Showing papers on "Isotropic etching published in 1968"

Growth of Diamond Seed Crystals by Vapor Deposition

Abstract: Carbon was deposited on virgin, natural diamond powder from methane gas at 1050°C and 0.3 Torr. The deposits were identified as new diamond by chemical analysis, chemical etching, density measurements, x‐ray and electron diffraction, microwave absorption, electron spin resonance, and visual observations. The crystalline quality of the new diamond layers has not been established; it cound range from polycrystalline material with a large number of defects to true epitaxial layers.

Method of making patterned metal coatings by selective etching of metal

Abstract: Web substrates (such as plastic film) are coated with metal (as by vacuum aluminizing) and etched in selected areas of the metal coating. The etching medium comprises an etchant, a body-forming member to trap the etchant, a volatile carrier and a dispersing member which holds the etchant and body-forming member in intimate mixture.

Process for etching composite layered structures including a layer of fluoride-etchable silicon nitride and a layer of silicon dioxide

Abstract: A single etchant process for etching a composite layered structure of silicon nitride and silicon dioxide. Hydrogen and fluoride ion-containing aqueous etching solutions, such as hydrofluoric acid having a concentration of less than approximately 2 percent by weight, and other equivalent solutions including ammonium fluoride and ammonium bifluoride solutions and fluosilicic acid, are applied to the structure while the temperature is maintained below the boiling point of these solutions, whereby the rate of etching of the silicon nitride is substantially equal to the rate of etching of the silicon dioxide.

Improved gas-discharge etching techniques in the electron microscope study of polyamide structure

Abstract: ACCORDING to establ ished views, fibrils, spherulites and single crystals are typica l supermolecular structures of polyamides. Fibr i l lar structures mainly characterize oriented systems [1, 2]. Xray diffraction a t low angles reveals a fairly strict al ternation of ordered and disordered regions along the fibrils [3], which is confirmed by an electron microscopic method of negative contrast [4] and are known as long periods. For polyamides they are within the range of 70-700 •, according to the chemical nature and t rea tment conditions of samples. Polyamide spherulites are large (up to several microns) formations with fibrils growing in a radial direction from the spherulite centre. They normally characterize crystallized, non-oriented systems. Up to recently single crystals were.considered as unlikely structural forms of polyamides since they can only be formed with unbranched polyamides and under certain conditions of crystall ization. For the same reason i t is difficult to imagine the simultaneous coexistence in the polymer of two crystalline morphological forms--single crystals and spherulites. The aim of this s tudy was to use etching with active oxygen (EAO) obtained in a field of a.c., linear, electrodeless, high-frequency discharge to examine the supermolecular structure of polyamide materials. Wi th most methods of electron microscope investigation used up to now, model polymer films have been used obtained under special conditions. We sought to observe s t ructural detai ls in industr ial polymer samples using EAO combined with the replica method. The use of chemical etching to reveal the supermolecular structure of polyamides does not enable the rate of etching to be controlled to the required extent and almost inevi tably causes s tructural variat ions in the surface layers of the polymer. The use of cathode sputtering (ion bombardment in plasma of high-voltage d.c. discharge) results in considerable heating of the polymer surface layer by absorption of par t of the electronic plasma component mainly consisting of fast electrons and recombination of electrons and ions in the polymer. The use of EAO based both on the effect of ionic polymer bombardment and the action of act ivated oxygen, apparent ly consisting of neutral atoms and gas molecules, in burning

Method for etching chromium oxide films

Abstract: A method of etching using weaker acid etchant solutions than heretofore possible wherein interaction between the chloride ions in solution and the film is initiated by producing an electrical potential across a thin oxide layer on the film sufficient to allow the chloride ions to permeate therethrough. Because a weaker etchant can be used in the process, thinner and softer photoresistive protective coatings can also be used for obtaining decorative film patterns, microcircuit masks, and the like. Further, the rate at which etching proceeds can now be controlled over a wider range than heretofore possible, thus effecting the amount of undercutting of the acid-resistant mask by the etchant.

Etching method and apparatus

Abstract: TO ETCH AN ELECTRICALLY CONDUCTING METAL SURFACE, THIS SURFACE IS ATTACKED WITH A LIQUID MORDANT THROUGH A PHOTOGRAPHICALLY TREATED RESIST WHICH IS SEMI-PERMEABLE TO THE MORDANT WHILE VARYING THE COMPOSITION OF THE MORDANT SUCH THAT THE ETCHING RATE TENDS TO LAG SLIGHTLY BEHIND THE IDEAL THEORETICAL RATE, THIS LAG BEING COMPENSATED BY APPLYING TO THE SURFACE A POSITIVE ELECTRICAL POTENTIAL WITH RESPECT TO THE MORDANT.

Improvements in or relating to the production of printed circuits

Abstract: 1,134,632. Printed circuits. ELLIOTT BROS. (LONDON) Ltd. 10 Feb., 1966 [13 Feb., 1965], No. 6330/65. Heading H1R. In a printed circuit arrangement, holes in or through an insulating substrate are formed by chemical etching of the substrate material. The substrate may comprise a polyimide film or sheet, and may be etched by alternate treatment at at least 80‹ C. with cone. H 2 SO 4 and NaOH; alternatively the substrate may be of glass fibre impregnated with epoxy resin or a polyester. The invention is described with reference to printed circuits formed from double-sided Cuclad laminates, although Ni, "Kovar" (Registered Trade Mark), or stainless steel may replace Cu. Holes are etched in the Cu cladding on one or both sides of the laminate at the sites of the substrate holes; the desired circuit pattern is photo-deposited in negative form on the cladding in a plating resist material; the exposed areas of the Cu are electroplated with an etchant resist, e.g. Au; the plating resist is removed and the substrate holes etched out; finally, the exposed Cu is removed by etching. If the Cucladding is bonded to the substrate by a resin adhesive, this is removed with an aqueous solution of chromic trioxide and acetic acid. In an alternative embodiment, the plating step is omitted, the circuit pattern being photo-printed in positive form in an etchant-resist material on the Cu, followed by etching. Single- and double-sided circuits may be formed. The formation of holes with overhanging conductors is described; when electroplating is employed the plated layer may be thickened so that the underlying Cu of the overhanging portions may be removed in the etching step; otherwise, the underside of the overhanging portion is protected by an etchant resist. Use may be made of the lateral etching tendency of the substrate etchant to produce overhanging conductors. Holes in multilayer printed circuit assemblies may be formed by the method of the invention.

Thermal etching of (100) surfaces in sodium chloride single crystals

Abstract: Freshly cleaved sodium chloride single crystals thermally etched both in air and in vacuum (10−5 torr) show three types of evaporation pit: concentric square pits and concentric circular pits in air etched crystals, and pyramidal pits in vacuum etched crystals. The pyramidal pits may be of three kinds: those with symmetric diagonals, those with one symmetric and one non-symmetric diagonal, and finally those with two non-symmetric diagonals. These pyramidal pits are of the same nature as those associated with dislocations, found on chemical etching of LiF crystals. The differences between pits produced in air and pits produced in vacuum are discussed in terms of surface fusion.

Dry etching system with inert particles coated with adsorbed acid

Abstract: THIS DISCLOSURE REFERS TO OR DESCRIBES CERTAIN PRIOR ART SYSTEMS FOR ETCHING THE SURFACE OF METALS AND PLASTICS TO FORM IMPRESSIONS ON SUCH SURFACE OR TO MAKE SUCH SURFACES RECEPTIVE TO COATINGS. ALSO DISCLOSED HEREIN IS A NEW ETCHING SYSTEM WHICH IS PARTICULARLY EFFECTIVE FOR THE AFOREMENTIONED, AND OTHER, PURPOSES.

Range and depth dose distribution of low energy charged particles in dosimeter glasses

Abstract: : A new method for the direct determination of particle ranges and depth dose distributions in silver-activated phosphate glasses is based on the successive removal of extremely thin surface layers from the exposed glass by chemical etching ('peeling') and measurement of the residual radiophotoluminescence between successive etchings. Glass composition, etching chemicals and etching speed can be varied within wide limits. The experimental technique, using Yokota-type dosimeter glasses and 28% NaOH at 60C (etching speed 0.12 microns/min.) is briefly described. As examples for the practical application of the method, measurements using several types of radiation sources (aqueous solutions of 3H, 63Ni and 35S, solutions and thin and thick solid sources of 239Pu, 237Np and 235U, monoenergetic protons, deuterons and He(+) ions in a wide energy range) were made. Accuracy, possibilities and limitations of the method are briefly discussed. Possible sources of error are: discoloration of the glass because of very high surface doses; incertainties in the determination of the etching speed; etching speed along charged particle tracks higher than the bulk etch rate for ions of very high LET. (Author)

Electron microprobe analysis of impurity heterogeneities in thermally grown silicon oxide

Abstract: The electron probe X-ray microanalyzer is a powerful tool for studying impurity distribution and motion in thin films. This analytical instrument is capable of detecting metallic impurities present in areas as small as 1 × 10-6mm2and in concentrations of greater than 1 × 1019atoms/cm3. The analysis requires no sample preparation and is essentially a nondestructive test. This instrument was used to examine unoxidized and oxidized silicon surfaces and a finished microcircuit. With the electron microprobe, aluminum-bearing regions approximately one microns in diameter were detected on the bare surface of mechanically polished silicon slices. These aluminum-rich regions are believed to be alumina abrasive used in polishing. If these regions are not removed by chemical etching they will generate oxide defects during oxidation. These defects were found to contain Al (1 × 1021atoms/cm3and Na (1 × 1020atoms/cm3). Other oxide defects, i.e., pinholes, generated during oxidation varied in size from 0.5 to 5.0 microns and were found to contain Na (1×1021atoms/cm3) and K (5×1021atoms/cm3). Mg and Ca (1 × 1020atoms/cm3) were occasionally observed in these defects. After oxidation, all these impurities could be removed with a hot hydrochloric acid and deionized water rinse; surprisingly, this treatment reduced the silicon surface charge in the MOS structure ( X_{0} \cong 1500 A) by approximately 1.4 × 1011charges/cm2. The surface charge could be further reduced by heating the oxidized wafer at 900°C in a silicon nitride tube.

Improvements in or relating to metallizing insulating surfaces

Abstract: At least part of a surface of an electrically insulating member, e.g. forming an insulating sleeve of an electric coaxial cable or at least part of a waveguide or delay-line cable and made of polyethylene or propylene, P.V.C., P.T.F.E. or epoxy resins, is metallized by attacking the surface part to remove an outermost skin therefrom, e.g. by subjecting surface part to an oxidizing flame, corona-discharge, electron beam bombardment, chemical etching, abrasion by blasting, liquid or vapour honing, wet-cleaning the so exposed surface part e.g. using a detergent, aqueous alkaline solution or organic solvent and drying, wet-priming the surface part e.g. with an organic or aqueous solution of a tin or silver salt and washing, applying a catalyst such as a solution of auric or platinic salt in alcohol, ketone, ester or acidified water incorporating a surface active wetting and penetrating agent, diffusing the catalyst into the member under heat-treatment, applying a reduction solution to the surface part, and chemically depositing a metal e.g. Cu, Ni, Co, Ag, Au, Pt, Pd or alloy thereof on the surface part. The catalyst may be in a liquid resin bonded on the surface part upon polymerization and the metal chemically deposited on the polymerized resin. The catalyst may comprise finely divided autocatalytic metal. After deposition, the surface part may be rinsed, dried and heat-treated prior to electro-plating.