scispace - formally typeset
Search or ask a question

Showing papers on "Hydrofluoric acid published in 1993"


Journal ArticleDOI
G. A. C. M. Spierings1
TL;DR: The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced as discussed by the authors, since the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions.
Abstract: The etching of silicate glasses in aqueous hydrofluoric acid solutions is applied in many technological fields. In this review most of the aspects of the wet chemical etching process of silicate glasses are discussed. The mechanism of the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions, resulting in the breakage of the siloxane bonds in the silicate network. The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced. In the second part of this review, diverse applications of etching glass objects in technology are described. Etching of SiO2 and doped SiO2 thin films, studied extensively for integrated circuit technology, is discussed separately.

371 citations


Patent
28 Jan 1993
TL;DR: In this article, a process for preparing a semiconductor device substrate comprises a step of making at least one surface of a first substrate composed of Si material porous, oxidizing inside walls of pores in the resulting porous Si surface layer, forming a monocrystalline Si layer on the porous Si layer, and bonding the mon-coalescence Si layer to one substrate through an insulating layer therebetween.
Abstract: A process for preparing a semiconductor device substrate comprises a step of making at least one surface of a first substrate composed of Si material porous, a step of oxidizing inside walls of pores in the resulting porous Si surface layer, a step of forming a monocrystalline Si layer on the porous Si surface layer, a step of bonding the monocrystalline Si layer to one surface of a second substrate through an insulating layer therebetween, a first etching step of removing the first substrate by selective etching except for the porous Si layer, and a second etching step of impregnating the porous Si layer exposed by the removal of the first substrate with hydrofluoric acid or a first liquid mixture of hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, or by buffered hydrofluoric acid or a second liquid mixture of bufffered hydrofluoric acid and at least one of an alcohol and an hydrogen peroxide solution, thereby selectively removing the porous Si layer.

130 citations


Journal ArticleDOI
TL;DR: In this article, an approach to selectively dissolve neo-formed fluorides in a two-step demineralizing process, by reaction with BF 3, which is a highly water soluble gas.

111 citations


Patent
15 Jun 1993
TL;DR: A method of cleaning semiconductor substrates after polishing, particularly chem-mech polishing a semiconductor substrate to planarize a layer, to remove excess material from atop a layer and to strip back a defective layer is disclosed as discussed by the authors.
Abstract: A method of cleaning semiconductor substrates after polishing, particularly chem-mech polishing a semiconductor substrate to planarize a layer, to remove excess material from atop a layer, and to strip back a defective layer is disclosed. Aluminum oxide particles having a small, well controlled size, and substantially in the alpha phase provide beneficial results when polishing. A phosphoric acid cleaning solution is used. The aluminum oxide particles are soluble in the phosphoric acid solution, which does not significantly attack silicon dioxide. The phosphoric acid solution can include a small concentration of hydrofluoric acid to aid in removing silicon dioxide detritus from the surface of the wafer.

107 citations


Journal ArticleDOI
TL;DR: In this article, an ex situ etching with various solutions of hydrofluoric acid (HF) and ammonium fluoride (NH4F) was performed on Si(111) samples and characterized by scanning tunneling microscopy (STM).
Abstract: After ex situ etching with various solutions of hydrofluoric acid (HF) and ammonium fluoride (NH4F) Si(111) samples are transferred into ultrahigh vacuum with an ultrafast load‐lock and characterized by scanning tunneling microscopy (STM): Concentrated HF selectively removes any surface oxide and, thus chemically prepares the initially burried, isotropically rough Si/SiO2 interface while highly buffered HF (i.e., NH4F) attacks bulk silicon anisotropically. After a rapid homogenization of the chemical surface termination (HF: various hydrides, fluorine, ...) towards a perfect, unreconstructed monohydride phase, Si(111)‐(1×1):H, NH4F etching leads to a time‐dependent transformation of isotropic roughness into a pattern of triangular etch defects with monohydride steps perpendicular to <211≳ due to a preferential removal of lower‐coordinated atomic defect sites. A predominant atomic step structure due to sample miscut (vicinal surfaces with azimuth ≠<211≳) can oppose the anisotropic NH4F etching: At low st...

88 citations


Journal ArticleDOI
TL;DR: In this paper, the etch kinetics for several silicon dioxide films in various hydrofluoric acid solutions have been studied, and expressions for etch rate as a function of acid concentration are presented.
Abstract: Etching kinetics for several silicon dioxide films in various hydrofluoric acid solutions have been studied. The low temperature silicon dioxide films were deposited at 450 o C and 300 mTorr in SiH 4 , O 2 , and PH 3 and annealed at 950 o C for 1 h. The thermal oxides were grown at 1100 o C in H 2 O and O 2 . Four hydrofluoric acid solutions were used: dilutions of 49 weight percent HF with deionized water, buffered hydrofluoric acid, surfactant-buffered hydrofluoric acid, and hydrofluoric acid/hydrochloric acid mixtures. Expressions for etch rate as a function of hydrofluoric acid concentration are presented

49 citations


Patent
Kaiser H. Wong1
10 May 1993
TL;DR: In this paper, a thin layer of Class 1B and IIB, IIIA, IVB, VB, VIIB, VIIB or VIIIB metal is deposited on silicon or a silicon-based compound by immersion in a buffered metallic salt bath containing a hydrofluoric acid etchant followed by an electroless plating bath to build up the metal thickness.
Abstract: A thin layer of Class 1B, IIB, IIIA, IVB, VB, VIB, VIIB or VIIIB metal is deposited on silicon or a silicon-based compound by immersion in a buffered metallic salt bath containing a hydrofluoric acid etchant followed by an electroless plating bath to build up the metal thickness. This process can also be used to pattern deposited metal on silicon or a silicon-based compound. An additional use of this process is to form metal silicides out of the deposited metal.

45 citations


Journal ArticleDOI
TL;DR: In this paper, the electroluminescence of porous silicon (PS) layers obtained from lightly doped p-type substrates has been investigated and it is shown that the wettability of PS, which is a highly hydrophobic and organophilic material, strongly affects its electrolumeinescence (EL) during anodic oxidation and its chemical etch rate in HF solutions.
Abstract: Anodic oxidation in hydrochloric (HCl) acid and chemical dissolution in hydrofluoric (HF) acid solutions of porous silicon (PS) layers obtained from lightly doped p‐type substrates have been investigated. It is shown that the wettability of PS, which is a highly hydrophobic and organophilic material, strongly affects its electroluminescence (EL) during anodic oxidation and its chemical etch rate in HF solutions. When the solutions do not penetrate the pores, a very weak EL intensity is obtained and the chemical etch rate in HF is found to be very slow. However, when the solutions infiltrate the pores, both the EL intensity and chemical etch rate are dramatically increased. In the first case, only the top surface of the porous layer is accessible to the liquids while in the second case the whole volume of the material and its vast inner surface are involved.

43 citations


Journal ArticleDOI
01 Aug 1993-Talanta
TL;DR: A chemically modified platinum electrode with coated poly[tetra(4-aminophenyl)porphyrin] has been used as a potentiometric pH sensor that gives a linear response over the pH range 1.5-13.7 with a slope of 55 mV/pH.

27 citations


Patent
30 Apr 1993
TL;DR: In this article, a silicon substrate 1 is cleaned by ultrapure water which contains ozone, a silicon oxide film 3 is formed, and particles 2 and metal impurities M are taken into the inside an the surface of the silicon oxide 3.
Abstract: PURPOSE: To easily remove particles and metal impurities which have adhered to the surface of a semiconductor substrate. CONSTITUTION: A silicon substrate 1 is cleaned by ultrapure water which contains ozone, a silicon oxide film 3 is formed, and particles 2 and metal impurities M are taken into the inside an the surface of the silicon oxide film 3. Then, the silicon substrate 1 is cleaned by a dilute hydrofluoric acid aqueous solution, the silicon oxide film 3 is etched and removed, and, at the same time, the particles 2 and the metal impurities M are removed. COPYRIGHT: (C)1994,JPO

24 citations


Patent
19 Jan 1993
TL;DR: In this article, a method for separating conjunct polymers and sulfolane from a mixture of conjun polymers, sulfols, and hydrofluoric acid is described.
Abstract: A method for separating conjunct polymers and sulfolane from a mixture containing conjunct polymers, sulfolane, and hydrofluoric acid is disclosed, which method comprises the sequential steps of separating hydrofluoric acid from the mixture to provide an intermediate stream containing less than 30 percent hydrofluoric acid by weight and gravitationally separating the intermediate stream into a sulfolane-enriched stream and a conjunct polymer-enriched stream.

Journal ArticleDOI
TL;DR: The use of m-benzene disulphonic acid and hydrofluoric acid mixture is recommended during the dissolution of silicate rocks and minerals for purposes of routine analysis of trace elements.

Journal ArticleDOI
TL;DR: In this article, an internal reflection infrared cell has been employed to study aqueous hydrofluoric acid (HF) and ultraviolet (UV)/ozone processing of Si(100) surfaces in situ.
Abstract: An internal reflection infrared cell has been employed to study aqueous hydrofluoric acid (HF) and ultraviolet (UV)/ozone processing of Si(100) surfaces in situ. The useful range of the infrared experiment was extended below 1500 cm−1 to examine the Si–O–Si asymmetric stretching region by using a thin (75 μm) silicon single crystal in optical contact with a germanium internal reflection element. UV/ozone cleaning produces hydrophilic surfaces by oxidative removal of adventitious hydrocarbon on SiO2 or by oxidation of hydrogen terminated silicon to SiO2. Hydrophobic Si–H terminated surfaces are produced using dilute aqueous HF and are characterized by an increase in the intensity of the Si–H stretching mode and a concomitant decrease in the intensity of the Si–O–Si mode. UV/ozone oxidation of the HF treated surface produces oxidized silicon hydrides while removing Si–H and growing SiO2. Where appropriate, comparisons will be made between the corresponding XPS and infrared spectra to demonstrate the complementary information provided by these spectroscopies.

Journal ArticleDOI
TL;DR: In this article, the anodic oxidation of zirconium was studied by in situ ellipsometry together with capacity measurements, and the oxides were grown under potentiodynamic, galvanostatic, and potentiostatic conditions up to final potentials of 100 V in 0.5M H[sub 2]SO[sub 4] solution.
Abstract: The anodic oxidation of zirconium was studied by in situ ellipsometry together with capacity measurements. The oxides were grown under potentiodynamic, galvanostatic, and potentiostatic conditions up to final potentials of 100 V in 0.5M H[sub 2]SO[sub 4] solution. The refractive index of the oxides changes depending on the growth current. The films were slightly absorbing but their absorption coefficient was independent of the oxide growth conditions. Different methods of surface preparation including etching in hydrofluoric acid-based mixtures, electropolishing and mechanical polishing were used. The surfaces and oxides were characterized by SEM examination and XPS measurements. The surface pretreatment affects both the substrate and the oxide optical constants as well as the rate of oxide growth. The density and dielectric constant of the oxides were calculated performing simultaneous ellipsometric, coulometric, and capacity measurements.

Journal ArticleDOI
TL;DR: In this article, a highly sensitive multielement analytical method known as vapor phase decomposition flow injection inductively coupled plasma mass spectrometry (ICP-MS) was developed and used to measure the concentration of trace metals on silicon wafer surfaces.
Abstract: A highly sensitive multielement analytical method known as vapor phase decomposition flow injection inductively coupled plasma-mass spectrometry (ICP-MS) was developed and used to measure the concentration of trace metals on silicon wafer surfaces. The method uses hydrogen fluoride vapor to decompose and release metal contaminants from a surface oxide. These trace metals are then collected by scanning a small drop of dilute acid solution throughout the wafer surface. Trace metals in the solution are measured by ICP-MS using flow injection (FI) sample introduction. Potentially, 60 8 11 2 elements can be measured with detection limits ranging from 10 to 10 atom/cm. Typical surface concentrations of trace metals on silicon wafers with native oxides and dielectric oxides were measured and presented.

Journal ArticleDOI
TL;DR: In this paper, the surface structure of lepidolite and muscovite mica was measured at tracks of two types of low-energy heavy ions: recoil daughter nuclei emitted in alpha decay of uranium and thorium impurity atoms in the mica over geological time, and 400 keV cesium ions produced at an accelerator.

Journal ArticleDOI
TL;DR: In this article, the authors used hydrofluoric acid solutions as the suspending media to prolong the lifetime of platforms and tubes when slurries prepared from samples with a high silica content are used.
Abstract: The samples are suspended in water containing hydrofluoric acid and then injected into the electrothermal atomizer. To decrease the heating programme time, the drying step is performed at higher than usual temperatures, and ashing and clean-up steps are omitted. Simple aqueous standards are used for calibration. The results reveal no significant differences at the 95% confidence level (Wilcoxon T-test and use of regression lines) from those obtained using acid digestion of the samples. The analysis of certified reference materials shows the reliability of the approach. The use of hydrofluoric acid solutions as the suspending media is confirmed to be a reliable way of prolonging the lifetime of platforms and tubes when slurries prepared from samples with a high silica content are used.

Journal ArticleDOI
TL;DR: For example, this article showed that trifluoro(methyl)pyrrolidiniomethyl)silane with hydrogen fluoride at 0 o C in ethanol/hydrofluoric acid yielded 90% and 89% yield, respectively.
Abstract: Reactions of dimethoxy(methyl)(pyrrolidinomethyl)silane [Me(MeO) 2 SiCH 2 NC 4 H 8 , NC 4 H 8 =pyrrolidino] and methoxy(methyl)phenyl(pyrrolidinomethyl)silane [MePh(MeO)SiCH 2 NC 4 H 8 ] with hydrogen fluoride at 0 o C in ethanol/hydrofluoric acid yielded trifluoro(methyl)pyrrolidiniomethyl)silicate [F 3 Si(Me)CH 2 N(H)C 4 H 8 (9), N(H)C 4 H 8 =pyrrolidinio] (yield 90% and 89%, respectively).

Patent
07 Jul 1993
TL;DR: In this article, the anodic oxide film is formed on the semiconductor substrate by anodic oxidation method and then removed by a mixture of hydrofluoric acid and ammonium fluoride.
Abstract: Crystal evaluation apparatus is disclosed which includes a cell region having an anode and a cathode, a reservoir tank for supplying of an aqueous solution for forming an anodic oxide film in the cell region, a reservoir tank for supplying of an aqueous solution for removing the anodic oxide film and a scanning microprobe microscope having a scanning microprobe, installed inside the cell region. A crystal evaluation method is also disclosed which contains anodic oxidation on a semiconductor substrate, removal of an anodic oxide film developed. The semiconductor substrate is observed with a scanning probe microscope having a scanning microprobe. The oxide film is formed on the semiconductor substrate by the anodic oxidation method and then removed by a mixture of hydrofluoric acid and ammonium fluoride. The anodic oxidation method exerts no or little physical impact on the substrate. The hydrofluoric acid and ammonium fluoride mixture removes selectively only the oxide film so that secondary ion implantation defects are exposed to a surface of the substrate. The shape or configuration of the secondary ion implantation defects is observed with an atomic force microscope having a high resolution on the order of nano meter. Therefore, the shape of the defects on the order of nano meter may be observed. In addition, the distribution of impurity concentration over the surface of the substrate may be measured very accurately.

Patent
12 Feb 1993
TL;DR: In this article, the authors proposed to prevent the emitting intensity of photoluminescence from receiving any adverse effect by forming porous silicon by subjecting single-crystal silicon to an anode formation treatment and removing an oxide film formed on the surface of the porous silicon with diluted hydrofluoric acid.
Abstract: PURPOSE:To prevent the emitting intensity of photoluminescence from receiving any adverse effect by forming porous silicon by subjecting single-crystal silicon to an anode formation treatment and removing an oxide film formed on the surface of the porous silicon with diluted hydrofluoric acid CONSTITUTION:After an aluminum electrode board 2 is put on the rear surface of a p-type single-crystal silicon substrate 1, the substrate 1 and board 2 are coated with wax 3 so that the front surface of the substrate 1 can be exposed The substrate 1 and board 2 are dipped in 25% hydrofluoric acid 4 and a platinum electrode 5 is also dipped in the acid 4 at the opposite position of the substrate 1 Then the surface of the substrate 1 is subjected to an anode formation treatment by using the substrate 1 as an anode and electrode 5 as a cathode Namely, the silicon of the substrate 1 is oxidized to SiO2 by active oxygen generated on the surface of the substrate 1 and the SiO2 dissolves in the acid 4 As a result, columnar porous silicon having a pore diameter of about 50Angstrom is formed on the surface of the substrate Then the substrate 1 coated with the porous silicon is dipped in 5% hydrofluoric acid for five minutes and a surface oxide film is removed Therefore, the emitting intensity of photoluminescence can be improved

Patent
26 May 1993
TL;DR: In this article, the surface of glass is mirror-finished and immersed into one or more kinds of an etching solns, selected from among HNO3, H2SO4 and HCl, alkaline such as NaOH and NH3, and org. acid solns.
Abstract: PURPOSE:To reduce the haze of ruggedness formed on the surface of glass by carrying out pre-etching with a hydrofluoric acid etching soln. or an etching soln. selected among inorg. acid, alkali and org. acid solns. CONSTITUTION:The surface of glass is mirror-finished and immersed into one or more kinds of an etching solns. selected among one or more kinds of hydrofuloric acid type etching soln selected from among 0.1-65wt.% HF, NH4 and HBF4, one or more kinds of inorg. acids selected among HNO3, H2SO4 and HCl, alkaline such as NaOH and NH3, and org. acids such as acetic acid at room temp. for about 5 min. The surface of the glass is then washed and dried.

Journal ArticleDOI
TL;DR: In this article, a statistical approach was used to analyze the strength of glass rods, etched with hydrofluoric acid, and the analysis allowed some results about the stress concentration factor of this defect family to be obtained.
Abstract: Hydrofluoric acid solution etching has long been known as a useful method for strengthening glass. In this way surface flaws are at first reduced in length and rounded then completely removed. At this point glass strength depends only on defects emerging from the bulk or on damage produced by the etching reaction products. In this study more than a hundred values of strength of glass rods, etched with hydrofluoric acid, are elaborated by means of a statistical approach, and attention is focused on what have previously been called ‘volume defects’. The analysis allows some results about the stress concentration factor of this defects family to be obtained.

Patent
22 Nov 1993
TL;DR: In this paper, a dangling bond on the rear surface of a substrate with a hydrogen active species is terminated by spraying ultrapure water on the dangling bond, thus drying the wafer.
Abstract: PURPOSE: To inhibit adhesion of dust particles, which causes lowering of yield, and to allow easy removal of adhered dust particles in vapor phase by terminating a dangling bond on the rear surface of a substrate with a hydrogen active species. CONSTITUTION: N gas containing a hydrogen active species is introduced through a nozzle 106 and while rotating a wafer 103 at 1500-3000 r.p.m., 1). ultrapure water added with ozone (2-10ppm),2). hydrofluoric acid + hydrogen peroxide + pure water (0.03:1:2),3). ammonium hydroxide + hydrogen peroxide + ultrapure water (0.05:1:5), hydrofluoric acid + ultrapure water (0.03:1:2), and ultrapure water are dripped sequentially onto the surface and rear of a wafer 103 through a chemical nozzles 102 and 108. Subsequently, a gas containing a hydrogen species is blown through mixture gas supply pipes 106, 107 to the surface and the rear of the wafer 103 rotating at 1500 r.p.m. thus drying the wafer 103. COPYRIGHT: (C)1995,JPO

Patent
07 Sep 1993
TL;DR: In this article, a method for separating conjunct polymers which are formed as byproducts of acid catalyzed isoparaffin-olefin alkylation and sulfolane from a mixture of polymeric components was proposed.
Abstract: The present invention provides a method for separating conjunct polymers which are formed as byproducts of acid catalyzed isoparaffin-olefin alkylation and sulfolane from a mixture containing conjunct polymers, sulfolane, and hydrofluoric acid, and for minimizing accumulation of conjunct polymeric byproducts in the recycled acid catalyst.

Patent
29 Apr 1993
TL;DR: In this paper, a brightening chemical polishing solution for a hardened steel article (e.g., a carburized and quenched gear) comprises hydrofluoric acid having a molar concentration of from 0.2 to 2 mol/l, hydrogen peroxide having a maximum concentration of 0.4 to 4 mol/l and water, amolar ratio of the HFO to HFO being from 1:1.5 to 1:2.8.
Abstract: A brightening chemical polishing solution for a hardened steel article (e.g., a carburized and quenched gear) comprises hydrofluoric acid having a molar concentration of from 0.2 to 2 mol/l, hydrogen peroxide having a molar concentration of from 0.4 to 4 mol/l, and water, a molar ratio of the hydrofluoric acid to the hydrogen peroxide being from 1:1.5 to 1:2.8. The steel article is quench hardened and is chemically polished in the solution. A shot-peening is additionally performed, prior to the polishing.

Journal ArticleDOI
A. Tiburcio-Silver1, Arturo Maldonado1, A. Escobosa1, E. Saucedo1, J.M. Montoya1, J.A. Moreno1 
TL;DR: The incorporation of fluorine in SnO2 layers deposited using the spray pyrolysis technique has been studied in this paper, where an anomalous behaviour of electrical properties was observed on layers grown under 350°C.

Journal ArticleDOI
TL;DR: In this article, the sacrificial metal anodes in the presence of hydrogen peroxide (15%) and hydrofluoric acid (10%) have been used to synthesize peroxofluoro complexes of the transition metals.

Patent
07 Sep 1993
TL;DR: In this paper, the authors proposed a method to efficiently remove surface scales and scale flaws of ferritic stainless steel hot rolled stock by combining nitric acid/hydrofluoric acid.
Abstract: PURPOSE:To efficiently remove surface scales and scale flaws of ferritic stainless steel hot rolled stock. CONSTITUTION:Ferritic stainless steel hot rolled stock is pickled by a soln. of sulfuric acid of 80 to 100 deg.C in which the concn. of sulfuric acid per 1 liter soln. is regulated to 200 to 400g and is thereafter pickled by a soln. of 40 to 80 deg.C whose cocn. is regulated to a one mixed with 20 to 160g nitric acid and 10 to 200g hydrofluoric acid per 1 liter soln. Furthermore, as for stainless steel hot rolled stock in which intergranular erosion is generated by the pickling by nitric acid hydrofluoric acid, its surface layer is dissolved and ground by 20mum by the pickling by sulfuric acid. By the combination of the pickling by sulfuric acid removing scales on the normal part and the pickling by nitric acid/hydrofluoric acid selectively and efficiently removing scale flaws, the productivity of the pickling of ferritic stainless steel hot rolled stock is remarkably improved.

Patent
05 Feb 1993
TL;DR: In this paper, the surface of a substrate is etched with hydrofluoric acid vapor or hydrogen fluoride gas, then rinsed with pure water or water vapor, and dried up.
Abstract: PURPOSE:To provide a cleaning method of rinsing the surface of a substrate subjected to an etching treatment, where the surface of the substrate free fromg a natural oxide film, adsorbed harmful contaminant, and water marks can be obtained. CONSTITUTION:Following a process where the surface of a substrate is etched with hydrofluoric acid vapor or hydrogen fluoride gas, then rinsed with pure water or water vapor, and dried up, the surface of the substrate subjected to a drying process is etched with hydrofluoric acid vapor or hydrogen fluoride.

Journal ArticleDOI
TL;DR: In this paper, a thin semiconductor wafer is mounted on a germanium internal reflection crystal by wafer-bonding and measurements are performed in a wide frequency range (800-4000 cm−1).