Showing papers on "Etching (microfabrication) published in 1972"

Semiconductor structure having metallization inlaid in insulating layers and method for making same

Abstract: In a semiconductor structure with multiple levels of metallization on the surface, each metallization pattern is inlaid in trenches formed in an insulating layer. The surface of the metallization is flush with or somewhat lower than the surface of its associated insulating layer. In a preferred embodiment, the different etching characteristics of glass and silicon nitride are utilized to form the trenches in the glass layer. The glass comprises the insulating layer and the nitride forms the bottom of the trench.

Composition for etching copper with reduced sideways-etching

Abstract: An etching bath composition which reduces the extent of side or lateral etching is prepared by admixing an additive selected from a group consisting of aliphatic amines having a straight chain of more than four carbon atoms, cyclohexylamine, benzotriazole or N, N-dialkylaniline, with a basic composition of sulfuric acid and hydrogen peroxide.

A method of improving the adherence of a metal deposit to a polyimide surface

Abstract: An etching composition and a method utilizing such a composition for etching a surface of a polyimide is disclosed. The method comprises exposing the polyimide surface to an etching composition comprising an aqueous solution of a basic compound and ethylene diamine. The ethylene diamine synergistically increases the etching rate of the polyimide. When the ethylene diamine is present in an amount in excess of its degree of solubility the etching of the polyimide results in a frosted or matte finish thereof.

Method of planar mounting of silicon solar cells

Abstract: A method of mounting silicon solar cells in a planar array that not only lds electrical insulation between cells but allows for a multifold increase in thermal dissipation of the cell array, comprising metallizing a wafer of beryllium oxide on each side so that the outer surface is copper, etching the wafer on one side so that the only metallized parts which remain are those on which the solar cells are to be mounted or wiring is to be attached, soldering the solar cells on the unetched copper prominences, coating the aluminum panel on which the cells are mounted with a copper layer, soldering the underside of the wafer on the upper surface of the aluminum panel with soft solder such as indium, and covering all remaining passive surfaces with a teflon F.E.P. tape the underside of which carries a layer of slver and then a layer of inconel metal.

Differential etching of garnet materials

Abstract: A method for etching selected areas of single crystal garnets. The crystal is subjected to an ion implantation in the area to be etched. A proper etching solution is then applied to the crystal. The damaged area formed by the ion implantation will etch at a significantly greater rate than the remainder of the material. The process is self-limiting since the depth to which the crystal is etched is dependent upon the depth of the implantation and not upon the etching temperature or the length of time the etchant is applied. The differential etching rate also eliminates undesirable undercutting which usually results from the use of masked chemical etching techniques. The process may be used to form a wide variety of structures in garnet material for application in magnetic domain devices and integrated optics components.

Process of producing semiconductor devices

Abstract: By etching away a silicon nitride coating on a semiconductor substrate by photolithographic technique, windows of a predetermined pattern are formed in the coating to serve to deposit electrodes on and diffuse active regions into the substrate. Then a silicon dioxide coating deposited on the nitride coating and within the windows and partly removed by photolithographic technique to again form the windows for diffusion followed by the diffusion of the active regions into the substrate. An etchant chiefly attacking the oxide coating is used to again make all the windows for depositing the electrodes within them on the substrate.

Prolonged etching factor in solid state track detection and its applications

Abstract: It has been observed that the number density of etch pits resulting from spontaneous or induced fission within a solid state track detector (SSTD) is a function of the duration of etching, other conditions being constant. As the etching proceeds, the net number of etch pits observed per unit area continues to increase. This necessitates a modification of the conventional equations governing the observed etch-pit densities in SSTD. A prolonged etching factor f(t) is defined, and its value measured as a function of time under various specific etching conditions, in a number of materials of interest, including ‘reference glass’. Furthermore, the theoretical relationship of this factor with the general velocity of etching in a given material, and with the average range R of fission fragments in it, is utilized in deriving self-consistent and very satisfactory values of R in the above-mentioned materials.

PRODUCTION OF SiO{11 {11 TAPERED FILMS

Abstract: During SiO2 etching, when the oxide surface etch rate is larger than the bulk etch rate and the photoresist adheres tenaciously to the surface, a near vertical wall or cusp will be formed. This will create potential fracture spots in sputtered or evaporated metal which covers the steps. In the fabrication of self-aligned gate IGFETs, where the gate material acts as a mask against either etching or ion implantation, holes in the step metal will allow regions under the nominal gate to be doped during the source-drain doping. The slope of an etched step can be controlled by fabricating a double layer in which the top layer etches faster than the bulk. The specification describes the use of the enhanced etch rate of ion bombarded SiO2 to generate controlled tapers on window openings.

Direct observations of filaments in the ovonic read-mostly memory

Abstract: Etching methods have been developed to reveal the morphology, chemistry and structural characteristics of the conducting filaments formed during the memory setting of an RM 256 memory array. Scanning electron microscopy (SEM) and μ-probe analysis are used together with microstructural and thermodynamic results to detail the mechanism of memory switching in these devices.

Preparation of high resolution shadow masks

Abstract: The specification describes a method for preparing a thin silicon high resolution shadow mask, the latter adapted especially for use in processing materials by ion implantation. The method makes use of the preferential etch technique for silicon in which, for example, n+ material can be electrolytically removed in preference to higher resistivity ntype silicon. A thin (e.g. < 10 Mu ) epitaxial layer of n-silicon is deposited on an n+ substrate. The open regions of the mask are then converted, through the thickness of the epitaxial layer, to n+ material. After exposure to the preferential electrolytic etch treatment, a thin silicon shadow mask is left. Also disclosed are ribbed structures for enhancing the physical durability of the mask and techniques using crystallographic etching for further improving resolution.

Detection of discontinuities in passivating layers on silicon by NaOH anisotropic etch

Abstract: Discontinuities in glasses deposited on silicon substrates are readily detected by a silicon-preferential etch that uses single component alkali solutions. The etchants can be applied to thermally grown oxide films, pyrolytically-deposited passivating layers or sputtered quartz. The character of the discontinuities in these films is shown and the size can be estimated (although both observations are subject to the limitations of the optical tools used for observation or micrography). When applied in the temperature range below +70°C, the etchant attacks the oxides insignificantly and the concentration, as well as the temperature, is chosen for convenience. Above +70°C the passivating layers, particularly thermal SiO2, are etched at higher rates, and the etching effects must be taken into account if the oxide thickness is less than 1000 A. The etchants are applicable to intrinsic as well as extrinsic silicon up to a doping level of 1020 cm-3.

Method of fabricating an apertured mask for a cathode-ray tube

Abstract: A metal sheet is embossed by a special embossing tool to provide regions in the sheet of minimum thickness at the intended aperture locations thereon. Following embossing, the sheet is shaped into a desired mask contour and the embossed side of the sheet is coated with a stop-off substance to prevent subsequent removal of material from that side. The regions of minimum thickness are then removed, such as by etching the uncoated side of the sheet, to provide the apertures.

Method and material for passivating the junctions of mesa type semiconductor devices

Abstract: The method of producing mesa type semiconductor devices having passivated mesa junctions comprises the steps of providing a wafer having layers of P and N type semiconductor material deposited thereon removing semiconductor material from the layers at spaced intervals, preferably by etching, depositing high resistivity polycrystalline silicon material in the valleys created by removing the semiconductor material to passivate the mesa junctions and separating adjacent semiconductor devices by cutting through the wafer therebetween.

Process for fabricating passivated transistors

Abstract: An integrated circuit technique for passivating transistors and, at the same time, providing that the passivating material serve as part of the diffusion mask so as to avoid mask alignment difficulties, particularly the difficulty encountered when the steps of diffusing impurities and forming contact holes are to be performed in a very restricted area. The present technique involves the formation of a diffusion mask which is constituted of a film of a first material which is subject to ready etching by a first etchant but which is substantially unaffected by a second etchant; and of another, passivating, film which is constituted of a second material, the latter being subject to ready etching by the second etchant, but not by the first etchant. The first film is preferably made of silicon oxide (SiO2). The second film is preferably constituted of silicon nitride (Si3N4); however, other materials can be used for passivation, such as aluminum oxide (Al2O3). Only one etching step is required to be performed on the passivating film, whereby both the emitter window or opening and the base region contact openings are formed together. As a consequence, the mask alignment difficulties normally attending separate etching steps are obviated.

Anisotropic etching of silicon and germanium

Abstract: SINGLE CRYSTAL SILICON AND GERMANIUM HAVING MAJOR FACES PARALEL TO THE (100) PLANE MAY BE ETCHED ANISOTROPICALLY WITH AN ETCHANT COMPRISING AN OXIDIZING AGENT, AN ALCOHOL AND AN ALKALI METAL HYDROXIDE. IT HAS BEEN FOUND IN THE CASE OF SILICON THAT THE PRESENCE OF THE OXIDIZING AGENT IS NOT REQUIRED FOR ETCHING BUT INHIBITS THE FORMATION OF PYRAMIDS WHICH TERMINATE THE ETCHING PROCESS.

The effect of radio-frequency sputter ion etching and ion-beam etching on biological material: a scanning electron microscope study

Abstract: Mammalian and avian cells have been examined in the scanning electron microscope either after prior radio‐frequency sputter ion etching with different ions (hydrogen, helium, argon, oxygen) or after argon ion bombardment in the SEM. Whilst the pattern of erosion is similar in the different specimens, the etching pattern varies with the different gases. It has not been possible to relate the etching patterns to characteristic subsurface structures.

Landless plated-through hole photoresist making process

Abstract: A method for producing landless plated through holes in a printed circuit board. Holes are drilled through a copper clad insulating board and all exposed surfaces are sensitized and plated. A tenting photoresist material is placed over at least one of the major surfaces of the drilled board. In a first species, negative or positive photoresist is placed on both sides of the board. In a second species, positive photoresist is placed on one surface of the board at a time. A desired circuit pattern is produced in the tented photoresist, the circuit pattern including hole configurations having diameters no greater than the drilled holes. Tin-lead solder is placed through the circuit and the hole locations in the photoresist, the photoresist is removed and the unwanted copper cladding is etched away using the solder as an etching resist. In the first species, the holes in the photoresist are made smaller than the drilled holes using a separate photomask. In the second species, the holes in the positive photoresist are made precisely equal in size to the drilled holes using the board itself as a photomask.

Method of producing aluminum planographic printing plates

Abstract: A PROCESS OF PRODUCING ALUMINUM CONTAINING SUPPORTS, WHICH COMPRISES ETCHING A GRAINED ALUMINUM SURFACE WITH A BASIC OR ACIDIC ETCHING SOLUTION WITHIN THE RANGE OF 0.5 TO 30 G./M.2 AND THEN SUBJECTING THE ETCHED SURFACE TO ANODIC OXIDATION.

Etching of polyimide films

Abstract: A process for the etching of polyimide films which includes applying a photo sensitive resist of a predetermined viscosity and utilizing hydrazine as an etchant to remove unwanted sections of the polyimide film after exposing and developing the light sensitive resist.

Etching control system

Abstract: In an etching system utilizing ferric chloride solution or equivalent spray directed onto copper work pieces to be etched, the etchant in the etcher sump is circulated through a chlorinator under control of an etching control monitor. This introduces gaseous chlorine and effectively maintains the etching potential of the ferric (Fe 3) ions present in the solution. As copper accumulates in the etchant, a part is removed, ammonium chloride is added, and this mixture is then cooled. A crystallized double salt containing copper is separated, and the solution, thus reduced in copper content, is stored for subsequent reintroduction to the etching system.

Method for selectively etching alxga1-xas multiplier structures

Abstract: A method for selectively etching a layer of AlxGa1 xAs with a low concentration of Al in a multilayer structure while leaving adjacent layers of AlxGa1 xAs material of higher concentration Al relatively unaffected. The structure is immersed in an etchant consisting essentially of an H2O2 solution neutralized to a pH of 6-8 with a suitable hydroxide such as NH4OH. Preferably, the solution is agitated to insure that the etched surfaces are smooth. This selective etching technique may be used to form a variety of structures including a passive optical waveguide of extremely small dimensions.

Method of controlling an etching process

Abstract: In an etching process, the degree of etching of a workpiece is controlled by scanning a segment of the workpiece at an intermediate point in the process to derive a measure of the portion of the segment from which a surface layer has been removed. A variable parameter of the etching process, such as the conveyor speed or the etchant flow rate, is adjusted, according to the difference between the derived measure and a standard measure, in a direction tending to reduce the difference.