Showing papers on "Hydrofluoric acid published in 1980"

Etchant solution containing HF-HnO3-H2SO4-H2O2 for etching Al-Ti-Cu or Ni contact metallurgy on silicon substrates

Abstract: An etchant solution for multilayered metal layers comprising an aqueous solution of from 0.5 to 50 percent by weight of nitric acid, from 0.03 to 1.0 percent by weight of hydrofluoric acid, from 0.05 to 0.5 percent by weight of hydrogen peroxide and from 0.1 to 1.0 percent by weight of sulphuric acid. The solution is compatible with photolithographic techniques and uniformly etches three or more metals.

Potential Column Chromatography for Ionic Ga-68. II: Organic Ion Exchangers as Chromatographic Supports

Abstract: A potential Ge-68 leads to Ga-68 generator system, based on the adsorption of Ge-68 from a dilute hydrofluoric acid eluent onto a commercially available organic anionexchange resin, is described. The distribution coefficients between the resin and dilute hydrofluoric acid were measured for germanium and gallium, and the breakthrough of germanium from a generator column determined. Using 0.01 N HF, the Kd values are 27 and greater than 4,000 for gallium and germanium, respectively. Gallium-68 can be quantitatively collected with 4 ml of 0.01 N HF. After neutralization, this provides a biologically safe concentration of NaF for injection. The breakthrough levels of germanium-68 remain lower than 10(-4) for up to 600 collections.

Method for stimulating siliceous subterranean formations

Abstract: Wells of subterranean siliceous formations containing hydrocarbons are stimulated by the injection of crosslinked acid polymers wherein the polymer is a polysaccharide selected from the group consisting of carboxymethyl hydroxypropyl guar and carboxymethyl hydroxyethyl cellulose. The crosslinked acid polymer is a gel formed from a hydrated polysaccharide sol containing from about 1 to about 15 weight percent hydrochloric acid and from about 0.2 to about 6 weight percent hydrofluoric acid to which a water hydrolyzable polyvalent metal salt is added to cause the crosslinking. The metal salt is zirconium, titanium or hafnium. Additionally, an adjunct salt can be added in an amount of from about 5 to about 50 pounds per 1,000 gallons acid prior to the addition of the hydrolyzable polyvalent metal salt. The crosslinked acid polymer retards the chemical reactivity of the acid mixture of hydrochloric and hydrofluoric acid, thereby allowing the acid mixture to penetrate deeper into the formation before the activity of the acids are spent. After its injection, the crosslinked acid polymer breaks down as a result of time and temperature of the reservoir into a less viscous fluid allowing the acids to react with the formation.

Method of polishing glass ware with sulfuric acid and hydrofluoric acid

Abstract: The invention relates to a polishing method for pressed glass or ground glass articles. As is conventional, polishing is effected in a bath containing sulfuric acid and hydrofluoric acid. Rinsing with a sulfuric acid and/or water washing bath intervenes and follows the polishing process. According to the method of the invention, the sodium and/or potassium ions resulting from the dissolution of glass constituents are removed from the polishing bath by the following means: (a) by adding fluorosilicic acid to the polishing bath, precipitating the corresponding silicofluorides and filtering off the solid matter, (b) by electrolysis in a mercury cell with the formation of sodium- and/or potassium amalgam, (c) by electrolysis in a cell having a cation semi-permeable membrane or (d) with the aid of cation exchangers.

Process for producing fluorine compounds and amorphous silica

Abstract: Hydrofluoric acid and/or other fluorine compounds are recovered by reacting fluosilicic acid with a sodium-containing compound to form an alkaline aqueous slurry comprising precipitated amorphous silica and dissolved sodium fluoride. The precipitated amorphous silica is separated from the alkaline aqueous slurry leaving an aqueous solution of sodium fluoride. The sodium fluoride solution can be used as such or reacted with other substances (such as alumina, to form synthetic cryolite). Sodium fluoride is recovered from the aqueous solution (as by evaporation or extraction) and used per se or reacted with sulfuric acid to produce hydrogen fluoride.

Glasses containing fluorine, their preparation and their application

Abstract: Glasses containing fluorine. These glasses are characterized by the fact that they contain at least 25% in moles, approximately, of a fluoride or a mixture of fluorides MX(X1)2, in which: X and X1 each represent a fluorine atom, and M then represents a metal chosen from among the group consisting of gallium, iron, chromium, vanadium, indium, and the rare earths, or X represents an oxygen atom, X1 represents a fluorine atom, and M then represents a titanium atom, it being understood that the said glasses contain no hydrofluoric acid as a network former and that, in the case in which M represents a gallium or indium atom, the glasses do not contain more than 15% in moles of BaPO3 F. Application notably in obtaining glasses containing various cations conferring particular optical or magneto-optical properties.

Process for the recovery of hydrofluoric acid and depositable residues during treatment of niobium- and/or tantalum-containing raw materials

Abstract: Raw materials containing tantalum or niobium are treated to obtain aqueous solutions containing fluoroacid complexes of niobium or tantalum These solutions are decomposed by pyrolysis and calcined to obtain pure oxides of niobium or tantalum The hydrofluoric acid separated during pyrohydrolysis is recovered and reused A niobium or tantalum-free raffinate solution obtained, on extraction, with the above aqueous solutions contains dissolved metalloids which are recovered as oxides which are deposable waste products

Method of chemically polishing a doubly rotated quartz plate

Abstract: At least one side of a doubly rotated quartz plate whose theta (θ) angle is between about 33° and 36° and whose phi (φ) angle is between about 10° and 26° is chemically polished by lapping the quartz plate with an abrasive and etching the lapped quartz plate in a fluoride type etchant selected from the group consisting of a 5 percent to 25 percent solution of hydrofluoric acid, a 5 percent to 50 percent solution of ammonium bifluoride, and a mixture of 40 percent ammonium fluoride with 49 percent hydrofluoric acid in the ratio ranging from about 1:3 to 10:1, the etching being carried out until a thickness is removed from the plate that is at least twice the average abrasive particle diameter in the final lapping abrasive.

Method of manufacturing semiconductor device

Abstract: PURPOSE:To enable easily the etching of alumina alone steadily and with good reproducibility without solving aluminium by etching selectively an aluminium oxide film on an aluminium film on a substrate using the mixture of ethylene glycol and hydrofluoric acid of a particular mixture ratio. CONSTITUTION:Mixture liquid of the weight ratio 100:1-5:1 of ethylene glycol and hydrofluoric acid is used as etching liquid to etch selectively an aluminium oxide (alumina) film on an aluminium film on a substrate. For example, aluminium is coated on a semiconductor substrate 1 having a PN junction, wiring is formed by an anodic oxidation method, alumina 4 on aluminium wiring 3 is etched for several minutes at room temperatures with above-mentioned etching luquid using a photoresist 5 as a mask. By so doing, the aluminium 3 is little etched, therefore, the depth of etching can be kept unaffected by the change of etching time or temperatures.

Recovery of hydrofluoric acid from fluosilicic acid

Abstract: Hydrofluoric acid is recovered from fluosilicic acid by reacting fluosilicic acid with sodium sulfate to form sodium fluosilicate. The sodium fluosilicate is reacted with a sodium-containing compound to form an alkaline aqueous slurry comprising silica and dissolved sodium fluoride. The reaction occurs under such conditions that the slurry contains precipitated amorphous silica. The precipitated amorphous silica is separated from the alkaline aqueous slurry leaving an aqueous solution of sodium fluoride. Sodium fluoride is recovered from the aqueous solution and reacted with sulfuric acid to produce hydrogen fluoride.

Etching Silicon Nitride and Silicon Oxide Using Ethylene Glycol / Hydrofluoric Acid Mixtures

Abstract: Concentrated (49%) aqueous HF and ethylene glycol solutions were investigated for a wet strip process requiring a LPCVD Si 3 N4 to thermal SiO2 etch rate selectivity of between 1 and 2. Si 3 N4 etch rates of higher than 20 nm per minute were also desired in order to obtain high throughputs on the single-wafer spray tool. Water, temperature, and HF concentration were found to play a significant role in defining both the etch rates and etch-rate selectivity of LPCVD Si 3 N4 and thermal SiO2 films. The desired Si 3 N4:SiO2 selectivity was achieved at low HF concentrations; at higher HF concentrations, the selectivity decreased rapidly below 1. Water additions to the system produced similar results. Particulate contamination levels were also significantly reduced when a deionized water rinse was used.

Silicic acid scale removing agent

Abstract: PURPOSE:The chemical cleaning agent which comprises containing acidic fluorine compounds and hydrogen peroxide and is capable of removing scale readily and completely CONSTITUTION:This comprises compounding acidic fluorine compounds such as hydrofluoric acid, acid ammonium fluoride, acid potassium fluoride and acid sodium fluoride and hydrogen peroxide Here, the respective concentrations of the acid fluorine compounds and hydrgoen peroxide may be suitably selected over a considerably wide range, but an example shown is like this: An aqueous solution containing acid ammonium fluoride 20%, hydrogen peroxide 10% and nonionic surface active agent 05% or more This compounded product is used by being diluted 3-10 times with water depending upon the conditions of scale

Component solution for etching

Abstract: PURPOSE:To enable to perform a selective etching on n amorphous silicon by a method wherein the etching compound solution, consisting of hydrofluoric acid, nitric acid and glacial acetic acid with the concentration of nitric acid of 0.15-0.65 in mixture ratio by volume and the concentration of hydrofluoric acid of below 0.04, is prepared. CONSTITUTION:In the case of etching compound solution consisting of hydrofluoric acid (46% aqueous solution), nitric acid (d=1.38, 60% aqueous solution, 14 normality) and glacial acetic acid, the concentration of nitric acid is to be at 0.15- 0.65 in the mixture ratio by volume and the concentration of hydrofluoric acid is to be below 0.04. The selective etching is performed on an n amorphous silicon using the above solution. Accordingly, the thin film transistor with a glass substrate, a long-sized optical sensor and a thin film IC can be manufactured.

Method for removing borosilicate and boron rich oxides from a silicon body prior to doping silicon bodies with a SiB6 solid source

Abstract: A method for doping silicon bodies by the diffusion of boron into the bodies is described. The method is an improvement of processes where the silicon bodies are exposed in a first heating process to a gas mixture containing a predetermined boron quantity and boron and oxygen in a predetermined quantitative ratio and a second heating process is used to drive the boron into the silicon. In the method, a borosilicate glass layer and a boron-rich silicon dioxide layer are removed by first immersing the silicon body in hydrofluoric acid diluted with water and subsequently in an aqueous sulfuric acid/potassium permanganate solution.

The rate equation for the dissolution of silica in hydrochloric-hydrofluoric acid mixtures

Abstract: Kinetic equations for the solubility of silica in HF — HCI aqueous mixtures based on a molecular model for the reactivity of silica surface with this medium arc proposed.These kinetic equations postulate a first order dependence on the HF2 - ion concentration in the solution, and a dependence on H+ expressed by Langmuir’s isotherm.The experimental results obtained confirm that the time averaged rate of silica dissolution follows a first order dependence on [HF2- - ].The Arrhenius plot of In kr versus 1/T is linear. The over-all activation energy of solubility is 9, 7 ± 0, 3 kcal.The rates reported over the temperature range 30-69,5 °C and HF concentration 1,15-2,56 M HF show a definite dependence on HCI concentration. The use of Langmuir’s isotherm appears as correct, in the region of weak acid concentration (first order relation in respect to H+ ) but further experiments have to be made to ascertain this in the region of higher acid concentrations.

Method for storage and transportation of hydrofluoric acid

Abstract: PURPOSE: To enable the safe storage and transportation of hydrofluoric acid, by reacting hydrofluoric acid with pyridine to obtain a pyridine.hydrofluoric acid complex containing high molar ratio of hydrofluoric acid, and distilling the complex at the desired time and place to obtain hydrofluoric acid. CONSTITUTION: Hydrofluoric acid (HF) is made to react with pyridine (Py) to obtain Py.(HF) n complex (n≥3), or Py.(HCl) complex is made to react with ≥8 equivalent of HF to obtain Py.(HF) m complex (m≥8). The complex thus obtained has low HF vapor pressure and high safety, and can be stored or transported to anywhere in a conventional container made of, e.g. PE. For obtaining HF, most part of the HF can be released by the vacuum distillation of the complex, according to the formula. When the valve of (n) is large, the utilization ratio of Py becomes sufficiently high, and the resultant Py.(HF) 3 can be recycled and reused as the raw material of Py.(HF) n . Or the residual 3mol of HF can be utilized by reacting the Py.(HF) 3 with HCl. COPYRIGHT: (C)1982,JPO&Japio

Glazed ceramic substrate

Abstract: PURPOSE:To provide the title substrate with good surface smoothness, good electrical charcteristics, improved heat and acid resistances for electronic parts by covering a SiO2-Al203-CaO-alkali metal oxide type glass film of a specified compsn on an insulating ceramics substrate CONSTITUTION:A glass film consisting of, by wt, SiO2 70-85%, Al2O3 7-17%, CaO 05-5% and one or more kinds of alkali metal oxides 5-15% is formed on an insulating ceramics substrate by a usual method A glass thin film formed on a conventional glazed ceramics substrate has a softening point of about 600-800 degC, and the highest service temp is about 700 degC in practical use The glass film of this invention withstands heat of temps as high as 950-1050 degC, and the acid resistance is 20-50% higher than that of the conventional film with respect to solubility in a mixed soln of hydrofluoric acid/nitric acid=1/1

Manufacture of semiconductor device

Abstract: PURPOSE:To make it possible to operate accurate control on the threshold voltage of a semiconductor device and at the same time to increase pn voltage resistance in the boundary surface between the substrate and SiO2 film, by operating drying at a temperature below the boiling point of hydrofluoric acid after the surface of a semiconductor device is exposed by using hydrofluoric acid. CONSTITUTION:In the manufacturing processes of semiconductor devices, the process of exposing the substrate surface by using etching solution containing hydrofluoric acid or a water solution of hydrofluoric acid is frequently used. Subsequently, drying of the exposed substrate and its maintenance and operated at room temperature. But, since the substrate is generally exposed to a temperature above the boiling point, 19.4 deg.C, of hydrofluoric acid, its surface is activated. For this reason, drying and maintenance are operated at a temperature below the boiling point of hydrofluoric acid, 19.4 deg.C, so that no activated hydrofluoric acid is produced. By this, no variation occurs on the substrate surface, and a desired semiconductor device is obtained.

Zeolites bearing fluoride anions

Abstract: The present invention provides the following: (a) A fluoride-treated zeolite in which the number of equivalents of fluoride exceeds the sum of the numbers of equivalents of all cations except for hydrogen, aluminium and silicon cations in the zeolite. (b) A process for fluoride-treating a zeolite wherein the zeolite is treated with a concentrated aqueous solution of a salt of hydrofluoric acid. (c) A process for at least partially removing metal ions from an aqueous solution, which comprises contacting the aqueous solution, containing the metal ions, with the fluoride-treated zeolite specified in (a) above or produced as specified in (b) above. (d) A process for the chromatographic separation of two or more metal ions in aqueous solution wherein the chromatographic stationary phase comprises the fluoride-treated zeolite specified in (a) above or produced as specified in (b) above.

Zeolites, a method for their treatment and the use of the treated zeolites

Abstract: he present invention provides the following: (a) A fluoride-treated zeolite in which the number of equivalents of fludride exceeds the sum of the numbers of equivalents of all cations except for hydrogen, aluminium and silicon cations in the zeolite. (b) A process for fluoride-treating a zeolite wherein the zeolite is treated with a concentrated aqueous solution of a salt of hydrofluoric acid. (c) A process for at least partially removing metal ions from an aqueous solution, which comprises contacting the aqueous solution, containing the metal ions, with the fluoride-treated zeolite specified in (a) above or produced as specified in (b) above. (d) A process for the chromatographic separation of two or more metal ions in aqueous solution wherein the chromatographic stationary phase comprises the fluoride-treated zeolite specified in (a) above or produced as specified in (b) above.

Process for preparing hydrofluoric acid

Abstract: Fluorspar (CaF2) and sulphuric acid (H2SO4) are employed in a two-step process which also involves the input of heat, to produce hydrofluoric acid. In the first step, the heat is supplied by indirect heating of the reaction mixture and/or by latent heat of the previously heated starting materials, while in the second stage heating is effected at least in part by direct heat exchange with a gas. The direct heating of the reaction material in the second reaction stage permits a considerably shorter reaction time and smaller equipment units.

Method and an installation for obtaining or recovering hydrofluoric acid

Abstract: A method of obtaining or recovering hydrofluoric acid from metal fluorides and solutions containing such, e.g. pickling solutions. In this procedure heavy metal fluorides are brought into contact with water vapor at 200° C. to 800° C., with an overall pressure of about 1 bar keeping the vapor partial pressure in a sufficiently linear relationship with the temperature in this range at a minimum of 0.9 bar at 400° C. and at a minimum of 0.5 bar at 600° C., separating the solid reaction material from the gaseous phase while still hot and obtaining aqueous hydrofluoric acid from the latter by--preferably indirect--cooling.

Synthesis of High-Purity Copper(II) Fluoride Dihydrate for Carrier-Distillation Emission Spectroscopy

Abstract: The preparation and analysis of high-purity copper fluoride dihydrate for use as a carrier in emission spectroscopy is described. Copper metal was oxidized with hydrogen peroxide or nitric acid in the presence of an excess of different grades of hydrofluoric acid. The resulting copper fluoride was analyzed to determine the effect of different factors on the levels of impurities. The quality of the hydrofluoric acid was the main factor affecting the purity of the product. The order of appearance of contaminants during crystallization of copper fluoride is described. Iron, nickel, and manganese gradually appear as the mother liquor is concentrated, while silicon, tin, aluminum, and lead usually contaminate only the lots immediately preceding evaporation of the solution to dryness. Magnesium, regard-less of its concentration in the mother liquor, coprecipitates with all lots of copper fluoride.

Concentration meter of hydrogen ion and hydrofluoric acid

Abstract: PURPOSE:To simultaneously measure the concentrations of the afore-mentioned substances in a solution by accomplishing calculations with the use of the potential differences between a reference electrode (or S electrode), a hydrogen ion electrode (or H electrode) and a fluorine ion electrode (or F electrode). CONSTITUTION:An S electrode 2, an H electrode 3 and an F electrode 4 are placed in a solution 1 to be measured so that the potential difference FH between the S and H electrodes and the potential difference E between the F and H electrodes can be interchangeably measured by the action of a switch 5. Piror to the measurements, a number of liquids of known concentrations are used to measure the potential EH with respect to the hydrogen ion. From the straight line of log[H ] plotted against EH-, E0H (or EH at log[H ]=0 and SH (or the gradient of the straight line) are determined. Likewise, the values E0F and SHF relating to the fluorine ions (in the above operations, the gain adjustor 6 is operated to make SH and SF take the same value, and at the same time the value E0 is determined according to Equation I (wherein KHF stands for the dissociation constant of the hydrofluoric acid. Then, the liquid to be measured is poured into the cell, and EH is measured so that Equation II is used to measure the Hydrogen ion concentration [H ]. And, E is measured so that hydrofluoric concentration [HF] is calculated with the use of Equation III.

Production of high-purity potassium fluorotantalate

Abstract: PURPOSE: A hydrogen fluoride solution of crude tantalum or crude tantalum compound is gradually added to a potassium compound aqueous solution that has a specific potassium ion concentration and is kept at temperature higher than a specific one and the mixture is cooled to lower than room temperature to effect crystallization, thus producing high-purity potassium fluorotantalate. CONSTITUTION: Crude tantalum or crude tantalum compound is dissolved in about 70wt% hydrofluoric acid aqueous solution to form a Ta aqueous solution. The concentration of tantalum in the aqueous solution is preferably 0.1W0.5g/l. In the meantime, an aqueous potassium compound solution of 0.01W0.15g/ml potassium ion conceneration such as potassium fluoride solution is prepared and the solution is heated up to higher than 50°C. Then, the above tantalum solution is gradually added to the potassium aqueous solution and they are cooled to lower than room temperature to crystallized out high-purity potassium fluorotantalate. COPYRIGHT: (C)1982,JPO&Japio

Recovering method for mixture of hydrofluoric acid and nitric acid

Abstract: PURPOSE:To economically recover the mixture of hydrofluoric acid and nitric acid from waste acid with a simple apparatus, by carrying out electrolytic treatment using electrolysis vessel partitioned betwen cathode and anode by monovalent selective anion exchange membrane. CONSTITUTION:Inner part of the electrolysis vessel 1 made of anticorrosive steel plate, is divided into two rooms partitioning by the monovalent selective anion exchange membrane 2 and one room becomes a cathode room 3' by inserting the cathode plate 3 and another room becomes an anode room 4' by inserting the anode plate 4. Then, water or dilute nitric acid or dilute mixture of hydrofluoric acid and nitric acid, is injected in the room 4' and the waste mixture solution is injected in the room 3'. Next, electrolytic treatment is carried out by applying more than 2.5V of voltage between both electrodes 3, 4 and the mixture of hydrofluoric acid and nitric acid is recovered in the room 4'.