Showing papers on "Hydrofluoric acid published in 2003"

Low-temperature NMR studies of the structure and dynamics of a novel series of acid-base complexes of HF with collidine exhibiting scalar couplings across hydrogen bonds.

Abstract: The low-temperature 1 H, 19 F, and 15 N NMR spectra of mixtures of collidine- 15 N (2,4,6- trimethylpyridine- 15 N, Col) with HF have been measured using CDF3/CDF2Cl as a solvent in the temperature range 94-170 K. Below 140 K, the slow proton and hydrogen bond exchange regime is reached where four hydrogen-bonded complexes between collidine and HF with the compositions 1:1, 2:3, 1:2, and 1:3 could be observed and assigned. For these complexes, chemical shifts and scalar coupling constants across the 19 F 1 H 19 F and 19 F 1 H 15 N hydrogen bridges have been measured which allowed us to determine the chemical composition of the complexes. The simplest complex, collidine hydrofluoride ColHF, is characterized at low temperatures by a structure intermediate between a molecular and a zwitterionic complex. Its NMR parameters depend strongly on temperature and the polarity of the solvent. The 2:3 complex (ColHFHCol)+(FHF)- is a contact ion pair. Collidinium hydrogen difluoride (ColH)+(FHF)- is an ionic salt exhibiting a strong hydrogen bond between collidinium and the (FHF)- anion. In this complex, the anion (FHF)- is subject to a fast reorientation rendering both fluorine atoms equivalent in the NMR time scale with an activation energy of about 5 kcal mol-1 for the reorientation. Finally, collidinium dihydrogen trifluoride (ColH)+(F(HF)2)- is an ionic pair exhibiting one FHN and two FHF hydrogen bonds. Together with the (F(HF)n)- clusters studied previously (Shenderovich et al., Phys. Chem. Chem. Phys. 2002, 4, 5488), the new complexes represent an interesting model system where the evolution of scalar couplings between the heavy atoms and between the proton and the heavy atoms of hydrogen bonds can be studied. As in the related FHF case, we observe also for the FHN case a sign change of the coupling constant1JFH when the F‚‚‚H distance is increased and the proton shifted to nitrogen. When the sign change occurs, that is, 1 J FH ) 0, the heavy atom coupling constant 2J FN remains very large, of the order of 95 Hz. Using the valence bond order model and hydrogen bond correlations, we describe the dependence of the hydrogen bond coupling constants, of hydrogen bond chemical shifts, and of some H/D isotope effects on the latter as a function of the hydrogen bond geometries.

Characterization of masking materials for deep glass micromachining

Abstract: In this paper the characterization of different masking materials for the fabrication of flow channels or thin diaphragms in aluminosilicate glass substrates (Corning 1737) is presented. Materials such as photoresist, polysilicon and gold were investigated with concentrated hydrofluoric acid, HF 48% used as an isotropic etchant. The use of single material masks restricts the useable etch depth to less than 250 µm. Surface and material imperfections result in weaknesses in the masking layer and subsequent penetration by the etchant. An etch depth of greater than 300 µ mw as achieved using a combination of thick SU-8 photoresist and polished polycrystalline silicon as the masking material. The two materials act as double protection to the glass substrate and the etch depth obtained is approximately three to six times larger than those published for standard photoresist or SU-8 etch mask.

Formation of new crystal faces on TiO2 particles by treatment with aqueous HF solution or hot sulfuric acid

Abstract: We have demonstrated that new crystal faces are generated on anatase and rutile TiO2 particles by means of chemical etching in aqueous hydrofluoric acid or hot sulfuric acid. In the treatment with aqueous hydrofluoric acid, the {112} face of anatase particles and the {021} face of rutile particles are newly formed. When treated with hot sulfuric acid, anatase particles exposed the {122} face and rutile particles exposed the {001}, {010}, {021} and {121} faces. In both cases, anatase particles are etched at a higher rate than rutile particles. The etched particles are expected to show photocatalytic properties unique to the crystal faces. For example, the {112} face of anatase particles is demonstrated to be active in the oxidation of Pb2+ ions.

Different Behavior in Immersion Plating of Nickel on Porous Silicon from Acidic and Alkaline Fluoride Media

Abstract: Immersion plating of nickel (Ni) on a porous silicon (PS) layer has been investigated in concentrated ammonium fluoride and dilute hydrofluoric acid (HF) solutions containing When the PS sample was exposed to the bath containing 5 M and 50 mM at pH 8, metallic Ni was clearly observed at the open-circuit potential without using a reducing agent or any activation treatment at room temperature. However, no deposition was detected when the sample was immersed in a 0.5 wt % HF solution containing the same concentration of at pH 2. The different deposition behavior is discussed on the basis of mixed potential theory, changes in the stability of Si-H bonds of PS as indicated in the Fourier transform infrared spectra, and the different state of Ni complex formation as obtained from the UV-vis spectra. The position of the Ni redox levels in both solutions with respect to the bandedges of Si was also determined and the results revealed a nearly similar energetic situation. Results from current-potential curves showed that a slow Ni deposition from the alkaline solution occurred in the dark and different possible reaction mechanisms were proposed. They also revealed the enhancement of the deposition under illumination, indicating that the deposition mechanism is electron transfer from the conduction band. X-ray photoelectron spectroscopy detected no silicon oxides on the PS surface after being immersed in the alkaline solution, giving merit that a binary PS/Ni nanostructure without Si oxides can be successfully achieved. © 2003 The Electrochemical Society. All rights reserved.

Immersion plating of nickel onto a porous silicon layer from fluoride solutions

Abstract: The deposition of nickel (Ni) onto a porous silicon (PS) layer by immersion plating from acidic and alkaline fluoride solutions has been studied. In an immersion plating bath of simple hydrofluoric acid (HF) of pH 2 containing Ni ions, no metal deposition was observed. However, visible metallic Ni was deposited from the ammonium fluoride (NH 4 F) alkaline solution of pH 8. The different deposition behaviors are discussed on the basis of mixed potential theory, etching rate of PS and the state of Ni complex formation. The modified PS layers after the immersion plating were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Fourier transform infrared spectroscopy and scanning electron microscopy were also performed to investigate the structural changes and characterizations of PS samples after the plating process. A binary PS/Ni nanostructure without Si oxides is successfully achieved from the alkaline bath.

Cleaning composition for removing resists and method of manufacturing semiconductor device

Abstract: The cleaning composition for removing resists includes a salt of hydrofluoric acid and a base not containing a metal (A component), a water-soluble organic solvent (B1 component), at least one acid selected from a group consisting of organic acid and inorganic acid (C component), water (D component), and optionally an ammonium salt (E1 component), and its hydrogen ion concentration (pH) is 4-8. Thus, in the manufacturing process of a semiconductor device such as a copper interconnecting process, removing efficiency of resist residue and other etching residue after etching or ashing improves, and corrosion resistance of copper and insulating film also improves.

Structural change induced in TiO 2 by swift heavy ions and its application to three-dimensional lithography

Abstract: A rutile ${\mathrm{TiO}}_{2}$ single crystal was irradiated by heavy ions with a high energy of the order of several tens of MeV. A good etching selectivity, where only the irradiated surface is well etched by hydrofluoric acid is induced by the irradiation. Through x-ray diffraction and high-resolution electron microscopy, it became clear that the irradiated region lost crystallization. It is considered that this amorphous region and the surrounding region are dissolved in hydrofluoric acid. Through the calculation of the ion energy, it was found that the etching always stopped at the depth where the electronic stopping power of the ion decayed to a critical value of 6.2 keV/nm, regardless of the ion species in the case of I, Br, Cu, and Ti ions. However, in the case of Ca ions with energies higher than about 72 MeV or Cl ions with energies higher than about 77 MeV, the irradiated top surface was not etched with hydrofluoric acid, but the inside surface several \ensuremath{\mu}m deep from the irradiated surface was etched. A calculation shows that the critical factor which determines whether the irradiated surface can be etched or not is the lateral energy density on the surface deposited by ions. The etched surface observed by atomic force microscopy is very smooth with a roughness of the order of nm. Therefore, a combination of ion irradiation and etching can be used as a novel fabrication method of nanostructures in rutile.

Acidizing stimulation method using a pH buffered acid solution

Abstract: A method of stimulating subterranean formations in oil and gas wells using a high pH buffered acid system. The method may be used to treat sandstone formations wherein the pH buffered acid system is used as the preflush or overflush or both. The method consists of introducing into the well a hydrofluoric acid containing sandstone acidizing solution either prior to or subsequent to introduction of the pH buffered acid system. The pH buffered acid system may further be used in the treatment of carbonate reservoirs. The pH of the buffered acid solution is substantially equivalent to that of the pH of the acidizing solution. The buffered acid solution is void of either hydrofluoric acid or hydrofluoric acid precursors.

Glass substrate for magnetic disk and method for manufacturing

Abstract: A method of manufacturing a glass substrate for a magnetic disk. The method includes the step of scrub-etching the glass substrate using a pad in the presence of an acid treatment solution. As the acid treatment solution, hydrofluoric acid is used in a range of 0.01 to 1 wt %. The scrub-etching step is performed at temperatures ranging from 5 to 60° C. for 1 second to 300 seconds. The method produces a substrate that is substantially free of asperity.

Method for fabricating semiconductor device

Abstract: There is provided a method for fabricating a semiconductor device involving the formation of two or more oxide films having different etching properties. A multilayer-film sidewall including a first oxide film such as an NSG film, a TEOS film, or a HTO film and a second oxide film such as a BPSG film or a PSG film is formed over the side surfaces of a gate electrode. After the multilayer-film sidewall is used as an implantation mask for forming the source and drain of a MIS transistor, wet etching is performed by using an aqueous solution mixture containing a hydrofluoric acid and an inorganic acid (a hydrochloric acid, a sulfuric acid, or the like) in selectively removing the second oxide film. This increases the etching selectivity between the individual oxide films and allows the removal of only the upper-layer second oxide film.

Carbonate-Melt Oxidized Iridium Wire for pH Sensing

Abstract: A new approach to the preparation of an iridium oxide film for pH sensing is demonstrated. A thick, uniform and dense ceramic oxide layer was grown on the surface of an iridium wire by oxidizing the wire in a molten alkali metal carbonate at high temperature. The alkali metal ion from the carbonate melt was incorporated into the oxide, resulting in a highly stable oxide compound. After treated in acid solution, the oxide layer became hydrated. SEM, XRD, TGA and element analysis were carried out to characterize the oxide film, and a possible formula of the oxide was computed as Li0.86IrO2.34(OH)0.76⋅0.39H2O. The electrode made with this new type of oxide film exhibited good pH sensitivity and stability, even in strong acid/base solutions, or in strong corrosive solution such as hydrofluoric acid. Furthermore, the electrode showed excellent long-term stability over the test period of two and a half years. In addition, individual electrodes prepared from the same batch exhibited remarkable agreement with respect to potential/pH slopes and apparent standard electrode potentials. The performance of the electrodes depends on the properties of the oxide film, such as composition, hydration state and oxidation state.

Glass substrate with fine hole and method for producing the same

Abstract: As a feature of a glass substrate having at least one fine hole according to the invention, a side wall surface of the fine hole is connected to each surface of the glass substrate by a curved surface as a boundary portion between the two. As another feature of the glass substrate, a layer denatured by machining is removed from the inner wall surface of the fine hole and the boundary portion between the wall surface and each surface of the glass substrate. The fine hole is produced by: forming a fine hole in a glass substrate by machining or laser machining; and then applying liquid-phase chemical etching to surfaces of the glass substrate and the fine hole. On this occasion, it is desirable that the etching liquid used for the liquid-phase chemical etching is either of an aqueous solution of hydrofluoric acid and an aqueous mixture solution of hydrofluoric acid and ammonium fluoride.

Silicon Texturing in Alkaline Media Conducted Under Extreme Negative Potentials

Abstract: Novel electrochemical method for texturing p-type silicon (〈100〉) was obtained by applying extreme high cathodic potentials combined with illumination. This texturing process is potential dependent and resulted in different textured surfaces. Unlike the custom wet etching techniques, conducted mainly in strong alkaline or in hydrofluoric acid solutions at potential near the open-circuit potential, this novel method is performed at very high negative potentials in alkaline solutions containing potassium hydroxide. Experimental data obtained from negatively polarized p-type 〈100〉 silicon at different potentials is described. © 2003 The Electrochemical Society. All rights reserved.

Method of manufacturing silicon substrate with porous layer

Abstract: PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar battery with good mass-productivity by which a porous layer can be formed at a low cost without generating harmful gases as by-products. SOLUTION: By dipping a polycrystalline silicon substrate into a mixed aqueous solution of an oxidant such as a hydrogen peroxide and a hydrofluoric acid which contains silver ions, a porous silicon layer is formed on the surface of the substrate. According to circumstances as taking another step, alkali treatment is conducted and the upper porous layer is removed to form a texture structure. COPYRIGHT: (C)2005,JPO&NCIPI

Electrochemical etching of n-type silicon based on carrier injection from a back side p-n junction

Abstract: A technique for electrochemical etching of n-type silicon in aqueous hydrofluoric acid is presented. This technique differs from photoelectrochemical etching because the holes (positive carriers) ...

Method for reducing and controlling hexafluorosilicate concentration during the polishing of glass objects in a polishing bath containing sulphuric acid and hydrofluoric acid

Abstract: The invention relates to a method for reducing and controlling the concentration of hexafluorosilicate ions arising when glass objects are polished in a polishing bath containing sulphuric acid and hydrofluoric acid. Potassium floride, potassium sulphate, sodium fluoride, sodium sulphate or aluminium sulphate is added to the polishing bath or sulphuric acid rinsing bath in quantities such that a drop in the concentration of fluoride ions below the optimum working range is avoided.

Functional water, method and apparatus of producing the same, and method and apparatus of rinsing electronic parts therewith

Abstract: A functional water containing a fluorine-containing component obtained by electrolyzing an aqueous solution containing fluoride ion using electrodes having conductive diamonds, a method of producing the same, and a method and an apparatus of rinsing electronic parts using the functional water as a rinsing water. The fluorine-containing component produced by electrolyzing the fluoride ion using the conductive diamond, has stronger rinsing effect than that of a fluorine-containing component obtained by electrolyzing the fluoride ion itself before electrolysis or the fluoride ion using other electrodes. Therefore, an amount of hydrofluoric acid used can greatly be decreased.

Method of recovering silicon wafer and tempered glass from solar battery module

Abstract: PROBLEM TO BE SOLVED: To provide a method of recovering silicon wafers and tempered glass from discarded solar battery modules and defective products produced in the course of production thereof and for recycling them. SOLUTION: The discarded solar battery modules are immersed in nitric acid, which contains a surfactant and is kept at a liquid temperature of 50°C or above, to decompose and remove EVA (ethylene-vinyl acetate) and to separate and recover silicon wafers and tempered glass with a high efficiency. The recovered tempered glass is cleaned with an alkaline solution for recycling. The recovered silicon wafer is cleaned with an organic solvent to provide a reclaimed silicon wafer having a clean surface. Prior to the cleaning with the organic solvent, the silicon wafer may be washed with nitric acid. The recovered or reclaimed silicon wafer is immersed in a mixed solution, composed of hydrofluoric acid, nitric acid, and acetic acid and/or sulfuric acid, or phosphoric acid to provide a reclaimed high-purity silicon wafer. Defective products produced during the production of silicon wafers can be reclaimed in the same method to provide silicon wafers having a clean surface or high-purity silicon wafers. COPYRIGHT: (C)2004,JPO

Prepn of sulfur-free low-ash high-purity expanded graphite

Abstract: High-carbon natural scale graphite, nitric acid, acetate anhydride and perchloric acid in the mass ratio of 1 to 0.5-1.0 to 1-2 to 3-7 are mixed and reacted at 30-50 deg.c for 30-120 min to prepare acidified graphite. Through further water washing, drying, soaking in mixed acid of hydrochloric acid and hydrofluoric acid, deacidifying, re-drying and puffing at 900-1100 deg.c, sulfur-free, low-ashand high-purity expanded graphite is prepared. The preparation process is simple and easy to operate, and the prepared expanded graphite has ash content lower than 400 ppm.

Method for manufacturing semiconductor light emitting element

Abstract: PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor light emitting element capable of enhancing emission output sufficiently by taking out internally emitted light sufficiently without causing cost increase or lowering of productivity. SOLUTION: On an n-GaAs substrate 1, an n-GaAs buffer layer 2, an n-(Al 0.7 Ga 0.3 ) 0.5 In 0.5 P clad layer 3, an undoped (Al 0.10 Ga 0.90 ) 0.5 In 0.5 P active layer 4, a p-(Al 0.7 Ga 0.3 ) 0.5 In 0.5 P clad layer 5, and p-GaP current dispersion layer 6 (thickness 14,000 nm, Zn doped at 3×10 18 cm -3 ) are formed sequentially by MOVPE. Before an upper surface electrode 7 is formed on the p-GaP current dispersion layer 6, protrusions and recesses 9 are formed on the surface of the p-GaP current dispersion layer 6 using hydrofluoric acid (HF), a mixture liquid of hydrofluoric acid and water, or a mixture liquid of hydrofluoric acid and hydrogen peroxide. COPYRIGHT: (C)2005,JPO&NCIPI

Compositions for the treatment of magnesium alloys

Abstract: The invention relates to a composition for treating magnesium alloys aimed at improving the resistance thereof to corrosion. The composition is an aqueous solution with a pH ranging between 7 and 10, containing a niobium salt, hydrofluoric acid, and optionally a zirconium salt, phosphoric acid, and boric acid. The alloy is treated in an electrochemical cell in which said alloy acts as an anode. The cell contains an inventive composition at a temperature between 20 °C and 40 °C as an electrolyte. An initial voltage which is sufficient to create a current density between 1.5 and 2.5 A/dm2 is applied to the cell, whereupon the voltage is progressively increased to a level ranging between 240 and 330 V in order to maintain the initial current density.

Mixing apparatus and mixing method for treating liquid, and substrate processing apparatus

Abstract: PROBLEM TO BE SOLVED: To provide a mixing apparatus for mixing the different amounts of pure water and hydrofluoric acid to a uniform density SOLUTION: The mixing apparatus for mixing the different amounts of the pure water and the hydrofluoric acid and attaining a treating liquid comprises: a mixing tank 1 where the pure water and the hydrofluoric acid are mixed; first and second flow rate integrating meters 4 and 6 for supplying the pure water and the hydrofluoric acid to the mixing tank respectively for preset amounts; and a controller 11 for controlling a flow rate per unit time of a mass flow controller 9 so as to make the supply time to the mixing tank of respective liquids whose supply amounts are set by the flow rate integrating meters be the same COPYRIGHT: (C)2003,JPO

Hydrofluoric acid wastewater treatment method and device

Abstract: The invention provides a hydrofluoric acid wastewater treatment method that achieves efficient recovery of hydrofluoric acid from hydrofluoric acid wastewater and also achieves sufficient reduction in the hydrofluoric acid concentration of the dehydrofluorinated water after treatment. The hydrofluoric acid wastewater treatment method comprises the following steps: a hydrofluoric acid concentration step (S1) comprising concentrating hydrofluoric acid wastewater by evaporation to produce a concentrated hydrofluoric acid water and a hydrofluoric acid-containing vapor; a dissolution step (S2) comprising bringing the hydrofluoric acid-containing vapor obtained in the hydrofluoric acid concentration step (S1) into contact with dissolution water to dissolve the vapor; a neutralization step (S3) comprising bringing the residual hydrofluoric acid-containing vapor left from the dissolution step (S2) into contact with an alkali to produce a neutralized liquid and a dehydrofluorinated vapor; and a condensation step (S4) comprising condensing the dehydrofluorinated vapor obtained in the neutralization step (S3) to produce condensed water.

Influence of water vapor adsorption on the C-V characteristics of heterostructures containing porous silicon

Abstract: Porous silicon (por-Si) is prepared by the electrochemical etching of single-crystal n-silicon in an aqueous-alcoholic solution of hydrofluoric acid in the presence of hydrogen peroxide oxidizer. The dependence of the high-frequency C-V characteristics of Al/por-Si/Si heterostructures on the relative humidity is studied. A model of capacitor structure is proposed, and a method of analyzing its capacitance as a function of the water vapor partial pressure in terms of the adsorption isotherm is elaborated. Within the framework of this model, the porosity of the material, the effective fraction of silicon dioxide in the por-Si, the fraction of intercommunicating porosity, the micropore-to-mesopore volume ratio, and the mesopore size distribution are determined. The porous silicon prepared in this work seems promising as a sensitive layer in capacitance-type humidity sensors.

Method for producing light-transmitting three-D patterned glass

Abstract: A process for preparing the glass product with transmissive three-D pattern includes washing transparent glass plate, drying in air, silk screen print of designed pattern, coating anticorrosion painton the back of glass plate, single-surface emulsifying, washing, etching in the etching liquid prepared from water, sulfuric acid and hydrofluoric acid for 10-20 min, flushing with water to remove ink and anticorrosion paint, and drying. Its advantages are transparent pattern and high artistic effect.

Method of improving the burn rate and ignitability of aluminium fuel particles and aluminium fuel so modified

Abstract: A method of improving the burn rate and ignitability of aluminium fuel particles, and a thus modified aluminium fuel for use in propellant and explosive compositions and pyrotechnic charges Aluminium fuel particles are treated with an aqueous solution of hydrofluoric acid and a fluoride and/or complex fluoride salt of an alkali metal and/or alkaline earth metal to form a surface layer of a fluoride complex bound to the aluminium fuel particle