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1

Dental zirconia can be etched by hydrofluoric acid.  

PubMed

The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25°C for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80°C for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25°C for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface. PMID:24492116

Sriamporn, Tool; Thamrongananskul, Niyom; Busabok, Chumphol; Poolthong, Sushit; Uo, Motohiro; Tagami, Junji

2014-01-01

2

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

E-print Network

Hydrogen Fluoride Emergency Protocol. 4. HF must be brought into the lab using only approved carrier of the HF Etch Solution 1. Either Buffered Oxide Etch (BOE) (mixture of ammonium fluoride (40% by weight in water solution) and HF in a 10:1 ratio - 10 parts ammonium fluoride:1 part Hydrofluoric Acid

Thompson, Michael

3

Influence of strengthening by deep etching in hydrofluoric acid on the strength in axial tension of technical glass  

Microsoft Academic Search

1.The relationship of the axial compressive strength of sheet-glass samples ground and chemically treated in a hydrofluoric acid solution to the depth of the layer removed was experimentally established.2.The axial compressive strength of cylindrical samples after etching to a depth of not less than 50µm depends upon their form and the chemical composition of the glass. The maximum strengthening (~

G. M. Okhrimenko; V. P. Pukh

1982-01-01

4

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

PubMed Central

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

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

2014-01-01

5

Chemical milling of quartz using a solution based on organic solvents and anhydrous hydrofluoric acid  

Microsoft Academic Search

The use of hydrofluoric acid solution in chemically milling, etching and polishing quartz has been accepted for many years. Several papers have been presented addressing aqueous HF solutions. In this paper the use of a solution based on organic solvents and anhydrous HF to chemically mill or etch mesa structures in quartz plates is investigated. The etch rate figures and

David A. Neumeier

2002-01-01

6

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

7

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

8

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

9

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

E-print Network

with hydrofluoric acid. Definition: Hydrofluoric acid (HF) is a very corrosive solution of hydrogen fluoride glass and should not be stored in glass containers. · HF reacts with carbonates, cyanides, and sulfates

10

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

11

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

Code of Federal Regulations, 2010 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...

2010-07-01

12

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

Code of Federal Regulations, 2012 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...

2012-07-01

13

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

Code of Federal Regulations, 2014 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...

2014-07-01

14

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

Code of Federal Regulations, 2011 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...

2011-07-01

15

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

Code of Federal Regulations, 2012 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...

2012-07-01

16

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

Code of Federal Regulations, 2014 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...

2014-07-01

17

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

Code of Federal Regulations, 2011 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...

2011-07-01

18

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

19

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

Code of Federal Regulations, 2010 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...

2010-07-01

20

Title: Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Prepared By: Associate Director, WSEP  

E-print Network

Title: Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Prepared By: Associate Director, WSEP........................................................................................................ 6 #12;Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Date effective: July 21, 2010 Workplace DF #12;Hydrofluoric Acid/Hydrogen Fluoride Emergency Protocol Date effective: July 21, 2010 Workplace

Saskatchewan, University of

21

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

2012-11-15

22

Accidental intoxication with hydrochloric acid and hydrofluoric acid mixture.  

PubMed

The paper describes a fatal case of accidental ingestion of a mixture of hydrochloric acid and hydrofluoric acid. The man was admitted to hospital, where appropriate treatment, adequate to his condition, was instituted. Numerous ventricular fibrillation episodes, for which the patient was defibrillated repeatedly, were observed during the period of hospitalization. The patient was in a critical condition, with progressive symptoms of hypovolemic shock and multiorgan failure. On the next day after admission, signs of electromechanical dissociation progressing to asystole were noted. The instituted resuscitation procedure proved ineffective and the patient died. Autopsy revealed brownish discoloration of the esophageal, gastric, and small intestinal mucous membranes. Numerous ulcerations without signs of perforation were found both in the esophagus and in the stomach. The mucous membrane of the small intestine demonstrated focal rubefactions, whereas no focal lesions of the large intestinal mucosa were seen. Microscopic investigation of the biopsy specimens collected from the stomach, duodenum and small intestine revealed mucous membrane necrosis foci, reaching the deeper layers of the wall of these organs. The mucous membrane of the large intestine was congested. Bioptates obtained from the lungs indicated the presence of hemorrhagic infarcts and focal extravasations. Poisoning with the aforementioned acids with consequent necrosis of the esophageal, gastric, duodenal and small intestinal walls with hemorrhages to the gastrointestinal tract, as well as extravasations and hemorrhagic infarcts in the lungs was considered to be the cause of death. PMID:25184427

Sm?dra-Ka?mirska, A; K?dzierski, M; Barzdo, M; Jurczyk, Ap; Szram, S; Berent, J

2014-01-01

23

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

NASA Astrophysics Data System (ADS)

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

Li, Guangming

24

Systemic and topical effects of intradermal hydrofluoric acid.  

PubMed

A 35-year-old man attempted suicide by subcutaneous self-administration of hydrofluoric acid (5 cc of a domestic rust removal solution containing 7% hydrofluoric acid). A burn 9 x 7 cm in diameter immediately appeared at the injection site (left forearm and fold of the elbow). In the emergency department, the burn was copiously washed with isotonic solution and treated with cutaneous and subcutaneous injections of magnesium chloride, 10% solution of calcium gluconate, and 2% xylocaine, then continuously maintained under topical treatment with calcium gluconate. Seven hours after injection, the patient was severely hypocalcemic (Ca+2 0.64 mmol/L). Ten hours after injection, in addition to the persistent hypocalcemia (Ca+2 0.81 mmol/L), hyponatremia (123 mmol/d), hypokalemia (3.4 mmol/L), and hypochloremia (95.6 mmol/L) had developed. The hypocalcemia was corrected with infusion of calcium gluconate (8.92 mEq of Ca+2 as total amount). The patient underwent surgical intervention 7 days after admission, followed by several interventions of plastic surgery. PMID:9725972

Gallerani, M; Bettoli, V; Peron, L; Manfredini, R

1998-09-01

25

Treatment of hydrofluoric acid exposure to the eye  

PubMed Central

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

Atley, Katherine; Ridyard, Edward

2015-01-01

26

[Occupationally induced hydrofluoric acid burns: an analysis of 9 patients from the aspect of occupational health].  

PubMed

We report here 9 patients suffering from hydrofluoric acid burn who visited our clinic from July, 1979 to February, 2000. These 9 cases occupied 25% of all chemical burn cases experienced in our clinic. All the patients were men ranging in age from 20 to 53 (mean age 35 years; average 36.8 years). At the time of accidental exposures, 6 patients had been engaged in washing or cleaning work, and 2 had been changing the parts of instruments containing hydrofluoric acid. Eight patients received burns on the hands and/or fingers. During the work, 2 patients had used vinyl chloride or rubber gloves, but three patients employed no protection for the hands. After the symptoms began to develop, it was found that the glove of one patient had a pin hole. Coupled with the occasions described in previous reports, the causal factors of hydrofluoric acid burn could be divided as follows: 1) negligence or carelessness of workers, in particular skilled persons, in handling hydrofluoric acid, 2) ignorance of the dangerousness of hydrofluoric acid, 3) the presence of pin hole (s) in protection gloves, and 4) unexpected accident. Hydrofluoric acid is one of the most corrosive inorganic acids, and can produce progressive and serious tissue necrosis with severe pain. To prevent burns due to this chemical, enlightenment and reeducation of the workers regarding the hazard of hydrofluoric acid are necessary. PMID:10862411

Yamamoto, O; Yasuda, H; Izu, K; Nishio, D; Asahi, M

2000-06-01

27

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

PubMed

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

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

2015-02-01

28

Management of a Patient With Faciocervical Burns and Inhalational Injury Due to Hydrofluoric Acid Exposure.  

PubMed

Hydrofluoric acid, a highly dangerous substance, can cause tissue damage and systemic toxicity by its unique mechanisms. Many cases of severe faciocervical burns due to hydrofluoric acid exposure are lethal. Herein, we present a case of 37-year-old man who suffered from hydrofluoric acid burns to his face, anterior neck, lips, and nasal cavity. On admission, this patient coughed with much sputum, and the chest auscultation detected rough breath sounds, wheezes, and very weak heart sounds, indicating possible inhalation injury. This case highlights the extreme complexity of managing this kind of injury. Timely and accurate wound treatment and respiratory tract care, as well as active systematic support treatment, played vital roles in the management of this patient. PMID:24807997

Yuanhai, Zhang; Xingang, Wang; Liangfang, Ni; Chunmao, Han

2014-05-01

29

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

30

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

PubMed Central

A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO2 sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO2 sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations. PMID:22319388

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

2011-01-01

31

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

PubMed

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

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

2010-06-15

32

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

33

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

E-print Network

Hydrofluoric Acid (HF) is an inorganic acid which is derived from dissolving hydrogen fluoride in water. HF-the-counter products at concentrations of 6% to 12%. Synonyms include hydrogen fluoride, fluoric acid, hydrofluoride all tissues of the body. These effects are due to the fluoride ion's aggressive, destructive

Jia, Songtao

34

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

Microsoft Academic Search

When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0â) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution anneal and water quench is necessary to assure that these phases redissolve into the solid. When a post weld solution anneal and

Norby

1992-01-01

35

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

SciTech Connect

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

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

2008-07-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

37

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

SciTech Connect

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

Thomas, D., E-mail: daniel.thomas@ukb.uni-bonn.de; Jaeger, U. [Radiologische Universitaetsklinik, Universitaet Bonn (Germany); Sagoschen, I. [Klinikum der Johannes Gutenberg Universitaet, Poison Control Center, Medizinische Klinik und Poliklinik II (Germany); Lamberti, C. [Universitaet Bonn, Medizinische Klinik und Poliklinik I (Germany); Wilhelm, K. [Radiologische Universitaetsklinik, Universitaet Bonn (Germany)

2009-01-15

38

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

PubMed

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

De Sio, Stéphanie M; Wilson, Richard E

2014-12-01

39

A review of treatment strategies for hydrofluoric acid burns: current status and future prospects.  

PubMed

Hydrofluoric acid (HF), a dangerous inorganic acid, can cause severe corrosive effects and systemic toxicity. HF enters the human body via where it contacts, such as skin and mucosa, alimentary and respiratory tracts, and ocular surfaces. In the recent years, the incidence of HF burn has tended to increase over time. The injury mechanism of HF is associated primarily with the massive absorption of HF and the release of hydrogen ions. Correct diagnosis and timely treatment are especially important for HF burns. The critical procedure to treat HF burn is to prevent on-going HF absorption, and block the progressive destruction caused by fluoride ions. Due to the distinct characteristics of HF burns, the topical treatment, as well as systemic support, has been emphasised. Whereas, management of patients with HF burns remains a great challenge in some situations. To date, there has been no widely accepted protocol for the rescue of HF burns, partly due to the diversity of HF burns. This paper overviews the current status and problems of treatment strategies for HF burns, for the purpose of promoting the future researches and improvement. PMID:24946967

Wang, Xingang; Zhang, Yuanhai; Ni, Liangfang; You, Chuangang; Ye, Chunjiang; Jiang, Ruiming; Liu, Liping; Liu, Jia; Han, Chunmao

2014-12-01

40

Upgrading of natural gasoline with trifluoromethane sulfonic acid, hydrofluoric acid and Lewis acid catalyst  

SciTech Connect

Natural gasoline of low octane value derived from natural gas is upgraded to higher octane value by means of a liquid ternary catalyst comprising trifluoromethane-sulfonic acid and hydrogen fluoride in conjunction with a Lewis acid of the formula MX /SUB n/ wherein M is selected from Group III-A, IV-B or V elements of the Periodic Table, x is a halogen and n is a number varying from 3 to 6. Effective upgrading is achieved when the Lewis acid:HF mole ratio of the catalyst ranges from 1:2 to 2:1 at temperatures less than about 120/sup 0/ C. under liquid phase conditions.

Olah, G.A.

1984-09-18

41

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

SciTech Connect

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

Hui Tian; Charles Reece; Michael Kelley; Sean Corcoran

2008-02-12

42

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

PubMed

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

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

2015-01-01

43

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

PubMed

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

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

2015-02-01

44

Experimental 70% hydrofluoric acid burns: histological observations in an established human skin explants ex vivo model  

PubMed Central

Background: Hydrofluoric acid (HF) is particularly dangerous due to the potential for systemic effects and induction of severe skin necrosis through two mechanisms: corrosiveness and local tissue toxicity. In addition, because it is only partially dissociated (pKa 3.2), it is capable of penetrating deeply into tissues. There is a lack of experimental studies that objectively characterize the behavior of HF diffusion into human skin, specifically the kinetics of tissue penetration resulting in severe cellular lesions. Methodology/principal findings: We describe the cutaneous effects of HF using an established ex vivo human skin model. The diffusion of 70% HF starts within the first minute of contact at the epidermal surface and after 2min reaches the basal layer. In the subsequent minute, the epidermis is destroyed and lesions appear in the papillary dermis after 4min. Soon after, damage appears in the upper reticular dermis. Thus, 70% HF needs only 5min of contact to completely penetrate human skin explants. This experiment is reproducible and corroborates previous studies and clinical effects reported in accidental HF exposures. Conclusion/significance: This study shows that the management of HF chemical skin exposure is a question of minutes, especially for initial decontamination. These experimental observations could be useful for objectively comparing skin decontamination methods. Further studies should help to confirm these preliminary results. PMID:21077748

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

2011-01-01

45

Cation-exchange behavior of scandium, titanium, and vanadium in various degrees of oxidation in dilute hydrofluoric acid solutions  

SciTech Connect

The distribution coefficients of scandium, titanium, and vanadium in various degrees of oxidation between the sulfonic acid type cation-exchange resin KRS-8p and hydrofluoric acid solutions in the concentration range 0.1-1.0 mole/liter have been determined by static and dynamic methods. On the basis of the research performed, a procedure is suggested for separating the radionuclides vanadium 48 and vanadium 49 from a titanium target irradiated in a cyclotron. The procedure has been tested on a real industrial target and has given good results.

Razbash, A.A.; Sevast'yanov, Yu.G.

1987-01-01

46

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.

2007-07-01

47

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

SciTech Connect

In the Fluorinel Dissolution Process (FDP) upgrade, excess hydrofluoric acid in the dissolver product must be complexed with aluminum nitrate (ANN) to eliminate corrosion concerns, adjusted with nitrate to facilitate extraction, and diluted with water to ensure solution stability. This is currently accomplished via batch processing in large vessels. However, to accommodate increases in projected throughput and reduce water production in a cost-effective manner, a semi-continuous system (In-line Complexing (ILC)) has been developed. The major conclusions drawn from tests demonstrating the feasibility of this concept are given in this report.

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

1993-04-01

48

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

USGS Publications Warehouse

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

May, I.; Rowe, J.J.

1965-01-01

49

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

50

Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives  

PubMed Central

Objective: To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin. Material and Methods: Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12) as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100) were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37ºC, 100% humidity) with a testing machine (Ultra-tester) at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis. Results: Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05). Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05) only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa) and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa) among all tested groups (p<0.05). Conclusion: The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin. PMID:23559113

SABATINI, Camila

2013-01-01

51

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

PubMed Central

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

Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

2013-01-01

52

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

SciTech Connect

When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0{sub 3}) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution anneal and water quench is necessary to assure that these phases redissolve into the solid. When a post weld solution anneal and water quench is not feasible, improved corrosion resistance can be obtained by welding with INCO 72 weld wire. When welding Hastelloy G-30 with INCO 72, there can be a region at the weldmetal/base-metal interface that does not benefit from the INCO 72 weld wire. This region consists of melted and resolidified Hastelloy G-30. This unmixed zone can be preferentially attacked in HN03 solutions contaminated with minor amounts of HF. Long term corrosion immersion tests have shown that the rate of attack at the weld-metal/base-metal interface can be as high as 50 mpy. Welding techniques that increase the mixing of the melted Hastelloy G-30 with the INCO 72 weld wire can reduce the interface corrosion rate.

Norby, B.C.

1992-03-03

53

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

SciTech Connect

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

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

2014-06-16

54

Wide-rang tuning of the titanium dioxide flat-band potential by adsorption of fluoride and hydrofluoric acid  

SciTech Connect

The adsorption of fluoride, (HF){sub n}F{sup {minus}} ions, and hydrofluoric acid at the surface of n-type TiO{sub 2{minus}x}F{sub x} (x {approx} 0.001) electrodes was studied by electrochemical methods. Adsorption of F{sup {minus}} from acetontrile/tetraethylammonium fluoride (TEAF) solution follows a Langmuir isotherm above a fractional coverage of about 0.5, and the equilibrium constant for adsorption is 8,300 M{sup {minus}1}. Specific adsorption of fluoride ions, at millimolar concentration in acetonitrile, results in a large negative shift in the flat-band potential, as manifested by capacitance measurements and cyclic voltammetry of Ru(bpy){sub 3}{sup 2+}. Fluoride ions are strongly complexed by HF in acetonitrile to form (HF){sub n}F{sup {minus}} ions (n = 1,2), which are also specifically adsorbed at the TiO{sub 2{minus}x}F{sub x}(001) surface.

Wang, Chong Mou; Mallouk, T.E. (Univ. of Texas, Austin (USA))

1990-05-17

55

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

PubMed

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

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

2013-01-01

56

Orthodontic bonding to acid- or laser-etched prebleached enamel  

PubMed Central

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

Ozdemir, Fulya; Cakan, Umut; Gonul, Nese

2013-01-01

57

Copper-assisted, anti-reflection etching of silicon surfaces  

SciTech Connect

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

Toor, Fatima; Branz, Howard

2014-08-26

58

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

59

HYDROFLUORIC ACID Safety Office  

E-print Network

) and absorbed with spill control pads or other absorbent materials. Add sodium bicarbonate or magnesium oxide to an absorbent and place in a plastic container for disposal. Wash the spill site with a sodium bicarbonate

Davis, Lloyd M.

60

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. PMID:22229008

Lima, Adriano Fonseca; da Silva, Vinícius Brito; Soares, Giulliana Panfiglio; Marchi, Giselle Maria; Baggio Aguiar, Flávio Henrique; Lovadino, José Roberto

2012-01-01

61

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

PubMed Central

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

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

2011-01-01

62

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

63

Hazardous waste reduction from mixed acid titanium etching  

Microsoft Academic Search

This paper presents the findings of a technical study performed by the New York State Pollution Prevention Institute at Rochester\\u000a Institute of Technology to evaluate process modifications that would reduce hazardous waste generated from the manufacture\\u000a of titanium alloy turbine blades. This study focused on the acid etch process step in which titanium alloy turbine blades\\u000a are immersed in a

Richard Poduska; David Fister; Newton Green; Paul McAndrew

64

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

E-print Network

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

Mou, Jianye

2010-10-12

65

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

SciTech Connect

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

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

2011-06-01

66

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

E-print Network

The conductivity of acid-etched fractures highly depends on spaces along the fracture created by uneven etching of the fracture walls remaining open after fracture closure. Formation heterogeneities such as variations of mineralogy and permeability...

Deng, Jiayao

2011-02-22

67

Improvement of direct determination of Cu and Mn in seawater by GFAAS and total elimination of the saline matrix with the use of hydrofluoric acid.  

PubMed

Hydrofluoric acid, added to seawater, can assist in the removal of chloride in the drying step by precipitating fluoride salts, thus suppressing the chloride interference effects induced on the atomization signals of Cu and Mn. By adding HF to seawater before the analysis, MgF(2) and CaF(2) are precipitated at the bottom of the sampling flask, without precipitating Cu and Mn, and are consequently not introduced into the graphite furnace. Because sodium salts are eliminated at the pretreatment step, the whole seawater matrix is eliminated before the atomization of Cu or Mn. Therefore, the analyzed volume of seawater can be increased by using the multi-injection procedure without degradation of the limit of detection and risks of spectral interferences. The limit of detection obtained for Cu and Mn are 0.05 and 0.01mugL(-1), respectively, for a 50muL analyzed seawater volume. PMID:18969813

Cabon, J Y

2005-01-30

68

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

69

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

PubMed

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

Doukoudakis, A; Cohen, B; Tsoutsos, A

1987-10-01

70

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

71

Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings With an Etching Process  

Microsoft Academic Search

A new structure of long-period grating (LPG) sensor is introduced for simultaneous measurement of the refractive index (RI) and temperature. This type of grating device consists of two LPG sections, one of which is post etched by hydrofluoric acid (HF) solution and, therefore, has an improved RI sensitivity (the demonstrated improvement of sensitivity is 3.6 times). The experimental results show

Jinhua Yan; A. Ping Zhang; Li-Yang Shao; Jin-Fei Ding; Sailing He

2007-01-01

72

Submicron hiati in acid-etched dentin are artifacts of desiccation  

Microsoft Academic Search

Objectives. The submicron hiatus represents a potential space between the base of the collagen network and the mineralized dentin when dentin is acid-etched for bonding. These spaces were observed in SEM studies after acid-etched dentin specimens were critical point dried or dehydrated in hexamethyldisilasane. However, they have never been identified in TEM studies of dentin hybrid layers. This study critically

Kelli L Agee; Edna L Pashley; Anut Itthagarun; Hidehiko Sano; Franklin R Tay; David H Pashley

2003-01-01

73

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

PubMed

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

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

2012-01-01

74

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

75

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

Microsoft Academic Search

Chemical acid etching alone of the titanium implant surface have the potential to greatly enhance osseointegration without adding particulate matter (e.g. TPS or hydroxyapatite) or embedding surface contaminants (e.g. grit particles). The aims of the present study were to evaluate any differences between the machined and dual acid etching implants with the removal torque as well as topographic analysis.A total

Sung-Am Cho; Kyung-Tae Park

2003-01-01

76

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

SciTech Connect

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

Despotopulos, J D; Sudowe, R

2012-02-21

77

Nanoparticle-based etching of silicon surfaces  

DOEpatents

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

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

2011-12-13

78

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

Microsoft Academic Search

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

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

2008-01-01

79

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

80

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

PubMed

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

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

2012-01-01

81

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

82

Formation of nanostructured silicon surfaces by stain etching.  

PubMed

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

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

2014-01-01

83

Formation of nanostructured silicon surfaces by stain etching  

PubMed Central

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

2014-01-01

84

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

PubMed Central

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

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

2013-01-01

85

Metal etching composition  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

86

PIRANHA USE GENERAL INSTRUCTIONS Piranha etch is used to remove organic residues from substrates. The standard acid piranha  

E-print Network

PIRANHA USE ­ GENERAL INSTRUCTIONS Piranha etch is used to remove organic residues from substrates. The standard acid piranha used in the CEPSR Clean Room is a 3:1 mixture of concentrated sulfuric acid (H2SO4) with hydrogen peroxide (H2O2); 3 parts acid and 1 part peroxide. Acid piranha is a self-starting reaction

Kim, Philip

87

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

88

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

89

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

90

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

PubMed Central

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

Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

2013-01-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

92

Analysis methods for meso- and macroporous silicon etching baths  

PubMed Central

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

2012-01-01

93

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

E-print Network

*Additional SOPs available, see: 1. PPE Choice and Cleaning 2. Work Station Cleaning 3. Pouring process stations 2, 3, 11, acid & base fume hood2. If heated only acid & base fume hood. Additional-MicroManufacturing Hazards: *Poor warning properties*: harmful exposure and workstation contamination are initially very

Woodall, Jerry M.

94

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

E-print Network

*Additional SOPs available, see: 1. PPE Choice and Cleaning 2. Work Station Cleaning 3. Pouring, acid & base fume hood2. If hotter than a simmer, only acid & base fume hood. Additional Process Notes-MicroManufacturing Hazards: *Poor warning properties*: harmful exposure and workstation contamination are initially very

Woodall, Jerry M.

95

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

PubMed

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

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

2009-06-01

96

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

PubMed Central

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

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

2014-01-01

97

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

PubMed

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

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

2014-01-01

98

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

PubMed Central

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

Alsulaimani, Fahad F.

2014-01-01

99

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

PubMed

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

Song, Qingfang

2015-05-01

100

Wet Chemical Etching and X-ray Photoelectron Spectroscopy Analysis of BaSi2 Epitaxial Films Grown by Molecular Beam Epitaxy  

NASA Astrophysics Data System (ADS)

Approximately 250-nm-thick undoped n-type BaSi2 epitaxial films were grown on n-Si(111) substrates by molecular beam epitaxy, and 1-mm-diameter mesa-isolated n-BaSi2/n-Si diode structures were successfully produced by wet chemical etching. Etching of BaSi2 layers was carried out using diluted hydrochloric acid solution, followed by diluted hydrofluoric acid solution. X-ray photoelectron spectroscopy measurements revealed that the surface of BaSi2 was changed to Si oxides by treatment with the hydrochloric solution, and these oxides were then etched away by the hydrofluoric solution. The surface morphology of samples was significantly dependent on the ratio of H2O included in the etching solutions. Lower ratios of H2O resulted in rougher sample surfaces. Wet chemical etching of BaSi2 layers was successfully carried out by first using HCl:H2O = 1:199 and then HF:H2O = 1:49 solutions at 0 °C.

Saito, Takanobu; Tsukada, Dai; Matsumoto, Yuta; Sasaki, Ryo; Takeishi, Michitoshi; Ootsuka, Teruhisa; Suemasu, Takashi

2009-10-01

101

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

102

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

PubMed

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

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

2014-01-01

103

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

PubMed Central

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

2014-01-01

104

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

PubMed Central

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

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

2013-01-01

105

Resin–dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding  

PubMed Central

Objective To compare resin–dentin bond strengths and the micropermeability of hydrophobic vs. hydrophilic resins bonded to acid-etched or EDTA-treated dentin, using the ethanol wet-bonding technique. Methods Flat dentin surfaces from extracted human third molars were conditioned before bonding with: 37% H3PO4 (15 s) or 0.1 M EDTA (60 s). Five experimental resin blends of different hydrophilicities and one commercial adhesive (SBMP: Scotchbond Multi-Purpose) were applied to ethanol wet-dentin (1 min) and light-cured (20 s). The solvated resins were used as primers (50% ethanol/50% comonomers) and their respective neat resins were used as the adhesive. The resin-bonded teeth were stored in distilled water (24 h) and sectioned in beams for microtensile bond strength testing. Modes of failure were examined by stereoscopic light microscopy and SEM. Confocal tandem scanning microscopy (TSM) interfacial characterization and micropermeability were also performed after filling the pulp chamber with 1 wt% aqueous rhodamine-B. Results The most hydrophobic resin 1 gave the lowest bond strength values to acid-etched dentin and all beams failed prematurely when the resin was applied to EDTA-treated dentin. Resins 2 and 3 gave intermediate bond strengths to both conditioned substrates. Resin 4, an acidic hydrophilic resin, gave the highest bond strengths to both EDTA-treated and acid-etched dentin. Resin 5 was the only hydrophilic resin showing poor resin infiltration when applied on acid-etched dentin. Significance The ethanol wet-bonding technique may improve the infiltration of most of the adhesives used in this study into dentin, especially when applied to EDTA-treated dentin. The chemical composition of the resin blends was a determining factor influencing the ability of adhesives to bond to EDTA-treated or 37% H3PO4 acid-etched dentin, when using the ethanol wet-bonding technique in a clinically relevant time period. PMID:20074787

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H.; Tay, Franklin R.; Watson, Timothy F.; Osorio, Raquel

2013-01-01

106

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

PubMed

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

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

2008-09-01

107

Guidance Document SafeHandlingofHydrofluoricAcid  

E-print Network

quantities can include bone loss, kidney dysfunction, joint damage and blood disorders. Persons with pre-existing skin disorders, eye problems, kidney or pulmonary function may be more susceptible. #12;Exposure

108

Vacuum-jacketed hydrofluoric acid solution calorimeter  

USGS Publications Warehouse

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

Robie, R.A.

1965-01-01

109

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

PubMed

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

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

2011-01-01

110

Mixed matrix membranes with HF acid etched ZSM-5 for ethanol/water separation: Preparation and pervaporation performance  

NASA Astrophysics Data System (ADS)

The mixed matrix membranes (MMMs) were prepared from crosslinked PDMS incorporated with HF acid etched ZSM-5. ZSM-5 zeolite was etched with a series of HF aqueous-acetone solution and characterized by SEM, BET, XRD and FT-IR. It was found that HF etching process was very effective for removing organic impurities in zeolite and micro-pores were observed out of the surface of zeolite particles, which enhanced the hydrophobicity and surface roughness of ZSM-5 successfully. Both tensile strength and swelling resistance of ZSM-5/PDMS MMMs increased with the rising concentration of HF solution, which can mainly be attributed to the improved zeolite-PDMS interfacial adhesion resulted from the intrusion of PDMS into micro-pores out of the ZSM-5 surface. Subsequently, the sorption experiment was performed with the results suggesting preferential sorption of ethanol by MMMs. Moreover, the sorption selectivity of ZSM-5/PDMS MMMs increased notably as the concentration of HF solution increased. The pervaporation performance of ethanol/water mixtures using MMMs was also investigated in detail. The MMMs filled with etched ZSM-5 showed much better selectivity than that filled with non-etched ones, with a little expense of permeability. It was found that with the same zeolite loading, increasing the HF acid concentration in etching process enhanced the zeolite-PDMS interfacial adhesion which promoted the ethanol selectivity of MMMs, while depressed the total permeation flux a little. In addition, both ethanol permeation and the selectivity increased with an increase of the zeolite loading from 10% to 30%. Nevertheless, excessive zeolite loading or decreasing thickness of selective layer led to the poor selectivity to ethanol. A decline of the ethanol selectivity was also observed as the feed ethanol concentration as well as feed temperature increased.

Zhan, Xia; Lu, Juan; Tan, Tingting; Li, Jiding

2012-10-01

111

Effect of Alkaline pH on Polishing and Etching of Single and Polycrystalline Silicon  

NASA Astrophysics Data System (ADS)

In this paper, the polishing and etching behavior of single and polycrystalline silicon were studied. Prior to chemical mechanical polishing (CMP) process, the surfaces were treated with dilute hydrofluoric acid (DHF) to remove native oxides. The surface analysis shows that the poly contains trace amount of oxygen even after DHF treatment. The static and dynamic etch rates, and removal rates were measured as a function of slurry pH. The single silicon showed a higher static etch rate than the poly. After static etch rate measurements, poly showed higher surface roughness and more hydrophilic which indicates that the surface of poly is different from single crystal silicon. The friction force between pad and substrate and pad temperature was also measured as a function of pH during polishing in order to get more understanding of polishing process. At all the pH values being investigated, poly showed lower dynamic and removal rates, higher friction force and higher temperature. This indicates that the removal of poly in CMP is predominantly by mechanical actions. Also, these results, suggest a mechanism in which the oxygen present in the poly grain boundaries strongly influences the etching and removal mechanism.

Venkatesh, R. Prasanna; Prasad, Y. Nagendra; Kwon, Tae-Young; Kang, Young-Jae; Park, Jin-Goo

2012-07-01

112

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

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

114

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

SciTech Connect

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

Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)] [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Hinata, Toru; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)] [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Oshima, Akihiro; Tagawa, Seiichi [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan) [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2013-10-14

115

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

116

Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel.  

PubMed

The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment. PMID:25740168

Nogawa, Hiroshi; Koizumi, Hiroyasu; Saiki, Osamu; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

2015-04-01

117

Investigations of AlGaN/GaN HFETs utilizing post-metallization etching by nitric acid treatment  

NASA Astrophysics Data System (ADS)

This work investigates AlGaN/GaN heterostructure field-effect transistors (HFETs) processed by using a simple post-metallization etching (PME) treatment. Decreased gate length (LG) can be achieved by using nitric acid (HNO3) PME treatment owing to the high etching selectivity of HNO3 of Ni against the Au and GaN layer. Influences on LG, etched gate profiles and device characteristics with respect to different PME processing parameters by HNO3 treatment are systematically investigated. Optimum device performance is obtained as LG was reduced to 0.5 µm by using a 1 µm long gate mask by immersing the device into a 45% diluted HNO3 solution for 35 s. Improved device performances, including maximum drain-source current density (IDS, max: 657.6 mA mm-1 ? 898.5 mA mm-1), drain-source saturation current density at zero gate bias (IDSS0: 448.3 mA mm-1 ? 653.4 mA mm-1), maximum extrinsic transconductance (gm, max: 158.3 mS mm-1 ? 219.2 mS mm-1), unity-gain cut-off frequency (fT: 12.35 GHz ? 22.05 GHz), maximum oscillation frequency (fmax: 17.55 GHz ? 29.4 GHz) and power-added efficiency (P.A.E.: 26.3% ? 34.5%) compared to the untreated reference device, have been successfully achieved.

Chou, Bo-Yi; Hsu, Wei-Chou; Lee, Ching-Sung; Liu, Han-Yin; Tsai, Chih-Ming; Ho, Chiu-Sheng

2013-07-01

118

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

E-print Network

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

Zheng, Yufeng

119

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

120

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

PubMed

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

Bottino, Ma; Snellaert, A; Bergoli, Cd; Özcan, M; Bottino, Mc; Valandro, Lf

2015-01-01

121

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

PubMed

Sandblasting with large grit and acid-etching (SLA) treatment is considered to be a reliable modification to achieve excellent titanium surface. However, contamination of hydrocarbons would make SLA surface hydrophobic and influence its bioactivity. Thus, appropriate methods of preservation or further treatments could be used for improvement. In present study, preservation in deionized water (dH(2)O) and ultraviolet (UV) irradiation were, respectively, applied to achieve modSLA and UV-SLA surfaces. Surface characteristics were assessed by scanning electron microscopy, optical profilometer and x-ray photoelectron spectroscopy as well as wettability by optical contact angle analyzer. Additionally, biocompatibility was evaluated by the response to osteoblast-like MG63 cells. Prevented from further contamination, modSLA surface with fewer hydrocarbons (25.31%) remained hydrophilic and showed better affinity to mineralization of MG63 cells than hydrophobic polluted SLA surface (p < 0.01). Furthermore, with the lowest content of hydrocarbons (14.26%) and super-hydrophilicity, UV-SLA surface, which had the hydrocarbons effectively decomposed by photocatalysis and meanwhile acquired abundant hydroxyl groups, had most greatly promoted the attachment, proliferation, differentiation, and mineralization of MG63 cells (p < 0.05). Therefore, hydrocarbons were found to be an important influencing factor to compatibility of biomaterials. In addition, UV irradiation was recognized as a trustworthy method for surface cleaning without change of topography and roughness and could ever lead to greater biocompatibility of sandblasted and acid-etched titanium surface. PMID:22707456

Li, Shaobing; Ni, Jia; Liu, Xiangning; Zhang, Xueyang; Yin, Shiheng; Rong, Mingdeng; Guo, Zehong; Zhou, Lei

2012-08-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

123

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

PubMed

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

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

2010-01-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

125

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

PubMed

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

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

2014-06-01

126

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

E-print Network

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

Oeth, Cassandra V

2013-11-25

127

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

128

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

PubMed

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

Oikarinen, K S; Nieminen, T M

1994-12-01

129

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

PubMed

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

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

2011-01-01

130

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. PMID:21711891

2011-01-01

131

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

PubMed Central

The objective of the study was to gain more understanding on the photopolymerization mechanism and the role of individual monomers in the polymerization behavior of a PAE-based self-etch adhesive system with the presence of HAp and water. The photo-polymerization process of the model adhesive system (2MP / HEMA) was monitored by using real-time attenuated total reflectance Fourier transform infrared (ATR/FT-IR) technique. The effect of monomer ratio, HAp incorporation, and water content were investigated. The degree of conversion (DC) and the polymerization rate (PR) of the adhesives were determined to evaluate the polymerization efficacy. The results showed that the DC and PR increased consistently as the 2MP content increased from 30% to 70%, while they declined drastically as the 2MP content was further elevated to 100%. The incorporation of HAp considerably increased the DC and PR; however, the increase in water content was found to have negative influence on the photopolymerization. PMID:23370865

ZHANG, Ying; WANG, Yong

2014-01-01

132

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

PubMed

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

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

2012-09-26

133

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

NASA Astrophysics Data System (ADS)

Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05949b

Chen, Chia-Yun; Wong, Ching-Ping

2014-12-01

134

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

PubMed Central

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

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

2012-01-01

135

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

136

Serially etched shark enameloid observed by incident light microscopy  

Microsoft Academic Search

Longitudinal and transverse tooth sections oïhums oxyrinchus were serially etched in 2.6% nitric acid. The changing optical properties of the etched surfaces were observed during the serial etchings, and the descent of the enameloid surfaces was measured. Shark enameloid seems to be less effectively etched by acid than human enamel; this difference may be due to differences in solubility between

Steinar Risnes; Gisle Fosse

1979-01-01

137

Petrologic and experimental evidence for the etching of garnets by organic acids in the upper Jurassic Morrision Formation, northwestern New Mexico.  

USGS Publications Warehouse

Etching of garnets and partial to complete dissolution of other aluminosilicate minerals were caused by high concentrations of organic acids generated during the maturation of epigenetic organic matter (predominantly type-III kerogen) in the Morrison Formation. The presence of authigenic phases that form near 100oC indicates that temperatures were high enough during diagenesis to cause the thermal degradation of kerogen.-from Author

Hansley, P.L.

1987-01-01

138

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

PubMed Central

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

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

2013-01-01

139

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

NASA Astrophysics Data System (ADS)

Achieving mask blanks with defectivity less than 0.03 defects/cm2 at 30 nm SiO2 equivalent and above is one of the key goals for accomplishing high volume manufacturing capability for EUV lithography. Defect free blanks for lithography start from defect free substrates. Currently, defects on both LTEM and quartz substrates are dominated by pits, scratches, particles and residues left by the polishing processes used to achieve the roughness and flatness specifications of the substrates. Normally, such defects are extremely difficult to be removed and particles often leave pits as they are removed by cleaning. Standard cleaning processes relying on megasonic cavitations for particle removal are insufficient for removing such defects from substrates. It is well known that hydrofluoric acid is an etchant of fused silica (quartz) and buffered HF in different concentrations has been used in the past for cleaning quartz and silicon substrates. Ideally, an etch clean process should not increase the roughness of the substrate while cleaning. However, in the process of etching and removing the defects, the roughness of the substrates is invariably increased which is undesirable. The rate of roughness change is directly dependent on the concentration and time of exposure, which also affects the etch rate and defect removal rate. In this paper we report that a post polishing etch clean process has been developed for ULE and quartz substrates which meet the defectivity, roughness and flatness specifications for EUV blanks. We also examine the effects of substrate roughness on blank roughness, and inspection capability of substrates and blanks at different roughness levels using a defect inspection tool capable of inspecting defects down to 35 nm SiO2 equivalent size. Defect smoothing using etch clean processes have been proposed and demonstrated in the past using an anisotropic etch mechanism. This study focuses on complete removal of defects from EUV substrates, and therefore smoothing is not an issue. Multilayer blank deposition process is known to decorate defects on substrates. We use this as a technique to identify any defects that might be left on the substrate surface after etch cleaning. In most cases, we find that the substrates have low defectivity and do not affect the EUV requirements. We demonstrate that the etch clean process can be used to increase the yield of high quality ULE substrates to meet the high volume production requirements of euv masks.

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

2012-11-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

141

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

PubMed Central

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

2014-01-01

142

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

PubMed

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

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

2014-01-01

143

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

PubMed Central

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

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

2014-01-01

144

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. PMID:23306857

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

2012-01-01

145

vwDepartment of Geoscience Hydrofluoric Acid Policy  

E-print Network

the skin tissues towards the bone, and thus causes extensive done damage as well as skin burns. Inhalation and corrosive to skin and mucous membranes. It also has an affinity for calcium and is attracted through, even for brief exposures. HF produces severe skin burns which are slow in healing. The threshold limit

Habib, Ayman

146

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

147

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

148

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

PubMed Central

Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods. PMID:24413157

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

2014-01-01

149

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

PubMed

The aims of this study were to compare two pretreatment methods of a fiber post and to evaluate the effect of heat treatment to applied silane on the push-out bond strength for different levels of root. In this in vitro study, 40 glass fiber posts were divided into five groups (n=8) according to the kind of surface treatment applied. They were then inserted into extracted and endodontically treated human canines using a self-etch resin cement (Panavia F2.0, Kuraray, Japan). Group HF+S = hydrofluoric acid (HF) etching and silane (S) application; group HF+S+WP = HF etching and heat-treated silane application and warmed posts (WP); group H2O2+S = hydrogen peroxide etching and silane application; group H2O2+S+WP = hydrogen peroxide and heat-treated-silane application and warmed post; and group C, the control group, received no pretreatment. After completion of thermal cycling (1000 cycles, 5-55°C), all specimens were cut horizontally to obtain three sections. Each section was subjected to a push-out test, and the test results were analyzed using two-way analysis of variance, post-hoc Tukey honestly significant difference test, and a paired sample t-test (?=0.05). It was found that bond strength was not statistically influenced by the kind of etching material used (p=0.224), but was significantly affected by heat treatment of applied silane (p<0.001). The interaction between these two factors was not statistically significant (p=0.142). Group HF+S+WP showed the highest bond strength (12.56±1.73 MPa) (p<0.05). Scanning electron microscopy revealed the effect of the different treatments on the surface characteristics of posts. In the four pretreated groups, the bond strength decreased significantly from the coronal to the apical root canal sections (p?0.05). The results of this study show that the use of heat-treated silane significantly enhances the push-out bond strength of the fiber posts to root. HF acid etching with heat-treated silane application led to the highest bond strength. PMID:24809541

Samimi, P; Mortazavi, V; Salamat, F

2014-01-01

150

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

151

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

152

Bone response to alteration of surface topography and surface composition of sandblasted and acid etched (SLA) implants.  

PubMed

The titanium surface obtained by sandblasting and etching (SLA) is an easily alterable surface that smears and loose its typical texture. In addition, the etching process modifies the surface composition of commercially pure titanium; the latter contains titanium and an added 20-40% of titanium hydride. Therefore, the influence of a heavy surface alteration and the influence of the composition at the SLA surface, i.e. with and without titanium hydride, were investigated in vivo. Three implant groups were inserted in the mandible of Land Race pigs and left to heal during 10 weeks in a submerged way: (1). a standard SLA control group (SLAstd) with the SLA surface containing titanium hydride; (2). a test group with the SLA surface heavily altered at the thread level (SLAalt); (3). a test group with an SLA surface devoid of titanium hydride (SLAT). Sample size was n = 8. Histomorphometry analysis did not show a statistically significant difference between the control group (SLAstd: 82.12 + 6.1%), the altered surface test group (SLAalt: 86.25 + 7.4%) and the SLA without titanium hydride test group (SLAT: 75.12 + 7.6%). The data suggest that alteration of the SLA surface, if it occurs, should not be detrimental to bone response. The soft and easy smearable SLA surface might even be an advantage when surface maintenance is required. Surface composition did not play a significant role in the bone response to the SLA surface and it can therefore be concluded that the osteophilic properties of the SLA surface are due to its surface topography and not to its specific surface composition. PMID:12453122

Perrin, Daniel; Szmukler-Moncler, Serge; Echikou, Casimir; Pointaire, Philippe; Bernard, Jean-Pierre

2002-10-01

153

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

PubMed

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

Bücker, Stefan; Acker, Jörg

2012-05-30

154

Physico/chemical characterization and in vivo evaluation of nanothickness bioceramic depositions on alumina-blasted/acid-etched Ti-6Al-4V implant surfaces.  

PubMed

The objective of this study was to physico/chemically characterize and evaluate the in vivo performance of two nanothickness ion beam assisted depositions (IBAD) of bioceramic coatings on implants in a beagle model. Alumina-blasted/acid-etched (AB/AE) Ti-6Al-4V implants were subjected to two different IBAD depositions (IBAD I and IBAD II), which were physico/chemically characterized by SEM, EDS, XPS, XPS + ion-beam milling (depth profiling), XRD, AFM, and ToF-SIMS. A beagle dog tibia model was utilized for histomorphometric and biomechanical (torque) comparison between AB/AE, IBAD I, IBAD II, and plasma-sprayed hydroxyapatite (PSHA) coated implants that remained in vivo for 3 and 5 weeks. The coatings were characterized as amorphous Ca-P with high Ca/P stoichiometries with thicknesses of an order of magnitude difference (IBAD I = 30-50 nm and IBAD II = 300-500 nm). The histomorphometric and biomechanical testing results showed that the 300-500 nm thickness deposition (IBAD II) and PSHA positively modulated bone healing at early implantation times. PMID:18508352

Coelho, Paulo G; Lemons, Jack E

2009-08-01

155

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

E-print Network

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

Agarwal, Amit Kumar

2013-01-14

156

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

157

ELECTRICAL PROPERTIES OF POROUS SILICON PREPARED BY PHOTOCHEMICAL ETCHING  

Microsoft Academic Search

In this work, electrical properties of porous silicon (PS) structure fabricated by using the photochemical etching process in HF acid under different etching times was investigated. (111) n-type silicon wafers with two different resistivities (?1 = 3.25 x 10 -4 ?cm and ?2 = 4.3-5.6 ?cm) were used. The wafers were etched in 40% HF acid by using 100 W

A. M. Ahmmed; A. M. Alwan; N. M. Ahmed

158

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

159

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

PubMed Central

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

2012-01-01

160

Shallow Etching of GaAs/AlGaAs Heterostructures in Context of HEMT Fabrication  

NASA Astrophysics Data System (ADS)

Gate recess etching is a key step in the fabrication process of high electron mobility transistors (HEMTs). The thin n+ cap layer needs to be etched without destroying the underlying supply layer. Conventional GaAs etch solutions based on H2SO4 or H3PO4 acids have high etch rates and hence present difficulties in the control of etch rates for shallow etches. Etches using Citric acid (CA) based solutions have been reported to have potential in such applications. Such etches with varying ratio of CA:H2O2:H2O are compared. A suitable recipe has been obtained for shallow gate recess etch and a HEMT is fabricated using the process.

Kumar, Ch. Ravi; Rajaram, G.

2011-07-01

161

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

SciTech Connect

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

Brown, E V

1988-06-01

162

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

Microsoft Academic Search

This research accomplished two goals. The first was to develop a computer program to simulate a cascade dissolver system. This program would be used to predict the bulk rate of dissolution in incinerator ash. The other goal was to verify the model in a single-stage dissolver system using DyâOâ. PuOâ (and all of the species in the incinerator ash) was

1988-01-01

163

Plasma etch chemistry for anisotropic etching of silicon  

Microsoft Academic Search

A plasma etch chemistry which allows a near perfectly vertical etch of silicon is disclosed. A Cl-containing compound such as BClâ has Brâ added to it, readily allowing anisotropic etching of silicon. This is due to the low volatility of SiBrâ. The silicon surface facing the discharge is subjected to ion bombardment, allowing the volatilization (etching) of silicon as a

Purdes

1984-01-01

164

Study of selective gate recess etching of InGaAs\\/InAlAs\\/InGaAs metamorphic HEMT structures using succinic acid based etchant  

Microsoft Academic Search

Metamorphic HEMTs on GaAs substrates are promising devices of today as they are operated at even higher frequencies for microwave applications compared to pseudomorphic HEMTs. The selective removal of n+ InGaAs ohmic contact layer from the top of the device structure poses a major challenge during fabrication. We have studied the influence of temperature on the selectivity of etch rate

K. Mahadeva Bhat; G. Sai Saravanan; H. P. Vyas; R. Muralidharan; S. Dhamodaran; Mahaveer K. Jain; A. Subrahmanyam

2007-01-01

165

The Etch Process  

NSDL National Science Digital Library

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

166

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

E-print Network

are XeF2 and HF-Nitric acid etching. XeF2 is a gas phase etch, in which the XeF2 sublimates at room temperature to etch silicon according to the equation: 4 2 2 2 SiFXeSiXeF ++ (4) Surface roughness and higherISOTROPIC ETCHING OF 111 SCS FOR WAFER-SCALE MANUFACTURING OF PERFECTLY HEMISPHERICAL SILICON MOLDS

Afshari, Ehsan

167

Ion beam sputter etching  

NASA Technical Reports Server (NTRS)

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

Banks, Bruce A.; Rutledge, Sharon K.

1986-01-01

168

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

PubMed

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

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

2015-01-14

169

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

PubMed Central

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

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

2015-01-01

170

INVESTIGATION OF CORROSION INHIBITORS FOR FUMING NITRIC ACID. Period covered November 21, 1955 to June 7, 1957  

Microsoft Academic Search

Development of a corrosion inhibitor for fuming nitric acid that has ; corrosion-inhibiting and scale and sludge-formation properties superior to those ; of hydrofluoric acid was investigated. Amonium hexafluorophosphate in amount ; equivalent to 0.30% by weight hydrofluoric acid was found to provide better ; inhibition to the corrosion of 61S-T6 aluminum alloy and 17-7PH and AISI Type ; 304L

W. H. Bergdorf; E. J. Jr. Kinsey

1957-01-01

171

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

172

Orthodox etching of HVPE-grown GaN  

SciTech Connect

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

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

2006-08-10

173

Self-etch adhesive systems: a literature review.  

PubMed

This paper presents the state of the art of self-etch adhesive systems. Four topics are shown in this review and included: the historic of this category of bonding agents, bonding mechanism, characteristics/properties and the formation of acid-base resistant zone at enamel/dentin-adhesive interfaces. Also, advantages regarding etch-and-rinse systems and classifications of self-etch adhesive systems according to the number of steps and acidity are addressed. Finally, issues like the potential durability and clinical importance are discussed. Self-etch adhesive systems are promising materials because they are easy to use, bond chemically to tooth structure and maintain the dentin hydroxyapatite, which is important for the durability of the bonding. PMID:25672377

Giannini, Marcelo; Makishi, Patrícia; Ayres, Ana Paula Almeida; Vermelho, Paulo Moreira; Fronza, Bruna Marin; Nikaido, Toru; Tagami, Junji

2015-01-01

174

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

E-print Network

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

Kim, Philip

175

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

PubMed

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

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

2012-04-01

176

Silicon nanostructures from electroless electrochemical etching  

Microsoft Academic Search

Recent advances in the production of Si nanostructures from electroless etching are reviewed, including stain etching, metal-assisted etching and chemical vapour etching. A brief review of the explosion in applications of porous silicon over the past 18 months is also given. The stain film that results from the etching of (poly- or single-)crystalline Si is composed of a porous network

Kurt W. Kolasinski

2005-01-01

177

Wet Etching in Nanofabrication  

NSDL National Science Digital Library

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

178

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

Microsoft Academic Search

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

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

2010-01-01

179

Etch your name into Bobcat  

E-print Network

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

180

MEMS Pressure Sensor Backside Etch  

NSDL National Science Digital Library

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

181

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

182

ZERODUR: bending strength data for etched surfaces  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

183

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

184

Submicron patterned metal hole etching  

DOEpatents

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

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

2000-01-01

185

Decontamination of metals using chemical etching  

DOEpatents

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

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

1980-01-01

186

Etching and Growth of GaAs  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

187

Plasma etching using hydrogen bromide addition  

Microsoft Academic Search

The disclosure relates to a plasma etch chemistry which allows a near perfectly anisotropic etch of silicon. A Cl-containing compound such as HCl has HBr added thereto, readily allowing the anisotropic etching of silicon. This is due to the low volatility of SiBrâ. The silicon surface facing the discharge is subjected to ion bombardment, allowing the volatilization (etching) of silicon

Hartman

1984-01-01

188

Controlled in situ etch-back  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

189

Dry etching method for organic material layers  

SciTech Connect

A dry etching method for organic material layers is disclosed which utilizes a parallel plate electrode type plasma etching apparatus. An etching gas containing nitrogen as its primary constituent is introduced into the apparatus, and then the organic material layers are anisotropically etched by applying a high frequency electric power to the electrodes to produce a plasma.

Higashikava, I.; Arikado, T.

1984-09-25

190

Northern Arabia Etched Terrain  

NASA Technical Reports Server (NTRS)

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

2002-01-01

191

Etching Of Semiconductor Wafer Edges  

DOEpatents

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

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

2003-12-09

192

State of the art etch-and-rinse adhesives  

PubMed Central

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

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

2013-01-01

193

Lucian Freud: The Painter's Etchings  

NSDL National Science Digital Library

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

2008-01-01

194

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

195

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

196

Study on inductively coupled plasma etching induced damage of InSb  

NASA Astrophysics Data System (ADS)

InSb is an important ?-?narrow gap compound semiconductor material. It is widely used in optoelectronic devices manufacture especially mid-wave infrared detectors. With the application of ICP etching in large-scale InSb IRFPA detectors fabrication process, the influence of ICP etching induced damage on InSb IRFPA devices has been paid more attention. Surface states which reflect the characteristics of semiconductor surface play an important role in the study on etching damage of semiconductor materials. In this paper, the surface state density on three InSb samples: one sample without etching, one sample etched by ICP and another sample wet etched by lactic acid/nitric acid etchant after ICP etching, is tested and calculated by quasi-static C-V method. The characterization and removal of ICP etching induced damage are investigated. Furthermore, the method of testing and calculating the distribution of surface state density has been presented detailedly in this paper. This work plays a significant role in the development of large-scale InSb IRFPA detectors.

Wang, Liwen; Si, Junjie; Zhang, Guodong; Cheng, Caijing; Geng, Dongfeng

2014-11-01

197

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

198

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.

199

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

200

Surface texturing of p-GaN layer for efficient GaN LED by maskless selective etching  

Microsoft Academic Search

The maskless selective wet etching of p-GaN layer with KOH in ethylene glycol (KE) and H3PO4\\/H2SO4 (HH) acids was developed for the highly efficient light-emitting diodes (LEDs). The p-GaN surfaces textured by the selective wet etching process without using etch mask showed hexagonal and stripe shapes in the KE and HH solutions, respectively. The current-voltage (I-V) characteristics of the LED

Seok-In Na; Dae-Seob Han; Seok-Soon Kim; Jae-Hong Lim; Ja-Yeon Kim; Seong-Ju Park

2005-01-01

201

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

PubMed Central

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

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

202

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

PubMed Central

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

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

2013-01-01

203

ION BEAM ETCHING EFFECTS IN BIOLOGICAL MICROANALYSIS  

EPA Science Inventory

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

204

Apparatus for edge etching of semiconductor wafers  

NASA Technical Reports Server (NTRS)

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

Casajus, A.

1986-01-01

205

Dynamics of ion-assisted etching  

Microsoft Academic Search

In this thesis a study is presented on the fundamentals of ion-assisted etching of silicon. The research was performed in the Atomic Physics and Quantum Electronics Group (AQT\\/B) of the Physics Department at the Eindhoven University of Technology. Etching is a key technique in the production process of integrated circuits. Industrial etching is usually done in a plasma reactor. However,

Petrus Gerardus Maria Sebel

1999-01-01

206

Semiconductor etching by hyperthermal neutral beams  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

207

Surface reaction mechanisms in plasma etching processes  

Microsoft Academic Search

Plasma etching is an essential process in the fabrication of submicron features in the semiconductor industry. Plasma-surface interactions in plasma etching processes are capable of influencing bulk plasma properties as well as determining etch rates and feature profiles. To address the coupling of plasma and surface processes, the Surface Kinetics Model (SKM) was developed and was linked to the Hybrid

Da Zhang

2000-01-01

208

JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 12, NO. 6, DECEMBER 2003 761 Etch Rates for Micromachining Processing--Part II  

E-print Network

preparations of silicon nitride, sapphire, two preparations of aluminum oxide, aluminum, Al/2%Si, tita- nium etches: isotropic silicon etchant, potassium hydroxide, 10:1 HF, 5:1 BHF, Pad Etch 4, hot phosphoric acid, Aluminum Etchant Type A, titanium wet etchant, CR-7 chromium etchant, CR-14 chromium etchant, molybdenum

Lin, Liwei

209

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

210

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

211

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

PubMed

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

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

2013-11-01

212

Cryogenic electron beam induced chemical etching.  

PubMed

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

Martin, Aiden A; Toth, Milos

2014-11-12

213

One-Year Clinical Evaluation of the Bonding Effectiveness of a One-Step, Self-Etch Adhesive in Noncarious Cervical Lesion Therapy  

PubMed Central

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

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

2015-01-01

214

Aspect Ratio Independent Etching: Fact or Fantasy?  

NASA Astrophysics Data System (ADS)

The scaling of anisotropic plasma etch rates with feature dimensions is an important issue when fabricating microelectronic and photonic devices. For a wide rage of conditions, etch rates are found to scale primarily with the feature depth/width or aspect ratio. Features with large aspect ratios etch more slowly than those with low aspect ratios regardless of feature width. However, in the presence of etch inhibitors, the scaling of etching rates with feature dimensions becomes more complicated. Smaller aspect ratio features may etch more slowly than larger aspect ratio features suggesting that etch-inhibiting chemistry could be exploited in achieving the here-to-fore elusive goal of aspect ratio independent etching (ARIE). Using a well-established etching model, based on Langmuir adsorption kinetics, we derive the etch inhibitor flux and surface adsorption parameters required to achieve ARIE. Although the required parameters are non-physical when the range of aspect ratios is unconstrained, it is possible to achieve ARIE over a restricted range of aspect ratios. However, the balance required between ion, etchant, and inhibitor fluxes is a fragile one. The best approach to minimizing the variation in etching rate with aspect ratio is to operate a high density plasma at low pressure with high neutral flow rates.

Bailey, Andrew D., III; Gottscho, Richard

1995-04-01

215

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. PMID:20706618

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

2010-01-01

216

Plasmoids for etching and deposition  

NASA Astrophysics Data System (ADS)

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

Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter

2014-11-01

217

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

E-print Network

; Cu; Ag; Ti; GaAs; GaN Sulfuric Acid (H2SO4): C; Cu; GaAs; Fe; Pb; Ni; Ti Aqua Regia (3 HCl : 1 HNO3 : hydrofluoric acid (49%, aq) HNO3 : nitric acid (70%, aq) H2SO4 : sulfuric acid (96%, aq) H3PO4 : phosphoricAcetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In

Garmestani, Hamid

218

Determination of the Mode of Occurrence of As, Cr, and Hg in Three Chinese Coal Samples by Sequential Acid Leaching  

Microsoft Academic Search

Sequential acid leaching was used to leach minerals and the trace elements they contain. One-step leaching uses concentrated nitric acid as solvent, while three-step leaching uses 5M hydrochloric acid, concentrated hydrofluoric acid, and concentrated hydrochloric acid as solvents. The sequential acid leaching by three-and one-step leach was also examined. The results showed that one-step leaching could leach over 80% of

B. Wang; W. Li; G. Wang; H. Chen; B. Li

2007-01-01

219

Plasma technology for advanced quartz mask etching  

NASA Astrophysics Data System (ADS)

We review the state-of-art and issues of dry etching of masks for nano-device photo lithography. After introducing the basics of photo-mask structures and their plasma etching, we discuss the specifics of mask etching as compared to the etching of silicon wafers, focusing on processes for the two most-challenging cases: phase-shift masks and NGL where it is achieved by etching the quartz exactly to the prescribed depth. State-of the art solutions for the etching of such masks must provide stringent etching uniformity and accurate end-point monitoring. This can be addressed by either reducing the lithography fields to half or even quarter of their present area, with two to four times worse productivity, or working with larger masks of 9 and later 12 inch. The pressure for such development is becoming stronger with the wider adoption of 450 mm wafers. The new masks may need to be thicker to prevent unwanted deformations. Etching uniformity will have to be sustained over much wider areas. Furthermore, RF bias control for thicker substrates is not straightforward due to the quartz impedance preventing effective RF coupling. Our etching experiments in Ar and Cl2 showed that well established mask etching conditions can be reproduced for moderately thicker substrates, while further increase of substrate thickness may require essentially different approach, such as a series resonance of the inductive plasma bulk and the capacitive sheath.

Iwami, Munenori; Ita, Hirotsugu; Kase, Yoshihisa; Azumano, Hidehito; Nakazawa, Kazuki; Okamoto, Yoshie; Shirahama, Hiroki; Yoshimori, Tomoaki; Muto, Makoto; Ganachev, Ivan

2014-10-01

220

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

PubMed

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

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

2015-02-01

221

Etch challenges for DSA implementation in CMOS via patterning  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

222

Etching of glass microchips with supercritical water.  

PubMed

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

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

2015-01-01

223

Laser-driven fusion etching process  

DOEpatents

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

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

1989-01-01

224

Laser-driven fusion etching process  

DOEpatents

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

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

1987-08-25

225

Rotary replication for freeze-etching  

Microsoft Academic Search

Rotary replication has been adapted to freeze-etching and evaluated using T4 polyheads, erythrocyte ghosts, and chloroplast membranes. Conventional elec- tron 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. Freeze-etching has exposed

LUKAS H. MARGARITIS; ARNLJOT ELGSAETER; DANIEL BRANTON

1977-01-01

226

Selective etching of silicon carbide films  

DOEpatents

A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

Gao, Di; Howe, Roger T.; Maboudian, Roya

2006-12-19

227

Patterning by Etching at the Nanoscale (PENs) on Si(111) through the Controlled Etching of PDMS  

E-print Network

Patterning by Etching at the Nanoscale (PENs) on Si(111) through the Controlled Etching of PDMS molecules include dip pen lithography,10,11 electron-beam lithography,12-14 focused ion beam lithography,15

Kenis, Paul J. A.

228

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

SciTech Connect

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

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

2008-01-09

229

Fabrication of Semiconductors by Wet Chemical Etch  

E-print Network

, so that more data would be available for analysis. !e etch solution of 1:8:640 of H2SO4:H2O2:deionized water was prepared under the hood in manage- able proportions of 0.2:1.6:128 mL. Samples were individually immersed in the etch solution... in chemical engineering at the University of Kansas. Fabrication of Semiconductors by Wet Chemical Etch Selective Etching of GaAs Over InGaP in Dilute H2SO4:H2O2 58 epitaxial GaAs cap layer grown over an underlying InGaP layer were avail- able...

Francoviglia, Laura

2008-07-01

230

Dry etching technologies for reflective multilayer  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

231

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

232

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

233

Focused electron-beam-induced etching of silicon dioxide  

Microsoft Academic Search

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

S. J. Randolph; J. D. Fowlkes; P. D. Rack

2005-01-01

234

Etching radical controlled gas chopped deep reactive ion etching  

DOEpatents

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

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

235

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

236

Etch-induced damage of HgCdTe caused by inductively coupled plasma etching technique  

Microsoft Academic Search

HgCdTe third-generation infrared focal plane arrays such as avalanche photodiodes, two-color detectors and multi-color detectors require isolation of high aspect ratio trenches with admissible etch induced damage at the surface and sidewalls. Dry etch has many advantages compare with wet etch such as high anisotropy, good uniformity and good reproducibility. Inductively coupled plasma (ICP) etching is most widely used for

Wenting Yin; Wenzhong Zhou; Jian Huang

2010-01-01

237

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

E-print Network

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

Yu, K.N.

238

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 {11¯00}/ {112¯0} 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

239

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

240

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

241

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

PubMed

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

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

2012-01-01

242

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

E-print Network

silicates of aluminum, calcium, sodium, and potassium. The significance of the zeolites is that they will either decompose and/or gelatinize in hydrochloric acid at temperatures rise above approximately 75°F. Another important guideline outlined... al. 1991). The aim of the acid job is to bypass the near wellbore damage and restore the well productivity. Unlike other acids, hydrofluoric acid (HF) has a special ability to react with silica and silicates which makes it a fundamental component...

Abdelmoneim Mahmoud, Sherif

2014-08-08

243

Atmospheric downstream plasma etching of Si wafers  

Microsoft Academic Search

A dry etch technology for processing Si wafers using an atmospheric downstream plasma (ADP) source is described. Application of ADP etching for backside damage removal after grinding and wafer thinning is discussed. ADP is an inert gas thermal plasma generated by DC discharge at atmospheric pressure in the process chamber. The reactant (freon) is injected into the plasma stream outside

Oleg Siniaguine

1998-01-01

244

Dry etching method and device therefor  

SciTech Connect

A dry etching method and device involve induction of a magnetic field having field lines perpendicular to an electric field by magnets which are arranged in the vicinity of a cathode within a reaction chamber, on the surface of the cathode being placed a sample to be etched by a plasma of an etchant gas.

Okano, H.; Horiike, Y.

1985-01-08

245

Microleakage and penetration depth of three types of materials in fissure sealant: self-etching primer vs etching: an in vitro study.  

PubMed

Clinical preventive procedures must be done after a risk assessment. One of the risk factors is the occlusal morphology of the posterior teeth. These caries-free fissures must be sealed. This first in vitro experimentation of the study evaluated the microleakage and the penetration depth of three types of materials by Vivadent: Helioseal F, Tetric, Tetric Flow. The teeth were etched with phosphoric acid and bonded using a one bottle bonding in order to determine the best material for the sealing of the fissure. The depth of penetration of fuschine dye as well as that of the tested material was measured with a grid. The results, compared to the depth of the fissures, are expressed in percentage of penetration. The results were as follows: penetration of fuschine dye: 0% for the 2 composites, 100% for Helioseal F; penetration of the materials: 96.90% for Helioseal F, 70.82 for Tetric and 86.10 for Tetric Flow (significant difference, Wilcoxon test = 0.0105). In this first in vitro study, Tetric Flow shows no microleakage and is more efficient when compared to Helioseal F and Tetric in obturating deep fissures of non carious bicuspids. The second experiment of the study evaluated the microleakage and the penetration depth of Tetric Flow when it is bonded by two different methods: Group 1: total etch (phosphoric acid) and Scotch-bond 1 (3M), and Group 2: self-etching primer with Prompt (Espe). There was no significant difference (p > 0.03) between classical bonding vs self-etching primer. The self-etching primer Prompt is very efficient vs phosphoric acid in obturating the fissures of non carious bicuspids with Tetric Flow. It is concluded that for prevention by sealing, using a flowable ceromer (Tetric Flow) with the self-etching (Prompt), is a really good technique. PMID:11874009

Gillet, D; Nancy, J; Dupuis, V; Dorignac, G

2002-01-01

246

Developments of Plasma Etching Technology for Fabricating Semiconductor Devices  

Microsoft Academic Search

Plasma etching technologies such as reactive ion etching (RIE), isotropic etching, and ashing\\/plasma cleaning are the currently used booster technologies for manufacturing all silicon devices based on the scaling law. The needs-driven conversion from the wet etching process to the plasma\\/dry etching process is reviewed. The progress made in plasma etching technologies is described from the viewpoint of requirements for

Haruhiko Abe; Masahiro Yoneda; Nobuo Fujiwara

2008-01-01

247

Etching Behavior of Aluminum Alloy Extrusions  

NASA Astrophysics Data System (ADS)

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

Zhu, Hanliang

2014-11-01

248

Variable-angle dry etching with a hollow cathode  

NASA Astrophysics Data System (ADS)

Previous experiments have shown that very high etch rates can be obtained with an rf hollow cathode reactive sputter etching apparatus. This letter shows that hollow cathode etching also permits profile control, without mask undercut or mask erosion. The angle of etching is here varied from 90° (i.e., normal to the etched surface) to 50°, at a constant pressure of CF4 and a constant applied rf voltage, by varying the etch conditions. The etch angle is largely independent of the etched material (SiO2 or Si).

Horwitz, Chris M.

1984-06-01

249

Extraction of Am(III) from different acid media by di-2-ethyl hexyl phosphoric acid containing phosphorous pentoxide  

Microsoft Academic Search

The extraction of Am(III) from nitric, hydrochloric, oxalic, phosphoric and hydrofluoric acids was studied using 0.4F di-2-ethyl hexyl phosphoric acid (HDEHP) containing 0.1M phosphorous pentoxide (P2O5) in dodecane\\/xylene. The extraction with pure 0.4F HDEHP was found to be negligible from all the media studied. However, the presence of a small amount of P2O5 in it increased the extraction substantially. The

M. M. Charyulu; D. G. Phal; D. M. Noronha; V. V. Ramakrishna; V. Venugopal

2001-01-01

250

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

EPA Science Inventory

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

251

Anisotropic fluorocarbon plasma etching of silicon\\/silicon germanide heterostructures and plasma etching-induced sidewall damage  

Microsoft Academic Search

Plasma etching is a critical tool in the fabrication of Si\\/SiGe heterostructure quantum devices, but with challenges addressed herein, including (1) control of etch profiles and (2) damage to etched feature sidewalls that affects device performance. (1) Fluorocarbon-based plasma etching often results in device profiles with undercuts due to preferential etching of SiGe over silicon. A C4F8\\/N2\\/Ar etch plasma gas

Ruhang Ding

2008-01-01

252

Etch-a-Sketch Nanoelectronics  

NASA Astrophysics Data System (ADS)

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

Levy, Jeremy

2009-10-01

253

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

SciTech Connect

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

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

2002-04-08

254

High density plasma etching of magnetic devices  

NASA Astrophysics Data System (ADS)

Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3-rich to achieve the highest etch rates. Several different mask materials were investigated, including photoresist, thermal oxide and deposited oxide. Photoresist etches very rapidly in CO/NH 3 and use of a hard mask is necessary to achieve pattern transfer. Due to its physically dominated nature, the CO/NH3 chemistry appears suited to shallow etch depth (?0.5mum) applications, but mask erosion leads to sloped feature sidewalls for deeper features.

Jung, Kee Bum

255

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

PubMed

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor-liquid-solid grown InAs nanowires with embedded InP segments of 10-60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap. PMID:25360747

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

2014-11-21

256

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

NASA Astrophysics Data System (ADS)

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor–liquid–solid grown InAs nanowires with embedded InP segments of 10–60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap.

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

2014-11-01

257

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

PubMed

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

Yao, Bo; Coffey, Kevin R

2008-04-01

258

Dynamics of ion-assisted etching  

NASA Astrophysics Data System (ADS)

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

Sebel, Petrus Gerardus Maria

259

Dry etching method for compound semiconductors  

DOEpatents

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

Shul, R.J.; Constantine, C.

1997-04-29

260

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

261

Aqueous etching of microfabricated and nanofabricated surfaces  

NASA Astrophysics Data System (ADS)

The techniques of silicon micromachining developed by the microelectronics industry are increasingly being used to fabricate a wide variety of microelectromechanical systems (MEMS). As the geometry of MEMS becomes more complicated, new chemical etching techniques need to be developed in order to meet technological demands. This thesis describes three separate investigations into different aspects of site-specific surface chemistry. In the first investigation, micromachined test patterns are used to perform orientation-dependent kinetic studies on the etching of silicon in aqueous KOH solutions. Standard models of chemical reactivity cannot accurately describe the observed kinetics. Temperature-dependent macroscopic etch rates exhibit non-Arrhenius behavior, and empirical rate laws do not fit the observed concentration dependence. The disagreements with standard models are attributed to the multisite nature of surface etching reactions. Deuterium substitution reduces the etch rate of all surfaces in the Si[110] zone. This kinetic isotope effect is attributed to the rate-limiting breaking of Si-H bonds. The kinetic studies show that surfaces in the Si(110) zone are divided into four regions of similar reactivity: vicinal Si(100), vicinal Si(110), and two types of vicinal Si(111). In the second investigation, a new technique was developed for fabricating nanoperiodic surfaces with periodicities of 2--100 nm. By selectively etching dislocations at the interface of two twist-bonded Si(100) surfaces, a periodic array of hillocks is produced. The etch rates of tilt- and twist-dislocations are compared. Both types of dislocations etch at very similar rates, even though their calculated strain field energies differ by two orders of magnitude. This observation contradicts long-held assumptions about dislocation etching. In the third investigation, nanofabricated arrays of silicon nanodots were used to study nanostructure-directed anodic etching. These experiments suggested that the current density, not the voltage, was the morphology-determining parameter of porous silicon formation. Removal of the porous silicon layer by both KOH etching and a combination of thermal oxidation and selective oxide etching revealed that the nanostructures had been preserved at the bottom of the porous silicon layer. This preservation of the arrays was attributed to the formation of bulk-silicon nanopillars within a porous silicon medium.

Wind, Rikard Anton

262

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

263

Anisotropic reactive ion etching of vanadium dioxide  

E-print Network

with 5214 photo resist by means of a standard image reversal technique. This layer of photo-resist 51 will protect the optical windows and the small gaps between the windows and the metal leads. St ep: 12 Etch the highly doped Gallium Arsenide in a wet... the substrate. Higher ion ? bombardment energies enhance etch rate and directionality of the etch, but if energies are too high, substrate heating, mask erosion, and surface damage can occur. 31 Flow rate: The effects of gas flow rate vary from reactor...

Radle, Byron K

1990-01-01

264

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

PubMed Central

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

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

2014-01-01

265

InP-based waveguides: comparison of ECR plasma etching and wet-chemical etching  

Microsoft Academic Search

Electron Cyclotron Resonance (ECR) reactive ion etching of InP-based waveguide structures was studied using CH4\\/H2\\/Ar chemistry. The ECR process was first optimized on InP substrates before being used to process waveguides. Stripes of 2 µm width were patterned in silicon nitride and used as masking to etch strip-loaded waveguides. These waveguides were compared with wet-etched waveguides, in order to identify

Tol van der JJGM; M Silova; F Karouta; RG Broeke; HH Tan; C Jagadish; E Smalbrugge; Roy van BH

2000-01-01

266

Numerical study of the etch anisotropy in low-pressure, high-density plasma etching  

Microsoft Academic Search

Evolution of etched profiles has been numerically studied during low-pressure, high-density (LPHD) plasma etching of Si in Cl2. The surface etch rates were calculated using a reaction model of synergism between incoming ions and neutral reactants, including the spread of ion angular distributions due to their thermal motions and the transport of neutrals arising from the reemission on surfaces in

Mutumi Tuda; Kazuyasu Nishikawa; Kouichi Ono

1997-01-01

267

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala  

E-print Network

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

Kushner, Mark

268

Anisotropic reactive ion etching in silicon, using a graphite electrode  

Microsoft Academic Search

Monocrystalline silicon is etched in a simple reactive ion etching system with mixtures of SF6, Ar and H2 to obtain deep trenches. A graphite electrode is used to increase the anisotropy of the etching processes. The effect of varying flow, pressure and power levels on etch rate and anisotropy has been studied. Addition of Ar to SF6 results in an

Ronaldo D. Mansano; Patrick Verdonck; Homero S. Maciel

1998-01-01

269

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

270

Revelation of stepped dislocations in amethyst crystals by hydrothermal etching  

Microsoft Academic Search

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

M. S. Josut; M. A. IrryncHrN

271

HIGH ASPECT RATIO PARYLENE ETCHING FOR MICROFLUIDICS AND BIOMEMS  

E-print Network

." As in the Bosch process, the deposited fluoropolymer layer protects feature sidewalls from lateral etching. Etch "A" preferentially removes the fluoropolymer layer, exposing the parylene to the etching plasma. This step includes #12;SF6 which was found to aid in the removal of the deposited fluoropolymer layer. Etch

Meng, Ellis

272

Experimental Study of Acid Fracture Conductivity of Austin Chalk Formation  

E-print Network

Acid fracture conductivity and the effect of key variables in the etching process during acid fracturing can be assessed at the laboratory scale. This is accomplished by using an experimental apparatus that simulates acid injection fluxes comparable...

Nino Penaloza, Andrea

2013-05-01

273

Wafer Backside Anisotropic Wet Etching of Silicon  

NSDL National Science Digital Library

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

274

Defect-selective etching of scandium nitride crystals  

NASA Astrophysics Data System (ADS)

Defect-selective etching was developed for scandium nitride (ScN) crystals. ScN crystals were etched in fused KOH/NaOH eutectic mixtures between 180 and 440 °C for up to 10 min. Several etch pit shapes were observed, and their formation was dependent on the etching temperature. The different etch pit shapes probably originated from different crystalline orientations and defect types. Square etch pits with steps formed at screw and mixed dislocations, as verified by transmission electron microscopy. The density of the etch pits was on the order of 10 4-10 6 cm -2 for bulk ScN crystals produced by sublimation.

Gu, Z.; Edgar, J. H.; Coffey, D. W.; Chaudhuri, J.; Nyakiti, L.; Lee, R. G.; Wen, J. G.

2006-08-01

275

Investigations of Wafer Scale Etching with Xenon Difluoride  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

276

High density plasma etching of magnetic devices  

Microsoft Academic Search

Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this

Kee Bum Jung

1999-01-01

277

Selective dry etching of silicon with respect to germanium  

Microsoft Academic Search

We describe a plasma-based dry etching procedure which permits selective etching of Si over Ge with a Si\\/Ge etch rate ratio of over 70 and negligible etching of the Ge underlayer. This is achieved in a SF6\\/H2\\/CF4 gas mixture by the formation of a thin (&bartil;3 nm) involatile etch stop layer on the Ge surface which consists of Ge-sulfide and

G. S. Oehrlein; T. D. Bestwick; P. L. Jones; J. W. Corbett

1990-01-01

278

Selective dry etching of silicon with respect to germanium  

NASA Astrophysics Data System (ADS)

We describe a plasma-based dry etching procedure which permits selective etching of Si over Ge with a Si/Ge etch rate ratio of over 70 and negligible etching of the Ge underlayer. This is achieved in a SF6/H2/CF4 gas mixture by the formation of a thin (?3 nm) involatile etch stop layer on the Ge surface which consists of Ge-sulfide and carbonaceous material.

Oehrlein, G. S.; Bestwick, T. D.; Jones, P. L.; Corbett, J. W.

1990-04-01

279

Surface morphology of electrochemically etched porous GaP  

NASA Astrophysics Data System (ADS)

The mechanisms of porous gallium phosphide formation by anodic etching are studied. Gallium phosphide porous samples <100> oriented were prepared in sulfuric acid solution with different concentrations of NaF. The current-voltage characteristic curve depends on the NaF concentrations and shows the typical behavior for porous semiconductors formation. Four regions can be distinguished in the I-V curve: a pore formation zone, a dielectric layer growth, a transition region in which the two processes compete for the control of the surface morphology and finally the GaP surface electropolishing. The oxide formation shifts to higher potential and the pore formation zone is widened by adding fluorides in the etching solution. Raman spectroscopy is applied to investigate the surface morphology of samples prepared in different anodizing current density conditions and in different acid solutions. As regards the dielectric growth, the direct observation of the sample surface and the analysis of the vibrational spectra indicate that in different potential regimes two chemically different oxides can be formed.

Ricci, Pier Carlo; Anedda, Alberto; Carbonaro, C. M.; Clemente, F.; Corpino, R.

2002-11-01

280

Chrome dry etching for 65-nm node mask manufacturing  

NASA Astrophysics Data System (ADS)

A new chrome etch system was acquired and implemented to manufacture 65 nm node critical level masks. The etch performance of FEP 171, ZEP 7000, NEB 22, and REAP 200 resist systems in this new chrome etch system was evaluated. The critical dimension (CD) uniformity, etch bias, and etch linearity of this new etch system relative to the older generation etch system is presented. Implementation of the new etch system resulted in a 40-60 nm reduction in etch bias with no degrade in CD uniformity performance. In addition, it was found that the etch contribution to CD linearity was reduced by 50%. Detailed characterization of both macroloading and microloading etch effects was performed and showed substantial improvement relative to the previous generation etch system. The change in chrome etch rate as a function of etch area was reduced by 50%, improving mean to target CD performance on new designs. Implementation of the new etch system has enabled achievement of CD and defect density performance requirements for 65 nm node mask manufacturing. The results presented in this paper were collected during the process development phase and are not necessarily representative of the final optimized process.

Faure, Thomas; Fisch, Emily; Huynh, Cuc; Crawford, Shaun

2004-12-01

281

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

PubMed

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

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

2002-12-01

282

Modification of H-terminated Ge surface in hydrochloric acid  

NASA Astrophysics Data System (ADS)

Various amounts of H-termination on a Ge surface were prepared by dipping a Ge wafer in differentially diluted hydrofluoric acid solutions for different periods of time. Formation of Ge sbnd H x in hydrofluoric acid and its disappearance in hydrochloric acid (HCl) were directly measured by using multiple internal reflection Fourier transform infrared spectroscopy (MIR FT-IR). Peak intensity of Ge sbnd H x vibration mode was increased with diluted hydrofluoric acid (DHF) treatment time and the concentration of HF solution. Therefore, it is suggested that microroughness of a Ge surface changes depending on the concentration of HF. Peak intensity of Ge sbnd H x vibration mode was reduced when the Ge sbnd H x surface was treated in HCl solution. With an increase in HCl treatment time, peak intensity of Ge sbnd H x vibration mode was reduced. Ge surfaces treated in a more diluted HF solution were barely modified, because it was thought to have fewer kink sites, dihydrides and trihydrides.

Park, Kibyung; Lee, Younghwan; Lim, Sangwoo

2008-01-01

283

Anisotropic Deep Reactive Ion Etching without Aspect Ratio Dependence Etching for silicon power devices  

E-print Network

a thermal silicon oxide mask: SiO2 thicknesses have been determined in order to obtain the same depth whatever the trench aperture. Critical points for deep trenches etching are: High Aspect Ratio (HAR), CD than for a 6µm one. In order to reduce this etching rate difference, an oxide mask has been added only

Paris-Sud XI, Université de

284

Mechanism of Reactive Ion Etching Lag in WSi2 Etching Using Electron Cyclotron Resonance Plasma  

NASA Astrophysics Data System (ADS)

The electron cyclotron resonance (ECR) plasma is one of the suitable methods to generate plasma at a low pressure; however, unprecedented low pressure (<0.1 Pa) and smaller feature size have created unexpected problems. We study the relationship between ion energy and WSi2 etching products in order to discuss the mechanism of the reactive ion etching (RIE) lag observed in the WSi2 etching results. We investigate the dependence of WSi2 etch rate and RIE lag on etching parameters at low pressures (4×10-2 Pa). The RIE lag of WSi2 etching is stronger than that of poly-Si etching. Also, the RIE lag increases as rf power increases. Two possible reasons for the RIE lag can be suggested. One is the decrease of the flux ratio of a high-aspect-ratio pattern. Another is that partial pressure of the etch products at the bottom of a narrow space pattern is higher than that at the wide space pattern.

Maruyama, Takahiro; Fujiwara, Nobuo; Yoneda, Masahiro; Tsukamoto, Katsuhiro; Banjo, Toshinobu

1994-04-01

285

Etch-induced damage of HgCdTe caused by inductively coupled plasma etching technique  

NASA Astrophysics Data System (ADS)

HgCdTe third-generation infrared focal plane arrays such as avalanche photodiodes, two-color detectors and multi-color detectors require isolation of high aspect ratio trenches with admissible etch induced damage at the surface and sidewalls. Dry etch has many advantages compare with wet etch such as high anisotropy, good uniformity and good reproducibility. Inductively coupled plasma (ICP) etching is most widely used for its low etch induced damage which is a new high density plasma technique. It's very important to understand etching mechanisms and reduce etch induced damage for the low damage threshold of HgCdTe which is due to weak Hg-Te bond and low volatility of CdTe component. The main work of this paper is researching the influence of etch induced damage caused by different mask technique using inductively coupled plasma etching instrument with a feasible technics. In this experiment we used two different masks, one only has a film of silicon dioxide which we called thin mask, its thickness is less than one micrometer, and the other is composed of resist and silicon dioxide which we called complex thick mask, its thickness is several micrometers. We tested the current-voltage (I-V) characteristics of a chip which has a special structure achieved by dry etch and about one micrometer wet etch to remove the etch induced damage film. Then we found that in a same condition the I-V characteristics of the chip which used complex thick mask is distinctly better than the chip which used thin mask. Resist and silicon dioxide complex thick mask can effectively reduce etch induced damage. The reasons for this result have two aspects, in one hand, the grown process of silicon dioxide can cause damage of HgCdTe surface, make a thick resist between HgCdTe and silicon dioxide can reduce the damage of HgCdTe surface, in the other hand, complex thick mask can hold up the damage of trench sidewall in etch process.

Yin, Wenting; Zhou, Wenzhong; Huang, Jian

2010-10-01

286

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

NASA Technical Reports Server (NTRS)

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

Lerner, N. R.; Wydeven, T.

1989-01-01

287

Plasma characteristics and etch uniformity in CF4 magnetron etching using an annular permanent magnet  

NASA Astrophysics Data System (ADS)

Etch characteristics of SiO2 and Si obtained by magnetron etching using an annular permanent magnet were analyzed. From these analyses, etch characteristics were found to be classified into three regimes. Remarkable enhancements in SiO2 etch rate, 25-40 times, were observed at constant Vrf by applying magnetic field of 150 G. Ion densities over the cathode were found to be distributed linearly along the E×B drift direction. Such an ion density distribution will be formed by the repeated process (ionization?ion bombardment?electron emission and drift?ionization). Etch distribution can be averaged and flattened to a uniformity of below ±2% by the magnetic field being rotated in 90° steps.

Kinoshita, Haruhisa; Ishida, Toshimasa; Ohno, Seigo

1987-11-01

288

Purified water etching of native oxides on heteroepitaxial CdTe thin films  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

289

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

PubMed Central

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface. PMID:24495647

2014-01-01

290

Evaluation of Cu Ion Concentration Effects on Cu Etching Rate in Chemical-Mechanical Polishing Slurry  

NASA Astrophysics Data System (ADS)

The effects of Cu ion concentration of the different solutions on Cu etching rate were investigated. From the dipping experiment of Cu substrates in different solutions of malic acid, hydrogen peroxide (H2O2), benzotriazole (BTA), and Cu ions, it was revealed that Cu etching rate is increased if the concentration of Cu(II) ions added in the solution is high. This is considered to be caused by the effect of Cu(II) ions on H2O2 molecules. In the solution of pH 7, the Cu etching rate increased markedly between 1.7× 10-4 and 3.4× 10-4 M Cu(II) ion concentrations. The maximum increase in the etching rate was from 990 to 2200 nm/min at a H2O2 concentration of 2 wt %. In the solution of pH 3, a marked change in the etching rate was not observed. Our results show that the concentration of Cu ions on the polishing pad in chemical-mechanical polishing (CMP) process is very important.

Nishizawa, Hideaki; Sugiura, Osamu; Matsumura, Yoshiyuki; Kinoshita, Masaharu

2007-04-01

291

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

NASA Astrophysics Data System (ADS)

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface.

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

2014-02-01

292

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

NASA Astrophysics Data System (ADS)

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

Stráský, Josef; Havlíková, Jana; Ba?áková, Lucie; Harcuba, Petr; Mhaede, Mansour; Jane?ek, Miloš

2013-09-01

293

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

294

Plasma etching a ceramic composite. [evaluating microstructure  

NASA Technical Reports Server (NTRS)

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

1992-01-01

295

Pulsed plasma etching for semiconductor manufacturing  

NASA Astrophysics Data System (ADS)

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

Economou, Demetre J.

2014-07-01

296

SUPPLEMENTARY INFORMATION DOI: 10.1038/NNANO.2011.226  

E-print Network

and length of 50~200 µ m were chosen for the nanowire endoscope fabrication. Optical Fibre Etching. Tapered optical fibre tips were fabricated by etching the fibre tips in the stack solution of hydrofluoric acid of the optical fibre. To minimize the scattering loss at the nanowire-fibre junction and optimize the coupling

Yang, Peidong

297

Micro-chamber filling experiments for validation of macro models with applications in capillary driven microfluidics  

E-print Network

...........................................................................15 4.2 Hydrofluoric Acid Etching.....................................................................................16 4.3 Drilling Flow Ports.................................................................................................20 4... microchambers of various geometric dimensions were microfabricated by etching glass substrates with depths between 20 and 50?m. The general layout of these chambers is shown in Figure 4. Figure 4: Typical Microchamber Setup In Figure 4, L 1 and L 2...

Gauntt, Stephen Byron

2009-05-15

298

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

299

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

SciTech Connect

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

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

2014-08-04

300

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

301

49 CFR Appendix D to Part 180 - Hazardous Materials Corrosive to Tanks or Service Equipment  

Code of Federal Regulations, 2012 CFR

...Hydrochloric acid solution Hydrofluoric acid and Sulfuric acid mixtures Hydrofluoric acid Hydrogen peroxide...solution Sodium hydrosulfide Sulfur, molten Sulfuric acid Sulfuric acid, fuming Sulfuric acid, spent Zinc...

2012-10-01

302

49 CFR Appendix D to Part 180 - Hazardous Materials Corrosive to Tanks or Service Equipment  

Code of Federal Regulations, 2013 CFR

...Hydrochloric acid solution Hydrofluoric acid and Sulfuric acid mixtures Hydrofluoric acid Hydrogen peroxide...solution Sodium hydrosulfide Sulfur, molten Sulfuric acid Sulfuric acid, fuming Sulfuric acid, spent Zinc...

2013-10-01

303

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

NASA Astrophysics Data System (ADS)

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

Katsumata, Nobuyuki; Ishida, Masafumi

304

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

SciTech Connect

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

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

2012-11-30

305

Surface kinetics modeling of silicon oxide etching in fluorocarbon plasmas  

E-print Network

Fluorocarbon plasma for silicon oxide etching is a complicated system involving many ion and neutral species. Depending on the plasma condition, many difficulties arise such as RIE lag, etch stop, and low selectivity to ...

Kwon, Ohseung, 1969-

2004-01-01

306

Plasma etching of the Group-III nitrides  

SciTech Connect

In reactive ion etching (RIE) of GaN, the ion bombardment can damage the material, so it is necessary to develop plasma etch processes. This paper reports etching of GaN in an ECR (electron cyclotron resonance) etch system using both the ECR/RIE mode and the RIE-only mode. Group III (Ga, In, Al) nitride ECR etching is reviewed as a function of plasma chemistry, power, temperature, and pressure; as the ECR microwave power increased, the ion density and etch rates increased, with the etch rate increasing the most for InN. GaN etch rates > 6500 {angstrom}/min have been observed in the ECR/RIE mode. 2 figs, 6 refs.

Shul, R. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J.; Abernathy, C.R. [Univ. of Florida, Gainesville, FL (United States)

1996-01-01

307

Isotropic etching of silicon in fluorine gas for MEMS micromachining  

Microsoft Academic Search

Etching of silicon with molecular fluorine for the micromachining of micro electro mechanical systems (MEMS) has been evaluated. The etching process is carried out in a continuous flow etching system that uses a 25 vol% mixture of F2 in N2 and operates at room temperature and atmospheric pressure. Fluorine etches silicon isotropically at a rate of 0.2 µm min?1 and

Leonel R Arana; Nuria de Mas; Raymond Schmidt; Aleksander J Franz; Martin A Schmidt; Klavs F Jensen

2007-01-01

308

Enhanced etching of sapphire damaged by ion implantation  

Microsoft Academic Search

Enhanced ion beam etching and chemical etching of sapphire damaged by ion implantation have been investigated. In our experiments an amorphous layer or a damaged layer were produced respectively by high-dose yttrium ion or platinum ion implantation. Rutherford backscattering spectrometry and channelling (RBS-C) was used to analyse the material removed by ion beam etching or chemical etching. For 500 eV

Xie Dongzhu; Zhu Dezhang; Pan Haochang; Xu Hongjie; Ren Zongxin

1998-01-01

309

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

PubMed Central

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

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

2014-01-01

310

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

311

Selective oxygen plasma etching of coatings  

Microsoft Academic Search

The technology of selective oxygen plasma etching is presented. It enables the evaluation of the state of pigment dispersion, as well as the distribution of other solid particles that are added in pigmented coatings for various functional purposes. The technology is based on the selective interaction of reactive gaseous particles from oxygen plasma with the pigment-polymer composite. In our case,

U. Cvelbar; M. Mozetic; M. Klanjsek-Gunde

2005-01-01

312

Etch Profile Simulation Using Level Set Methods  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

313

Dry etching of III-V nitrides  

SciTech Connect

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

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

1995-12-01

314

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

315

Chromium Etching Revised: 2009-12-15  

E-print Network

Chromium Etching Revised: 2009-12-15 Source: www. Chromium Chromium is a hard metal with good adhesion to many materials. Therefore, in the field of micro- structuring chromium is used for photo masks and as adhesion promotor for subsequently coated materials

Yoo, S. J. Ben

316

Etching of silicon in fluoride solutions  

Microsoft Academic Search

The development and status of what is commonly called the Gerischer mechanism of silicon etching in fluoride solutions is reviewed. The two most widely used and studied wet etchants of silicon are F? and OH?. Their mechanisms of atom removal share many things in common; in particular, chemical passivation by a hydrogen-terminated surface plays an important role in both. Crucially,

Kurt W. Kolasinski

2009-01-01

317

Surface roughness studies of deep plasma etching in crystalline silicon  

Microsoft Academic Search

A study of the parameters influencing the roughness of plasma etched surfaces of monocrystalline silicon was conducted, using a commercial reactive ion etcher (RIE) and a Gaseous Electronic Conference (GEC) Plasma Standard Cell as the etching tools. Relatively deep (6 micrometer) etching was done using pure SF6 and mixtures of SF6 with additions of either oxygen or hydrogen. Other parameters

Zhong Li

1995-01-01

318

Electrical Characterization of Plasma Etching Damage in Ulsi Processes  

Microsoft Academic Search

In modern integrated circuit (IC) fabrication, plasma etching technique is used mainly due to the reason that it can provide precise anisotropic etching. However, energetic atoms, UV photons, ions and electrons as well as large plasma-substrate potential difference present during the plasma etching process can all have detrimental effects and potentially degrade the gate oxide and the processed device. The

Xiaoyu Li

1995-01-01

319

Oxygen etching of thick MoS2 films.  

PubMed

Oxygen annealing of thick MoS2 films results in randomly oriented and controllable triangular etched shapes, forming pits with uniform etching angles. These etching morphologies differ across the sample based on the defect sites situated on the basal plane surface, forming numerous features in different bulk sample thicknesses. PMID:25116379

Ionescu, Robert; George, Aaron; Ruiz, Isaac; Favors, Zachary; Mutlu, Zafer; Liu, Chueh; Ahmed, Kazi; Wu, Ryan; Jeong, Jong S; Zavala, Lauro; Mkhoyan, K Andre; Ozkan, Mihri; Ozkan, Cengiz S

2014-10-01

320

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

PubMed Central

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

Zhang, Ying; Wang, Yong

2012-01-01

321

TiN Etching and Its Effects on Tungsten Etching in SF6\\/Ar Helicon Plasma  

Microsoft Academic Search

Etching characteristics of TiN film have been investigated in SF6\\/Ar helicon plasma. The etch rate of TiN film increases with increasing source power, bias power and temperature, exhibits a maximum at a moderate pressure as a function of pressure. A possible mechanism of titanium fluoride formation is proposed based on the results of optical emission spectroscopy (OES). In order to

Chang Ju Choi; Yeo Song Seol; Ki-Ho Baik

1998-01-01

322

High-Temperature Etching of PZT/Pt/TiN Structure by High-Density ECR Plasma  

NASA Astrophysics Data System (ADS)

Submicron patterning technologies for the PZT/Pt/Ti/TiN/Ti structure with a spin on glass (SOG) mask were demonstrated using a high-density ECR plasma and a high substrate temperature above 300° C. A 30%-Cl2/Ar gas was used to etch a lead zirconate titanate (PZT) film. No deposits remained, which resulted in an etched profile of more than 80°. A 40%-O2/Cl2 gas was used to etch a Pt film. The etching was completely stopped at the Ti layer. 30-nm-thick deposits remained on the sidewall. They were removed after dipping in hydrochloric acid. The etched profile of a Pt film was more than 80°. The Ti/TiN/Ti layer was etched with pure Cl2 gas. The size shift from the SOG mask was less than 0.1 µ m. Interdiffusion between SOG and PZT was not detected by transmission electron microscopy and energy dispersive X-ray spectroscopy (TEM-EDX) analysis.

Yokoyama, Seiichi; Ito, Yasuyuki; Ishihara, Kazuya; Hamada, Kazuyuki; Ohnishi, Shigeo; Kudo, Jun; Sakiyama, Keizo

1995-02-01

323

Selective wet-etching of filtered-arc-deposited TiN films on Cr sacrificial layers  

NASA Astrophysics Data System (ADS)

Titanium Nitride (TiN) is a wear resistant and complementary metal oxide silicon (CMOS) compatible material that is increasingly being investigated for MEMS applications. Incorporating any new material into a MEMS device requires the development of a processing strategy. This paper discusses a wet-etching strategy for patterning and releasing TiN features on Cr sacrificial layers. Filtered arc TiN films were deposited onto Cr coated Si (100) substrate. A Cr contact mask was sputtered over the TiN and patterned using UV photolithography. Patterned TiN features were examined using scanning electron microscopy (SEM). Rutherford Backscattering Spectroscopy (RBS) was carried out to investigate the selective etching of TiN and Cr in their respective etchants, which consisted of SC-1 for etching the TiN and a commercial chromic acid solution for etching the Cr. The results showed that Cr was not etched by SC-1 and that TiN was not etched by the Cr etchant.

Dowling, Andrew J.; Ghantasala, Muralidhar K.; Doyle, E. D.; Harvey, Erol C.

2004-04-01

324

Effect of surface etching on the flexure strength and fracture toughness of Dicor disks containing controlled flaws.  

PubMed

Previous studies have shown an increase in the failure load of Dicor glass-ceramic crowns of up to 97% when they were etched with NH4HF2 and luted with a resin-based cement compared with the use of unetched crowns luted with zinc phosphate cement. The objective of this study was to evaluate the effect of the acid-etch treatment on the flexure strength and fracture toughness of Dicor glass-ceramic specimens containing controlled flaws. Annealed disks were divided into two groups of 14 each, and microcracks were induced in the surface with a Vickers indenter. Seven specimens from each sample set were etched with 10% NH4HF2 (Dicor etching gel) and were fractured in air using a piston-on-three-ball biaxial fixture. Fracture toughness values were determined from the flexure strengths and fractographic measurements of fracture-initiating flaws. Analysis of data by ANOVA and the Tukey's Studentized Range Test revealed no significant difference (p > 0.05) in the mean flexure strength or fracture toughness of the etched and unetched samples within group A or group B. For the sample groups tested, flaw modification by etching had no effect on the flexure strength or on the fracture toughness of Dicor specimens containing controlled flaws. PMID:8120213

Thompson, J Y; Anusavice, K J

1994-02-01

325

Investigation and simulation of XeF2 isotropic etching of silicon  

Microsoft Academic Search

Trenching and loading phenomena observed on XeF2-etched (100) silicon wafers are explained in this article. Trenching refers to deeper etching at the side of an etch feature with respect to the middle of the feature. Loading is the reduction in etch depth that adjacent etched regions impose on their respective etch profiles. These two phenomena are especially recognized at locations

Behraad Bahreyni; C. Shafai

2002-01-01

326

Acid inhibition of CRA`s: A review  

SciTech Connect

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

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

1994-12-31

327

A Novel Model for Fracture Acidizing with Important Thermal Effects  

E-print Network

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

Lyons, John

2013-12-05

328

Modeling Wet Chemical Etching of Surface Flaws on Fused Silica  

SciTech Connect

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

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

2009-10-28

329

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

330

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

NASA Technical Reports Server (NTRS)

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

Garner, Charles

1987-01-01

331

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

SciTech Connect

The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical probability of damage initiation at 12 J/cm{sup 2} of an ensemble of scratches decreased from {approx}100 mm{sup -1} of scratch length to {approx}0.001 mm{sup -1}.

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

2010-02-23

332

Element sensitive atom beam etching based on projectile mass  

NASA Astrophysics Data System (ADS)

A new approach of ion/atom beam etching is proposed, which utilizes the projectile mass dependence of the sputtering process. As a model experiment, we etch YBa 2Cu 3O 7- ? films using inert gases having different masses. Various etching characteristics are found to depend evidently on the mass of the gases. Substantial improvements such as 2.5-fold increase of the etching selectivity and the reduction of the etching damage of the etched area are demonstrated by using Kr. A primitive semi-empirical extension of Sigmund theory is proposed, which explains the results indeed as a mass effect and suggests the directions of further improvements. The results show a new important factor in plasma and ion/atom beam etching, which can be useful for realizing artificial structures of metal oxides.

Watanabe, Y.; Tanamura, M.

2003-02-01

333

Diagnostics of low-pressure oxygen RF plasma and the mechanism for polymer etching: A comparison of reactive sputter etching and magnetron sputter etching  

SciTech Connect

The authors compare low-pressure oxygen RF plasmas and the etching of photoresist in a reactive sputter etch reactor and in a magnetron etch reactor using Langmuir probe, optical emission actinometry, and mass spectrometry measurements. The Langmuir probe data allow the determination of the plasma ion density and electron temperature, and thus the ion flux onto the substrate. The optical data yield information on the presence of O atoms and O/sub 2//sup +/ ions. Stable reactant and product species are monitored with a mass spectrometer. The main difference between the two reactors is that in magnetron sputter etching (MSE), the ion flux to the substrate is about an order of magnitude higher, under comparable plasma conditions, than in reactive sputter etching (RSE). This accounts for the higher etch rate in MSE. However, the etch yield per ion is higher in RSE because of the higher ion energy. Etch rates correlate neither with the ion flux to the substrate nor with the density of O atoms in the plasma, but change in parallel with the consumption of reactant gas. They conclude that in etching a polymer in a low-pressure oxygen plasma, the main neutral reactant species are O/sub 2/ molecules, and an important role of the ions is to remove reaction products from the substrate surface.

Steinbruchel, C.H.; Curtis, B.J.; Lehmann, H.W.; Widmer, R.

1986-04-01

334

Three-dimensional and histochemical studies of peroxisomes in cultured hepatocytes by quickfreezing and deep-etching method  

Microsoft Academic Search

Summary  Primary cultured mouse hepatocytes were treated with clofibric acid to induce peroxisome proliferation. They were briefly fixed with paraformaldehyde and centrifuged to prepare pellets. The hepatocytes were split open to remove cytoplasmic soluble proteins and fixed with glutaraldehyde. They were routinely incubated for catalase enzyme cytochemistry and fixed in osmium tetroxide. The specimens were quickly frozen, deeply etched and rotary

S. Ohno; Y. Fujii

1990-01-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

336

Crystallographic polarity and etching of cadmium telluride  

NASA Astrophysics Data System (ADS)

This paper resolves the inconsistency in the literature on the determination of the polarity of CdTe and CdxHg1-xTe from their etching behavior. The etch (H2O:H2O2:HF, 2:2:3 v/v) has been shown to reveal pits on the Cd (111) A face and not on the Te (1¯1¯1¯) B face in contradiction to the previously published work of Warekois, Lavine, Mariano, and Gatos [J. Appl. Phys. 33, 690 (1962)] and Nakagawa, Maeda, and Takeuchi [Appl. Phys. Lett. 34, 574 (1979)]. This result agrees with the observations of Fewster, Cole, Willoughby, and Brown [J. Appl. Phys. 52, 4568 (1981)] for CdxHg1-xTe grown epitaxially on CdTe.

Fewster, P. F.; Whiffin, P. A. C.

1983-08-01

337

Harvard University Department of Chemistry and Chemical Biology  

E-print Network

Properties Compound: Hydrofluoric acid Synonyms: Hydrogen fluoride, fluoric acid, hydrofluoride, fluorine to potential over-pressurization from hydrogen gas formation. #12;2 "Many fluoride-containing chemicals (e acid etches glass, due to the strong bond formed between fluoride anions and the silicon molecules

Heller, Eric

338

Etch Overview for Microsystems Learning Module  

NSDL National Science Digital Library

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

339

Plasma Etching Induced Gate Oxide Leakage  

Microsoft Academic Search

The paper discusses mechanisms of process-induced damage observed in plasma etched CMOS devices. The low-level oxide leakage and degraded breakdown properties are investigated and experimentally simulated with thin oxide MOS structures. It is shown, that both low-level oxide leakage and degraded QBD, with their strong antenna dependence to plasma charging, are a result of temperature accelerated low-current Fowler-Nordheim injection of

Tomasz Brozek; Y. David Chan; Chand R. Viswanathan

1995-01-01

340

Stain etching of silicon pillars and macropores  

Microsoft Academic Search

We used a XeCl excimer laser (308 nm, 3 J cm-2) and chemically enhanced laser ablation in the presence of SF6 to create arrays of silicon pillars. Etching of these pillars with KOH leads to arrays of macropores whose morphology depends on surface crystallography. Several new stain etchants - containing some combination of HF, NH4HF2, HCl, HNO3, Fe(III), Mn(VII) and

David Mills; Mona Nahidi; Kurt W. Kolasinski

2005-01-01

341

Capability of etched multilayer EUV mask fabrication  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

342

Wafer level bulk titanium ICP etching using SU8 as an etching mask  

NASA Astrophysics Data System (ADS)

Recent developments of ICP deep etching have allowed for the realization of bulk titanium high-aspect-ratio structures with high mechanical endurance, excellent corrosion resistance and bio-compatibility, which are very attractive for in vivo and/or harsh environment applications. In this paper, bulk titanium deep reactive ion etching (DRIE) has been carried out and evaluated at wafer level. A new mask material SU8 is introduced instead of an oxide hard mask, which has suffered from limited depth and laborious masking protocols. In order to optimize the process design, the influence of process parameters (coil power, platen power and Cl2 flow rate) on the etch rate, surface roughness, etch profile and wafer uniformity was investigated. By varying these parameters, an optimized recipe is obtained; an etching rate of 1 µm min-1 has been achieved with a vertical sidewall profile and smooth floor. High-aspect-ratio comb finger structures and beams were fabricated on the titanium substrate, which can potentially be used to realize many novel titanium-based microelectromechanical systems (MEMS) devices. Ultra-deep grooves up to 200 µm have been fabricated with this technology, which is among the best of the present reports.

Zhao, Gang; Shu, Qiong; Tian, Yao; Zhang, Yiming; Chen, Jing

2009-09-01

343

Effects of aperture size and pressure on XeF 2 etching of silicon  

Microsoft Academic Search

We developed a XeF2 pulse etching system and clarified the Si etching characteristics. Dependencies of Si etching rates and etched roughness\\u000a on the crystallographic orientation, number of pulses, pulse duration time, aperture size and etching pressure were measured.\\u000a An etching depth and an etched roughness were 12.9 ?m and 115 nm, respectively under charge pressure of 390 Pa, a pulse

K. Sugano; O. Tabata

2002-01-01

344

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

SciTech Connect

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

Muttalib, Muhammad Firdaus A., E-mail: mfam1g08@ecs.soton.ac.uk; Chen, Ruiqi Y.; Pearce, Stuart J.; Charlton, Martin D. B. [Nano Research Group, Electronics and Computer Science, Faculty of Physical and Applied Sciences, University of Southampton, Southampton SO17 1BJ (United Kingdom)

2014-07-01

345

Recovery from Plasma-Process-Induced Damage in Porous Silica Low-k Films by Organosiloxane Vapor Annealing  

Microsoft Academic Search

It was demonstrated that recovery from dry etching and ashing damage in porous silica low-k films occurred by 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) vapor annealing. The increase in k-value after Ar\\/C5F8\\/O2 plasma etching was reduced from 35 to 6.5% of the initial value (k=2.25) by TMCTS vapor annealing. Leakage current also returned to the initial level. Hydrofluoric acid wet etching revealed the sidewall

Tetsuo Ono; Keizo Kinoshita; Hideki Takahashi; Nobutoshi Fujii; Yuzuru Sonoda; Yoshiaki Oku; Kazuo Kohmura; Ryotaro Yagi; Nobuhiro Hata; Takamaro Kikkawa

2006-01-01

346

Extreme ultraviolet lithography mask etch study and overview  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

347

Cervical compomer restorations: the role of cavity etching in a 48-month clinical evaluation.  

PubMed

Compomers are defined as polyacid-modified resin composites. They are supposed to combine the advantages of traditional glass-ionomer cements with resin composites. This study clinically evaluated a compomer in cervical cavities. Sixty cervical cavities in premolars and molars (24 with cervical caries and 36 with abrasions) randomly divided into two groups of 30 teeth (Group 1 and Group 2) were restored with Dyract (DeTrey-Dentsply, York, PA 17405-0872). The cavities of Group 2 were etched for 30 seconds with orthophosphoric acid before compomer application, while the Group 1 cavities received no treatment. All the restorations were evaluated every six months, up to 48 months: characteristics assessed according to USPHS-modified standards were retention, secondary caries, post-operative sensitivity, marginal adaptation and discoloration, color and wear. The Kaplan-Meier's survival analysis was performed. In both groups, retention was high without any statistically significant difference. No difference was found between the two groups for caries, post-operative sensitivity and wear--that all had a low incidence. Color was not perfectly matched, however, there was no statistically significant difference between the two groups. Marginal discoloration and marginal adaptation loss were significantly higher in non-etched group (p < 0.05). Clinically relevant failure required 17.2% of restorations in the non-etched group and 10% in the etched group to be replaced: this difference was not statistically significant. Dyract has an acceptable clinical behavior when used in cervical cavities. Its marginal adaptation is enhanced by etching. PMID:11203846

Di Lenarda, R; Cadenaro, M; De Stefano Dorigo, E

2000-01-01

348

ICP dry etching of III-V nitrides  

SciTech Connect

Inductively coupled plasma etching of GaN, AlN, InN, InGaN and InAlN was investigated in CH{sub 4}/H{sub 2}/Ar plasmas as a function of dc bias, and ICP power. The etch rates were generally quite low, as is common for III-nitrides in CH{sub 4} based chemistries. The etch rates increased with increasing dc bias. At low rf power (150 W), the etch rates increased with increasing ICP power, while at 350 W rf power, a peak was found between 500 and 750 W ICP power. The etched surfaces were found to be smooth, while selectivities of etch were {le} 6 for InN over GaN, AlN, InGaN and InAlN under all conditions.

Vartuli, C.B.; Lee, J.W.; MacKenzie, J.D. [Univ. of Florida, Gainesville, FL (United States)] [and others

1997-10-01

349

ECR, ICP, and RIE plasma etching of GaN  

SciTech Connect

The group III-nitrides continue to generate interest due to their wide band gaps and high dielectric constants. These materials have made significant impact on the compound semiconductor community as blue and ultraviolet light emitting diodes (LEDs). Realization of more advanced devices; including lasers and high temperature electronics, requires dry etch processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {mu}m/min. In this paper, we compare electron cyclotron resonance (ECR), inductively coupled plasma (ICP), and reactive ion etch (RIE) etch results for GaN. These are the first ICP etch results reported for GaN. We also report ECR etch rates for GaN as a function of growth technique.

Shul, R.J.; McClellan, G.B.; Rieger, D.J.; Hafich, M.J. [and others

1996-06-01

350

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

PubMed

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

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

2014-07-01

351

Investigations of Wafer Scale Etching with Xenon Difluoride  

Microsoft Academic Search

A good and uniform bulk silicon wafer etching method can be applied to the wafer thinning process in MEMS and 3D applications. In this study, the use of a Xenon Difluoride (XeF2) gas-phase etching system, operating at room temperature, has been investigated for bulk silicon wafer thinning. We investigated the Si-wafer surface morphology and profile following each XeF2 etching process

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

2006-01-01

352

Ion beam sputter etching and deposition of fluoropolymers  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

353

Ion beam sputter etching and deposition of fluoropolymers  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

354

Dielectric film etching in semiconductor device manufacturing. Development of SiO 2 etching and the next generation plasma reactor  

NASA Astrophysics Data System (ADS)

The progress of the dry etching technology for dielectric materials and the ASET project were reviewed. Reactive ion etching (RIE) replaced a wet chemical etching in 1970s and has been forwarding the size shrinkage of electron devices and the improvement of device capacity and speed greatly. The technology is continuously evolving this last two decades to meet the requirements from the device performance and the productivity. Developments of SiO 2 etching technology during that period were introduced with the concept to use fluorocarbon (CF) gases. Magnetically enhanced plasma reactor was also reviewed especially about the improvement for a charging damage. The RIE system has been improved with a new magnetic field arrangement and a new control methodology of chemical species, especially for a self-aligned contact (SAC) hole etching. The capacitive-coupled (parallel plate) plasma sources are the standard for the SiO 2 etching nowadays. Conventional developments were conducted in a very empirical way, such as a trial and error, with many speculation using qualitative data. This approach requires more and more resources and time for the development of future devices with a design rule below 100 nm in the SOC (system on a chip) era. It is necessary to establish a systematic methodology for process development and qualification. ASET Plasma Laboratory had been found to research a basis for the systematic development of the plasma etching technology. CF plasma for the etching of high-aspect-ratio contact holes in SiO 2 was investigated intensively in the 5-year program that had finished in March 2001. They introduced five plasma sources that can etch 0.1 ?m contact hole on a 200 mm wafer in production, and state-of-the-art diagnostics tools for the plasma and etched surface. The SiO 2 etch mechanism was revealed from the etch species generation to the reaction in a deep hole. The number of electron collisions to CF gas molecule is proposed as an important parameter to control the gas dissociation and etch species flux to the surface. An etch reaction model was also proposed using the estimated surface reaction probability that is a function of ion energy and CF polymer thickness that reduces the net ion energy to the reaction layer. The CF polymer thickness was determined by a balance equation of generation term (radical fluxes) and loss terms (etching by ions, radicals and outflux oxygen from SiO 2). A program was developed and successfully predict the etch rates of Si-containing materials including organic dielectrics. Requirements for the next generation plasma etch tools were also discussed.

Sekine, Makoto

2002-05-01

355

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

PubMed Central

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

Bortolotto, Tissiana; Roig, Miguel; Krejci, Ivo

2014-01-01

356

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

2006-05-01

357

A survey on the reactive ion etching of silicon in microtechnology  

Microsoft Academic Search

This article is a brief review of dry etching as applied to pattern transfer, primarily in silicon technology. It focuses on concepts and topics for etching materials of interest in micromechanics. The basis of plasma-assisted etching, the main dry etching technique, is explained and plasma system configurations are described such as reactive ion etching (RIE). An important feature of RIE

Henri Jansen; Han Gardeniers; Meint de Boer; Miko Elwenspoek; Jan Fluitman

1996-01-01

358

Fabrication of honeycomb texture on poly-Si by laser interference and chemical etching  

NASA Astrophysics Data System (ADS)

In this paper, we present a laser-interference method to fabricate honeycomb textures on poly-Si wafer for reflection reduction. When exposed to three interfering pulsed laser beams at 532 nm, the Si surface was periodically melted in accordance with the interference pattern. As a result, concave holes were generated on the surface because the melted material overflowed and condensed at the periphery. Subsequent acid etching revealed uniform and clean honeycomb textures. The texture depth could be controlled by varying the irradiation condition and a minimum reflectance of 10% was obtained. Transmission electron microscopy analysis showed that no irradiation-induced damage remained after etching. This approach can be a cost-effective alternative to lithographic processes for fabricating high-efficiency poly-Si solar cells.

Yang, Bogeum; Lee, Myeongkyu

2013-11-01

359

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

360

Depth-resolved subsurface defects in chemically etched SrTiO3  

NASA Astrophysics Data System (ADS)

Depth-resolved cathodoluminescence spectroscopy of atomically flat TiO2-terminated SrTiO3 single crystal surfaces reveals dramatic differences in native point defects produced by conventional etching with buffered HF (BHF) and an alternative procedure using HCl-HNO3 acidic solution (HCLNO), which produces three times fewer oxygen vacancies before and nearly an order of magnitude fewer after pure oxygen annealing. BHF-produced defect densities extend hundreds of nanometers below the surface, whereas the lower HCLNO-treated densities extend less than 50 nm. This "Arkansas" HCLNO etch and anneal method avoids HF handling and provides high-quality SrTiO3 surfaces with low native defect density for complex oxide heterostructure growth.

Zhang, Jun; Doutt, D.; Merz, T.; Chakhalian, J.; Kareev, M.; Liu, J.; Brillson, L. J.

2009-03-01

361

Ion-beam etching enhances adhesive bonding  

NASA Technical Reports Server (NTRS)

Metals and fluoropolymers exposed to 0.5 to 1.0 keV argon ions at current densities of 0.2 to 1.5 mA/sq cm develop surface texturing that increases tensile and shear strength of epoxy bonds. Bonds are 46 to 100 percent stronger than those of chemically etched surfaces. Metals require 3 to 4 hours of bombardment to become properly textured. Fluoropolymers require 5 seconds to 30 minutes. Ion beam will not texture nickel. Unlike chemical treatments, bonding of fluoropolymers can be done days or months after ion treatment.

Banks, B. A.; Mirtich, M. J.; Sovey, J. S.

1980-01-01

362

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

PubMed

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

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

2015-04-15

363

Evaluation of Pentafluoroethane and 1,1-Difluoroethane for a Dielectric Etch Application in an Inductively Coupled Plasma Etch Tool  

Microsoft Academic Search

In this work, a combination of two hydrofluorocarbon compounds, pentafluoroethane (FC-125, C2HF5) and 1,1-difluoroethane (FC-152a, CF2H-CH3), was evaluated as a potential replacement for perfluorocompounds in dielectric etch applications. A high aspect ratio oxide via etch was used as the test vehicle for this study, which was conducted in a commercial inductively coupled high density plasma etch tool. Both process and

Simon Karecki; Ritwik Chatterjee; Laura Pruette; Rafael Reif; Terry Sparks; Laurie Beu; Victor Vartanian

2000-01-01

364

Inorganic Bi/In Thermal Resist as a High Etch Ratio Patterning Layer for CF4/CHF3/O2 Plasma Etch  

E-print Network

Inorganic Bi/In Thermal Resist as a High Etch Ratio Patterning Layer for CF4/CHF3/O2 Plasma Etch mask layers for Si anisotropic etch and plasma etch. Keywords: inorganic photoresist, thermal resist, such as Bi/In, have been found to form highly sensitive thermal resists. They can be exposed by lasers

Chapman, Glenn H.

365

Development of Localized Plasma Etching System for Failure Analyses in Semiconductor Devices: (3)
Etching-Monitoring Using Quadrupole Mass Spectrometry
 

NASA Astrophysics Data System (ADS)

Quadrupole mass spectrometry (QMS) has been applied to monitor the etching processes in a localized plasma etching system. An inward plasma was employed for etching in which the etching gas was discharged in the narrow gap between the etched sample and the entrance of an evacuating capillary tube. As the etching products are immediately evacuated through the capillary, a QMS system equipped at the capillary exit is able to analyze the products without any loss in concentration via diffusion into the chamber. Two kinds of samples, thermally grown SiO2 on Si and spin-coated polyimide film on Si, were etched, and the chemical species in the evacuated etching gas were analyzed with QMS, which enables monitoring of the composition of the surface being etched. Samples of thermal SiO2 were etched with CF4 plasma. The peak height of the SiF3+ signal during the SiO2 etching was lower than that observed during etching of the silicon substrate, leading to endpoint detection. The endpoint detection of the polyimide film etching was conducted using two etching gases: pure O2 and pure CF4. When O2 was used, the endpoint was detected by the decrease of the mass peak attributed to CO. When CF4 was employed, the plasma was able to etch both the polyimide film and Si substrate. Then the endpoint was detected by the increase of the mass peak of SiF3+ produced by the etching of the Si substrate.

Takahashi, Satoshi; Horie, Tomoyuki; Shirayama, Yuya; Yokosuka, Shuntaro; Kashimura, Kenta; Hayashi, Akihiro; Iwase, Chikatsu; Shimbori, Shun'ichiro; Tokumoto, Hiroshi; Naitoh, Yasuhisa; Shimizu, Tetsuo

366

Investigation and simulation of XeF2 isotropic etching of silicon  

NASA Astrophysics Data System (ADS)

Trenching and loading phenomena observed on XeF2-etched (100) silicon wafers are explained in this article. Trenching refers to deeper etching at the side of an etch feature with respect to the middle of the feature. Loading is the reduction in etch depth that adjacent etched regions impose on their respective etch profiles. These two phenomena are especially recognized at locations where the substrate is etched through large mask openings. Both phenomena were reported by other groups, but no explanation was given for them. A novel model explaining these phenomena is developed in this article, and the etching process is simulated in software. The results are compared to several etched samples with varying mask aperture size and etch depth. Good agreement is found between simulated profiles and actual measured etch profiles at given mean-free paths. Furthermore, our simulator predicts that the reaction probability between etchant and substrate molecules influences surface roughness of the etched regions.

Bahreyni, Behraad; Shafai, C.

2002-11-01

367

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

368

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

369

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

Code of Federal Regulations, 2014 CFR

...Applicability: Description of the chemical etching and milling subcategory. 413.60...POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60...wastewaters resulting from the chemical milling or etching of ferrous...

2014-07-01

370

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

Code of Federal Regulations, 2013 CFR

...Applicability: Description of the chemical etching and milling subcategory. 413.60...POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60...wastewaters resulting from the chemical milling or etching of ferrous...

2013-07-01

371

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

Code of Federal Regulations, 2012 CFR

...Applicability: Description of the chemical etching and milling subcategory. 413.60...POINT SOURCE CATEGORY Chemical Etching and Milling Subcategory § 413.60...wastewaters resulting from the chemical milling or etching of ferrous...

2012-07-01

372

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

SciTech Connect

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

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

2013-06-24

373

Focused electron-beam-induced etching of silicon dioxide  

NASA Astrophysics Data System (ADS)

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 SiO2 matrix, and subsequently rate limited by XeF2 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 SiO2 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.

2005-08-01

374

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

E-print Network

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

Martin, Jan M.L.

375

Quantum electron beam probe of sidewall dry-etch damage  

Microsoft Academic Search

Damage as a result of ion bombardment may occur both at top surfaces and at sidewalls. We propose a method of probing sidewall damage using coherent electron focusing. A collimated electron beam is reflected off an internal boundary formed by dry etching. Spectra measured in an applied magnetic field are influenced strongly by increased levels of etch damage. Monte Carlo

M. Rahman; J. G. Williamson; K. Mathieson; G. Dick; M. J. Brown; S. Duffy; C. D. W. Wilkinson

2000-01-01

376

Mechanism study of sidewall damage in deep silicon etch  

NASA Astrophysics Data System (ADS)

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

Meng, Lingkuan; Yan, Jiang

2014-12-01

377

Amorphous Silicon and Tungsten Etching Employing Environmentally Benign Plasma Process  

NASA Astrophysics Data System (ADS)

A novel dry etching process for amorphous silicon (a-Si) and tungsten (W) for chemical vapor deposition (CVD) chamber cleaning has been performed by electron cyclotron resonance (ECR) O2 plasma employing a solid-material evaporation system where fluorocarbon species are produced from fluorinated ethylene propylene (FEP) by CO2 laser evaporation for preventing global warming. This process enables us to realize etching of materials without using any perfluorocompound (PFC) feed gases which have a high global warming potential (GWP). Etching characteristics together with diagnostics of the F atom density, CFx (x=1--3) radical densities, electron density and temperature have been investigated as functions of pressure. As a result, it was found that etching rates of a-Si and W films were determined based on the F atom density, ion flux and ion bombardment energy. Furthermore, etching rates of a-Si and W films increased by heating the fluorocarbon species before introducing them into the plasma reactor. Thus, high rates of etching of a-Si and W films were successfully achieved by this novel etching process compared with conventional etching using ECR plasma with CF4/O2 feed gases.

Fujita, Kazushi; Kobayashi, Shigeto; Ito, Masafumi; Hori, Masaru; Goto, Toshio

2001-02-01

378

Study for amorphous silicon etching process using dielectric barrier discharge  

Microsoft Academic Search

Characteristics of amorphous silicon (a-Si) etching using atmospheric pressure plasma discharge had been studied. Dielectric barrier discharge (DBD) plasma with nitrogen gas was employed for the study. The active chemical agent for etching was generated by mixing a small quantity of sulfur hexafluoride (SF6) gas into the plasma. The two distinguishable plasma zones are generated with the specially designed DBD

D. C. Seok; T. Lho; S. R. Yoo; Y. C. Hong; B. J. Lee

2011-01-01

379

Reactive ion etched substrates and methods of making and using  

DOEpatents

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

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

2007-08-07

380

A prediction of thermal device damage during plasma etching  

Microsoft Academic Search

Device heating during plasma etching for ULSI circuits fabrication will become one of the practical issues under the recent trend of the shrinkage of chips. Especially, the application of Low-k materials ,which have poor thermal conductivity and thermal instability, for interlayer dielectrics makes it more serious. Wafer surface is locally etched reactively by incident ions with high energy, and the

M. Osaka; T. Yagisawa; T. Shimada; T. Makabe

2004-01-01

381

Plasma etching as a diagnostic technique in silicon surface studies  

Microsoft Academic Search

This paper describes a new application of plasma etching, namely as an aid to the characterization of specular semiconductor surfaces. The technique, which is simple and quick to perform, consists of subjecting the semiconductor slice to a brief etching treatment in a fluorocarbon plasma at low pressure, followed by inspection of the surface, using Nomarski microscopy. The whole operation is

D. P. Griffiths; S. H. Bradley

1977-01-01

382

Plasma etching as a diagnostic technique in silicon surface studies  

Microsoft Academic Search

A new application of plasma etching is described as an aid to the characterization of specular semiconductor surfaces. The technique, which is simple and quick to perform, consists of subjecting the semiconductor slice to a brief etching treatment in a fluorocarbon plasma at low pressure, followed by inspection of the surface, using Nomarski microscopy. The whole operation is designated diagnostic

D. P. Griffiths; S. H. Bradley

1977-01-01

383

Laser etching: A new technology to identify Florida grapefruit  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

384

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

E-print Network

by an etch mask), and thus we are concerned with design or layout-specific variation in etch depth or rate species. That is to say, we assume key reactions are: -··- ++++ eFFSFSeSF yxyx6 (1) nSiFnFSi + · (2) Eq. 1

Boning, Duane S.

385

Deep NLD Plasma Etching of Fused Silica and Borosilicate Glass  

E-print Network

photoresist mask [2]. The KMPR photoresist showed some promise. However, etching with the KMPR suffers from aspect ratio deep etching (100 µm) using four different masks (Ni, KMPR photoresist, amorphous silicon and bonded silicon). Experiments were performed to eliminate Ni re-deposition. KMPR, amorphous silicon

Tang, William C

386

Microwave plasma etching of silicon and silicon dioxide  

Microsoft Academic Search

Summary form only given. Studies are being conducted on the etching characteristics of silicon and silicon dioxide in a microwave plasma etching system, having a pulse modulated microwave source. The source can be adjusted for varying pulse widths and duty cycles. A slotted waveguide is used to radiate the microwaves from the source into a quartz chamber, where the process

C. Grabowski; J. Gahl

1990-01-01

387

Plasma chemistry of fluorocarbon RF discharges used for dry etching  

Microsoft Academic Search

Investigations on capacitively coupled RF plasma in flurocarbon gases excited at 13.56 MHz are reported. These plasmas are commonly used for many applications where a substrate must be etched, for example in the manufacturing of integrated circuits. Diagnostics to measure the densities of both neutral and charged species in RF plasma of fluorocarbon gases that are widely used for etching

Marco Haverlag

1991-01-01

388

Time series modeling of reactive ion etching using neural networks  

Microsoft Academic Search

Neural networks have been used to model the behavior of real-time tool data in a reactive ion etch (RIE) process. An etch monitoring and data acquisition system for transferring data from the RIE chamber to a remote workstation was designed and implemented on a Plasma Therm Series 700 Dual Chamber etcher. This system monitors gas flow rates, RF power, temperature,

Michael D. Baker; Christopher D. Himmel; Gary S. May

1995-01-01

389

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

390

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

PubMed Central

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

Abinaya; Karthikeyan; Sarvanan; Vikram, Raj

2014-01-01

391

Direct writing onto Si by electron beam stimulated etching  

NASA Astrophysics Data System (ADS)

Direct writing onto Si has been demonstrated by electron beam induced surface reaction using a XeF2 source. The electron beam stimulated etched depth for Si(100) is proportional to the electron dose. Etch depth by electron beam stimulated etching is 500 nm at 10 kV accelerating voltage, 4×10-3 C/cm2 dose, and 5 mTorr XeF2 gas pressure. An enormously high etching yield of about 100 Si atoms per electron has been observed for electron stimulated etching using the XeF2 source. A 0.5-?m linewidth pattern has been fabricated at a 4×10-3 C/cm2 dose.

Matsui, Shinji; Mori, Katsumi

1987-11-01

392

Misorientation/local plastic strain manifestations in chemical etching color.  

PubMed

Cold plastic deformation produces misorientations inside the crystal grains, and the distribution of the misorientation is quite crucial to understand the deformation behavior of the metals or alloys. The misorientation manifestations in chemical etching contrast are investigated in this study in the case of cold-deformed iron. The chemical etching is performed by using nital, while the crystal orientation is determined by electron backscatter diffraction (EBSD). The correlation between the chemical etching contrast and crystal orientation have been studied in both cold-deformed and undeformed iron. The results clearly show that the chemical etching contrast strongly reflects the crystallographic orientation. The gradual change in chemical etching contrast inside the individual deformed grains gives information of both the misorientation and local plastic strain within the grains. This method can provide an easy and alternative way to qualitatively understand the misorientation and local plastic strain distributions in the microstructures. PMID:24530362

Zhang, Xianguang; Matsuura, Kiyotaka; Ohno, Munekazu

2014-04-01

393

High rate ECR etching of III-V nitride materials  

SciTech Connect

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

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

1994-12-31

394

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

395

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

396

Composition/bandgap selective dry photochemical etching of semiconductor materials  

DOEpatents

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

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

1985-10-11

397

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

398

Miniature pulse compressor of deep-etched gratings.  

PubMed

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

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

2008-11-10

399

Waste acid detoxification and reclamation  

Microsoft Academic Search

Economically feasible processes that reduce the volume, quantity, and toxicity of metal-bearing waste acids by reclaiming, reusing, and recycling spent acids and metal salts are being developed and demonstrated. The acids used in the demonstrations are generated during metal-finishing operations used in nuclear fuel fabrication; HF-HNOâ, HNOâ, and HNOâ-HâSOâ wastes result from Zr etching, Cu stripping, and chemical milling of

T. M. Brouns; T. L. Stewart

1988-01-01

400

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

SciTech Connect

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

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

2013-05-13

401

Optical diagnostic instrument for monitoring etch uniformity during plasma etching of polysilicon in a chlorine-helium plasma  

SciTech Connect

Nonuniform etching is a serious problem in plasma processing of semiconductor materials and has important consequences in the quality and yield of microelectronic components. In many plasmas, etching occurs at a faster rate near the periphery of the wafer, resulting in nonuniform removal of specific materials over the wafer surface. This research was to investigate in situ optical diagnostic techniques for monitoring etch uniformity during plasma processing of microelectronic components. We measured 2-D images of atomic chlorine at 726 nm in a chlorine-helium plasma during plasma etching of polysilicon in a parallel-plate plasma etching reactor. The 3-D distribution of atomic chlorine was determined by Abel inversion of the plasma image. The experimental results showed that the chlorine atomic emission intensity is at a maximum near the outer radius of the plasma and decreases toward the center. Likewise, the actual etch rate, as determined by profilometry on the processed wafer, was approximately 20% greater near the edge of the wafer than at its center. There was a direct correlation between the atomic chlorine emission intensity and the etch rate of polysilicon over the wafer surface. Based on these analyses, 3-D imaging would be a useful diagnostic technique for in situ monitoring of etch uniformity on wafers.

Hareland, W.A.; Buss, R.J.

1993-06-01

402

Optical measurement for the concentrations of the pickling acid with near infrared spectroscopy in steel making industry  

NASA Astrophysics Data System (ADS)

In the manufacturing process of stainless steel, it is essential to pickle the oxide layer of steel surface for high corrosion resistance and fine surface quality. Pickling liquor of stainless steel is commonly composed of mixed hydrofluoric and nitric acid. Real time monitoring of concentrations of each acid is crucial to optimize pickling process. It also reduces cost of production and decreases the generation of waste acid. We used non-contact near infrared spectroscopy technique and rapid analysis method, for the quantification of each acid in an on-line manner. Multivariate calibration such as partial least square regression method is employed for the better prediction results.

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

2010-08-01

403

Solid polymer electrolyte composite membrane comprising plasma etched porous support  

DOEpatents

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

404

SU8 photoresist as an etch mask for local deep anodic etching of silicon  

NASA Astrophysics Data System (ADS)

For the formation of an ordered porous structure, the distance between two nearest neighbor pores cannot be more than a certain size, otherwise random nucleated pores arise spontaneously between ordered pores. The proximity effect does not allow the production of macropores with variable interpore distances on the surface of Si wafers. More precisely, it does not allow one to increase arbitrarily the distance between single pores, which is necessary, for example, in the manufacture of photovoltaic devices with improved radiation hardness. Moreover, for many electronic, electromechanical, and optical applications, it is highly desirable to pattern porous silicon in defined two- and three-dimensional geometrical layouts. The simplest solution to such problems is anodic etching through a photoresist mask. In the present work, results on deep anodic etching of silicon through a mask of SU8 photoresist are presented.

Starkov, V. V.; Gavrilin, E. Yu.; Konle, J.; Presting, H.; Vyatkin, A. F.; König, U.

2003-05-01

405

Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.  

PubMed

The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding. PMID:24372961

Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

2014-02-01

406

Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin.  

PubMed

This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5). The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT) or absolute ethanol wet-bonding (EBT). The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP) or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB). Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey's test (a = 5%). The failure modes were verified using a stereomicroscope (40'). For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05). The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05). No significant interaction between adhesives and bonding techniques was noticed (p = 0.597). There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach. PMID:22473355

Guimarães, Leandro Afonso; Almeida, Júlio César Franco; Wang, Linda; D'Alpino, Paulo Henrique Perlatti; Garcia, Fernanda Cristina Pimentel

2012-01-01

407

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

E-print Network

sharps for standard cleanroom procedures. Cleaning broken glass and wafers. Materials: Razor blades, syringes, scalpels, chipped wafers, broken glassware and others. Incompatible Materials: When possible, try their impressive ability to slash and cut. The edges of chipped wafers are sharp enough to cut, though rarely do

Woodall, Jerry M.

408

Role of sulfur atoms in microwave plasma etching of silicon  

NASA Astrophysics Data System (ADS)

The Si etch rate in an (F2+O2) microwave plasma has been measured as a function of O2 mixing ratio at a fixed total pressure of 5.3×10-2 Pa. The etch rate significantly decreases with the mixing ratio. This etch rate decrease is due primarily to surface oxidation. When sulfur is added to the (F2+O2) plasma, the Si surface is much less oxidized and the etch rate increases by about a factor of 4. Such sulfur-containing species as S atoms react with O atoms or ions in the plasma and form O atom-containing species, such as SO2, SO+, SOF+, and SOF+2, thereby reducing the O atom and O+ ion concentrations in the plasma. As a result, the Si surface is scarcely oxidized, so that the etching reaction can easily proceed. Sulfur atoms inhibit surface oxidation and promote Si etching. Sulfur atoms contained in SF6, which is usually used in microwave plasma etching of Si, are expected to have the same role.

Ninomiya, Ken; Suzuki, Keizo; Nishimatsu, Shigeru; Okada, Osami

1987-08-01

409

Dry etching technologies for the advanced binary film  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

410

Porous silicon formation during Au-catalyzed etching  

SciTech Connect

The formation of “black” nano-textured Si during the Au-catalyzed wet-chemical etch process was investigated with respect to photovoltaic applications. Cross-sectional scanning electron microscopy (SEM) images recorded at different stages of the etch process exhibit an evolution of a two-layer structure, consisting of cone-like Si hillocks covered with a nano-porous Si (np-Si) layer. Optical measurements confirm the presence of a np-Si phase which appears after the first ?10?s of the etch process and continuously increases with the etch time. Furthermore, the etch process was investigated on Si substrates with different doping levels (?0.01–100 ? cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 ? cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of “black” Si on various Si substrates, which is of significant interest for photovoltaic applications.

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

2014-04-28

411

Structural and Optical properties of HNO3 etched Ag thin films  

NASA Astrophysics Data System (ADS)

Structural and optical properties, elemental analysis of Ag thin films before and after etching were investigate by using XRD, UV-Vis spectrophotometer, Raman spectroscopy and FESEM. These films were found to exhibit a strong SERS effect and excellent thermal stability. The HNO3 roughened silver film seems to be a more routinely preparable substrate system for SERS study. The HNO3 roughened Ag thin films exhibits excellent stability for enhancement, because the acid roughened Ag films features a strong enhancement factor better stability than pure Ag thin films. Hence, the method will be useful in the development of plasmon-based analytical devices, specifically SERS-based biosensors.

Rajesh, Desapogu; Sunandana, C. S.

2015-02-01

412

In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study  

PubMed Central

Aim: To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin–dentin interfacial ultrastructure under scanning electron microscope (SEM). Materials and Methods: 100 extracted human premolars were divided into two groups for different adhesives (Clearfil S3 and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin–dentin interface. Results: At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin–dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied. Conclusions: In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage. PMID:22025829

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

2011-01-01

413

Justification for Selecting Level A vs. Level B Personal Protective Equipment to Remediate a Room Containing Concentrated Acids, Bases and Radiological Constituents  

SciTech Connect

Selecting the appropriate personal protective equipment (PPE) is based on providing an adequate level of employee protection relative to the task-specific conditions and hazards. PPE is categorized into four ensembles, based on the degree of protection afforded; e.g., Levels A (most restrictive), B, C, and D (least restrictive). What is often overlooked in preparing an ensemble is that the PPE itself can create significant worker hazards; i.e., the greater the level of PPE, the greater the associated risks. Furthermore, there is confusion as to whether a more ''conservative approach'' should always be taken since Level B provides the same level of respiratory protection as Level A but less skin protection. This paper summarizes the Occupational Safety and Health Administration regulations addressing Level A versus Level B, and provides justification for selecting Level B over Level A without under-protecting the employee during a particular remediation scenario. The scenario consisted of an entry team performing (1) an initial entry into a room containing concentrated acids (e.g., hydrofluoric acid), bases, and radiological constituents; (2) sampling and characterizing container contents; and (3) retrieving characterized containers. The invasive nature of the hydrofluoric acid sampling and characterization scenario created a high potential for splash, immersion, and exposure to hazardous vapors, requiring additional skin protection. The hazards associated with this scenario and the chemical nature of hydrofluoric acid provided qualitative evidence to justify Level A. Once the hydrofluoric acid was removed from the room, PPE performance was evaluated against the remaining chemical inventory. If chemical breakthrough from direct contact was not expected to occur and instrument readings confirmed the absence of any hazardous vapors, additional skin protection afforded by wearing a vapor-tight, totally-encapsulated suit was not required. Therefore, PPE performance and instrument data provided quantitative evidence to justify Level B.

Hylko, J. M.; Thompson, A. L.; Walter, J. F.; Deecke, T. A.

2002-02-25

414

Etching of photosensitive chalcogenide glasses:experiments and simulations.  

PubMed

We have developed a three-dimensional simulation algorithm based on fast marching method that mimics the etching behavior of chalcogenide photoresists, especially for maskless interference lithography. This lithography exposure is characterized by continuous variation of the exposure intensity inside the photoresist, without step like variation. Furthermore, the chalcogenide photoresist has a "gray-scale" behavior, without definite threshold. The resulting etching process is very sensitive to exposure dose and etching time. The optimal relations between these parameters are determined both theoretically and experimentally. A very good agreement between calculation and experimental results is shown, opening the door to complex nanostructures engineering. PMID:19547624

Dror, Raphi; Sfez, B; Goldin, Sh Y; Cashingad, A

2007-09-17

415

Selectively-etched nanochannel electrophoretic and electrochemical devices  

DOEpatents

Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

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

2006-06-27

416

Chlorine-based plasma etching of GaN  

SciTech Connect

The wide band gap group-III nitride materials continue to generate interest in the semiconductor community with the fabrication of green, blue, and ultraviolet light emitting diodes (LEDs), blue lasers, and high temperature transistors. Realization of more advanced devices requires pattern transfer processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {micro}m/min. The utilization of high-density chlorine-based plasmas including electron cyclotron resonance (ECR) and inductively coupled plasma (ICP) systems has resulted in improved GaN etch quality over more conventional reactive ion etch (RIE) systems.

Shul, R.J.; Briggs, R.D. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J.; Vartuli, C.B.; Abernathy, C.R.; Lee, J.W. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Constantine, C.; Baratt, C. [Plasma-Therm, Inc., Saint Petersburg, FL (United States)

1997-02-01

417

Selectively-etched nanochannel electrophoretic and electrochemical devices  

DOEpatents

Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

Surh, Michael P.; Wilson, William D.; Barbee Jr., Troy W.; Lane, Stephen M.

2004-11-16

418

Metal-assisted chemical etch porous silicon formation method  

DOEpatents

A thin discontinuous layer of metal such as Au, Pt, or Au/Pd is deposited on a silicon surface. The surface is then etched in a solution including HF and an oxidant for a brief period, as little as a couple seconds to one hour. A preferred oxidant is H.sub.2 O.sub.2. Morphology and light emitting properties of porous silicon can be selectively controlled as a function of the type of metal deposited, Si doping type, silicon doping level, and/or etch time. Electrical assistance is unnecessary during the chemical etching of the invention, which may be conducted in the presence or absence of illumination.

Li, Xiuling; Bohn, Paul W.; Sweedler, Jonathan V.

2004-09-14

419

CDU improvement technology of etching pattern using photo lithography  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

420

Precision integrated thickness control with gas cluster ion beam etch  

NASA Astrophysics Data System (ADS)

Gas cluster ion beam (GCIB) etching is a technique, which among other attributes, enables advanced process control of feature height uniformity, increasingly critical to sub 16nm FINFET performance. GCIB can have a high local etch rate in a focused beam, which combined with location specific processing (LSP) algorithms, enables high-precision correction of incoming or downstream thickness uniformity. Applications of this technique include trimming of RF filter devices (in production now for over 10 years), as well as emerging applications in thickness control enabling for FINFET device integration. Here we describe the GCIB etch technology and the LSP method and capabilities.

Russell, N. M.; Gizzo, V.; LaRose, J. D.; Pfeiffer, B. D.; Dasaka, R.; Economikos, L.; Wise, R.

2014-03-01

421

Structural and magnetic etch damage in CoFeB  

SciTech Connect

A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

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

2014-05-07

422

Evaluation of Pentafluoroethane and 1,1-Difluoroethane for a Dielectric Etch Application in an Inductively Coupled Plasma Etch Tool  

NASA Astrophysics Data System (ADS)

In this work, a combination of two hydrofluorocarbon compounds, pentafluoroethane (FC-125, C2HF5) and 1,1-difluoroethane (FC-152a, CF2H-CH3), was evaluated as a potential replacement for perfluorocompounds in dielectric etch applications. A high aspect ratio oxide via etch was used as the test vehicle for this study, which was conducted in a commercial inductively coupled high density plasma etch tool. Both process and emissions data were collected and compared to those provided by a process utilizing a standard perfluorinated etch chemistry (C2F6). Global warming (CF4, C2F6, CHF3) and hygroscopic gas (HF, SiF4) emissions were characterized using Fourier transform infrared (FTIR) spectroscopy. FC-125/FC-152a was found to produce significant reductions in global warming emissions, on the order of 68 to 76% relative to the reference process. Although etch stopping, caused by a high degree of polymer deposition inside the etched features, was observed, process data otherwise appeared promising for an initial study, with good resist selectivity and etch rates being achieved.

Karecki, Simon; Chatterjee, Ritwik; Pruette, Laura; Reif, Rafael; Sparks, Terry; Beu, Laurie; Vartanian, Victor

2000-07-01

423

Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.  

PubMed

In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control. PMID:19071540

Weinreich, Wenke; Acker, Jörg; Gräber, Iris

2007-03-30

424

Protein adsorption and cell adhesion on three-dimensional polycaprolactone scaffolds with respect to plasma modification by etching and deposition techniques  

NASA Astrophysics Data System (ADS)

In this work, protein adsorption and cell adhesion on three-dimensional (3D) polycaprolactone (PCL) scaffolds treated by plasma etching and deposition were performed. The 3D PCL scaffold used as a substrate of a bone tissue was fabricated by recent rapid prototype techniques. To increase surface properties, such as hydrophilicity, roughness, and surface chemistry, through good protein adhesion on scaffolds, oxygen (O2) plasma etching and acrylic acid or allyamine plasma deposition were performed on the 3D PCL scaffolds. The O2 plasma etching induced the formation of random nanoporous structures on the roughened surfaces of the 3D PCL scaffolds. The plasma deposition with acrylic acid and allyamine induced the chemical modification for introducing a functional group. The protein adsorption increased on the O2 plasma-etched surface compared with an untreated 3D PCL scaffold. MC3T3-E1 cells adhered bioactively on the etched and deposited surface compared with the untreated surface. The present plasma modification might be sought as an effective technique for enhancing protein adsorption and cell adhesion.

Myung, Sung Woon; Ko, Yeong Mu; Kim, Byung Hoon

2014-11-01

425

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components  

NASA Technical Reports Server (NTRS)

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

1984-01-01

426

Bonding of self-adhesive resin cements to enamel using different surface treatments: bond strength and etching pattern evaluations.  

PubMed

This study evaluated the shear bond strengths and etching patterns of seven self-adhesive resin cements to human enamel specimens which were subjected to one of the following surface treatments: (1) Polishing with #600 polishing paper; (2) Phosphoric acid; (3) G-Bond one-step adhesive; or (4) Phosphoric acid and G-Bond. After surface treatment, the human incisor specimens were bonded to a resin composite using a self-adhesive resin cement [Maxcem (MA), RelyX Unicem (UN), Breeze (BR), BisCem (BI), seT (SE), Clearfil SA Luting (CL)] or a conventional resin cement [ResiCem (RE)]. Representative morphology formed with self-adhesive resin cements showed areas of etched enamel intermingled with areas of featureless enamel. In conclusion, etching efficacy influenced the bonding effectiveness of self-adhesive resin cements to unground enamel, and that a combined use of phosphoric acid and G-Bond for pretreatment of human enamel surfaces improved the bond strength of self-adhesive resin cements. PMID:20668359

Lin, Jie; Shinya, Akikazu; Gomi, Harunori; Shinya, Akiyoshi

2010-08-01

427

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

SciTech Connect

We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I{sup -}, Br{sup -}...) in HF/HNO{sub 3}/CH{sub 3}COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br{sup -}, I{sup -}..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.

Abbadie, A.; Hamaide, G.; Chaupin, M.; Brunier, F. [SOITEC, Parc Technologique des Fontaines, 38920 Crolles cedex (France); Mariolle, D.; Martinez, E. [CEA, LETI, MINATEC, F38054 Grenoble (France); Maehliss, J. [Goethe University, Institute of Inorganic and Analytical Chemistry, 60438 Frankfurt (Germany)

2012-03-15

428

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

NASA Astrophysics Data System (ADS)

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

Abbadie, A.; Hamaide, G.; Mariolle, D.; Chaupin, M.; Brunier, F.; Martinez, E.; Mähliß, J.

2012-03-01

429

Etch Induction Time in CR-39 Detectors Etched in Na2CO3 Mixed NaOH Solution  

NASA Astrophysics Data System (ADS)

Six different solutions of 6M NaOH, containing different amounts of Na2CO3 at 70°C were used for the revelation of latent damage trails in CR-39 plastic track detectors. These detectors were earlier exposed to fission fragments from 252Cf source for 30 min in vacuum and were then etched in the respective solutions for different etching time intervals of 5-20 min starting from 5min up to 160min. The etch induction time in each detector was obtained by extrapolating the intersection of resulting curves of track lengths and track diameters with the time axis.

N., Ali; Khan U., E.; K., Khan

2009-09-01

430

CCMR: Effect of Etchant Concentration and Etch Duration on the Morphology of Potassium-Hydroxide-Etched Si(100) Surfaces  

NSDL National Science Digital Library

Infrared spectroscopy was employed in the multiple-internal-reflectance geometry to analyze the nanoscale morphology of H-terminated Si(100) samples etched in dilute potassium hydroxide solutions. The effect of etch time and etchant concentration on hillock formation was measured from the relative intensities of the absorption bands associated with Si–H stretch vibrations on Si(111) and Si(110) microfacets. Under some etch conditions, a nominally flat Si(100) surface would spontaneously transform into a microfaceted surface, which is evidence of nanoscale hillock formation.

Hallman, Kent A.

2009-08-15

431

Influence of doping on the etching of Si(111)  

NASA Astrophysics Data System (ADS)

Exposure of solid surfaces to reactive gases (or radicals) often leads to chemical reactions which produce volatile products. These are frequently called etching reactions. The example discussed in this paper involves the reaction of XeF2 with Si(111) to produce SiF4(gas). It will be shown that the etch rate depends strongly upon the concentration and type of dopant. It also depends upon the thickness of the fluorosilyl (SiFx) layer on the surface. The trends previously observed in plasma-assisted etching environments are shown to also occur in the XeF2-Si reaction. A simple model will be developed which indicates a strong correlation between the number of negative ions on the surface and the etch rate. The model is based upon some of the ideas originally proposed by Mott and Cabrera to describe oxide growth and on the Poisson-Boltzmann equation which describes the space charge at a semiconductor interface.

Winters, Harold F.; Haarer, D.

1987-10-01

432

Evaluation of unsaturated fluorocarbons for dielectric Etch applications  

E-print Network

The semiconductor industry is currently faced with the problem of the use and emissions of strong global warming compounds, known as perfluorocompounds (PFCs) for dielectric etch applications. The release of global warming ...

Chatterjee, Ritwik, 1974-

2003-01-01

433

Catalytic etching of synthetic diamond crystallites by iron  

NASA Astrophysics Data System (ADS)

For the expansion of the functionality of diamond crystallites by modification of surface morphology, catalytic etching of synthetic diamond crystallites at 1173 K by iron, which were loaded by the impregnation method using an aqueous solution of iron nitrate; in a streaming mixed gas (pH2=0.1 ??MPa, pN2=0.9 ??MPa), has been investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The dependence of the crystal planes {1 1 1} and {1 0 0}, of the diamond crystallites and the loading amount of iron on the diamond on the etching behavior by iron particles, the morphology of the etch pits, and potential formation of iron carbide through the catalytic etching, were discussed.

Ohashi, Tatsuya; Sugimoto, Wataru; Takasu, Yoshio

2012-08-01

434

Enhanced photoluminescence from porous silicon by hydrogen-plasma etching  

NASA Astrophysics Data System (ADS)

Porous silicon (PS) was etched by hydrogen plasma. On the surface a large number of silicon nanocone arrays and nanocrystallites were formed. It is found that the photoluminescence of the H-etched porous silicon is highly enhanced. Correspondingly, three emission centers including red, green, and blue emissions are shown to contribute to the enhanced photoluminescence of the H-etched PS, which originate from the recombination of trapped electrons with free holes due to Si ?O bonding at the surface of the silicon nanocrystallites, the quantum size confinement effect, and oxygen vacancy in the surface SiO2 layer, respectively. In particular, the increase of SiOx(x <2) formed on the surface of the H-etched porous silicon plays a very important role in enhancing the photoluminescence properties.

Wang, Q.; Gu, C. Z.; Li, J. J.; Wang, Z. L.; Shi, C. Y.; Xu, P.; Zhu, K.; Liu, Y. L.

2005-05-01

435

Analysis of EUV mask durability under various absorber etch conditions  

NASA Astrophysics Data System (ADS)

During EUV exposure, more frequent mask cleaning is essential for removing not only particles from lack of pellicle but also the carbon contamination due to accumulative EUV exposure. Because of this reason, process improvement for minimize corrosion and etching of the Ru capping layer is urgently needed. In this work, the influence of TaBN absorber etch condition on Ru integrity followed by repetitive cleaning was evaluated and the effects on long-term durability of Ru are compared under various cleaning conditions. Consequently, it was shown that Ru durability was strongly influenced by the gas contents and over etch time of absorber dry etch, not only as a function of cleaning conditions.

Lee, Dong Wook; Jo, Sang Jin; Oh, Sung Hyun; Ha, Tae Joong; Kim, Sang Pyo; Yim, Dong Gyu

2013-09-01

436

Removal of field and embedded metal by spin spray etching  

DOEpatents

A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment.

Contolini, Robert J. (Pleasanton, CA); Mayer, Steven T. (San Leandro, CA); Tarte, Lisa A. (Livermore, CA)

1996-01-01

437

Analysis of machining characteristics in electrochemical etching using laser masking  

NASA Astrophysics Data System (ADS)

Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.

Shin, Hong Shik; Chung, Do Kwan; Park, Min Soo; Chu, Chong Nam

2011-12-01

438

Visible luminescence from silicon wafers subjected to stain etches  

NASA Technical Reports Server (NTRS)

Etching of Si in a variety of solutions is known to cause staining. These stain layers consist of porous material similar to that produced by anodic etching of Si in HF solutions. In this work, photoluminescence peaked in the red from stain-etched Si wafers of different dopant types, concentrations, and orientations produced in solutions of HF:HNO3:H2O was observed. Luminescence is also observed in stain films produced in solutions of NaNO2 in HF, but not in stain films produced in solutions of CrO3 in HF. The luminescence spectra are similar to those reported recently for porous Si films produced by anodic etching in HF solutions. However, stain films are much easier to produce, requiring no special equipment.

Fathauer, R. W.; George, T.; Ksendzov, A.; Vasquez, R. P.

1992-01-01

439

Process development for dry etching polydimethylsiloxane for neural electrodes.  

PubMed

In order to create high density electrode arrays, a reactive ion (dry) etching process was developed using sulphur hexafluoride (SF(6)) and oxygen (O(2)) plasma to pattern micro-structures in medical grade polydimethylsiloxane (PDMS). The surface topography and etch performance were analyzed by employing surface profilometry, scanning electron micrographs (SEM) and atomic force miscroscopy (AFM). The maximum etch rate was approximately 0.22 ?m/min. The chemical modification of the PDMS structure in SF(6) and O(2) plasma was investigated through x-ray photoelectron spectroscopy (XPS). Micro-scale openings in PDMS were achieved using a dry etching method to allow charge injection at the electrode-tissue interface. PMID:22254966

Anenden, Melissa P; Svehla, Martin; Lovell, Nigel H; Suaning, Gregg J

2011-01-01

440

Characterization of silicon etching in synchronized pulsed plasma  

NASA Astrophysics Data System (ADS)

Pulsed plasmas have been proposed many years ago by research labs and have shown a great potential for etch process improvement. Nevertheless, they have been introduced in manufacturing only recently and the exact characteristics of pulsed plasmas in industrial scale reactors are hardly known. In this paper, we have characterized silicon etching in pulsed HBr/O2 plasmas using advanced plasma diagnostics (mass spectrometry and ion flux probe) in a 300 mm industrial reactor. We show that pulsing the plasma at low duty cycle reduces the gas molecules dissociation and plasma temperature, as well as the flux of energetic ions to the wafer. The ions during silicon etching are mostly silicon-containing ions that are heavier at low duty cycle. Silicon patterns etched using pulsed plasmas present improved profiles, which is attributed to more uniform passivation layers at low duty cycle.

Darnon, M.; Haass, M.; Cunge, G.; Joubert, O.; Banna, S.

2013-03-01

441

Laser Etching: A Novel Technology to Label Florida Grapefruit  

E-print Network

by experiments where Penicillium digitatum spores were coated on fruit surfaces before and after etching- paper, penetration by Penicillium digitatum was inhibited where cells at the surface produced lignin

Etxeberria, Edgardo

442

Removal of field and embedded metal by spin spray etching  

DOEpatents

A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment. 6 figs.

Contolini, R.J.; Mayer, S.T.; Tarte, L.A.

1996-01-23

443

SPENT ACID RECOVERY USING DIFFUSION DIALYSIS  

EPA Science Inventory

Each year, several million gallons of acid solutions are used by the Department of Defense (DoD) and its support contractors in various metal finishing operations such as stripping, etching, activation, passivation and pickling. Over time, these acids become contaminated with met...

444

Photostimulated desorption in laser-assisted etching of silicon  

NASA Astrophysics Data System (ADS)

Photodesorption of SiF3 groups, which are the principal adsorbates on a silicon surface during etching by XeF2, is found to be responsible for the etch-rate enhancement observed under illumination by low-power, cw band-gap radiation. It is proposed that desorption is stimulated by photogenerated-charge-carrier-mediated chemical reaction, and not the simple charge trapping and recombination mechanism usually invoked for desorption from semiconductor surfaces.

Houle, F. A.

1988-10-01

445

Photostimulated desorption in laser-assisted etching of silicon  

Microsoft Academic Search

Photodesorption of SiF3 groups, which are the principal adsorbates on a silicon surface during etching by XeF2, is found to be responsible for the etch-rate enhancement observed under illumination by low-power, cw band-gap radiation. It is proposed that desorption is stimulated by photogenerated-charge-carrier-mediated chemical reaction, and not the simple charge trapping and recombination mechanism usually invoked for desorption from semiconductor

F. A. Houle

1988-01-01

446

Focused, Nanoscale Electron-Beam-Induced Deposition and Etching  

Microsoft Academic Search

Focused electron-beam-induced (FEB-induced) deposition and etching are versatile, direct-write nanofabrication schemes that allow for selective deposition or removal of a variety of materials. Fundamentally, these processes are governed by an electron-induced reaction with a precursor vapor, which may either result in decomposition to a solid deposit or formation of a volatile etch by-product. The ability to induce such localized reactions

S. J. Randolph; J. D. Fowlkes; P. D. Rack

2006-01-01

447

Analysis of sidewall buildup during trilevel resist etching of metal  

Microsoft Academic Search

Sidewall buildup formed during trilevel resist etching of a layered metal was analyzed for individual etch steps using Auger electron and micro-Raman spectroscopy. Thick sidewall buildup was formed during the dry SOG strip in a fluorine-containing plasma and found to consist of the oxide forms of sputtered anti-reflective TiN, TiFx, and CFx polymers. From the sidewall buildup observed after the

Jae Hee Ha; Jin-Ki Jung; Yeo-Song Seol; Hee-Kook Park; Eun-Joo Shin; Dong-Ho Kim

1997-01-01

448

Fine Contact Hole Etching in Magneto-Microwave Plasma  

Microsoft Academic Search

Characteristics of fine contact hole etching have been investigated in hydro-fluorocarbon magneto-microwave plasma focusing on the z component of the gradient of magnetic field at 0.0875 T ( dB\\/ dz) and peak-to-peak voltage of RF bias (V pp) as parameters. Decrease of dB\\/ dz drastically decreases the etch rate of boro-phospho silicate glass (BPSG), critical dimension loss (defined as diameter

Yasuhiro Miyakawa; Jun Hashimoto; Naokatsu Ikegami; Takayuki Matsui; Jun Kanamori

1994-01-01

449

Study of etched ion track profiles in silicon dioxide membrane  

Microsoft Academic Search

A method was developed to investigate the profiles of etched ion tracks in silicon dioxide membranes that are thermally grown on silicon (100) substrates. These membranes were irradiated with 9MeV Cu5+63, 45MeV Br9+80 or 76.5MeV Br16+80 ions. The induced latent ion tracks were then selectively over-etched in aqueous 4% HF till reaching the silicon substrates. We used both the top

W. M. Zhang; J. Li; Y. D. Liu; W. Guo; A. F. Liang; J. M. Xue; Y. G. Wang

2008-01-01

450