for a suitable etch using optical microscopy was also identified. A glyceregia etch showed an excellent ability to reveal carbide morphology. Promising grain boundary etches for use with optical microscopy were also identified, including a modified nital etch and a hot oxalic acid etch, but further optimization of one or more of these methods is necessary before they can be fully recommended for use with alloy 690. 2 tabs.

Lowenstein, D.B.; Gorman, J.A. (Dominion Engineering, Inc., McLean, VA (USA))

1990-04-01

187

Selective etching of Al[sub x]Ga[sub 1[minus]x]As and In(Al[sub x]Ga[sub 1[minus]x])As alloys in succinic acid-hydrogen peroxide solutions  

SciTech Connect

Selective etching plays a vital role in compound semiconductor device fabrication. Succinic acid-hydrogen peroxide solutions were used to etch Al[sub x]Ga[sub 1[minus]x]As and In(Al[sub x]Ga[sub 1[minus]x])As alloys, and the etch rates were investigated with the varying alloy mole fractions. It was found that Al[sub x]Ga[sub 1[minus]x]As (x[le]0.4) may be selectively etched over Al[sub y]Ga[sub 1[minus]y]As(y[ge]0.5), with a selectivity better than 150. Extended surface exposure to air was found to affect the etch rates, most interestingly for Al[sub 0.4]Ga[sub 0.6]As. In the In(Al[sub x]Ga[sub 1[minus]x])As system, alloys with x[le]0.8 can be preferentially etched over In[sub 0.52]Al[sub 0.48]As with a selectivity of better than 20.

Tang, A.J.; Sadra, K.; Streetman, B.G. (Univ. of Texas, Austin (United States))

1993-05-01

188

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

189

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

190

Microstructuring of stainless steel implants by electrochemical etching  

Microsoft Academic Search

The effects of electrochemically enhanced etching on stainless steel coronary stent surfaces have been investigated in respect to their applicability as surface modifications prior drug-coating. Two methods have been investigated, one basing on grain boundary etching with diluted HNO3 and the other one on hydrochloric acid etching. The etching current was in the range of 30–200 mA which accounts for 0.34–2.28 mA\\/mm

M. Stöver; M. Renke-Gluszko; T. Schratzenstaller; J. Will; N. Klink; B. Behnisch; A. Kastrati; R. Wessely; J. Hausleiter; A. Schömig; E. Wintermantel

2006-01-01

191

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

192

Balloon-borne observations of mid-latitude hydrofluoric acid  

SciTech Connect

Measurements of stratospheric HF have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35{degrees}N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N{sub 2}O profiles, indicate an average rate of HF increase of (5.5{+-}0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements. 17 refs., 3 figs., 3 tabs.

Sen, B.; Toon, G.C.; Blavier, J.F. [Jet Propulsion Lab., Pasadena, CA (United States)] [and others

1995-04-01

193

Ultrasonic-assisted ac etching of aluminum foils for electrolytic capacitor electrodes with enhanced capacitance  

Microsoft Academic Search

ac etching of high-purity aluminum foils in hybrid acids including hydrochloric acid, sulphuric acid and oxalic acid was investigated and the effects of ultrasonic-assisted stirring on the performances of the etched foils were investigated in this work. Scanning electron microscopy (SEM) was used for observation of the etched foils. Compared with the classically used mechanical stirring (magnetic stirring), the assistance

Zhaohui Hou; Jianhuang Zeng; Jianjun Chen; Shijun Liao

2010-01-01

194

Acidizing: A well completion reference  

SciTech Connect

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

NONE

1997-11-01

195

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

PubMed

Potyvirus resistance in Capsicum spp. has been attributed to amino acid substitutions at the pvr1 locus that cause conformational shifts in eukaryotic translation initiation factor eIF4E. The viral genome-linked protein (VPg) sequence was isolated and compared from three Tobacco etch virus (TEV) strains, highly aphid-transmissible (HAT), Mex21, and N, which differentially infect Capsicum genotypes encoding Pvr1(+), pvr1, and pvr1(2). Viral chimeras were synthesized using the TEV-HAT genome, replacing HAT VPg with Mex21 or N VPg. TEV HAT did not infect pepper plants homozygous for either the pvr1 or pvr1(2) allele. However, the novel chimeric TEV strains, TEVHAT(Mex21-VPg) and TEV-HAT(N-VPg), infected pvr1 and pvr1(2) pepper plants, respectively, demonstrating that VPg is the virulence determinant in this pathosystem. Three dimensional structural models predicted interaction between VPg and the susceptible eIF4E genotype in every case, while resistant genotypes were never predicted to interact. To determine whether there is a correlation between physical interaction of VPg with eIF4E and infectivity, the effects of amino acid variation within VPg were assessed. Interaction between pvr1(2) eIF4E and N VPg was detected in planta, implying that the six amino acid differences in N VPg relative to HAT VPg are responsible for restoring the physical interaction and infectivity. PMID:23134519

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

2012-12-01

196

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

197

Surface analysis of etched molar enamel by gas adsorption.  

PubMed

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson's Correlation Coefficient showed a lack of relationship between etch pattern and total surface area. PMID:18502960

Orellana, M F; Nelson, A E; Carey, J P R; Heo, G; Boychuk, D G; Major, P W

2008-06-01

198

Photoassisted anodic etching of gallium nitride  

SciTech Connect

The first study of photo-assisted anodic etching of unintentionally doped n-GaN at room temperature is reported here. The electrolyte used is a mixture of buffered aqueous solution of tartaric acid and ethylene glycol. The etching rate varies from {approximately}20 {angstrom}/min to as high as 1600 {angstrom}/min. A systematic study shows that (1) the etch rate, as well as the surface roughness, increases with the current density; (2) the etching rate is the highest when the pH of the electrolyte is {approximately}7; and (3) the etching is faster when there is more ethylene glycol in the electrolyte solution. Ga-N-based III-V nitrides are important candidates for applications in blue light emitters and lasers, high voltage and high temperature electronics.

Lu, H.; Wu, Z.; Bhat, I. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Electrical, Computer, and System Engineering

1997-01-01

199

Influence of asymmetric etching on ion track shapes in polycarbonate  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

200

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

SciTech Connect

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

Maish, A.B.

1991-01-01

201

Selective plasma etching  

NASA Astrophysics Data System (ADS)

Plasma etching of silicon nitride glassivation layers on silicon dice using CF4 was successfully carried out with a commercial plasma etcher. The parameters of power level and partial pressure gas were downscaled from the commercial plasma etcher to a bench-top plasma etcher. Plasma etching of silicon nitride was successfully performed in the bench-top plasma etcher.

Franti, G. W.

1991-12-01

202

Chemical etching of aluminium  

Microsoft Academic Search

Chemical etching is employed as micromachining manufacturing process to produce micron-size components. The process applies a strong chemical etchant solution to remove unwanted part in the workpiece material. It is basically a corrosion-controlled process. Chemical etching process has a long history and accepted one of the important nontraditional machining processes during the last half century. The method is widely applied

O. Çak?r

2008-01-01

203

AlAs etch-stop layers for InGaAlAs\\/InP heterostructure devices and circuits  

Microsoft Academic Search

Wet chemical etching solutions were developed that allow the selective etching of InP lattice-matched InGaAs and InAlAs compounds using thin pseudomorphic AlAs layers as etch stop. Several dicarboxylic acids were found that allow the etching of indium compounds. The best results were obtained for etchants consisting of succinic acid, ammonia, and hydrogen peroxide. The etch rate in In0.53Ga0.47 As is

Tom P. E. Broekaert; Clifton G. Fonstad

1992-01-01

204

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

PubMed Central

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

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

2010-01-01

205

In vitro bonding effectiveness of three different one-step self-etch adhesives with additional enamel etching.  

PubMed

AIM: To evaluate the effect of additional enamel etching on the shear bond strength of three self-etch adhesives. METHODS: Class II box type cavities were made on extracted human molars. Teeth were randomly divided into one control group of etch and rinse adhesive and three test groups of self-etch adhesives (Clearfil S3 Bond, Futurabond NR, Xeno V). The teeth in the control group (n = 10) were treated with Adper™ Single Bond 2. The three test groups were further divided into two subgroups (n = 10): (i) self-etch adhesive was applied as per the manufacturer's instructions; (ii) additional etching of enamel surfaces was done prior to the application of self-etch adhesives. All cavities were restored with Filtek Z250. After thermocycling, shear bond strength was evaluated using a Universal testing machine. Data were analyzed using anova independent sample's 't' test and Dunnett's test. The failure modes were evaluated with a stereomicroscope at a magnification of 10×. RESULTS: Additional phosphoric acid etching of the enamel surface prior to the application of the adhesive system significantly increased the shear bond strength of all the examined self-etch adhesives. CONCLUSIONS: Additional phosphoric acid etching of enamel surface significantly improved the shear bond strength. PMID:23596010

Batra, Charu; Nagpal, Rajni; Tyagi, Shashi Prabha; Singh, Udai Pratap; Manuja, Naveen

2013-04-17

206

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

PubMed

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

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

2012-09-25

207

Recovering obliterated engraved marks on aluminium surfaces by etching technique  

Microsoft Academic Search

A study has been made of the characteristics of restoration of obliterated engraved marks on aluminium surfaces by etching technique. By etching different reagents on 0.61mm thick sheets of aluminium (99wt%) on which some engraved marks had been erased to different depths it was found that the reagent 60% hydrochloric acid and 40% sodium hydroxide on alternate swabbing on the

Mohd. Izhar Mohd. Baharum; R. Kuppuswamy; Azari Abd. Rahman

2008-01-01

208

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

209

The facet selectivity of inorganic ions on silver nanocrystals in etching reactions  

NASA Astrophysics Data System (ADS)

The facet selectivity of the halide ions and chlorauric acid for several shaped silver nanocrystals is presented in this paper. Two inorganic ions show different representations when they are used for etching silver nanocrystals in the self-sacrificial template reaction. The morphological changes of the silver nanocrystals indicate that the halide ions prefer to etch the (110) facets of silver nanocrystals, while in the chlorauric acid etching reaction, gold first modifies the (110) facets and then lets chlorauric acid etch the (111) facets instead. The selective facet etching on individual nanoparticles in the solution phase has crucial significance in the control-synthesis of nanocrystals and the facet asymmetric reaction.

Xu, Shuping; Tang, Bin; Zheng, Xianliang; Zhou, Ji; An, Jing; Ning, Xiaohua; Xu, Weiqing

2009-10-01

210

An evaluation and comparison of orthodontic bracket bond strengths achieved with self-etching primer  

Microsoft Academic Search

The bonding of orthodontic brackets to enamel is a multistep process. To simplify bonding and decrease chair time, Transbond Plus Self-Etching Primer (3M Unitek, Monrovia, Calif) has been introduced; the primer combines the etching, rinsing, and priming steps. This in vitro study evaluated the shear bond strengths and interoperator variability of self-etching primer, as compared with conventional phosphoric acid etching

Helen S. I Grubisa; Giseon Heo; Don Raboud; Kenneth E Glover; Paul W Major

2004-01-01

211

Optimization of roughness, reflectance and photoluminescence for acid textured mc-Si solar cells etched at different HF\\/HNO 3 concentrations  

Microsoft Academic Search

The surface structure of multi-crystalline silicon (mc-Si) etched in HF\\/HNO3 at different HF\\/HNO3 concentrations is optimized for being applied in solar cells. The resulting texture, which determines the efficiency of solar cells, was characterized by means of scanning electron microscopy (SEM) and optical spectroscopy. The roughness of the surface increases and the reflectance decreases when the content of HNO3 in

B. González-Díaz; R. Guerrero-Lemus; B. Díaz-Herrera; N. Marrero; J. Méndez-Ramos; Dietmar Borchert

2009-01-01

212

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

213

Influence of preliminary etching on the stability of bonds created by one-step self-etch bonding systems.  

PubMed

We evaluated the effects of preliminary etching of dentine on the stability of the bond created by one-step self-etch adhesives under different storage conditions. Adper Easy Bond (3M ESPE) and iBond Self-Etch (iBond SE; Heraeus Kulzer) were applied with an etch-and-rinse (i.e. after preliminary phosphoric acid etching for 15 s) or a self-etch approach. Resin-dentine bonded specimens were sectioned perpendicularly to the adhesive interface according to the 'non-trimming technique'. Beams were stored in artificial saliva for 24 h, 6 months, or 1 yr at 37°C, or in 10% NaOCl for 5 h at room temperature, and then stressed until failure; the microtensile bond strengths were calculated. Interfacial nanoleakage of additional teeth was evaluated using light microscopy or transmission electron microscopy. Adper Easy Bond showed higher bond strength than iBond SE, regardless of the dentine treatment. Similar microtensile bond strength results were obtained for teeth subjected to artificial ageing in 10% NaOCl for 5 h at room temperature and for teeth stored in artificial saliva for 6 months at 37°C. The additional etching step increased the microtensile bond strength for Adper Easy Bond and iBond SE. This study supports the use of one-step adhesives on etched dentine because of the increased bond strength compared with their application onto smear-layer-covered dentine, regardless of storage conditions. PMID:22607341

Taschner, Michael; Nato, Fernando; Mazzoni, Annalisa; Frankenberger, Roland; Falconi, Mirella; Petschelt, Anselm; Breschi, Lorenzo

2012-04-21

214

Effects of different silanes and acid concentrations on bond strength of brackets to porcelain surfaces.  

PubMed

The aim of this study was to determine the optimum silane-coupling agent and the optimum concentration of acid agent when bonding to porcelain surfaces. Eighty deglazed feldspathic porcelain discs with a diameter of 10 mm and a thickness of 2 mm mounted in acrylic resin blocks were randomly divided into four groups. In groups 1 and 2, the porcelain surfaces were etched with 9.6 per cent hydrofluoric (HF) acid and in groups 3 and 4 with 5 per cent HF acid. In groups 1 and 3, the Dynalock maxillary central incisor brackets were bonded with Pulpdent silane and Unite bonding adhesive and in groups 2 and 4 with Reliance silane and Unite. Shear forces were applied to the samples using an Instron universal test machine. The non-parametric Kruskal-Wallis test was used to determine significant differences in bond strengths between the four groups and Dunn's multiple comparison test to compare subgroups. The mean bond strengths and standard deviations of groups 1 to 4 were 5.51 +/- 1.19, 6.54 +/- 0.002, 4.55 +/- 1.93, and 6.39 +/- 0.45 MPa, respectively. Specimens bonded with Reliance showed a statistically significantly higher in vitro bond strength than those bonded with Pulpdent. The concentration of etching gels did not result in any statistically significant difference on the in vitro bond strength when evaluated separately. PMID:19339674

Trakyali, Göksu; Malkondu, Ozlem; Kazazo?lu, Ender; Arun, Tülin

2009-04-01

215

A laboratory report on vibration etching for fissure sealants.  

PubMed

We have developed a vibration etching technique in which occlusal pits and fissures are simultaneously cleansed and acid-etched using a fissure needle mounted on an electromagnetic vibrator. When tested on extracted teeth, the needle completely cleansed the fissures by removing the contents and the prismless enamel layer, and widened them to from 100 to 150 micrometers to the depth reached by the needle. The sealant penetrated readily and adhered to the reduced and etched fissure walls interlocking with resin tags. PMID:7045183

Tadokoro, Y; Iwaku, M; Fusayama, T

1982-06-01

216

Etching of enamel for direct bonding with a thulium fiber laser  

NASA Astrophysics Data System (ADS)

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

Kaba? Sarp, Ay?e S.; Gülsoy, Murat

2011-02-01

217

Digital etching for highly reproducible low damage gate recessing on AlGaN\\/GaN HEMTs  

Microsoft Academic Search

A room temperature digital etching technique for aluminum gallium nitride has been developed. An oxidizing agent and an acid have been used in a two step etching cycle to remove aluminum gallium nitride in approximately 5-6 Å increments. The process has been characterized to be reasonably linear and highly repeatable, offering an alternative to currently not available gate recess etch

D. Buttari; S. Heikman; S. Keller; U. K. Mishra

2002-01-01

218

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

219

Transparentization of Tunnel-Etched Al Foil by Anodic Oxidation  

Microsoft Academic Search

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

Issei Mizuki; Toshiaki Kondo; Kazuyuki Nishio; Hideki Masuda

2009-01-01

220

Intergranular Corrosion Testing by Etching at a Constant Potential  

Microsoft Academic Search

Electrochemical etching at a constant potential (CPE) was used to study the intergranular corrosion (IGC) susceptibility of special-grade stainless steels (SS), with emphasis on the possibility of using this method for acceptance testing where the standard Strauss test is not applicable. The electrolyte selected for the CPE test was 3 M perchloric acid (HClOâ) with various additions of hydrochloric acid

R. Qvarfort

1995-01-01

221

Investigations on Acceleration and Control of the Wet Chemical Etching Procedure Using Ultrasonic Cavitation Untersuchungen ueber Beschleunigung und Steuerung Nasschemischer Aetzverfahren durch Gezielte Ultraschallkavitation.  

National Technical Information Service (NTIS)

The influence of ultrasonic and electric current on etching speed and etching quality was investigated. Tests were carried out with solution of ferric chloride, ammonium chloride or cupric chloride in water, or a mixture of phosporic acid, water, and nitr...

D. Leven R. Pohlman

1974-01-01

222

Influence of impurities on chemical etch pits in gypsum single crystals  

Microsoft Academic Search

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

KS Raju

1981-01-01

223

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

224

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

225

Acidizing sandstone formations with fluoboric acid  

SciTech Connect

The continuing search for an effective deep-penetrating sandstone acidizing system recently has focused on fluoboric acid (HBF/sub 4/). Because this acid first must hydrolyze in water to produce HF, it was believed that deeper radial penetration of live acid could be achieved during matrix acidizing operations. However, a thorough experimental study has shown that typical formation temperatures will cause fluoboric acid to spend at a rapid rate similar to that of conventional hydrofluoric acid (HF), thereby severly limiting its usefulness in most sandstone formations. Furthermore, the same silica reprecipitation potential associated with HF acidizing is also inherent in the HBF/sub 4/ system.

Kunze, K.R.; Shaughnessy, C.M.

1983-02-01

226

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

227

Electrochemical etch stop engineering for bulk micromachining  

Microsoft Academic Search

Microelectromechanical systems (MEMS) may be fabricated with several micromachining techniques, the oldest and most widespread technique being that of bulk-micromachining. Although there are alternative etching techniques, wet anisotropic etching is still favoured by industry in many cases because of its simplicity and low costs. Electrochemically controlled etching allows for reproducible fabrication of structures with a uniform thickness. Recently, new etch

C. M. A. Ashruf; P. J. French; P. M. Sarro; P. M. M. C. Bressers; J. J. Kelly

1998-01-01

228

Sacrificial oxide etching compatible with aluminum metallization  

Microsoft Academic Search

This paper reports on sacrificial oxide etching with very high selectivity to aluminum metallization using mixtures of 73% HF and IPA. Etch rate ratios up to 680 have been achieved even for (slow etching) thermal oxide. Thermal oxide etch rates up to 1.8 ?m\\/min. are reported. Thick polysilicon accelerometers with aluminum metallization and thermal sacrificial oxide have been made as

P. T. J. Gennissen; P. J. French

1997-01-01

229

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

231

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

232

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

233

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

Microsoft Academic Search

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

Y. Wang; P. Spencer

2005-01-01

234

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

235

A surface study of wet etched AlGaN epilayers grown by hot-wall MOCVD  

NASA Astrophysics Data System (ADS)

Epitaxial layers of AlGaN were grown by hot-wall MOCVD and their surfaces wet chemically etched with phosphorous acid. The as-grown surfaces and the development of the etched surfaces after 10 and 20 min of etching were studied with atomic force microscopy (AFM) and CL. In the as-grown layers growth features may be resolved while the RMS is as low as 1.4 Å in a scan area of 2×2 ?m. Surfaces etched for 10 min had developed etch pits and a low RMS roughness of 7 Å indicating a uniform quality of the layers. Micrometer scale hexagonal features were observed after 20 min of etching. In some cases a deep hexagonal etch pit is observed in the centre of the hexagonal feature with a 30° rotation to each other, suggesting that the origin is substrate-induced defects.

Syväjärvi, M.; Kakanakova-Georgieva, A.; Yazdi, G. R.; Karar, A.; Forsberg, U.; Janzén, E.

2007-03-01

236

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

237

MBE-grown InGaAlAs 1.5 micron MQW ridge waveguide laser diodes with AlAs etch stop layers  

Microsoft Academic Search

Ridge waveguide multiple quantum well laser diodes in which the ridge heights are predetermined by etch stop layers have been fabricated for the first time in InGaAlAs materials lattice-matched to InP. A 3 nm thick pseudomorphic AlAs layer forms the etch stop layer in these devices and the selective etching was performed by a succinic acid solution that etches InGaAs

W.-Y. Choi; T. P. E. Broekaert; C. G. Fonstad

1993-01-01

238

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

239

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

240

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

241

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

242

A generalized plasma etching model  

NASA Astrophysics Data System (ADS)

A generalized plasma etching model was developed on the basis of the Zawaideh and Kim (1987) model, which includes the effects of multiion and multineutral gas species. New generalized plasma-transport equations were derived for multiion species, which are valid for collisional to weakly collisional plasma. In addition, a new particle-balance model is introduced, which incorporates the effects of gas composition, gas-flow rate, pumping rate, ion and neutral-gas chemistry, and atomic reactions on the neutral gas and plasma parameters such as densities and pressures of the neutral-gas and plasma species. Predictions obtained for SiO2 plasma etching with CF4 gas agreed well with the results of the measurements of etch rate as functions of neutral gas pressure, CF4 flow rate, and RF power.

Zawaideh, Emad; Kim, N. S.

1988-10-01

243

Defect reduction strategy for plasma etch  

NASA Astrophysics Data System (ADS)

Plasma etch has always played an important role in microelectronic manufacturing. Defects observed at post-etch usually have significant impact on yield. The visual post-etch defects are generally divided into three major categories. Those defects discovered at etch but not generated by etch, the defects generated during etch, and the defects generated by interaction between different process layers. The prior layer defects are the defects uncovered by the etch process but originated in prior layers such as film or lithography. The true plasma etch-generated defects usually consist of process-induced defects and equipment defects. Process integration defects are those type of defects that are caused by interaction between different layer stoichiometry and process chemistry. The origin of these defects observed at post-etch need to be identified and isolated in order to make defect reduction in the plasma etch area manageable. The best defect yield management strategy is to use an integrated monitoring scheme consisting of in-line, short-loop, and equipment monitor wafers to monitor defect levels in the production line and to troubleshoot yield loss caused by defects. This paper discusses how to set up effective integrated short-loop patterned etch and blank resist-coated etch equipment monitors to isolate the contribution of different components of post-etch defects listed above.

Yang, Richard Y.

1999-08-01

244

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

245

A Highly Uniform, and High Throughput, Double Selective pHEMT Process Using an All Wet Etch Chemistry  

Microsoft Academic Search

Epitaxial material structure and wet-etch methods have been developed for a Double Selective Recess (DSR) power pHEMT process at X-band. Seven citric acid based etch solutions and eight different epitaxial material structures with AlAs etch stop layers have been investigated. The optimized epitaxial material produces devices with DC and RF performance that are similar to the ones fabricated with Selective

Kamal Alavi; Serap Ogut; Peter Lyman; William Hoke; Michael Borkowski

246

Effects of metal ion impurities on PuOâ dissolution in nitric--hydrofluoric acid solution  

Microsoft Academic Search

The effects of Cu\\/sup 2 +\\/, Hg\\/sup 2 +\\/, Zn\\/sup 2 +\\/, La\\/sup 3 +\\/, Ce\\/sup 3 +\\/, Al\\/sup 3 +\\/, Pu\\/sup 4 +\\/, Th\\/sup 4 +\\/, and Zr\\/sup 4 +\\/ metal ion impurities on PuOâ dissolution in 8.0M HNOâ--0.1M HF solution at 100°C have been investigated. Results based on 1.0 h of dissolution time show that such metal ions

O. K. Tallent; J. C. Mailen

1977-01-01

247

The effects of zirconium on the dissolution rate of thoria in nitric-hydrofluoric acid solutions  

Microsoft Academic Search

Dissolution tests using ThOâ microspheres, ThOâ pellets, and Zircaloy tubing were performed to establish conditions that can be used for the selective dissolution of thoria from Zircaloy cladding. Although additional work is needed in several areas, the following conditions are tentatively recommended for use in process demonstration tests: 0.02 to 0.04 M HF in refluxing 8 to 12 M HNOâ

O. K. Tallent; S. R. Buxton; D. O. Campbell; J. C. Mailen

1983-01-01

248

Effects of impurities on PuO dissolution in nitric-hydrofluoric acid solutions  

Microsoft Academic Search

The effects of 0.10 M Cu\\/sup 2 +\\/, Hg\\/sup 2 +\\/, Zn\\/sup 2 +\\/, La\\/sup 3 +\\/, Ce\\/sup 3 +\\/, Al\\/sup 3 +\\/, Th\\/sup 4 +\\/,Zr\\/sup 4 +\\/, Cr\\/sup 3 +\\/, and Fe\\/sup 3 +\\/ on PuO dissolution in 8.0M HNO--0.1M HF were investigated. Except for Cr\\/sup 3 +\\/ and Fe\\/sup 3 +\\/, the amount of Pu dissolved in 1

O. K. Tallent; J. C. Mailen

1976-01-01

249

In situ functionalization of porous silicon during the electrochemical formation process in ethanoic hydrofluoric acid solution.  

PubMed

In this work, the results of a new method for the preparation of porous silicon (PS) layers with in situ simultaneous functionalization with organic molecules are reported. The molecules of interest are dissolved in the HF ethanoic solution used to prepare the PS layers by partial anodic dissolution of a Si electrode. The method has been proved to be effective with various molecules. In this Communication, the case of PS functionalization with heptyne molecules, studied by FTIR spectroscopy, is reported in detail. The results demonstrate that this new functionalization method, accompanied by a low-level oxidation, is simple, fast, and effective and that it can allow the confinement of the adsorbed molecules selectively in a single layer of a PS stack. PMID:12904025

Mattei, Giorgio; Valentini, Veronica

2003-08-13

250

Assembly Methods for Etched Foil Regenerators  

Microsoft Academic Search

Etched foil appears to offer substantial advantages over other regenerator materials, especially for annular regenerators. However, assembly of etched foil regenerators has been difficult because etching regenerator patterns in foil is most satisfactorily accomplished using pieces too small for a complete, spiral-wrapped regenerator. Two techniques have been developed to deal with that problem: For spiral-wrapped regenerators, a new technique for

Matthew P. Mitchell

2004-01-01

251

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

PubMed Central

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

2012-01-01

252

Method of treating a well using fluoboric acid to clean a propped fracture  

Microsoft Academic Search

The permeability of the prop pack in a subterranean fracture containing a propping agent is affected by contacting the propping agent with fluoboric acid. The fluoboric acid slowly forms hydrolysis products, including hydrofluoric acid and hydroxyfluoboric acid, which react with and stabilize clays and other fines in the prop pack, thereby affecting its permeability. Because the fluoboric acid hydrolyzes slowly,

R. L. Thomas; F. A. Suhy

1979-01-01

253

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

PubMed Central

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

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

254

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

NASA Astrophysics Data System (ADS)

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

Hui, Wing C.

2004-04-01

255

Bond strength of resin-reinforced glass ionomer cements after enamel etching.  

PubMed

This study evaluated the shear bond strength of resin-reinforced glass ionomers to enamel etched or unetched. Human, non-carious extracted permanent molars stored in distilled water were used. Flat buccal and lingual enamel surfaces were ground wet on 600-grit silicon carbide paper. The teeth were then distributed at random into six groups of 5 teeth (10 surfaces) each: Group 1: Fuji II LC, no enamel etching; Group 2: Fuji II LC, enamel etched with 10% phosphoric acid for 10 seconds; Group 3: Dyract, no enamel etching; Group 4: Dyract, enamel etched with 10% phosphoric acid for 10 seconds; Group 5: Photac-Fil, no enamel etching; Group 6: Photac-Fil, enamel etched with 10% phosphoric acid for 10 seconds. Cylindrical samples of the glass ionomers were prepared in plastic molds and bonded to the enamel surface according to the manufacturers' instructions. All samples were placed in distilled water for 24 hours, and sheared with an Instron at a crosshead speed of 0.5 mm/minute. The results (in MPa) were: Group 1: 11.29 +/- 4.84; Group 2: 19.64 +/- 5.43; Group 3: 8.26 +/- 3.61; Group 4: 22.04 +/- 5.40; Group 5: 2.05 +/- 3.05; Group 6: 9.12 +/- 6.61. ANOVA and Student-Newman-Keuls procedure revealed that on etched enamel, Fuji II LC and Dyract had a significantly higher bond strength than all the other groups tested (P < 0.0001), but not significantly different between each other. With these two groups, cohesive failure within the material was recorded in all samples while in the unetched samples, all specimens displayed an adhesive failure (glass ionomer-enamel interface). All samples with Photac-Fil, with or without enamel etching had adhesive failures. PMID:7880480

Cortes, O; Garcia-Godoy, F; Boj, J R

1993-12-01

256

Apparent and steady-state etch rates in thin film etching and under-etching of microstructures: II. Characterization  

NASA Astrophysics Data System (ADS)

The apparent and steady-state etch rates of PECVD SiO2, HDP SiO2 and PECVD Si3N4 are measured both in a single thin film and a stacked film configuration. This is done for a HF:H2O/1:1, a HF_{49\\, wt%}:IPA/1:1 and a BHF solution. It is shown that etch rates vary with the used etch time, confirming the influence of both an incubation and a rinsing period on the average etch rate when performing typical ex situ etch rate experiments. Hence, this second part of a set of two papers provides the experimental evidence for part I where a general etch rate model was proposed. Furthermore this work shows that the etch rate varies whether it is determined on a single layer, in a stacked configuration or while under-etching a structural layer. This confirms the need of a straightforward characterization method for under-etching measurements at the sacrificial release stage of MEMS fabrication processes. Therefore, a new characterization method, using a suspended beam array and a surface profilometer, is proposed to determine the amount of under-etch after sacrificial release of surface micromachined devices.

Van Barel, Gregory; Du Bois, Bert; Van Hoof, Rita; De Wachter, Jef; De Ceuninck, Ward; Witvrouw, Ann

2010-05-01

257

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

SciTech Connect

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.

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

1981-05-05

258

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

259

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

DOEpatents

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

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

1979-11-23

260

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

PubMed Central

Microsystem technology is well suited to batch fabricate microelectrode arrays, such as the Utah electrode array (UEA), intended for recording and stimulating neural tissue. Fabrication of the UEA is primarily based on the use of dicing and wet etching to achieve high aspect ratio (15:1) penetrating electrodes. An important step in the array fabrication is the etching of electrodes to produce needle-shape electrodes with sharp tips. Traditional etching processes are performed on a single array, and the etching conditions are not optimized. As a result, the process leads to variable geometries of electrodes within an array. Furthermore, the process is not only time consuming but also labor-intensive. This report presents a wafer-scale etching method for the UEA. The method offers several advantages, such as substantial reduction in the processing time, higher throughput and lower cost. More importantly, the method increases the geometrical uniformity from electrode to electrode within an array (1.5 ± 0.5 % non-uniformity), and from array to array within a wafer (2 ± 0.3 % non-uniformity). Also, the etching rate of silicon columns, produced by dicing, are studied as a function of temperature, etching time and stirring rate in a nitric acid rich HF-HNO3 solution. These parameters were found to be related to the etching rates over the ranges studied and more-importantly affect the uniformity of the etched silicon columns. An optimum etching condition was established to achieve uniform shape electrode arrays on wafer-scale.

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

2010-01-01

261

Reversal of Compromised Bonding to Oxidized Etched Dentin  

Microsoft Academic Search

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

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

2001-01-01

262

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

Microsoft Academic Search

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

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

2006-01-01

263

Zero etch clear — a new modular clear coat system with excellent scratch\\/mar performance  

Microsoft Academic Search

The aggravated demands regarding the etch\\/mar resistance of clear coats due to aggressive atmosphere pollution has led to new clear coat systems with extraordinary etch performance. One of the most promising key-chemistries is based on the epoxy\\/acid reaction. In contrast to the introduced clear coats on this chemistry basis, this new clear coat system has changed the former drawbacks, storage

Carmen Flosbach; Walter Schubert

2001-01-01

264

Resin Tag Length of One-Step and Self-Etching Adhesives Bonded to Unground Enamel  

Microsoft Academic Search

Length of resin tags yielded by utilization of an one-step conventional adhesive system and self-etching adhesive system on unground enamel was observed. In study Groups I and III, the enamel surface was etched for 60 seconds with 35% phosphoric acid gel and adhesive systems PQ1 (Ultradent Products, Inc) and Adper Prompt L Pop (3M\\/ESPE) were applied. Adper Prompt L Pop

Renato Herman Sundfeld; Carlos Henrique de Oliveira; Adriana Maria Jorge Dal'acqua da Silva; André Luiz Fraga Briso; Maria Lúcia Marçal Ma Sundfeld

2005-01-01

265

The corrosion behavior of TiAlN coatings prepared by PVD in a hydrofluoric gas atmosphere  

Microsoft Academic Search

The corrosion behavior of a TiAlN coated surface in a hydrofluoric gas atmosphere was investigated for its application to the Teflon extrusion process. Teflon is a high temperature thermo-plastic that fills the need for molded parts, electrical insulation or extrusions requiring chemical resistance and good dielectric properties. Its properties are well suited for mechanical, electrical and chemical components and cable

In S. Choi; Jong C. Park

2000-01-01

266

Dry etching of polydimethylsiloxane for microfluidic systems  

Microsoft Academic Search

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

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

2002-01-01

267

Method of sputter etching a surface  

Microsoft Academic Search

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

Henager; C. H. Jr

1984-01-01

268

Assembly Methods for Etched Foil Regenerators  

Microsoft Academic Search

Etched foil appears to offer substantial advantages over other regenerator materials, especially for annular regenerators. However, assembly of etched foil regenerators has been difficult because etching regenerator patterns in foil is most satisfactorily accomplished using pieces too small for a complete, spiral-wrapped regenerator. Two techniques have been developed to deal with that problem:For spiral-wrapped regenerators, a new technique for joining

Matthew P. Mitchell

2004-01-01

269

Controlled ion implant damage profile for etching  

DOEpatents

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

Arnold, G.W. Jr.; Ashby, C.I.H.; Brannon, P.J.

1988-08-18

270

Controlled ion implant damage profile for etching  

SciTech Connect

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

Arnold, G.W. Jr.; Ashby, C.I.H.; Brannon, P.J.

1990-12-18

271

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

272

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

273

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

274

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

275

Method for dry etching of transition metals  

DOEpatents

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

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

1998-09-29

276

Low pressure plasma etching of silicon carbide  

NASA Astrophysics Data System (ADS)

A low pressure etching of silicon carbide is qualitatively characterized by using a neural network. To construct a predictive model, the etch process was characterized by means of a 25 full factorial experiment. Experimental factors that were varied include radio frequency (rf) source power, bias power, pressure, O2 fraction, and gap between the plasma source and wafer. An additional 15 experiments were conducted to test the appropriateness of the trained model. An optimized etch rate model has a root mean-squared error of 12.78 nm/min. Model response surface behaviors were certified by actual measurements. Several noticeable features at lower pressure etching include a lower etch rate, inverse relationship between the source power level and the dc bias, and a smaller etch rate variation with the source power. The effect of the bias power on the etch rate or dc bias was affected little by the pressure level. Etch mechanisms for the gap variations were quite different depending on the bias powers. Several etching aspects useful for plasma control were revealed.

Kim, B.; Kim, S.; Lee, B. T.

2005-09-01

277

Etch profile control of high-aspect ratio deep submicrometer ?-Si gate etch  

Microsoft Academic Search

The well-acknowledged etch profile drift problem in chip production was investigated with a more accurate meads of measuring actual etch thickness to monitor and correct this drift. Using a high-aspect ratio, 0.1-?m ?-Si gate structure, the investigation was specifically focused on the control of transition timing in the critical interval from main etch (ME) to over etch (OE). This required

Hyun-Mog Park; Dennis S. Grimard; Jessy W. Grizzle

2001-01-01

278

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

2010-06-22

279

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

Microsoft Academic Search

Indium-tin oxide (ITO) films coated on glass have been etched by reactive ion etching (RIE) with a gas mixture of Ar and Cl2. The etching rates of ITO films depend strongly on power density, gas pressure, the composition of reactive gases, and the total flow rate of etchants. According to the results from the study, we can postulate that the

Meiso Yokoyama; Jiin Wen Li; Shui Hsiang Su; Yan Kuin Su

1994-01-01

280

The Noble Gases in the HF-Susceptible Portion of Ivuna (CI), Analyzed by Closed System Step Etching  

NASA Astrophysics Data System (ADS)

Primordial noble gases (possibly similar to Q or HF) are released from the HF-solvable portion of Ivuna during closed system step etching, indicating that information about primordial components is lost when studied only in acid-resistant residues.

Riebe, M.; Busemann, H.; Wieler, R.

2013-09-01

281

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 37°C 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.

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

2011-01-01

282

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

283

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

284

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

NASA Astrophysics Data System (ADS)

The quality of low-cost multicrystalline silicon (mc-Si) has improved to the point that it forms approximately 50 % of the worldwide photovoltaic (PV) power production. The performance of commercial mc-Si solar cells still lags behind c-Si due in part to the inability to texture it effectively and inexpensively. Surface texturing of mc-Si has been an active field of research. Several techniques including anodic etching, wet acidic etching, lithographic patterning, and mechanical texturing have been investigated with varying degrees of success. To date, a cost-effective technique has not emerged. In recent years, maskless reactive ion etching texturing techniques have received significant attention. Reactive ion etching (RE) texturing techniques to produce randomly distributed texture take advantage of the extensive infrastructure developed for Si microelectronics, and as such can lead to significant savings in tool development efforts for the PV manufacturers.

Zaidi, S. H.

2002-05-01

285

Rotary replication for freeze-etching  

PubMed Central

Rotary replication has been adapted to freeze-etching and evaluated using T4 polyheads, erythrocyte ghosts, and chloroplast membranes. Conventional electron microscopy, electron diffraction, and optical diffraction and filtering indicate that platinum-carbon rotary replication renders radially symmetrical contrast and 25 A resolution to freeze-etched specimens so as to clarify subunit structure not normally evident in unidirectional shadow replicas.

1977-01-01

286

Method of Sputter Etching a Surface.  

National Technical Information Service (NTIS)

A surface is textured by co-sputter etching with a target and a seed material with the surface at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties ...

C. H. Henager

1982-01-01

287

Particle control in dielectric etch chamber  

Microsoft Academic Search

A methodology for evaluating and controlling particle performance in a dielectric etch system is developed and presented. Analysis of particle samples, collected from premature chamber failures for out-of-control particle levels, suggests sputtering of the upper electrode during etching is a key modulator to this problem. To eliminate such sputtering, we designed a series of experiments with the objective of identifying

Makarem A. Hussein; Robert B. Turkot

2006-01-01

288

Note: Electrochemical etching of sharp iridium tips  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

289

Microstructural studies of reactive ion etched silicon  

SciTech Connect

The structures of Si near-surface damage induced after the removal of a thick SiO/sub 2/ layer on Si using reactive ion etching with various etching gases were studied by transmission electron microscopy. Cross-sectional micrographs showed the presence of a fluorocarbon film on the Si surface after the SiO/sub 2/ layer is etched away. No extended defects were observed in Si etched utilizing pure CF/sub 4/ or CF/sub 4//20% H/sub 2/ etching gas, even after a 25-min overetch into Si. For a CF/sub 4//40% H/sub 2/ etching gas, no extended lattice defects were evident for overetch times of up to 5 min. However, extensive damage was found in the Si surface layer after a 10-min or longer overetch. This extensive damage consists of /111/ planar defects distributing underneath the Si surface to a depth of 300 A. The planar defects are highly decorated by impurities, likely H and possibly C, F. A pure H/sub 2/ etching gas was found to introduce a heavily damaged layer and a high density of extended defects near the Si surface after only a 5-min overetch. These observations indicate that H ion bombardment plays an important role in the formation of Si near-surface damage during reactive ion etching.

Jeng, S.J.; Oehrlein, G.S.

1987-06-29

290

Controlled ion implant damage profile for etching.  

National Technical Information Service (NTIS)

This invention pertains to a process for etching a material such as LiNbO(sub 3) by implanting ions having a plurality of different kinetic energies in an area to be etched, and then contacting the ion implanted area with an etchant. The various energies ...

G. W. Arnold C. I. H. Ashby P. J. Brannon

1988-01-01

291

Trends in Dielectric Etch for Microelectronics Processing  

Microsoft Academic Search

Dielectric etch technology faces many challenges to meet the requirements for leading-edge microelectronics processing. The move to sub 100-nm device design rules increases the aspect ratios of certain features, imposes tighter restrictions on etched features' critical dimensions, and increases the density of closely packed arrays of features. Changes in photolithography are driving transitions to new photoresist materials and novel multilayer

Eric A. Hudson

2003-01-01

292

Highly selective PEC etching of gallium nitride device structures  

Microsoft Academic Search

Photoelectrochemical (PEC) wet etching is an attractive wet etch approach for III-Nitride materials. Compared to dry etch techniques normally applied in prevalent GaN device fabrications, PEC wet etching can provide low damage, selective etching and understanding of material defects. This dissertation work has carried out an in-depth exploration of the dependence of PEC etching on both process variables and materials

Yan Gao

2004-01-01

293

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

SciTech Connect

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

Berube, P.-M.; Poirier, J.-S.; Margot, J.; Stafford, L. [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Quebec H3C 3J7 (Canada); Ndione, P. F.; Chaker, M.; Morandotti, R. [INRS-EMT, 1650 Boulevard Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada)

2009-09-15

294

Catalytic membranes: alkene dimerisation by means of acidic porous thin-film composite membranes  

Microsoft Academic Search

Dimerisation of isobutene is of increasing interest to substitute oxygenated products such as MTBE or the like as fuel additives. Catalysts applied in commercial alkylation plants, e.g., hydrofluoric and sulfuric acid may be replaced by less harmful solid catalysts, for example by solid heteropolyacids (“super” acids) or polymeric sulfonic acids. To overcome decrease in catalyst performance by time and to

Igor Randjelovic; Gisela Bengtson; Detlev Fritsch

2002-01-01

295

Wet etching rates of InGaZnO for the fabrication of transparent thin-film transistors on plastic substrates  

Microsoft Academic Search

The wet etch process for amorphous indium gallium zinc oxide (a-IGZO or a-InGaZnO) by using various etchants is reported. The etch rates of a-IGZO, compared to another indium-based oxides including indium gallium oxide (IGO), indium zinc oxide (IZO), and indium tin oxide (ITO), are measured by using acetic acid, citric acid, hydrochloric acid, perchloric acid, and aqua ammonia as etchants,

Chi-Yuan Lee; Chienliu Chang; Wen-Pin Shih; Ching-Liang Dai

2010-01-01

296

Stability of carbon nanowalls against chemical attack with acid solutions  

NASA Astrophysics Data System (ADS)

In this paper we report on the stability of CNW layers, synthesized by a radiofrequency plasma jet, against the chemical attack with different acid solutions (sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid). We present the changes of the morphology and structure of the CNW caused by the post-growth chemical treatments. We demonstrate that self-sustaining and transferable CNW layers can be obtained, by chemically dissolving the substrates, while the initial characteristics of the material are well preserved.

Vizireanu, Sorin; Dinescu, Gheorghe; Nistor, Leona Cristina; Baibarac, Mihaela; Ruxanda, Grigore; Stancu, Mihaela; Ciuparu, Dragos

2013-01-01

297

Selective, deep Si trench etching with dimensional control  

SciTech Connect

The recent development of a high-aspect ratio Si etch (HARSE) process has enabled the fabrication of a variety of Si structures where deep trench etching is necessary. The HARSE process relies on the formation of a sidewall etch inhibitor to prevent lateral etching of the Si structures during exposure to an aggressive SF{sub 6}/Ar plasma etch chemistry. The process yields highly anisotropic profiles with excellent dimensional control for high aspect ratio features. In this study, Si etch rates and etch selectivities to photoresist are reported as a function of chamber pressure, cathode rf-power, ICP source power, and gas flow. Si etch rates > 3 {micro}m/min with etch selectivities to resist > 75:1 were obtained. Lateral dimensional control, etch selectivities to SiO{sub 2} and Si{sub 3}N{sub 4}, and aspect ratio dependent etching (ARDE) will also be discussed.

Shul, R.J.; Willison, C.G.; Zhang, L.

1998-08-01

298

Etch Characteristics of GaN using Inductively Coupled Cl2 Plasma Etching  

NASA Astrophysics Data System (ADS)

In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl2/Ar plasmas were investigated. It has shown that the results of a study of inductively coupled plasma (ICP) etching of gallium nitride by using Cl2/Ar is possible to meet the requirement (anisotropy, high etch rate and high selectivity), simultaneously. We have investigated the etching rate dependency on the percentage of Argon in the gas mixture, the total pressure and DC voltage. We found that using a gas mixture with 20 sccm of Ar, the optimum etch rate of GaN was achieved. The etch rate were found to increase with voltage, attaining a maximum rate 2500 Å/min at -557 V. The addition of an inert gas, Ar is found to barely affect the etch rate. Surface morphology of the etched samples was verified by scanning electron microscopy and atomic force microscopy. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer.

Rosli, Siti Azlina; Aziz, A. Abdul

2008-05-01

299

Trends in Dielectric Etch for Microelectronics Processing  

NASA Astrophysics Data System (ADS)

Dielectric etch technology faces many challenges to meet the requirements for leading-edge microelectronics processing. The move to sub 100-nm device design rules increases the aspect ratios of certain features, imposes tighter restrictions on etched features' critical dimensions, and increases the density of closely packed arrays of features. Changes in photolithography are driving transitions to new photoresist materials and novel multilayer resist methods. The increasing use of copper metallization and low-k interlayer dielectric materials has introduced dual-damascene integration methods, with specialized dielectric etch applications. A common need is the selective removal of multiple layers which have very different compositions, while maintaining close control of the etched features' profiles. To increase productivity, there is a growing trend toward in-situ processing, which allows several films to be successively etched during a single pass through the process module. Dielectric etch systems mainly utilize capacitively coupled etch reactors, operating with medium-density plasmas and low gas residence time. Commercial technology development increasingly relies upon plasma diagnostics and modeling to reduce development cycle time and maximize performance.

Hudson, Eric A.

2003-10-01

300

Galvanic etch stop for Si in KOH  

NASA Astrophysics Data System (ADS)

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

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

2004-08-01

301

Improved Cryofixation Applicable to Freeze Etching  

PubMed Central

Freeze etching of solute model systems (e.g., glycerol or ferritin solutions) demonstrates that cryofixation can introduce serious artifacts due to the segregation of the dissolved or dispersed material from the solvent. Since, in principle, this problem can be reduced by increasing the cooling rate, a new technique has been developed which combines spray freezing with freeze etching. This spray-freeze-etching is applied by first spraying the specimen into a liquid cryomedium. The frozen droplets are then “glued” together with butylbenzene to form a regular freeze-etch specimen, while the temperature of the sample is kept at -85°C. The results obtained by spray-freeze-etching are far superior to those obtained by standard freezing. Our results, using 5% glycerol as a test specimen, are equivalent to those obtained by the high-pressure method (1). The reduction of segregation during freezing makes freeze etching a method applicable for the investigation of solute systems. Furthermore, the study of unicellular organisms or cellular fractions by freeze etching without the use of antifreeze is made possible. Images

Bachmann, L.; Schmitt, W. W.

1971-01-01

302

Recovering obliterated engraved marks on aluminium surfaces by etching technique.  

PubMed

A study has been made of the characteristics of restoration of obliterated engraved marks on aluminium surfaces by etching technique. By etching different reagents on 0.61mm thick sheets of aluminium (99wt%) on which some engraved marks had been erased to different depths it was found that the reagent 60% hydrochloric acid and 40% sodium hydroxide on alternate swabbing on the surfaces was found to be the most sensitive one for these metal surfaces. This reagent was able to restore marks in the above plates erased down to 0.04mm below the bottom of the engraving. The marks also presented excellent contrast with the background. This reagent was further experimented with similar aluminium surfaces, but of relatively greater thickness of 1.5mm. It was noticed that the recovery depth increased slightly to 0.06mm; this suggested the dependence of recovery depth on the thickness of the sheet metal. Further, the depth of restoration decreased in cases where the original number was erased and over which a new number was engraved; the latter results are similar to those of steel surfaces reported earlier [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32]. PMID:18313246

Baharum, Mohd Izhar Mohd; Kuppuswamy, R; Rahman, Azari Abd

2008-03-04

303

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

PubMed

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

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

2012-02-15

304

Electroless epitaxial etching for semiconductor applications  

DOEpatents

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

McCarthy, Anthony M. (Menlo Park, CA)

2002-01-01

305

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

306

A Study of Sputtered TiN Gate Electrode Etching with Various Wet Chemicals and Post Etch Annealing for Complementary Metal--Oxide--Semiconductor Device Integration Applications  

NASA Astrophysics Data System (ADS)

Wet chemicals for etching sputtered TiN metal gate and post etch annealing on HfO2 and HfSiON gate dielectrics were studied with metal--oxide--semiconductor devices. Various wet solutions such as SC1 (NH4/H2O2/H2O= 1:2:5), SPM (H2SO4/H2O2= 10:1), and H2O2 were employed to etch the sputtered TiN. Difference in equivalent oxide thickness (EOT) is negligible among etchants while the lowest leakage current density (Jg) is attained with only SPM solution. Even though SPM treatment shows relative poor surface morphologies compared to H2O2 process, difference in Jg is mainly affected by the amount of absorbed Ti into high-k gate dielectrics during wet etch process. Lower Jg using SPM is attributable to the reduced amount of Ti-adsorption due to additional H2SO4 acid in wet chemical solution, which is confirmed by total reflection X-ray fluorescence. Post etch annealing on high-k layer improves film qualities such as suppressed defects --- less frequency dependence --- and lowers Jg further while EOT is slightly increased by about 0.2 nm due to SiO2 interfacial regrowth. HfSiON gate dielectric shows stronger immunity against TiN wet etch compared with HfO2. Thus, appropriate etchant and post annealing for the selective TiN etching are carefully considered to suppress defects and Jg for attaining complementary metal--oxide--semiconductor (CMOS) device.

Heo, Seung Chan; Yoo, Dongjun; Choi, Moon Suk; Kim, Dohyung; Chung, Chulwon; Choi, Changhwan

2012-10-01

307

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 concentrations 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, C.I.H.; Myers, D.R.

1989-11-24

308

In vitro permeability of etch-and-rinse and self-etch adhesives used for immediate dentin sealing.  

PubMed

To investigate the permeability of deep dentin following immediate sealing with different etch-and-rinse and self-etch adhesives (Single Bond 2, Adper Prompt L-Pop, Clearfil Protect Bond, Clearfil S3 Bond, G-Bond) and a dentin desensitizer (Gluma). Fluid-transport model was used to measure fluid conductance during and after application of adhesives. Polyvinylsiloxane impressions of bonded dentin were taken to monitor fluid transudation from the surface of the adhesives. The area and number of dentinal fluid droplets and/or blisters were calculated using image analysis. None of the adhesives were able to block fluid conductance completely. The fluid conductance values of the adhesives displayed the following statistical ranking (p<0.05): G-Bond?Clearfil Protect BondAcid-etched dentin. Highly significant correlation was observed between the permeability of the tested adhesives and the area fraction of fluid droplets/blisters on the adhesive surfaces (r=0.99, p<0.01). PMID:22673465

Sahin, Cem; Cehreli, Zafer C; Yenigul, Muhittin; Dayangac, Bulent

2012-05-14

309

MBE-grown InGaAlAs 1.5 micron MQW ridge waveguide laser diodes with AlAs etch stop layers  

NASA Astrophysics Data System (ADS)

Ridge waveguide multiple quantum well laser diodes in which the ridge heights are predetermined by etch stop layers have been fabricated for the first time in InGaAlAs materials lattice-matched to InP. A 3 nm thick pseudomorphic AlAs layer forms the etch stop layer in these devices and the selective etching was performed by a succinic acid solution that etches InGaAs and InAlAs but not AlAs. With this technique, more reliable and uniform ridge stripe device fabrication is expected.

Choi, W.-Y.; Broekaert, T. P. E.; Fonstad, C. G.

1993-03-01

310

Method for anisotropic etching in the manufacture of semiconductor devices  

NASA Astrophysics Data System (ADS)

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.; Cross, Jon B.

1993-12-01

311

Femtosecond laser assisted etching of quartz: microstructuring from inside  

Microsoft Academic Search

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

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

2006-01-01

312

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

313

Thermal Neutron Dosimetry Using Electrochemical Etching.  

National Technical Information Service (NTIS)

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

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

1979-01-01

314

THE ELECTROLYTIC POLISHING AND ETCHING OF URANIUM  

Microsoft Academic Search

The methods used for the electrolytic preparation of uranium sections ; for microscopical examination and for examination of the grain size are reviewed. ; Four electrolytes are recommended for polishing and four for etching to reveal ; the grain size. (auth);

B. W. Mott; H. R. Haines

1950-01-01

315

Chemical Etches for Lead Telluride Crystals.  

National Technical Information Service (NTIS)

The solution for etching lead telluride crystals consists essentially of hydroxyl ions and about 0.2 to 2 percent by weight of iodate ion. The crystals are useful semiconductor materials and are used in thermoelectric generators and refrigerators.

M. K. Norr

1964-01-01

316

Wet chemical etching of the (111)In and  

Microsoft Academic Search

This paper examines etching of the polar planes (111)In and $$\\u000a\\\\left( {\\\\bar 1\\\\bar 1\\\\bar 1} \\\\right)\\u000a$$Sb of InSb wafers for liquid phase epitaxy in various etchants after mechanical and chemomechanical polishing. We describe\\u000a procedures for polishing wafers and removing residual abrasive particles from the surface of polished wafers. A tartaric-acid-based\\u000a etchant is shown to ensure a mirror-smooth finish

Sh. O. Eminov; Kh. D. Jalilova; E. A. Mamedova

2011-01-01

317

Grain boundary etching in InP  

SciTech Connect

Grain boundaries in bulk polycrystalline InP wafers are preferentially attacked by a 5 HCl:3HNO/sub 3/:4 HF etch. Canyons with depth > 10 ..mu..m and widths approx. 1 ..mu..m are the most common form of attack. Although the etch has effect on simple twin boundaries, preferential attack occurs at interfaces formed by multiple twinning events.

Hershenson, L.; Zanio, K.

1980-07-01

318

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

319

CO+NH3 plasma etching for magnetic thin films  

NASA Astrophysics Data System (ADS)

Etching of magnetic thin films has been studied using CO/NH3 plasma with an electron cyclotron resonance plasma source and DC sample bias. Etch rates were proportional to bias power density. The maximum etch rate was 127nm/min. Both the pressure dependence of Ni-Fe etch rate and the results of appearance mass spectroscopy suggested that the chemical reaction induced by energetic CO molecules enhanced the etch rate.

Kubota, Hitoshi; Ueda, Kousei; Ando, Yasuo; Miyazaki, Terunobu

2004-05-01

320

Femtosecond laser assisted etching of quartz: microstructuring from inside  

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

321

Plasma etching of chromium films in the fabrication of photomasks  

NASA Astrophysics Data System (ADS)

To meet the advanced CD uniformity and resolution requirements of state-of-the-art maskmaking, dry chrome etch processing may be required. Dry etching is a more anisotropic process, significantly reducing etch undercut. The absence of undercutting allows the lithographer to image the resist at the iso-focal point, eliminating the need to underexpose to maintain CDs. Also, dry etch parameters can be precisely controlled via a microprocessor- controlled etch system with a highly accurate parameter-metering system that ensures greater process control. Using design-of-experiment methodologies, a chrome plasma etch process (using OCG-895i) was developed. This work proves the feasibility of plasma etching chromium patterns on photomasks. The results show an etch that has excellent uniformity, is anisotropic, and has excellent edge quality. Also, resist selectivity is high for the etching of thin chrome films. SEM results show a significant reduction in the bias needed to achieve nominal CDs. As with many dry etch processes, loading and microloading effects (i.e., localized pattern density effect on etch rates) are a concern. Initial investigations of loading and microloading effects were conducted. Results suggest that due to the high anisotropy of the etch, microloading is not an issue. However, plate loading (or the amount of chrome removed) increases etch times and can result in radial etch patterns. Loading effects must be minimized or eliminated to optimize etch uniformity.

Coleman, Thomas P.; Buck, Peter D.

1995-12-01

322

DEEP WELL STIMULATION WITH ALCOHOLIC ACID  

Microsoft Academic Search

A hydrofluoric-hydrochloric acid mixture containing an alcohol has proven to be highly successful in stimulating production from ''problem wells'' in sandstone formation. The primary advantage of this acid is the better and more rapid ''clean-up'' properties provided by the added alcohol. It is particularly useful in gas-producing formations, particularly those with a high clay content. Alcohol causes quick recovery of

H. O. McLeod; J. E. McGinty; C. F. Smith

1966-01-01

323

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

Microsoft Academic Search

The slowdown of the oxide etch rate with width of submicrometer structures is known as reactive ion etching (RIE) lag and has been explained by ion shadowing and differential charging of the sidewalls, among other effects [R. A. Gottscho and co-workers, J. Vac. Sci. Technol. B 10, 2133 (1992)]. Here we show for an inductively coupled high density plasma reactor

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

1996-01-01

324

Mechanism of Etch Stop in High Aspect-Ratio Contact Hole Etching  

Microsoft Academic Search

The mechanism of etch stop in contact hole etching has been studied. It was found that in high aspect ratio holes, even though the incident ions lose charge due to collision with the sidewall, they are able to bombard the bottom of the hole maintaining their high energy. It was also confirmed that the redeposition of sputtered species from the

Tokuhisa Ohiwa; Akihiro Kojima; Makoto Sekine; Itsuko Sakai; Shigeru Yonemoto; Yumi Watanabe

1998-01-01

325

Reactive ion etching of tantalum pentoxide  

SciTech Connect

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

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

1983-12-01

326

Ultrahigh-Aspect-Ratio Contact Hole Etching  

NASA Astrophysics Data System (ADS)

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

Ikegami, Naokatsu

1997-10-01

327

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

328

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

329

High Rate Deep Si Etching using Capacitively Coupled Plasma  

NASA Astrophysics Data System (ADS)

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

Sakai, Itsuko; Sakurai, Noriko; Ohiwa, Tokuhisa

330

Monitoring of highly selective plasma etch processes  

NASA Astrophysics Data System (ADS)

A very high selectivity is required in most of the plasma etching processes for the fabrication of subhalf micron devices. One of the most critical steps is the polysilicon etch, in which the etch stop layer is a thin oxide of 50 angstrom to 100 angstrom. An extended overetch is generally required to remove polysilicon stringers at the bottom corner of the topological steps. During this overetching step microtrenching can become a problem when the thin oxide film at the bottom corner of the polysilicon structure is removed. In the contact etch a very high selectivity is also required due to the increased aspect ratio and depth variation of the contact holes. High selectivity to the silicon substrate or to the thin silicide layer insures minimal loss of substrate silicon or silicide in the shallow contact region. In spacer etch, especially when dealing with SOI devices using an ultrathin silicon layer, a substantial amount of silicon can be lost if selectivity is not high enough, causing uncertainty in the composition and thickness of the silicide layer formed in the subsequent silicidation step. Oftentimes the problems in these plasma etch processes can not be detected until the device is tested after the completion of the metallization step. Due to the time lag, it is difficult to trace the real causes of the problems. This can represent a significant monetary loss especially when dealing with larger diameter wafers. An inline monitoring method is very essential especially in a high volume production environment. Analytical techniques such as TEM cross sectional work or even high resolution SEM work is difficult to implement as an in-line monitoring method. Controlling the etch processes by measuring the etch selectivity may be very troublesome. Determining a slight change of thickness of the etch stop layer in a highly selective process is quite difficult. Also, in most cases the structure on the test wafers is very different from the actual devices. Important parameters such as percentage of resist coverage or effect of line width and spacing, etc., are mostly ignored.

Maa, Jer-Shen; Allen, Lynn R.; Evans, Dave; Hsieh, Tzu Y.; Ulrich, Bruce D.; Hsu, Sheng T.; Grant, John M.; Stecker, Greg

1994-09-01

331

Plasma etching a ceramic composite. [Evaluating microstructure  

SciTech Connect

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

Hull, D.R.; Leonhardt, T.A.; Sanders, W.A.

1992-01-01

332

Patterning enhancement techniques by reactive ion etch  

NASA Astrophysics Data System (ADS)

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

Honda, Masanobu; Yatsuda, Koichi

2012-03-01

333

Plasma etch method for extreme ultraviolet lithography photomask  

SciTech Connect

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

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

2007-02-05

334

Solderability enhancement of copper through chemical etching  

SciTech Connect

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

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

1995-05-01

335

Pattern transfer with stabilized nanoparticle etch masks  

NASA Astrophysics Data System (ADS)

Self-assembled nanoparticle monolayer arrays are used as an etch mask for pattern transfer into Si and SiOx substrates. Crack formation within the array is prevented by electron beam curing to fix the nanoparticles to the substrate, followed by a brief oxygen plasma to remove excess carbon. This leaves a dot array of nanoparticle cores with a minimum gap of 2 nm. Deposition and liftoff can transform the dot array mask into an antidot mask, where the gap is determined by the nanoparticle core diameter. Reactive ion etching is used to transfer the dot and antidot patterns into the substrate. The effect of the gap size on the etching rate is modeled and compared with the experimental results.

Hogg, Charles R.; Picard, Yoosuf N.; Narasimhan, Amrit; Bain, James A.; Majetich, Sara A.

2013-03-01

336

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

337

Membrane Structure: Spin Labeling and Freeze Etching of Mycoplasma laidlawii*  

PubMed Central

A spin-labeled fatty acid was incorporated in vivo into the polar lipids of Mycoplasma laidlawii membranes. The electron paramagnetic resonance signal from either intact cells or their extracted lipids reflected the fatty acid composition of the Mycoplasma membranes. Comparison of signals from intact cells, gramicidin-treated cells, heat-treated cells, and extracted lipids indicates that a major portion of the membrane lipids is in a semiviscous hydrocarbon environment. The results also show that the spin label in the intact membrane is slightly but significantly less mobile than it is in protein-free lipid extracts made from these membranes. Correlated electron microscope examinations using the freeze-etch technique reveal particulate components in the hydrophobic region of the membrane. The mobility of the lipids in the intact cell membrane may be influenced by their association with these particles. Images

Tourtellotte, Mark E.; Branton, Daniel; Keith, Alec

1970-01-01

338

Etch durable spin-on hard mask  

NASA Astrophysics Data System (ADS)

As decreasing the device feature size, the film stack structure used in resist process is also changing. Especially multilayer stack film structure is getting popular for pattern formation on critical layers. Our approach is to form a spin-on hard mask film with high etch resistance by introduction of a new baking function. The results show that a spin-on hard mask film processed by an underlayer coating system of Tokyo Electron Ltd. (TEL) has drastically improved etch resistance compared to a conventional system. We will report the availability of new underlayer system using several kinds of underlayer materials.

Muramatsu, Makoto; Iwashita, Mitsuaki; Kondo, Takashi; Hirose, Hisashi; Fujimoto, Seiji

2011-03-01

339

Siliceous sponge spicules in coral reef sediments  

Microsoft Academic Search

Experimental etching with hydrofluoric acid indicated that silica deposition occurs in a recognizable pattern in common sponge microscleres. The postdepositional alteration of these spicules has previously been generally unrecognized or misinterpreted in the literature. Early stages of postdepositional etching of sponge spicules were observed in the acid insoluble fraction of sediments from the West Atlantic barrier reef near Carrie Bow

K. Rützler; I. G. Macintyre

1978-01-01

340

PECVD silicon carbide as a chemically resistant material for micromachined transducers  

Microsoft Academic Search

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

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

1998-01-01

341

Dielectric hard mask etching with ArF photo resist  

Microsoft Academic Search

The ArF photo resists are rapidly progressing just in time for the 0.1 ?m device generation and beyond. There is a complex interaction between the lithographic performance and plasma etching process. This study develop a plasma etching process to etch dielectric hard mask with a commercial ArF resist and address the issue of limited etching resistance of the ArF resist.

Leonard Hsu; TEOS Open

2002-01-01

342

High index contrast polysiloxane waveguides fabricated by dry etching  

SciTech Connect

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

Madden, S. J.; Zhang, M. Y.; Choi, D.-Y.; Luther-Davies, B.; Charters, R. [Laser Physics Centre, Research School of Physical Science and Engineering, Australian National University, Canberra ACT 0200 (Australia); RPO Inc., Innovations Building, Australian National University, Canberra ACT 0200 (Australia)

2009-05-15

343

Plasma etching of chromium films in the fabrication of photomasks  

Microsoft Academic Search

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

Thomas P. Coleman; Peter D. Buck

1995-01-01

344

Highly Selective Contact Hole Etching Using Electron Cyclotron Resonance Plasma  

Microsoft Academic Search

The SiO2 etching process is one of the most significant processes in ultra-large-scale integration (ULSI) fabrication. In order to obtain fine contact holes, it is necessary to achieve both highly selective etching of SiO2 over other materials, and non-reactive ion etch (non-RIE) lag. We investigated the etching characteristics and the effect of O2 addition in C4F8+O2 plasma using electron cyclotron

Hajime Kimura; Ken'ichiro Shiozawa; Kenji Kawai; Hiroshi Miyatake; Masahiro Yoneda

1995-01-01

345

Contact Hole Etch Scaling toward 0.1 µm  

Microsoft Academic Search

Reactive ion etching (RIE)-lag, i.e., the dependence of contact etched depth D on contact diameter phi, for deep quarter micron contact hole etching has been studied down to 0.1 µm contact. The nonlinearity between phi and D was found to be successfully converted into a linear relationship with reciprocal plots of phi and modified contact etched depth (D+h), taking into

Nobuo Aoi; Shigenori Hayashi; Michinari Yamanaka; Masafumi Kubota; Mototsugu Ogura

1999-01-01

346

Gas-phase selective etching of native oxide  

Microsoft Academic Search

Gas-phase selective etching of native oxide film formed on a silicon surface is an essential requirement for ULSI process technologies. Ultraclear anhydrous hydrogen fluoride (AHF) gas and a corrosion-free system were developed for this etching process. The reaction mechanism of silicon oxide film with moistureless HF was investigated, and selective etching conditions were developed. The gas-phase selective etching of native

NOBUHIRO MIKI; HIROHISA KIKUYAMA; ICHIROH KAWANABE; MASAYUKI MIYASHITA; TADAHIRO OHMI

1990-01-01

347

Molybdenum etching with chlorine atoms and molecular chlorine plasmas  

Microsoft Academic Search

Thin films of molybdenum were etched both within and downstream from a Clâ plasma at 200-mTorr pressure and temperatures below 180 °C. When samples were positioned downstream from the discharge, etching proceeded solely by chemical reaction of the film with chlorine atoms. Without a discharge, molecular chlorine did not etch molybdenum. Downstream and in-discharge etch rates were <20 nm\\/min and

D. S. Fischl; D. W. Hess

1988-01-01

348

The etching of alpha-recoil tracks in phlogopite  

Microsoft Academic Search

This work uses three phlogopite samples to investigate the etching behavior of alpha-recoil tracks (?-recoil tracks), which is a key problem in dating procedures. At the initial stage of the etching process, the number of alpha-recoil tracks increased linearly with etching time, then the linearity was interrupted due to the overlapping of alpha-recoil tracks. The slope of the etching line

Wanming Yuan; Shaokai Gao; Jinquan Dong; Zenkuan Bao; Xiuming Jia

2008-01-01

349

Wet KOH etching of freestanding AlN single crystals  

NASA Astrophysics Data System (ADS)

We investigated defect-selective wet chemical etching of freestanding aluminum nitride (AlN) single crystals and polished cuts in a molten NaOH KOH eutectic at temperatures ranging from 240 to 400 °C. Due to the strong anisotropy of the AlN wurtzite structure, different AlN faces get etched at very different etching rates. On as-grown rhombohedral and prismatic facets, defect-related etching features could not be traced, as etching these facets was found to mainly emphasize features present already on the un-etched surface. On nitrogen polar basal planes, hexagonal pyramids/hillocks exceeding 100 ?m in diameter may form within seconds of etching at 240 °C. They sometimes are arranged in lines and clusters, thus we attribute them to defects on the surface, presumably originating in the bulk material. On aluminum polar basal planes, the etch pit density which saturates after approx. 2 3 min of total etching time at 350 °C equals the density of a certain type of dislocations (presumably screw dislocations) threading the surface. Smaller etch pits form around annealed indentations, in the vicinity of some bigger etch pits after repeated etching, and sometimes also isolated on the surface area. Although alternate explanations exist, we attribute these etch pits to threading mixed and edge dislocations. This paper features etching parameters optimized for different planes and models on the formation of etching features especially on the polar faces. Finally, the issue of reliability and reproducibility of defect detection and evaluation by wet chemical etching is addressed.

Bickermann, M.; Schmidt, S.; Epelbaum, B. M.; Heimann, P.; Nagata, S.; Winnacker, A.

2007-03-01

350

Excimer laser induced etching of InP  

Microsoft Academic Search

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

V. M. Donnelly; T. R. Hayes

1990-01-01

351

Plasma etch processing of advanced ferroelectric devices  

Microsoft Academic Search

Ferroelectric structures are being used in SRAM devices and are migrating to DRAM devices. A DRAM cell size can be dramatically reduced by employing ferroelectric structures in place of the current silicon oxide capacitor structures. A 5? DRAM cell capacitor can be reduced in size by a factor of 20 using a ferroelectric structure.The current technology used to etch ferroelectric

Alferd Cofer; Paritosh Rajora; Steve Deornellas; Doug Keil

1997-01-01

352

Non-Chromate Metal Surface Etching Solutions.  

National Technical Information Service (NTIS)

Non-chromate solutions for treating and/or etching metals, particularly, aluminum, aluminum alloys, steel and titanium, and method of applying same wherein the solutions include either a titanate or titanium dioxide as a 'drop-in replacement' for a chromi...

M. G. Medeiros R. Brown W. C. Tucker

2002-01-01

353

Etch durable spin-on hard mask  

Microsoft Academic Search

As decreasing the device feature size, the film stack structure used in resist process is also changing. Especially multilayer stack film structure is getting popular for pattern formation on critical layers. Our approach is to form a spin-on hard mask film with high etch resistance by introduction of a new baking function. The results show that a spin-on hard mask

Makoto Muramatsu; Mitsuaki Iwashita; Takashi Kondo; Hisashi Hirose; Seiji Fujimoto

2011-01-01

354

Dry Etching for Coherent Refractive Microlens Arrays.  

National Technical Information Service (NTIS)

Coherent arrays of refractive micro-optics are fabricated in the surface of silicon using a combination of lithographic and reactive-ion etching (RIE) techniques. The aspheric profile can be approximated in a stepwise manner by iterative steps of photolit...

M. B. Stern T. R. Jay

1994-01-01

355

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

356

Diagnostics and etch characteristics in UHF plasmas  

Microsoft Academic Search

Plasma properties, etch characteristics and advantages of a new plasma source where a UHF power is used to ignite the plasma are reported. Plasma was produced using two different antennas and data obtained are discussed comparatively. First, a spokewise antenna consisted of 12 spokes arranged similar to the spokes in a wheel was studied. Though, the UHF power was applied

Yukito Nakagawa; Tsutomu Tsukada; Seiji Samukawa

1998-01-01

357

Energy Gaps in Etched Graphene Nanoribbons  

Microsoft Academic Search

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

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

2009-01-01

358

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

SciTech Connect

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

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

1990-01-01

359

Subliming Ice Surfaces: Freeze-Etch Electron Microscopy  

Microsoft Academic Search

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

J. Gordon Davy; Daniel Branton

1970-01-01

360

Fabrication of Nanotips for Microelectrode Array Sensors Using Meniscus Etching  

Microsoft Academic Search

In this paper, a substantially improved method of fabricating glass microelectrode array sensors for in situ measurements is reported. Meniscus etching with HF-based etchant was used to fabricate nanotips in a repeatable and consistent manner. The meniscus etching process was fully characterized for the etching of glass probe arrays, both numerically and experimentally. Overall, this fabrication method provides a simple,

Jayalakshmi Parasuraman; I. Papautsky

2006-01-01

361

New phase formation in titanium aluminide during chemical etching  

SciTech Connect

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

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

1994-05-01

362

Software to simulate dry etch in photomask fabrication  

Microsoft Academic Search

Dry etch in maskmaking is one of the major contributors to variation of critical dimensions (CD) which is caused primarily by the microloading and macroloading effects. CD variation during etch depends on the type of pattern involved. It would be highly desirable to run a pattern through the software to predict CD variation due to dry etch and decide if

Sergey Babin; Konstantin Bay; Sergey Okulovsky

2004-01-01

363

TRAVIT: software tool to simulate dry etch in maskmaking  

Microsoft Academic Search

A software tool, TRAVIT, has been developed to simulate dry etch in maskmaking. The software predicts the etch profile, etched critical dimensions (CDs), and CD-variation for any pattern of interest. The software also takes into account microloading effect that is pattern dependent and contributes to CD variation. Once CD variation is known, it can then be applied to correct the

S. Babin; K. Bay; S. Okulovsky

2005-01-01

364

Silicon dioxide sacrificial layer etching in surface micromachining  

Microsoft Academic Search

Silicon dioxide sacrificial layer etching has become a major surface micromachining method to fabricate microsensors and microactuators often made of polycrystalline silicon. An overview of the materials available in integrated circuit manufacturing is given, and the etch mechanism and sacrificial layer etch kinetics are reviewed. Selectivity issues important for the proper choice of layers and etchants are addressed discussing the

J Bühler; F-P Steiner; H Baltes

1997-01-01

365

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

366

CR-39 Track Etching and Blow Up Method.  

National Technical Information Service (NTIS)

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 fre...

D. E. Hankins

1985-01-01

367

Anisotropic Hydrogen Etching of Chemical Vapor Deposited Graphene  

NASA Astrophysics Data System (ADS)

In terms of the preparation of graphene, chemical vapor deposition (CVD) has raised its popularity as a scalable and cost effective approach for graphene synthesis. While the formation of graphene on copper foil has been intensively studied, the reverse reaction of graphene reacts with hydrogen has not been systematically studied. In this talk we will present a simple, clean, and highly anisotropic hydrogen etching method for CVD graphene catalyzed by the copper substrate. By exposing CVD graphene on copper foil to hydrogen flow around 800 ^oC, we observed that the initially continuous graphene can be etched to have many hexagonal openings. In addition, we found that the etching is temperature dependent and the etching of graphene at 800 oC is most efficient and anisotropic. 80% of the angles of graphene edges after etching are 120^o, indicating the etching is highly anisotropic. No increase of D band along the etched edges indicates that the crystallographic orientation of etching is zigzag direction. Furthermore, we observed that copper played an important role in catalyzing the etching reaction, as no etching was observed for graphene transferred to Si/SiO2 under similar conditions. This highly anisotropic hydrogen etching technology may work as a simple and convenient way to determine graphene crystal orientation and grain size, and may enable the etching of graphene into nanoribbons for electronic applications.

Zhang, Yi; Li, Zhen; Zhang, Luyao; Kim, Pyojae; Zhou, Chongwu

2012-02-01

368

CR39 track etching and blow-up method  

Microsoft Academic Search

This patent describes 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. A goal of the invention is to enlarge a broad spectrum of tracks in CR-39. Another goal

1987-01-01

369

CR39 track etching and blow up method  

Microsoft Academic Search

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.

1985-01-01

370

Polysilicon Etch Endpoint Detection using an rf Impedance Probe  

Microsoft Academic Search

In a typical capacitively coupled RIE etch system, the rf impedance parameters are dependent upon a number of factors. These include both the system hardware, chamber conditions, feedstocks gases, etch by-product gases, as well as the rf impedance of the wafer. At etch endpoint, the gas composition and also the wafer impedance can change, resulting in changes in the impedance

C. Almgren; D. M. Shaw; G. J. Collins; J. Gilmore

1996-01-01

371

Highly selective PEC etching of gallium nitride device structures  

NASA Astrophysics Data System (ADS)

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

Gao, Yan

372

Rapid reversible superhydrophobicity-to-superhydrophilicity transition on alternating current etched brass.  

PubMed

Reversible surface wetting behavior is a hot topic of research because of the potential engineering applications. In the present work, a hierarchical micro/nanostructure is fabricated on brass by alternate current (AC) etching. The superhydrophilic as-prepared etched brass (EB) turns into superhydrophobic after the modification of stearic acid for 1 min. After annealing at 350 °C for 5 min, the superhydrophobic modified EB surface becomes superhydrophilic again. Furthermore, the annealed EB can restore the superhydrophobicity with the remodification of stearic acid. The wetting transition is realized by stearic acid modification and annealing rapidly in 6 min. The wetting transition mechanism is discussed based on the surface chemical analysis. This method is facile and suitable for the construction of large-scale and complex brass surfaces with tunable wetting behaviors. PMID:23627251

Wang, Zhiwei; Zhu, Liqun; Li, Weiping; Liu, Huicong

2013-05-28

373

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

PubMed

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

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

2012-12-01

374

INVESTIGATION OF ION EXCHANGE PROCESSES IN HYDROFLUORIC ACID SOLUTIONS. SEPARATION OF RaD, RaE, AND POLONIUM  

Microsoft Academic Search

The separation coefficients of K\\/sub d\\/of lead (RaD) and bismuth (RaE) ; by the anion exchange resin AB-17 x 14 were determined, using K. Kraus's method. ; The value of K\\/sub d\\/ for Po was determined from the activity peak of a ; chromatographic column filled with the same resin. The K\\/sub d\\/value for Po was ; found to be

M. K. Nikitin; G. S. Katykhin

1963-01-01

375

Irregular shaping of polystyrene nanosphere array by plasma etching  

NASA Astrophysics Data System (ADS)

The morphology of nanospheres is crucial for designing the nanofabrication in the nanosphere lithography. Here, by plasma etching, the controllable tailoring of the nanosphere is realized and its morphology dependence on the initial shape, microscopic roughness, and the etching conditions is investigated quantitatively. The results show that the shape evolution strongly depends on the etching gas, power, and process duration. Particularly, the aspect ratio (diameter/height) significantly increases with violent etching, turning the spherical shape into tiny ellipsoidal nanoparticles. The findings are practical to the protocol of non-uniform etching of nanoobjects and provide the useful design tool for the device fabrication at nanoscale.

Luo, Hao; Liu, Tingting; Ma, Jun; Wang, Wei; Li, Heng; Wang, Pengwei; Bai, Jintao; Jing, Guangyin

2013-08-01

376

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

SciTech Connect

A chemically assisted ion beam etching (CAIBE) technique is described which employs an ion beam from an electron bombardment ion source and a directed flux of ClF/sub 3/ neutrals. This technique enables the etching of tungsten foils and films in excess of 40 ..mu.. thick with good anisotropy and pattern definition over areas 30 mm/sup 2/, 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, C.

1987-01-01

377

Determination of heavy metals in estuarine sediments by acid digestion and atomic absorption spectrometry  

Microsoft Academic Search

A method for the determination of environmentally significant elements in estilarme sediments is presented. Samples were digested with a mixture of nitric, perchloric and hydrofluoric acids in closed PTFE vessels without metallic mantle. Cadmium, chromium, copper, manganese, nickel, lead and zinc were determined by atomic absorption spectrometry. Good recoveries were obtained by analyzing those elements in reference sediments. Samples of

M. A. Bello; M. Callejón; J. C. Jimenez; F. Pablos; M. Ternero

1994-01-01

378

Enhanced resist and etch CD control by design perturbation  

NASA Astrophysics Data System (ADS)

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

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

2005-11-01

379

Etch induced losses in high Q-value superconducting resonators  

NASA Astrophysics Data System (ADS)

We have investigated how the microwave loss in coplanar wave-guide titanium nitride resonators fabricated on Si wafers is affected by the choice of etch method used to pattern the resonators. Three different etches has been investigated, one fluorine based reactive etch, one chlorine based reactive ion etch, and one argon ion mill. At high microwave probe powers, the two different reactive etches show low internal loss whereas the milled samples show dramatically higher loss. At single photon powers we observe that the fluorine etch resonators exhibit substantially lower loss than the chlorine etched resonators. In the single photon limit we observe loss tangents of 1.10-6 for the fluorine etched, 4.10-6 to 5.5.10-6 for the chlorine etch and 1.4.10-4 for the argon ion mill. We compare these results to numerically calculated filling factors and find that the chlorine etch Si surface has a higher loss tangent than the fluorine etched surface. We also find that re-deposition of Silicon onto the titanium nitride surfaces is the probable cause of the high loss observed for argon ion milled resonators.

Sandberg, Martin; Vissers, Michael; Kline, Jeff; Weides, Martin; Gao, Jiansong; Wisebey, David; Pappas, David

2012-02-01

380

Electrochemical Etching and CV-Profiling of GaN  

NASA Astrophysics Data System (ADS)

We report on the implementation of a robust and reproducible electrochemical CV (ECV) characterization for the (Al, In)GaN material system. A Schottky-like contact is formed by electrolyte, wetting the area of the semiconductor surface delimited by a sealing ring. In reverse bias with common CV technique the concentration of donors and acceptors can be evaluated. Using a newly developed etch procedure, which we call cyclic oxidation, n- and p-type nitrides can be etched (photo-)electrochemically (PEC) to yield reproducibly etched surfaces with mirror-like surface morphology at high etch rates (3 m/h). This new etch procedure is explained in detail. The influence of the process parameters on the etch rate is discussed. Using this new etch procedure, various MOVPE and HVPE grown samples have been characterized by CV-Profiling.

Wolff, T.; Rapp, M.; Rotter, T.

2004-07-01

381

Kinetic-Energy-Enhanced Neutral Etching  

Microsoft Academic Search

A review is presented of the emerging field of neutral-species kinetic-energy-enhanced etching of silicon. As the gate oxide thickness of metal oxide semiconductor field-effect transistors (MOSFET) is decreased to dimensions of 50 Å or less, the potentially damaging effects of high-kinetic-energy ions in plasma processing become important. New methods are required to remove material in a more refined, selective manner.

Stephen R. Leone

1995-01-01

382

Plasma Etching of Low Dielectric Constant Materials  

Microsoft Academic Search

\\u000a Directional plasma etching of vias and trenches in low dielectric constant insulators during the production of multilevel\\u000a interconnection schemes presents a rich spectrum of challenges. This is due to the multitude of low dielectric constant materials\\u000a that are being considered for these applications, and their widely varying properties. We review generic patterning issues\\u000a for inorganic, organic, and mixed organic\\/inorganic low

G. S. Oehrlein; T. E. F. M. Standaert; P. J. Matsuo

383

Modelling of Ion Neutralization for Plasma Etching  

NASA Astrophysics Data System (ADS)

Using fast neutrals for plasma etching in addition to ions or as their replacement has been proposed more than 10 years ago. However, only recently it became obvious that fast neutral based plasma etching could be a good way to avoid charging damage that limits the resolution of plasma etching of high aspect ratio structures. We have used a gas phase Monte Carlo simulation of ion neutralization by charge transfer collisions, as well as different models of neutralization at grazing incidence collisions with walls in an attempt to optimize the fast neutral source proposed by Samukawa [1] which consists of a set of narrow tubes. Estimates of the efficiency of neutralization were made either by assuming a 100 percent efficiency for singular collisions or by calculating the efficiencies for different models of surface neutralization. In all cases efficiency of neutralization on surfaces is high and optimization can be achieved by adjusting geometry of the tubes. [1] S.Samukawa, K. Sakamoto and K. Ichiki, J. Vac. Sci. Technol., A20, 1-8 (2002).

Stojkovi?, Aleksandra; Radjenovi?-Radmilovi?, Marija; Petrovi?, Zoran; Nedeljkovi?, Nataša; Nedeljkovi?, Lj.

2004-09-01

384

Morphological evaluation of new total etching and self etching adhesive system interfaces with dentin  

PubMed Central

Aim: The purpose of this study is to evaluate the resin-dentin interface, quality of the hybrid layer of total-etching and self-etching adhesive systems under scanning electron microscopy (SEM). Materials and Methods: Class V cavities were prepared in 40 extracted human molars. In Group I XP bond (Dentsply), in Group II Adper Single Bond II (3M ESPE), in Group III Adper Easy One (3M ESPE), and in Group IV Xeno V (Dentsply) were applied. Teeth were restored with resin composite, subjected to thermocycling, and sectioned in Buccolingual plane. The samples were demineralized using 6N HCl, for 30 sec, and deproteinized with 2.5% NaOCl for 10 min, gold sputtered, and viewed using a scanning electron microscope. Results: Among the total-etch systems used, the XP Bond showed a clear, thick hybrid layer, with long resin tags and few voids. Among the self-etch adhesive systems, the Xeno V did not show a clearly recognizable hybrid layer, but there were no voids and continuous adaptation was seen with the dentin. Conclusion: The adaptation of self-etch adhesives to the resin-dentin interface was good without voids or separation of phases; showing a thin, continuous hybrid layer.

Hegde, Mithra N; Hegde, Priyadarshini; Chandra, C Ravi

2012-01-01

385

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

SciTech Connect

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

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

1997-02-11

386

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

NASA Astrophysics Data System (ADS)

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

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

2004-01-01

387

Investigation on femtosecond laser-assisted microfabrication in silica glasses  

Microsoft Academic Search

Fabrication of microstructures embedded in silica glasses using a femtosecond (fs)-laser-assisted chemical etching technique is systematically studied in this work. By scanning the laser pulses inside samples followed by the treatment of 5%-diluted hydrofluoric (HF) acid, groups of straight channels are fabricated and the relationship between the etching rate and processing parameters, including laser power, scanning speed, scanning time and

Hewei Liu; Feng Chen; Qing Yang; Jinhai Si; Xun Hou

2010-01-01

388

Porous Silicon  

Microsoft Academic Search

Electrochemical etching in solutions based on hydrofluoric acid has been widely used to form light-emitting porous silicon. However, the effects of a number of the experimental parameters on the quality of the porous silicon produced have yet to be fully investigated. In the present paper the influence of temperature and viscosity of the etching solution is evaluated in terms of

D. J. Blackwood; Y. Zhang

2001-01-01

389

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.; Aït-Kaci, H.; Grech, P.; Rodriguez, J. B.; Christol, P.

2009-06-01

390

Silicon dioxide etching yield measurements with inductively coupled fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

Oxide etching yield has been measured directly with inductively coupled fluorocarbon plasmas. The yields measurement technique of this work can provide useful information for feature profile evolution modeling, which is essential to understand various issues in oxide etching such as reactive ion etching (RIE) lag, inverse RIE lag, etch stop, microtrenching, bowing, etc. Etching and deposition yields per ion were measured using quartz crystal microbalance (QCM) as a function of ion bombardment energy, ion-to-neutral flux ratio, and ion-impinging angle. C2HF5, C2F6, C2H4F2, and C4F8 were used for the oxide etching. Oxide etching mechanism with those gases is complex because etching and deposition are involved at the same time. In highly selective processes fluorocarbon deposition plays important role in determining etching characteristics. Two fluorocarbon deposition mechanisms are identified in this work: neutral deposition and ion-enhanced deposition. The low-energy ions are believed to enhance the deposition rates by creating active sites and fluorocarbon neutrals deposit on the active sites with higher sticking probability. A surface kinetic model is suggested to explain the ion-enhanced mechanism and shows good agreement with experimental data. Angular yield measurement shows that when fluorocarbon deposition is relatively severe, etching yield decreases significantly as the incident angle increases and deposit fluorocarbon at a high incident angle above 60°.

Chae, Heeyeop; Vitale, Steven A.; Sawin, Herbert H.

2003-03-01

391

Improving aluminum nitride plasma etch process for MEMS applications  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

392

NiCr etching in a reactive gas  

SciTech Connect

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

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

2007-05-15

393

Bonding of Self-adhesive (Self-etching) Root Canal Sealers to Radicular Dentin  

Microsoft Academic Search

The latest generation of methacrylate resin–based sealers has eliminated the use of separate self-etching primers by incorporating acidic resin monomers in the sealers to render them self-adhesive to dentin. This study examined the adhesive strengths, interfacial ultrastructure, and tracer penetration of a nonetching (EndoREZ; Ultradent, South Jordan, UT) and two self-adhesive methacrylate resin–based sealers (MetaSEAL; Parkell, Farmington, NY, and RealSeal

Brian R. Babb; Robert J. Loushine; Thomas E. Bryan; Jason M. Ames; Mark S. Causey; Jongryul Kim; Young Kyung Kim; R. Norman Weller; David H. Pashley; Franklin R. Tay

2009-01-01

394

Effect of the composition of etching agents on the mechanical properties of steel  

Microsoft Academic Search

For these experiments we selected 20% and 10% solutions of HeSO 4 and HC1, and mixtures of 10% H2SO 4 + 10 % HC1 and 15 % H2SO 4 + 6 % HC1. The acid corrosion inhibitors were I-1-V (0.2 %) and katapin BPV (0.2%), used extensively in the Soviet Union to etch steels. Ten-centimeter specimens of steel rod, made

A. S. Afanas'ev; E. N. Chankova; S. G. Tyr; L. D. Grigor'eva

1975-01-01

395

Cross-Sectional Conductive Atomic Force Microscopy of CdTe\\/CdS Solar Cells: Effects of Etching and Back-Contact Processes  

Microsoft Academic Search

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

H. R. Moutinho; R. G. Dhere; C.-S. Jiang; T. A. Gessert; A. M. Duda; M. Young; W. K. Metzger; X. Li; M. M. Al-Jassim

2006-01-01

396

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

397

Etch induced microwave losses in titanium nitride superconducting resonators  

NASA Astrophysics Data System (ADS)

We have investigated the correlation between the microwave loss and patterning method for coplanar waveguide titanium nitride resonators fabricated on silicon wafers. Three different methods were investigated: fluorine- and chlorine-based reactive ion etches and an argon-ion mill. At high microwave probe powers, the reactive etched resonators showed low internal loss, whereas the ion-milled samples showed dramatically higher loss. At single-photon powers, we found that the fluorine-etched resonators exhibited substantially lower loss than the chlorine-etched ones. We interpret the results by use of numerically calculated filling factors and find that the silicon surface exhibits a higher loss when chlorine-etched than when fluorine-etched. We also find from microscopy that re-deposition of silicon onto the photoresist and side walls is the probable cause for the high loss observed for the ion-milled resonators.

Sandberg, Martin; Vissers, Michael R.; Kline, Jeffrey S.; Weides, Martin; Gao, Jiansong; Wisbey, David S.; Pappas, David P.

2012-06-01

398

Correlated crystallographic etching of graphene and nanoribbon formation  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

399

High speed anisotropic etching of Pyrex ® for microsystems applications  

Microsoft Academic Search

We report high speed etching of glass (Pyrex® 7740) substrates using an inductively coupled plasma (ICP) reactive ion etching (RIE) process employing sulfur hexafluoride\\/argon (SF6\\/Ar) based chemistry. Electroplated Ni over a patterned Cr\\/Au seed layer was used as the hard mask for etching. Detailed process characterization was performed by varying the process parameters which include substrate temperature, ICP power, substrate

Abhijat Goyal; Vincent Hood; Srinivas Tadigadapa

2006-01-01

400

Development of TMAH anisotropic etching manufacturing process for MEMS  

Microsoft Academic Search

An investigation on the influence of etchant concentration, dissolving silicon content and additives during silicon anisotropic etching in TMAH has been carried out. Based on the Taguchi method, the etch rates of Si, Al, and SiO2 were measured via under-etch experiments using the wagon- wheel mask pattern. The improvement on the surface quality was observed by agitating solution under ultrasonic

Jiunn-Jye Tsaur; Shih-I. Yang; Chen-Hsun Du; Zong S. Lin; Cheng-Tang Huang; Chengkuo Lee

2000-01-01

401

Low-doped etch stopping for micromechanical device production  

Microsoft Academic Search

This paper describes significant advancements to a low doped etch-stop technique which increases the differential etch rate of high doped to low doped silicon (Rh\\/l) by a factor of 4 or greater, to a value of up to Rh\\/l approximately equals 50:1. The objective of the research was to achieve this increase in the differential etch rate by decreasing the

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

1995-01-01

402

Excimer laser direct etching of GaAs  

Microsoft Academic Search

The direct etching of GaAs substrates by excimer laser light has been studied at wavelengths of 193 nm (ArF). 248 nm (KrF) and 351 nm (XeF). For absorbed laser fluences greater than the direct etching fluence thresholds of 23 mJ cm-2 for ArF, 33 mJ cm-2 for KrF and 80 mJ cm-2 for XeF, the authors observe direct etching in

G. M. Davis; D. W. Thomas; M. C. Gower

1988-01-01

403

Development and analysis of etched-facet indium phosphide-based active photonic components for monolithically integrated fiber coupling assemblies  

NASA Astrophysics Data System (ADS)

In this dissertation we have investigated the design, development, and testing of etched-facet semiconductor lasers and amplifiers operating at a wavelength of 1.55 ?m. We first studied the process development of reactive ion etched laser facets using a methane-based plasma. Utilizing a design of experiment (DOE) approach, and optimizing the parameters for verticality and etch rate, we were able to obtain laser facets with very high verticality, 2° +/- 0.7°, and an rms surface roughness of 22 nm, the best recorded to date for methane based facet etching. We studied the long-term reliability of these etched facet lasers, in direct comparison to cleaved facet structures, by the use of a 70°C, 150 mA, 125 hour burn-in, followed by long-term testing of >2000 hours at 3mW output power. We found the room temperature mean- time-to-failure (MTTF) for the etched facets to be 75% of that of the cleaved devices, with values of 0.86 × 105 hrs and 1.15 × 105 hrs, respectively. The activation energy for the etched facet lasers was found to be 0.636 eV compared to 0.678 eV for cleaved devices. Extending the work of the etched facet laser to amplifiers, we studied the development of a monolithically integrated bowed amplifier with v-groove fiber coupling assembly. We studied the formation of high-quality InP-based v-grooves using both oxidizing and acidic etches, taking advantage of the vertical or recessed endwall profile to allow close fiber coupling. Using 4 quantum well laser material, we were able to show broadband gain of over 12 dB for 1 mm, 2.6 ?m ridge structures which closely resembles results from straight ridge devices. Utilizing the flexibility of fiber height control via the facet etching and v-groove profiles, we were able to control the lateral and transverse fiber position to within tenths of a micron.

Whaley, Ralph Doud, Jr.

2001-09-01

404

Inductively coupled plasma etching of III-nitride semiconductors  

NASA Astrophysics Data System (ADS)

The principal focus of this research was the employment of an in-house designed and constructed inductively coupled plasma (ICP) system for integrated studies pertaining to the etching rates and etching selectivity among AlN, GaN, and AlxGa1-xN. An (ICP) system was chosen because of its high plasma density and low cost relative to other high-density plasma etching systems. The etch rates were studied as a function of ICP power, pressure, DC bias, and gas composition. The use of a mixture of 2 sccm BCl 3 and 18 sccm Cl2 resulted in a maximum etch rate of 2.2 microm/min for GaN as well as nearly vertical sidewalls with proper masking. A selectivity value, i.e. the ratio of the etch rates between two materials, as high as 48 was achieved between GaN and AlN with the addition of low concentrations of O2 to a Cl2/Ar chemistry. The use of another selectivity technique, namely, low DC biases resulted in a maximum selectivity of 38. The mechanisms responsible for the GaN etching were determined by monitoring both the ion density with a Langmuir probe and the relative Cl radical density with an optical emission spectrometer. Increasing the ion density resulted in a non-linear increase in the etch rates; increasing the Cl radical density had a minimal affect on etch rate.

Smith, Scott Alan

405

TRAVIT: software tool to simulate dry etch in maskmaking  

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

406

Electrochemical etching and CV-profiling of GaN  

NASA Astrophysics Data System (ADS)

We report on the implementation of a robust and reproducible electrochemical CV (ECV) characterization for the (Al,In)GaN material system. A Schottky-like contact is formed by electrolyte, wetting the area of the semiconductor surface delimited by a sealing ring. In reverse bias with common CV technique the concentration of donors and acceptors can be evaluated. Using a newly developed etch procedure, which we call cyclic oxidation nitrides can be etched (photo-)electrochemically (PEC) to yield reproducibly etched surfaces with mirror-like surface morphology at high etch rates (3 ?m/h). This new etch procedure is not restricted to n-type nitrides, but works also for p-type nitrides. In the first time cycle the nitride semiconductor is electrochemically oxidized: UV illumination and forward voltage is applied to oxidize n-GaN and p-GaN, respectively. During this time cycle the local pH-value of electrolyte at etch area decreases. The established thin oxide film - essential for smooth etching - is dissolved by jet-pumping with fresh electrolyte during the complementary time cycle. The influence of the process parameters on the etch rate is discussed. The application of this new etch procedure to characterize various MOVPE and HVPE grown samples by CV-Profiling is presented.

Wolff, T.; Rapp, M.; Rotter, T.

2005-02-01

407

Investigation of acidic texturization for multicrystalline silicon solar cells  

Microsoft Academic Search

A new texturing method especially for multicrystalline silicon solar cells was investigated. This technique is based on a maskless acidic etching of silicon. It can texturize surfaces quite homogeneously in a short time and eliminate a saw damage removal process. The authors showed phosphoric acid (HâPOâ) is preferable as a catalytic agent to moderate etching rates without effecting texturing. A

Y. Nishimoto; T. Ishihara; K. Namba

1999-01-01

408

Improving the quality of the quartz fiber postcore bond using sodium ethoxide etching and combined silane/adhesive coupling.  

PubMed

The influence of different silane/dentin adhesives on the microtensile bond strengths of a hybrid composite to sodium ethoxide-etched quartz fiber posts was investigated. A prehydrolyzed silane was applied without an adhesive and compared to two-component systems in which hydrolysis of the silane occurred after mixing with the acidic monomer present in the dentin adhesives. Nanoleakage along post/core interfaces was examined after silver nitrate tracer penetration using scanning electron microscopy. Higher interfacial strengths and more uniform adaptation between the etched fiber post surface and the composite core were recorded after post treatment with silane/adhesive couplings. The combination of silane with two-step self-etch adhesives improves the chemical retention of composites around etched fiber posts with minimal nanoleakage. Although the one-step self-etching adhesive/silane combination enhances post adhesion, the extensive nanoleakage provides channels for rapid water sorption that may expedite hydrolytic degradation of the post/core interface. PMID:16631846

Monticelli, Francesca; Osorio, Raquel; Toledano, Manuel; Goracci, Cecilia; Tay, Franklin R; Ferrari, Marco

2006-02-07

409

Capacitive Systems for Dielectric Plasma Etch  

SciTech Connect

Two and three frequency capacitive systems are being used to generate weakly ionized plasma in Ar/O/CxFy chemistries at the millitorr pressure range. One or two of the frequencies are generally used to accelerate ions (by sheath rectification) while the third is generally used to independently raise plasma density to levels sufficient for etching. The choice of frequencies is based on plasma impedances, which then yield rf voltages that can either consume power by creating a DC plasma sheath or consume power by creating plasma density (when sheath power is minimized). Within the two frequencies that create sheaths, the choice of ion energy spreads is determined by ion sheath transit time relative to an rf cycle. Technology challenges arising from the required plasma creation include significant intermodulation, very high cross talk between generators, and the avoidance of arcing through on any of the surfaces in contact with the plasma (including the gas injection system). The etch chamber is designed such that all generators are directly linked on a single coupling point or the plasma directly connects one launcher to another. We discuss and analyze different frequency ranges and their impact on chamber design.

Hoffman, Daniel [Applied Materials, Inc., 974 E. Arques Avenue, Sunnyvale, CA 94086 (United States)

2005-09-26

410

Capacitive Systems for Dielectric Plasma Etch  

NASA Astrophysics Data System (ADS)

Two and three frequency capacitive systems are being used to generate weakly ionized plasma in Ar/O/CxFy chemistries at the millitorr pressure range. One or two of the frequencies are generally used to accelerate ions (by sheath rectification) while the third is generally used to independently raise plasma density to levels sufficient for etching. The choice of frequencies is based on plasma impedances, which then yield rf voltages that can either consume power by creating a DC plasma sheath or consume power by creating plasma density (when sheath power is minimized). Within the two frequencies that create sheaths, the choice of ion energy spreads is determined by ion sheath transit time relative to an rf cycle. Technology challenges arising from the required plasma creation include significant intermodulation, very high cross talk between generators, and the avoidance of arcing through on any of the surfaces in contact with the plasma (including the gas injection system). The etch chamber is designed such that all generators are directly linked on a single coupling point or the plasma directly connects one launcher to another. We discuss and analyze different frequency ranges and their impact on chamber design.

Hoffman, Daniel

2005-09-01

411

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

Microsoft Academic Search

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

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

2005-01-01

412

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

413

Step-etched prism coupling for optical waveguide biosensors  

Microsoft Academic Search

We report a light input coupling method into a buried planar waveguide that is very promising for applications in disposable optical waveguide biosensors. The superstrate of the waveguide is step-etched and a prism made from polystyrene is permanently bonded onto the etched step using optical glue. The plastic prism and the waveguide form a `plug-in' assembly of the disposable part

Yan Zhou; Yee Loy Lam; Shide Cheng; Chan Hin Kam

1998-01-01

414

Emissivity of etched Cu-Nb in-situ alloys  

SciTech Connect

Cu-Nb in-situ alloys possess high strenght plus thermal conductivity properties and are therefore of interest in heat transfer applications. Etching the surfaces of these alloys to preferentially remove Cu places the Nb filaments in relief. Experiments demonstrate that the emissivity of such etched surfaces can be increased from around 0.08 to values greater than 0.9.

Downing, H.L.; Verhoeven, J.D.; Gibson, E.D.

1987-04-01

415

Considerations on high resolution patterns engraved by ion etching  

Microsoft Academic Search

The theoretical model of a surface contour evolution under ion bombardment is applied to the study of the behavior of a mask during ion etching. Two new parameters are defined. The first gives an upper limit of the etching time when distortion-free patterns are needed. The second gives the lateral shift of the pattern if the previous limit is exceeded.

MICHEL CANTAGREL

1975-01-01

416

Focused electron-beam-induced etching of silicon dioxide  

SciTech Connect

Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO{sub 2} matrix, and subsequently rate limited by XeF{sub 2} availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO{sub 2} to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

Randolph, S.J.; Fowlkes, J.D.; Rack, P.D. [University of Tennessee, Department of Materials Science and Engineering, 434 Dougherty Engineering Building, Knoxville, Tennessee 37996-2200 (United States)

2005-08-01

417

Hafnium Oxide Film Etching Using Hydrogen Chloride Gas  

Microsoft Academic Search

Hydrogen chloride gas removes the hafnium oxide film formed by atomic layer deposition at the etch rate of about 1 nm\\/min. A 100 nm-thick hafnium oxide film was perfectly etched off at 1173 K for 60 min by 100% hydrogen chloride gas at 100 sccm. A weight decrease in the hafnium oxide film was observed at temperatures higher than ca.

Hitoshi Habuka; Masahiko Yamaji; Yoshitsugu Kobori; Sadayoshi Horii; Yasuo Kunii

2009-01-01

418

Etching Studies on Singly and Doubly Rotated Quartz Plates.  

National Technical Information Service (NTIS)

Experiments aimed at finding a chemical polish for the doubly rotated SC-cut have been performed with a variety of etchants. The surface morphologies of etched SC-cut plates depend strongly on the composition of the etching solutions. Some of the solution...

J. R. Vig R. J. Brandmayr R. L. Filler

1980-01-01

419

Laser Illuminated Track Etch Scattering(LITES) Dosimetry System.  

National Technical Information Service (NTIS)

It is proposed to build an instrument capable of automated reading of track etch CR-39 foils which have been exposed to neutron dose levels in between 0.0 and 5.0 rem of exposure. A new concept in track etch dosimetry reading has been developed at Los Ala...

M. E. Moore N. E. Hertel H. J. Gepford P. Wasiolik R. E. Hermes J. M. Hoffman R. J. McKeever

2001-01-01

420

RF plasma enhanced vapor deposition and etching of silicon nitride  

Microsoft Academic Search

This is a report on the deposition and etching of silicon nitride films using RF plasma techniques. Experiments were conducted to determine optimum operating parameters (e.g., gas flow rates, temperature, power, and pressure) for the AMT (Applied Materials Technology) Plasma I reactor in both the deposition and etching modes of operation. Silane and ammonia with nitrogen as a carrier gas

Hampy

1978-01-01

421

A geometric etch-stop technology for bulk micromachining  

NASA Astrophysics Data System (ADS)

This paper describes a new fabrication method for the simultaneous creation of multi-level single-crystalline silicon structures, each with a different thickness. The method combines deep dry etching and wet anisotropic etching of silicon in order to avoid multiple back-side alignment steps and timed etches. The levels are defined in a single lithographic step from the front side. The fabrication involves etching of deep trenches from the front side of the wafer followed by a refill and etch back process. The final structure is defined by maskless wet etching of the bulk silicon. The progress of the anisotropic wet etch is impeded by the geometric pattern at the bottom of the trenches, and thus structures with various thickness ranging from ten to a few hundred micrometres can be implemented. The effect of various design parameters, such as trench geometry, refill material and reactive ion etching lag, are discussed and design rules are established. The capabilities of the method are demonstrated by the fabrication of a number of devices, such as 1200×1200×3.5 µm diaphragms supported by a 40 µm thick rim and (1800×10×3 µm) embedded hot-wire anemometers suspended by a 0.2 µm thick dielectric bridge.

Amir Parviz, Babak; Najafi, Khalil

2001-05-01

422

Direct Measurement of Surface Charging during Plasma Etching  

Microsoft Academic Search

An on-wafer surface potential probe was developed for the direct real-time measurement of the local charging on a wafer surface during plasma etching. Pressure and rf power dependencies of the surface charging potential were measured in a nonuniform magnetron plasma by this probe. The variation in etching profiles was also observed by scanning electron microscopy (SEM). The measured surface charging

Shigemi Murakawa; James P. McVittie

1994-01-01

423

Qualitative modeling of silica plasma etching using neural network  

NASA Astrophysics Data System (ADS)

An etching of silica thin film is qualitatively modeled by using a neural network. The process was characterized by a 23 full factorial experiment plus one center point, in which the experimental factors and ranges include 100-800 W radio-frequency source power, 100-400 W bias power and gas flow rate ratio CHF3/CF4. The gas flow rate ratio varied from 0.2 to 5.0. The backpropagation neural network (BPNN) was trained on nine experiments and tested on six experiments, not pertaining to the original training data. The prediction ability of the BPNN was optimized as a function of the training parameters. Prediction errors are 180 Å/min and 1.33, for the etch rate and anisotropy models, respectively. Physical etch mechanisms were estimated from the three-dimensional plots generated from the optimized models. Predicted response surfaces were consistent with experimentally measured etch data. The dc bias was correlated to the etch responses to evaluate its contribution. Both the source power (plasma density) and bias power (ion directionality) strongly affected the etch rate. The source power was the most influential factor for the etch rate. A conflicting effect between the source and bias powers was noticed with respect to the anisotropy. The dc bias played an important role in understanding or separating physical etch mechanisms.

Kim, Byungwhan; Kwon, Kwang Ho

2003-01-01

424

Electron emission from etched diamond and its structural analysis  

Microsoft Academic Search

Discontinuous diamond films were deposited on silicon by microwave plasma chemical vapor deposition (MPCVD). The diamond films were sharpened by argon ion etching. Field emission turn-on field was drastically lowered after sharpening. Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were used for structural characterization. Possible mechanisms of field emission from the etched field emitter are discussed

W. B. Choi; D. R. McGregor; L. Bergman; R. J. Nemanich; J. J. Hren; J. J. Cuomo

1998-01-01

425

Correction for etch proximity: new models and applications  

NASA Astrophysics Data System (ADS)

Short-range etch proximity effects increase intra-die CD variability and degrade the IC performance and yield. Tight control of the etch bias is an increasingly critical factor in realizing the ITRS technology nodes. The 2000 technology nodes revision added a new category, the post-etch 'physical' gate length metric, that is 9 - 17% smaller than 'in-resist' gate length. We present new etch proximity correction methods and models designed to reduce negative impact of etch-induced CD variability and increase uniformity of the controlled over- etching. Resolution Enhancement Technologies (RET) design correction methods typically employ 'lumped' process models. We found that an alternative methodology based upon separation of the process factors and the related models may yield better accuracy, performance, and better suit the design and process optimization flows. The contributions from the reticle, the optics, the wafer, and etch are individually determined and then used either separately or in aggregation for the most flexible and optimum correction of their respective contributions. The etch corrections are based on the Variable Etch Bias model (VEB model). This semi-empirical model requires experimental CD information to be collected from the test patterns under fixed process conditions (point-process model). It demonstrates excellent fit to the early experimental CD-SEM data gathered to date, which spans a variety of layout features and process conditions. The VEB model works in conjunction with CalibreR software system's Variable Threshold Resist-Extended (VTR-E) model, however the etching is modeled separately from the optics and the resist processing. This yields better understanding and more accurate explanation of the experiments than those that are produced by the 'lumped' process modeling. The VEB model explains etch- induced bias in terms of the following three proximity characteristics or variables: effective trench width (or pattern separation), pattern density, and effective line width (or pattern granularity). We synthesized and studied their integral representations. Performance fitness of the various weighting, smoothing, and anisotropic integral kernels and their parameters were studied to correctly reflect the etch bias behavior on silicon. We found that depending on the resist composition and layer types (poly or metal), the etch bias can sometimes be explained only by one or two (out of three) proximity variables. The aperture and microloading etch effects are studied and shown to be correctly reflected in the model. We demonstrate how model-based corrections improve CD uniformity of the poly and metal layers by compensating for the iso/dense and inverse-iso/dense biases. More complicated 2-D proximity effects are also captured, which is confirmed by the comparison of the SEM images to the simulations.

Granik, Yuri

2001-09-01

426

Etching formation of GaN micro optoelectronic device array  

NASA Astrophysics Data System (ADS)

GaN based micro emitter optoelectronic device array has been proved to be the core component for wide variety of applications such as microdisplay, biosensor, projection etc. Etching is one of the key steps to form the GaN micro emitter array device, including inductively coupled plasma (ICP) dry etch and alkaline solution wet etch. This paper reports the recent progress made by Ostendo Technologies Inc in fabricating the ultra-high density, large aspect-ratio etching formed monolithic GaN micro emitter optoelectronic device array. The unit density reaches 1M per cm2, with good uniformity across the whole wafer. Perpendicular etching sidewall was achieved, with smooth surface roughness which is significance feature used for laser diodes (LDs) device.

Fan, Qian; Lee, Frank; Yadavalli, Kameshwar; Lee, Michael S.; Chuang, Chih-Li; El-Ghoroury, Hussein

2011-02-01

427

Low-doped etch stopping for micromechanical device production  

NASA Astrophysics Data System (ADS)

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

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

1995-09-01

428

Consideration of VT5 etch-based OPC modeling  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

429

Method for laser-assisted silicon etching using halocarbon ambients  

NASA Astrophysics Data System (ADS)

An etching process allows a selective single-step patterning of silicon devices in a noncorrosive environment. The etching of silicon relies on a maskless laser-assisted technique in a gaseous halocarbon ambient, such as the gaseous chlorofluorocarbons, dichlorodifluoromethane and chloropentafluoroethane. Laser-assisted photothermal chemical etching reactions on silicon occur in these ambients when the incident fluence from an excimer laser at 248 nm exceeds the melt threshold (approximately 0.75 J/sq cm). When incident fluence exceeds the ablation threshold (approximately 2.2 J/sq cm) an undesirable, increased surface roughness is observed. Etch rates as large as approximately 15 A per pulse are attained within predetermined processing windows. This provides a means for thin membrane formation in silicon, rapid etches and processing of packaged devices or partially fabricated dies.

Russell, Stephen D.; Sexton, Douglas A.; Orazi, Richard J.

1993-11-01

430

Software to simulate dry etch in photomask fabrication  

NASA Astrophysics Data System (ADS)

Dry etch in maskmaking is one of the major contributors to variation of critical dimensions (CD) which is caused primarily by the microloading and macroloading effects. CD variation during etch depends on the type of pattern involved. It would be highly desirable to run a pattern through the software to predict CD variation due to dry etch and decide if the variation is within the prescribed tolerance or if the pattern needs additional correction, and to what degree. In this paper, a dry etch simulation tool TRAVIT is introduced that is capable of simulating etch profile, CD, and CD errors. Using a set of desired process conditions, the software runs the simulation for the pattern of interest that helps to optimize sidewall, bias, and CD variation. Incorporating simulation into the maskmaking process can save cost and shorten the time to production.

Babin, Sergey; Bay, Konstantin; Okulovsky, Sergey

2004-10-01

431

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

432

An Autonomously Controllable Plasma Etching System Based on Radical Monitoring  

NASA Astrophysics Data System (ADS)

The optimum conditions for a plasma etching device are generally determined from the results of etching a sample while varying an external parameter (e.g., gas mass flow, gas mixing ratio, process chamber pressure, or plasma source power). However, to realize controlled plasma etching with few fluctuations on a subnanometer scale, it is essential to develop a system that is controlled in real-time based on internal plasma parameters (e.g., densities and energies of radicals and ions), which directly determine process characteristics, rather than external plasma parameters. We have developed an autonomously controlled plasma etching system that performs integrated monitoring of radicals in the gas phase and on the surface of films. The etching rate of organic materials could be autonomously controlled based on hydrogen and nitrogen radical densities obtained in real-time.

Takahashi, Shunji; Kawauchi, Ryota; Takashima, Seigo; Den, Shoji; Katagiri, Toshiro; Kano, Hiroyuki; Ohta, Takayuki; Ito, Masafumi; Suzuki, Tatsuya; Takeda, Keigo; Hori, Masaru

2012-07-01

433

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

434

Evaluation and Application of Resist for Alkaline Wet Etching  

NASA Astrophysics Data System (ADS)

ProTEK PSB and ProTEK B3 (Brewer Science, Inc.) are negative type photosensitive resist and non-photosensitive resist for alkaline wet etching, respectively. This paper mainly reports the patterning characteristics, etch resistance and removal characteristics of ProTEK PSB under practical conditions for a real application. Our study found two problems of ProTEK PSB: unacceptably-large side-etching and difficulty in removing the primer by organic solvents or O2 ashing. For the fabrication of a LSI-integrated tactile sensor, we used ProTEK PSB with a low temperature oxide underlayer. This combination solves both side etching problem for ProTEK PSB and pinhole problem for low temperature oxide, providing the practical alkaline etching mask which can be prepared at low temperature.

Takahashi, Tomokazu; Makihata, Mitsutoshi; Esashi, Masayoshi; Tanaka, Shuji

435

Anisotropic etching of silicon for accelerometer chip fabrication  

NASA Astrophysics Data System (ADS)

Anisotropic etching of (100) single crystal silicon (SCS) in potassium hydroxide (KOH) -- water solutions and Ethylene diamine pyrocatechol (EDP) -- water solutions has been investigated for fabrication of a seismic mass -- spring structure used in inertial accelerometers. The vertical anisotropic etching rate and lateral undercut rates have been experimentally determined in both the cases. For EDP the effect of temperature on the etching rates have been found to follow an Arrhenius type of temperature dependence. The activation energies vary from 0.17 eV to 0.58 eV for EDP solutions of varying concentration. The effect of addition of iso-propyl alcohol to KOH have resulted in reduction of etching rates. The basic design rules for etching a seismic mass structure with vertical end walls on (100) silicon wafer are highlighted.

Saha, I.; Joseph, J.; Islam, R.; John, J.; Kanakaraju, K.; Jain, Yashwant K.; Alex, T. K.

2003-10-01

436

Efficient solution to selective wet etching of ultra-thick copper sacrificial layer with high selective etching ratio  

Microsoft Academic Search

In this paper, developed is an effective solution to selective etching of ultra-thick copper sacrificial layer for the realization of3-D suspended metal microstructures, in which the thickness of sacrificial Cu laminations can reach more than 100 microns. The proposed effective etching solution is based on an additive complex in the ammonia liquor with the assistance of oxidant. The primary purposes

Y. B. Wu; G. F. Ding; H. Wang; C. C. Zhang

2011-01-01

437

Influence of etching current density on the morphology of macroporous silicon arrays by photo-electrochemical etching  

NASA Astrophysics Data System (ADS)

Macroporous silicon arrays (MSA) have attracted much attention for their potential applications in photonic crystals, silicon microchannel plates, MEMS devices and so on. In order to fabricate perfect MSA structure, photo-electrochemical (PEC) etching of MSA and the influence of etching current on the pore morphology were studied in detail. The current-voltage curve of a polished n-type silicon wafer was presented in aqueous HF using back-side illumination. The critical current density JPS was discussed and the basic condition of etching current density for steady MSA growth was proposed. An indirect method was presented to measure the relation of JPS at the pore tip and etching time. MSA growth was realized with the pore diameter constant by changing the etching current density according to the measuring result of JPS. MSA with 295 ?m of depth and 98 of aspect ratio was obtained.

Guozheng, Wang; Li, Chen; Xulei, Qin; Ji, Wang; Yang, Wang; Shencheng, Fu; Qingduo, Duanmu

2010-07-01

438

Homogeneous luminescent stain etched porous silicon elaborated by a new multi-step stain etching method  

NASA Astrophysics Data System (ADS)

This paper presents a new method to produce porous silicon which derived from the conventional stain etching (SE) method. But instead of one etching step that leads to formation of porous layer, the substrate is subjected to an initial etching step with a duration ?t0 followed by a number of supplementary short steps that differs from a layer to another. The duration of the initial step is just the necessary time to have a homogenous porous layer on the whole surface of the substrate. It was found that this duration is largely dependent of the doping type and level of the silicon substrate. The duration of supplementary steps was kept as short as possible to prevent the formation of bubbles on the silicon surface during silicon dissolution which leads generally to inhomogeneous porous layers. It is found from surface investigation by atomic force microscopy (AFM) that multistep stain etching (MS-SE) method allows to produce homogeneous porous silicon nanostructures compared to the conventional SE method. The chemical composition of the obtained porous layers has been evaluated using Fourier transform infrared spectroscopy (FTIR). Photoluminescence (PL) measurement shows that porous layers produced by SE and MS-SE methods have comparable spectra indicating that those layers are composed of nanocrystallites with comparable sizes. But the intensity of photoluminescence of layer elaborated by MS-SE method is higher than that elaborated by the SE method. Total reflectance characteristics show that the presented method allows the production of porous silicon layers with controllable thicknesses and optical properties. Results for porous silicon layers elaborated on heavily doped n-type silicon show that the reflectance can be reduced to values less than 3% in the major part of the spectrum.

Hajji, M.; Khalifa, M.; Slama, S. Ben; Ezzaouia, H.

2013-11-01

439

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

Microsoft Academic Search

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

Kensuke Nishioka; Tsuyoshi Sueto; Nobuo Saito

2009-01-01

440

Role of nitrogen in the downstream etching of silicon nitride  

SciTech Connect

Chemical downstream etching of silicon nitride (Si{sub 3}N{sub 4}) requires the addition of nitrogen to the discharge for obtaining efficient etch rates. A 10{percent} addition of N{sub 2} to a CF{sub 4}/O{sub 2} discharge (CF{sub 4}/O{sub 2} = 1.2, 0.525 Torr) causes a factor of 6 increase in the Si{sub 3}N{sub 4} etch rate and a 8{percent} decrease in the silicon dioxide etch rate. The result is selectivities approaching 9:1. Importantly, the conversion of CF{sub 4} to F and F-containing reactive species by the discharge decreases or remains constant as nitrogen is added to the discharge mix, indicating that the etching reaction is not limited by delivery of these species to the substrate. By measuring the amount of NO and NO{sub 2} in the etch chamber, it is found that the NO concentration increases by a factor of 6 as N{sub 2} is added, while the amount of NO{sub 2} remains small and constant. The NO signal is significantly reduced during nitride etching compared to the signal observed during a discharge with an empty etch chamber, implying that the increase in Si{sub 3}N{sub 4} etch rate is related to the formation of NO in the discharge. This view is consistent with the observation that an NF{sub 3} plasma in a quartz discharge tube results in a nitride etch rate which is a factor of 2 higher than for the same discharge in a sapphire tube. The conclusion is that the oxygen liberated by erosion of the quartz tube allows the formation of NO. That NO is a key Si{sub 3}N{sub 4} etch reactant was confirmed by performing a series of experiments in which N{sub 2}, NO, NO{sub 2}, and N{sub 2}O were injected into the discharge and then downstream in the reaction chamber during a CF{sub 4}/O{sub 2} discharge. Nitride etch rates increased significantly upon injection of NO into both discharge and etch chamber as compared to injection of the other N{sub {ital x}}O{sub {ital y}} species. {copyright} {ital 1996 American Vacuum Society}

Blain, M.G.; Meisenheimer, T.L.; Stevens, J.E. [Microelectronics Development Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87185-1077 (United States)

1996-07-01

441

Quantitative improvement in MD-based plasma etching simulator: Si etching by halogen-including plasmas  

NASA Astrophysics Data System (ADS)

Classical molecular dynamics (MD) is widely used as a numerical technique to simulate interactions between chemically reactive plasmas and solid materials. Although many MD studies have been published, discussions on the accuracy, capability, and validly are still lacking. Here we focus on simulations of Si etch by HBr/Cl2 plasmas because this is used in the state-of-art fabrication of gate structures or shallow trench isolators included in SRAMs. In this conference, recent progresses in our simulation technique are reported. First, a Stillinger-Weber-type interatomic potential for Si/H/Br systems was newly developed. Second, we modify its potential form adding a new term partially including multibody interactions, which enabled us to predict thicknesses of reaction layers more accurately. From the analysis of obtained etch yields for cases of Si etch by various ions such as Cl^+, Cl2^+, Br, Br2^+, HBr^+, and H^+, a new scaling law, which is an extension of Steinbruchel's scaling, were derived. Third, simulations including both high-energy ions and low-energy neutral radicals with high neutral-to-ion flux ratio were performed. The distinct characteristics (monotonically decreasing yield curve as a function of incident angle) in realistic plasma conditions could be reproduced.

Ohta, Hiroaki; Nagaoka, Tatsuya; Iwakawa, Akira; Eriguchi, Koji; Ono, Kouichi

2008-10-01

442

Super-selective cryogenic etching for sub-10 nm features  

NASA Astrophysics Data System (ADS)

Plasma etching is a powerful technique for transferring high-resolution lithographic masks into functional materials. Significant challenges arise with shrinking feature sizes, such as etching with thin masks. Traditionally this has been addressed with hard masks and consequently additional costly steps. Here we present a pathway to high selectivity soft mask pattern transfer using cryogenic plasma etching towards low-cost high throughput sub-10 nm nanofabrication. Cryogenic SF6/O2 gas chemistry is studied for high fidelity, high selectivity inductively coupled plasma etching of silicon. Selectivity was maximized on large features (400 nm-1.5 ?m) with a focus on minimizing photoresist etch rates. An overall anisotropic profile with selectivity around 140:1 with a photoresist mask for feature size 1.5 ?m was realized with this clean, low damage process. At the deep nanoscale, selectivity is reduced by an order of magnitude. Despite these limits, high selectivity is achieved for anisotropic high aspect ratio 10 nm scale etching with thin polymeric masks. Gentler ion bombardment resulted in planar-dependent etching and produced faceted sub-100 nm features.

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

2013-01-01

443

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

444

Chemical etching to dissolve dislocation cores in multicrystalline silicon  

NASA Astrophysics Data System (ADS)

Multicrystalline silicon wafers are used for approximately half of all solar cells produced at present. These wafers typically have dislocation densities of up to ˜106 cm-2. Dislocations and associated impurities act as strong recombination centres for electron-hole pairs and are one of the major limiting factors in multicrystalline silicon substrate performance. In this work we have explored the possibility of using chemical methods to etch out the cores of dislocations from mc-Si wafers. We aim to maximise the aspect ratio of the depth of the etched structure to its diameter. We first investigate the Secco etch (1K2Cr2O7 (0.15 M): 2HF (49%)) as a function of time and temperature. This etch removes material from dislocation cores much faster than grain boundaries or the bulk, and produces tubular holes at dislocations. Aspect ratios of up to ˜7:1 are achieved for ˜15 ?m deep tubes. The aspect ratio decreases with tube depth and for ˜40 ?m deep tubes is just ˜2:1, which is not suitable for use in bulk multicrystalline silicon photovoltaics. We have also investigated a range of etches based on weaker oxidising agents. An etch comprising 1I2 (0.01 M): 2HF (49%) attacked dislocation cores, but its etching behaviour was extremely slow (<0.1 ?m/h) and the pits produced had a low aspect ratio (<2:1).

Gregori, N. J.; Murphy, J. D.; Sykes, J. M.; Wilshaw, P. R.

2012-08-01

445

Formation of Al 2O 3–Bi 4Ti 3O 12 nanocomposite oxide films on low-voltage etched aluminum foil by sol–gel processing  

Microsoft Academic Search

A water-based bismuth titanate Bi4Ti3O12 (BTO) sol was synthesized by mixing bismuth nitrate, tetra-n-butyl titanate, lactic acid, acetic acid and distilled water. The sol was applied to low-voltage etched aluminum foil by dip-coating. The crystallization process of Bi4Ti3O12 on low-voltage etched aluminum foil was measured by thermal gravimetry–differential scanning calorimetry (TG–DSC) and high-temperature X-ray diffraction (HT-XRD). It was found that

Xianfeng Du; Youlong Xu

2008-01-01

446

Solid polymer electrolyte composite membrane comprising plasma etched porous support  

SciTech Connect

A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

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

2010-10-05

447

Decreased fibroblast and increased osteoblast adhesion on nanostructured NaOH-etched PLGA scaffolds  

PubMed Central

To facilitate locomotion and support the body, the skeleton relies on the transmission of forces between muscles and bones through complex junctions called entheses. The varying mechanical and biological properties of the enthesis make healing this avascular tissue difficult; hence the need for an engineered alternative. Cells in situ interact with their environment on the nano-scale which suggests that engineered approaches to enthesis regeneration should include such biologically-inspired nano-scale surface features. The present in vitro study investigated the effects of etching poly-lactic-co-glycolic acid (PLGA) scaffolds to produce nano-topography on the adhesion of fibroblasts and osteoblasts, two integral enthesis cell types. Nano-topography was produced on PLGA by etching the scaffolds in NaOH. Results showed that etching PLGA with NaOH to create nano-scale surface features decreased fibroblast adhesion while it increased osteoblast adhesion; criteria critical for the spatial control of osteoblast and fibroblast adhesion for a successful enthesis tissue engineering material. Thus, the results of this study showed for the first time collective evidence that PLGA can be either treated with NaOH or not on ends of an enthesis tissue engineering construct to spatially increase osteoblast and fibroblast adhesion, respectively.

Smith, Lester L; Niziolek, Paul J; Haberstroh, Karen M; Nauman, Eric A; Webster, Thomas J

2007-01-01

448

Fabrication of Pure Silica Core Multimode Ultraviolet Optical Fibre Probes by Tube Etching  

NASA Astrophysics Data System (ADS)

As a light wave-guide component for transmitting ultraviolet (UV) laser pulses, pure silica core UV fibre probes have attracted a great deal of attention in the near-field optical data storage and bio-medical studies. We fabricate UV fibre probes with tips in dimension of about 2-5 ?m and taper angle 16° by the tube etching method, using 40% HF acid as etching solution and xylene as overlayer. Probes produced have curvy configuration with smooth surface. The yield of fine probes is rather high and etching operation greatly simplified. With higher damage threshold, pure silica core multimode UV fibre probes can be coupled into more laser power. In addition, using UV light reduces the cutoff wavelength of the fibre probes, which is in favour of increasing the transmission efficiency of the probe. Furthermore, the larger tip dimension helps to enhance the light throughput either. The advances of fabrication technique of UV optical fibre probe may further support the studies of UV light data storage, pulsed laser biosurgery and UV photolithography.

Huo, Xin; Pan, Shi; Wu, Shi-Fa