Showing papers on "Hydrofluoric acid published in 2000"
TL;DR: In this paper, the authors have shown that an interlayer of a silicon oxide complex including hydrogen and fluorine atoms is formed between bonded SiO 2 to SiO2, and that the thickness of the interlayer depends strongly on the applied pressure during bonding.
Abstract: Studies on SiO 2 –SiO 2 bonding with hydrofluoric acid (HF) are described. This method has a remarkable feature that bonding can be obtained at room temperature. Advantages of this method are low thermal damage, low residual stress and simplicity of the bonding process, which are expected for the packaging and assembly of micro-electro-mechanical systems (MEMS). The bond characteristics were measured under different bonding conditions of HF concentration, applied pressure, another chemicals for bonding and so on. The bond strength depends on the applied pressure during bonding. To achieve reliable bonding, HF concentration of higher than 0.5 wt.% and a large applied pressure of 1.3 MPa are required. The bonding is also observed using KOH solution in stead of HF. Transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), radioactive isotope (RI) analysis and electron probe micro analysis (EPMA) were applied to evaluate the bonded interface. The results of these analysis indicated that an interlayer of a silicon oxide complex including hydrogen and fluorine atoms is formed between bonded SiO 2 to SiO 2 . The thickness of the interlayer depends strongly on the applied pressure during bonding. Large bond strength is obtained when the interlayer is thin. The bonding mechanism is expected when the SiO 2 at both surfaces is dissolved in HF solution, and that the interlayer, which is a binding layer, is formed between substrates by resolidification of dissolved silicon dioxide. Formation of the interlayer plays very important roles for the characteristics of HF-bonding.
109 citations
15 Jun 2000
TL;DR: In this paper, the authors present a survey of the physical and chemical properties of anhydrous Hydrofluoric acid (AHF) and its properties in the context of aluminum production.
Abstract: The article contains sections titled:
1. Hydrofluoric Acid
1.1. Physical Properties
1.1.1. Anhydrous Hydrofluoric Acid (AHF)
1.1.2. Aqueous Solutions
1.2. Chemical Properties
1.3. Manufacture
1.3.1. Fluorite Processes
1.3.2. Fluosilicic Acid Processes
1.3.3. Corrosion-Resistant Materials
1.3.4. Specifications and Analysis
1.4. Storage and Transport
1.5. Toxicology and Occupational Health
1.6. Economic Aspects and Uses
2. Calcium Fluoride
2.1. Physical and Chemical Properties
2.2. Production and Resources
2.3. Uses
2.4. Toxicology
2.5. Specifications
2.6. Chemical Analysis
3. Aluminum Fluoride and Fluoroaluminates
3.1. Aluminum Fluoride
3.1.1. Properties
3.1.2. Manufacture
3.1.2.1. Hydrofluoric Acid Processes
3.1.2.2. Fluosilicic Acid Processes
3.1.2.3. Recovery of Fluorine During Aluminum Production
3.2. Fluoroaluminates
3.2.1. Cryolite, AlF3· 3 NaF
3.2.1.1. Properties
3.2.1.2. Manufacture
3.2.2. Ammonium Cryolite
3.3. Environment Protection
3.4. Specifications
3.5. Chemical Analysis
3.6. Uses
3.7. Economic Aspects
3.8. Toxicology
4. Other Metal Fluorides
4.1. Ammonium Fluorides
4.2. Cobalt Fluorides
4.3. Lithium Fluorides
4.4. Magnesium Fluoride
4.5. Nickel Fluorides
4.6. Potassium Fluorides
4.7. Sodium Fluorides
4.8. Tungsten Hexafluoride
5. Fluorine - Silicon Compounds
5.1. Silicon Tetrafluoride
5.1.1. Physical Properties
5.1.2. Chemical Properties
5.1.3. Manufacture
5.1.4. Transport
5.1.5. Analysis
5.1.6. Use
5.1.7. Toxicology
5.2. Fluosilicic Acid
5.2.1. Physical Properties
5.2.2. Chemical Properties
5.2.3. Manufacture
5.2.4. Transport
5.2.5. Quality and Analysis
5.2.6. Use
5.2.7. Economic Aspects
5.2.8. Toxicity
5.3. Fluosilicates
5.3.1. Properties
5.3.2. Manufacture
5.3.3. Analysis
5.3.4. Uses, Economic Aspects
5.3.5. Toxicity
6. Other Inorganic FluorineCompounds
6.1. Sulfur Fluorides
6.1.1. Sulfur Hexafluoride
6.1.2. Sulfur Tetrafluoride
6.2. Nitrogen Fluorides
6.3. Oxygen - Fluorine Compounds
6.4. Phosphorus - Fluorine Compounds
6.5. Halogen Fluorides
6.6. Rare-Gas Fluorides
6.7. Graphite Fluorides
61 citations
TL;DR: In this paper, the properties of the purified multiwall carbon nanotubes are probed using 13C and 129Xe NMR spectroscopy under continuous-flow optical-pumping conditions.
Abstract: Multiwall carbon nanotubes are produced by decomposition of acetylene at 600 °C on metal catalysts supported on NaY zeolite. The support and the metal are eliminated by dissolving them in aqueous hydrofluoric acid (HF). Two methods were used to eliminate the pyrolitic carbon: oxidation in air at 500 °C and oxidation by potassium permanganate in acidic solution at 70 °C. The progress and efficacy of the purification methods are verified by TEM. The properties of the purified multiwalled carbon nanotubes are probed using 13C and 129Xe NMR spectroscopy under continuous-flow optical-pumping conditions. Xenon is shown to penetrate the interior of the nanotubes. A distribution of inner tube diameters gives rise to chemical shift dispersion. When the temperature is lowered, an increasing fraction of xenon resides inside the nanotubes and is not capable of exchanging with xenon in the interparticle space. In the case of the permanganate-oxidized sample, rapid xenon relaxation is attributed to interaction with re...
57 citations
Patent•
05 Jul 2000
TL;DR: In this article, the authors present a handy and efficient method for the generation of hydrogen gas, in which a reaction medium prepared by dissolving a metal hydrogen complex compound such as sodium borohydride NaBH 4 in an aqueous alkaline solution such as a 10% by weight solution of sodium or potassium hydroxide is brought into contact with a catalyst which is a metal such as cobalt and nickel or a so-called hydrogen absorbing alloy such as Mg 2 Ni.
Abstract: Disclosed is a handy and efficient method for generation of hydrogen gas, in which a reaction medium prepared by dissolving a metal hydrogen complex compound such as sodium borohydride NaBH 4 in an aqueous alkaline solution such as a 10% by weight aqueous solution of sodium or potassium hydroxide is brought into contact with a catalyst which is a metal such as cobalt and nickel or a so-called hydrogen-absorbing alloy such as Mg 2 Ni so that decomposition of the metal hydrogen complex compound proceeds even at room temperature to generate hydrogen gas. The catalytic activity of the catalyst can be increased by subjecting the catalyst to a fluorinating treatment in which the catalyst powder is immersed in an aqueous solution of potassium fluoride acidified with hydrofluoric acid.
49 citations
Patent•
10 Aug 2000
TL;DR: In this paper, a method for fabricating wafers is provided that uses a potassium-based oxidizer in the presence of hydrofluoric acid as the chemical etchant for etching the wafer edge.
Abstract: A method for fabricating wafers is provided that uses a potassium-based oxidizer in the presence of hydrofluoric acid as the chemical etchant for etching the wafer edge. The potassium-based chemical etchant is preferably potassium permanganate KMnO 4 that is mixed with hydrofluoric acid such that the ratio of hydrofluoric acid to potassium permanganate is between 2:1 and 4:1. The method for fabricating wafers initially divides a crystal ingot into a plurality of wafers before grinding the wafer edge to size and shape the wafer. The wafer can then be subjected to alkaline cleaning and acid etching. After a polysilicon layer is deposited on the wafer for gettering purposes and a silicon dioxide back seal layer, if any, is deposited, the wafer is then etched with the potassium-based chemical oxidizer in the presence of hydrofluoric acid to oxidize and remove the polysilicon layer and any silicon dioxide layer from the edge. The wafer is then rinsed and thermally annealed prior to undergoing edge polishing. In order to concentrate the potassium-based chemical etchant on the wafer edge, the opposed major surfaces can be covered, such as by being stacked in an alternating fashion with spacers. As such, the wafer edge can be reliably formed in an efficient and safe manner.
48 citations
TL;DR: In this article, a kinetic model was proposed to explain the dependence of the steady-state electrodissolution current density (I) of Si in acidic fluoride media on total fluoride concentration (C F ), pH, and mass transfer rate.
Abstract: With the aim of explaining the dependence of the steady-state electrodissolution current density (I) of Si in acidic fluoride media on total fluoride concentration (C F ), pH, and mass transfer rate, a kinetic model is proposed. The Si electrode is assumed to be covered by a thin SiO 2 layer, formed by an electrochemical reaction at the Si/oxide interface, which undergoes dissolution by three parallel chemical reactions. These reactions convert SiO 2 to SiF 6 2- , under the action of HF and HF - 2 , and occur under mixed control; their kinetics is assumed to be of the second order. Fast equilibria between fluoride species and H + are assumed. The model is compared with experimental results obtained by ourselves and with those in the literature. The C F , pH, and Ω dependencies of the current density measured at a fixed potential in the electropolishing domain are well reproduced with an appropriate choice of the rate constants of the dissolution reactions, the only adjustable parameters. It is shown that I depends on the angular speed of the electrode (Ω) in such a way that I -1 vs. Ω -1/2 plots are almost linear, resembling traditional Koutecky-Levich behavior.
45 citations
TL;DR: In this paper, the electrodissolution of Ti and p-Si electrodes in acidic fluoride solutions has been investigated by electrochemical impedance spectroscopy as a function of potential E, fluoride concentration, pH and angular speed of the electrode, with the aim of characterising the oxide layers covering both materials.
44 citations
TL;DR: Topical application of hydrofluoric acid appeared to provide a dentinal surface with an amorphous precipitate of fluoride, which may be important both for resistance of dental caries in dentin and for bonding reactions.
Abstract: Statement of Problem: Fracture of porcelain is a relatively common clinical misfortune. Recent research has indicated that strong bonds can be formed between composite and dental porcelain. Porcelain surfaces are etched with hydrofluoric acid and treated with silane coupling agents before composite application. The question is how exposed dentin may react to etching with hydrofluoric acid. Purpose: This investigation examined the effect of 9.5% buffered hydrofluoric acid, of 36% o-phosphoric acid alone and in combination on the surface structure of cut human dentin. Material and Methods: Human molar teeth were sectioned in approximately 0.8-mm thick slices and treated with different acids or their combinations. Application periods were 10, 60, and 180 seconds. Specimens were processed for SEM and for energy-dispersive x-ray (EDX) microanalysis. Results: The smear layer on the surface of sectioned dentin was not completely removed by hydrofluoric acid alone and that a dense amorphous precipitate was formed on the peritubular zone. Starlike structures in dentinal tubules were visible. EDX analysis revealed different fluoride content on the treated surface, dependent on the etchant used. Conclusion: Topical application of hydrofluoric acid appeared to provide a dentinal surface with an amorphous precipitate of fluoride. This layer may be important both for resistance of dental caries in dentin and for bonding reactions. (J Prosthet Dent 2000;83:668-74.)
41 citations
TL;DR: In this paper, the effect of acid-catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) was investigated by measuring their structural properties.
Abstract: Unsupported silica membranes were prepared via sol–gel processing through acid-catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS). The possibility of controlling the pore sizes and porosities of silica membranes were investigated by varying processing parameters. The effect of the type and concentration of the acid catalyst and molar ratio water/alkoxide on the structure of the membranes was determined by measuring their structural properties. The membranes catalyzed only with nitric acid have a smaller pore structure, with larger pore-solid surface areas and solid densities than the membranes catalyzed with a combination of nitric acid and hydrofluoric acid. The average pore size increases for larger hydrofluoric acid concentrations, in a range from 1.1±0.1 to 22±0.9 nm. Silica membrane obtained with molar ratio water/alkoxide equal to 2 has a pore structure differing from the pore structures of the other membranes. The connectivity (ca. 1019 cm−3) and the diffusion coefficients (ca. 1.6±0.2×10−6 to 2.8±0.3×10 −5 cm 2 / s ) of the Cu in the pore structure of these silica membranes indicate the feasibility of using these materials in impregnation and separation processes.
39 citations
Patent•
21 Jun 2000TL;DR: In this article, a method of enhancing the productivity of hydrocarbons from hydrocarbon bearing siliceous formations, particularly those made up at least in part of zeolites, is achieved by contacting the formation with a treatment solution comprising citric acid, phosphonate compounds, and hydrofluoric acid.
Abstract: A method of enhancing the productivity of hydrocarbons from hydrocarbon bearing siliceous formations, particularly those made up at least in part of zeolites, is achieved by contacting the formation with a treatment solution comprising citric acid, phosphonate compounds, and hydrofluoric acid. The treatment solution can be applied prior to gravel packing or fracturing. This solution may optionally contain ammonium salts. Similar solutions comprising citric acid and phosphonate compounds without hydrofluoric acid may also be used to contact the formation prior to contacting the formation with the citric acid and phosphonate solution containing hydrofluoric acid. Other preflushes known in the art, such as hydrochloric, acetic or formic acid solutions, may also be used.
29 citations
TL;DR: In this paper, the self-diffusion of water, ethanol and fluorine ions was studied by means of pulsed-field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy in anion-exchange materials such as membranes and a resin containing quaternary amines as functional groups.
Patent•
12 May 2000
TL;DR: In this paper, the acid resistance of the glass substrate and the average surface roughness of the recording surface of a glass substrate are specified for high density recording by specifying acid resistance and roughness.
Abstract: PROBLEM TO BE SOLVED: To obtain a glass substrate high in cleanness and smoothness and suitable for high density recording by specifying the acid resistance of the glass substrate and the average surface roughness of the recording surface of the glass substrate. SOLUTION: At least one of the surfaces of the glass substrate is used as the recording surface, and the glass substrate has the acid resistance such that the etching rate is not more than 45 nm/min when it is brought into contact with 0.1 wt.% hydrofluoric acid at 50 deg.C and the average surface roughness Ra of the recording surface is less than 0.3 nm. The glass composition satisfying an etching rate condition in the case of 0.1 wt.% hydrofluoric acid is preferably comprised of, by molar percentage, 63 to 70% SiO2, 4 to 11% Al2O3, 5 to 11% Li2O, 6 to 14% Na2O, 0 to 2% K2O, 0 to 6% MgO, 1 to 9% CaO, 0 to 3% SrO, 0 to 2% BaO, 0 to 5% TiO2, and 0 to 2.5% ZrO, with the proviso that the difference of the amounts of SiO2 and Al2O3 (SiO2-Al2O3) is not less than 56.5% and the amount of RO (RO=MgO+CaO+SrO+BaO) is 2 to 15%.
Patent•
01 Dec 2000TL;DR: In this article, a method for removing fluorine gas from a selected environment comprises contacting the fluorine with water to generate a solution of hydrofluoric acid and contacting the solution with an ion exchange resin having an active state operative to exchange selected ions therein for fluoride ions in the solution.
Abstract: A method for removing fluorine gas from a selected environment comprises contacting the fluorine gas with water to generate a solution of hydrofluoric acid and contacting the solution of hydrofluoric acid with an ion exchange resin having an active state operative to exchange selected ions therein for fluoride ions in the solution. The apparatus (200) may include a dual resin setup (222, 223) such that one of the ion-exchange resin can be in the service cycle while the other of the ion-exchange resins undergoes the regeneration and rinse/refill cycles.
Patent•
06 Nov 2000
TL;DR: In this paper, a glass substrate consisting of aluminosilicate-based glass material or the like is subjected to precision polishing treatment in a polishing stage 2 and the resultant glass substrate is washed by using an acid aqueous solution consisting of hydrofluoric acid and the like in a successive first washing stage 3.
Abstract: PROBLEM TO BE SOLVED: To manufacture a glass substrate for information recording medium having excellent flatness and cleanness SOLUTION: A glass substrate 1 consisting of aluminosilicate-based glass material or the like is subjected to precision polishing treatment in a polishing stage 2 and the resultant glass substrate is washed by using an acid aqueous solution consisting of hydrofluoric acid and the like and an alkaline aqueous solution consisting of sodium hydroxide and the like in a successive first washing stage 3 The resultant glass substrate is subjected to heat treatment, preferably concurrently including chemically strengthening treatment in a fused salt, in a heating stage 4 to relax the permanent set formed on the surface of the glass substrate 1 and then the glass substrate 1 is washed again by using an acid aqueous solution 5a and an alkaline aqueous solution 5b in a second washing stage 5
Patent•
13 Jul 2000
TL;DR: In this article, an etchant containing nitric acid and hydrofluoric acid is applied to silicon to etch the silicon, and the etchant used in the etching is recovered and brought into contact with a gas inert to the original etchant to reuse at least a part of the regenerated etchant.
Abstract: An etching method and an etching apparatus for applying an etchant containing nitric acid and hydrofluoric acid to silicon to etch the silicon. The etchant used in etching is recovered, and brought into contact with a gas inert to the etchant, whereby the etchant is regenerated. At least a part of the regenerated etchant is reused in etching.
Patent•
12 May 2000TL;DR: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C and a concentration of 0.1 weight % as mentioned in this paper.
Abstract: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.
TL;DR: In this article, the environmental stabilities of graphite intercalation compounds (GICs) containing bifluoride, nitrate, sulfate, C8F17SO3−, N(CF3SO2)2−, or n(CF2CF 3SO2)-2− were determined at 20°C in air, at 50°C and 100% relative humidity, and at 20 °C in liquid water.
TL;DR: In this article, Boric acid was added to the solution, the fluoride ions were consumed by the formation of BF 4−, and then the fluorocomplexes were hydrolyzed to (La,Sr)MeO 3 solid solutions in order to increase the amount of fluoride ions.
TL;DR: In this paper, the irreversible consumption of lithium during deposition and dissolution in nonaqueous electrolytes with a small amount of hydrofluoric acid was studied by an electrochemical in situ quartz crystal microbalance technique.
Abstract: The irreversible consumption of lithium during deposition and dissolution in nonaqueous electrolytes with a small amount of hydrofluoric acid was studied by an electrochemical in situ quartz crystal microbalance technique. It was found that lithium is not only consumed by chemical reactions with the electrolyte during deposition, but is also lost during dissolution. This result is strongly related to breakdown of the surface film formed on lithium during the deposition process. From the experimental data, it is concluded that the stability of the surface film on lithium metal during dissolution is a key requirement for high coulombic efficiency of lithium metal deposition and dissolution.
Patent•
07 Mar 2000
TL;DR: In this article, the authors proposed a method to reduce a fault generated on glass to be cleaned by recovering the cleaning ability of a glass cleaning liquid containing hydrofluoric acid utilized for the cleaning or the working of silicate glass and discharged in the large quantity to decrease industrial wastes and removing fluorosilicic acid generated while repeating the cleaning.
Abstract: PROBLEM TO BE SOLVED: To reduce a fault generated on glass to be cleaned by recovering the cleaning ability of a glass cleaning liquid containing hydrofluoric acid utilized for the cleaning or the working of silicate glass and discharged in the large quantity to decrease industrial wastes and removing fluorosilicic acid generated while repeating the cleaning. SOLUTION: A treating liquid 2 containing potassium fluoride is added into a cleaning liquid 3 discharged from a cleaning vessel 11 to react it with fluorosilicic acid in the cleaning liquid to deposit and remove a precipitate (potassium fluorosilicate). Into the cleaning liquid after removing the precipitates, hydrofluoric acid 6 is newly added in addition to hydrogen fluoride generated by the reaction, the mixture is sent to the cleaning vessel 11 again to be used as the cleaning liquid for a panel 20 for a cathode ray tube.
TL;DR: In this article, the extraction constants of both the acids are shown to be close to one another which results in their mutual displacement from the organic phase, and the extraction of thorium is much reduced as the concentration of hydrofluoric acid increases which may be explained by a stronger complexation of Th by fluoride ion in aqueous phase.
Abstract: The extraction of HNO3, thorium and uranium were studied in the presence of hydrofluoric acid. The extraction constants of both the acids are shown to be close to one another which results in their mutual displacement from the organic phase. Contrary to uranium, the extraction of thorium is much reduced as the concentration of hydrofluoric acid increases which may be explained by a stronger complexation of Th by fluoride ion in the aqueous phase.
Patent•
31 Aug 2000TL;DR: A direct dissolution method for the purification of technical grade hydrated ammonium tantalum oxide (HATO), (NH4)2−xHxTa2O6.nH2O), and related compounds such as tantalum hydroxide and tantalum oxides is described in this paper.
Abstract: A direct dissolution method for the purification of technical grade hydrated ammonium tantalum oxide (HATO), (NH4)2−xHxTa2O6.nH2O), and related compounds such as tantalum hydroxide and tantalum oxide is described. The method preferably uses ammonium bifluoride as fluoride source in place of the hydrofluoric acid used in the conventional methods. Other fluoride compounds such as NaF, KF, and CaF2 may be used.
TL;DR: In this paper, the rate of formation of photochemical porous silicon is measured in situ by studying the increase in the radius of the circular interference patterns contained in the reflected laser beam.
Abstract: The rate of formation of photochemical porous silicon is measured in situ by studying the rate of increase in the radius of the circular interference patterns contained in the reflected laser beam. This technique is used to study the effects on etch rate of: (a) the composition and concentration of the etchant; and (b) the wavelength and flux of the laser irradiation. The technique is applicable over a wide range of reaction conditions and rates. The etch rate is found to be linearly dependent on the formal concentration of aqueous hydrogen fluoride (HF(aq)). The effect of increasing the flux of the incident radiation on the rate is more complex. In 48% HF(aq), the rate of etching increases up to a certain flux, the value of which is dependent on wavelength, and then exhibits saturation. In 25% HF the rate increases linearly with flux. It appears that the transport of reactive chemical species to the interface is responsible for the saturation of the etch rate. It is demonstrated that the method introduced here may be used in rate studies to investigate other factors that influence the etch rate and can be used to help elucidate the mechanism of etching.
TL;DR: In this paper, the adsorption/desorption characteristics of polyglycidol type surfactant (OHS) onto/from silicon from buffered hydrofluoric acid (BHF) solutions was studied by in situ attenuated total reflection−Fourier transform infrared spectroscopy (ATR−FTIR).
Abstract: Buffered hydrofluoric acid (BHF) solutions containing HF and NH4F are widely used in the manufacturing of silicon-based integrated circuits. The adsorption/desorption characteristics of a commercially available, high purity, polyglycidol type surfactant (OHS) onto/from silicon from buffered hydrofluoric acid (BHF) solutions was studied by in situ attenuated total reflection−Fourier transform infrared spectroscopy (ATR−FTIR). The challenge in these measurements was to resolve the C−H peaks, in the 2800−3000 cm-1 region of the surfactant spectrum, that were masked by the strong absorbance due to N−H caused by a large amount of NH4+ ions in the solution. A technique has been developed to overcome this limitation. The principle of this technique is to carry out the surfactant adsorption in BHF solutions followed by the replacement of NH4+ ions by alkali-metal cations, such as K+ and Cs+, to allow better resolution of the C−H peaks from the baseline. Extrapolation of the adsorption density to time zero yields ...
Patent•
12 Dec 2000
TL;DR: In this paper, a method for the manufacture or post-manufacturing processing of porous semicondcutor material comprises treating substrate semiconductor material with an etching solution containing a semiconductor oxidant and a fluorine-containing Lewis acid.
Abstract: A method for the manufacture or post-manufacturing processing of porous semicondcutor material comprises treating substrate semiconductor material with an etching solution containing a semiconductor oxidant and a fluorine-containing Lewis acid. The fluorine-containing Lewis acid may be a fluorine-containing magic acid (e.g. SbF 3 .HF or SbF 5 HSO 3 F), or may be prepared by dissolution of fluorides in an aqueous or ether solution of hydrofluoric acid, or in gaseous hydrogen fluoride followed by solubilisation into an aqueous or ether solution. The Lewis acid may be prepared from ErF 4 , TiF 4 , ZrF 4 , BF 3 , PF 5 , SiF 4 and SbF 5 . The semiconductor oxidant may be a chemical that can dissociate to form the nitronium ion NO + in the etching solution (e.g. HNO 3 ). The porous material may be used for a hydrocarbon sensor, where porous silicon (21) is coated by a metal layer (22). Other applications include light emission devices, display devices, integrated circuits, photo-detectors and waveguides, and medical prostheses and implants.
Patent•
21 Mar 2000
TL;DR: In this paper, the first gas component is removed from the digester and heated to a temperature sufficiently high in a heater/oxidizer (38), heat produced is recovered in a boiler (42), and hydrogen fluoride gas is water scrubbed and formed into liquid hydrofluoric acid.
Abstract: Spent potliner from an aluminum reduction cell is subjected to an acid digest (24) and the digest may be adjusted to produce a first gas component comprised of at least one material selected from silicon tetrafluoride, hydrogen fluoride, hydrogen cyanide gas and water vapor (26) and a slurry component comprised of at least one material selected from carbon, silica, alumina, and sodium, iron, calcium and magnesium compounds. The first gas component is removed from the digester and heated to a temperature sufficiently high in a heater/oxidizer (38). Heat produced is recovered in a boiler (42). Hydrogen fluoride gas is water scrubbed (44) and formed into liquid hydrofluoric acid. Gases (56) from the water scrubber are then passed to a caustic scrubber (58) as a polishing step prior to release to the atmosphere.
Patent•
15 Dec 2000
TL;DR: In this paper, the authors proposed a method to obtain a semiconductor device which prevents sticking of a movable part by partially etching the surface of a substrate to be rough.
Abstract: PROBLEM TO BE SOLVED: To obtain a semiconductor device which prevents sticking of a movable part. SOLUTION: A surface 10 of a substrate 1 opposed to a movable part 300 is partially etched to be rough. Accordingly, the movable part 300 can be less stuck onto the surface 10. As a method of partially etching the surface 10, a vicinity of the surface 10, the movable part 300 and an active layer 3 are made of silicon (Si) having different impurity compositions, subjected to an electrolytic etching process using an aqueous solution of hydrofluoric (HF) acid, to a selective etching process using a mixture of hydrofluoric acid/ concentrated nitric acid/acetic acid, to an electrochemical etching stop process in an aqueous solution of potassium hydroxide (KOH), or an anodic oxidation process with use of a pulse current.
TL;DR: In this paper, the assignment of the Raman peaks of the Ag-deposited porous silicon are given, and the structure of porous silicon on which metal is immersion-plated is discussed.
Abstract: Raman scattering from porous silicon layer into which silver is immersion-plated was studied. Ag-deposited samples show extra Raman bands. Heat treatment of the Ag-deposited samples results in a great decrease in such Raman bands. Also dipping in hydrofluoric acid solution causes a spectral change. Some comments on the assignment of the Raman peaks of the Ag-deposited porous silicon are given, and the structure of porous silicon on which metal is immersion-plated is discussed.
Patent•
14 Aug 2000TL;DR: An aqueous liquid surface treatment composition that comprises molecules each of which contains at least two moieties that conform to general formula (I) wherein each of R?1, R2, and R3? is independently selected from the group consisting of hydrogen atoms and alkyl moieties containing from 1 to 4 carbon atoms, all of these molecules together having a quotient of average molecular weight to the average number per molecules of moieties conforming to formula(I) that is within a range from 100 to 30,000 as mentioned in this paper.
Abstract: An aqueous liquid surface treatment composition that comprises (i) molecules each of which contains at least two moieties that conform to general formula (I) wherein each of R?1, R2, and R3? is independently selected from the group consisting of hydrogen atoms and alkyl moieties containing from 1 to 4 carbon atoms, all of these molecules together having a quotient of average molecular weight to the average number per molecules of moieties conforming to formula (I) that is within a range from 100 to 30,000, and (ii) one or more substances selected from the group consisting of organic acids, phosphoric acid, hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, hexafluorotitanic acid, hexafluorozirconic acid, hexafluorohafnic acid, and ammonium salts of organic acids, phosphoric acid, hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, hexafluorotitanic acid, hexafluorozirconic acid, and hexafluorohafnic acid produces a highly corrosion-resistant, strongly paint-adherent film on metal surfaces without using a chromium containing composition.
Patent•
IBM1
TL;DR: In this paper, an organic solvent is separated from a waste stream comprising hydrofluoric acid, an organic solver and etchant contaminants by subjecting the waste stream to at least one of the following processes: ion exchange, extraction of the hydro fluid, electrophoresis, converting the acid to an insoluble salt, and then distilling the solvent to recover the organic solvent free of the etching contaminants.
Abstract: An organic solvent is separated from a waste stream comprising hydrofluoric acid, an organic solvent and etchant contaminants. The process comprises separating the hydrofluoric acid by subjecting the waste stream to at least one of the following processes: ion exchange; extraction of the hydrofluoric acid; electrophoresis; converting the hydrofluoric acid to an insoluble salt; to thereby obtain a first composition containing the hydrofluoric acid and a second stream containing the organic solvent and being substantially free of the hydrofluoric acid; and then distilling the second stream to recover the organic solvent free of the etching contaminants.