Showing papers on "Isotropic etching published in 1972"

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.

About the vitreous systems GeTeI and GeTeSi and the influence of microphase separation on the semiconductor behaviour of GeSe glasses

Abstract: The glass forming regions of the systems GeTeI and GeTeSi were estimated under standardized conditions, yielding the limits of composition as Ge17–23Te68–82I1–12 and Ge0–19.6Te75–86Si1.6–23 respectively. The glasses are characterized with respect to their transformation temperatures and their recrystallization behaviour. In the system GeSe a region of preferred glass formation was observed near the eutectic point of the compounds GeSe and GeSe2. The transformation temperatures reach 360°C. On annealing the glasses develop a significant microheterogeneous structure. Chemical etching experiments suggest a differential enrichment of GeSe in the droplets. These often contain a secondary separation which shows an etching behaviour similar to that of the glass matrix. There is a remarkable influence of the microheterogeneous structure on the electrical conductivity of the glasses.

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.

Continuous etching process

Abstract: This invention relates to a continuous process for etching cuprous metal which process comprises etching copper with the etchants of the invention, precipitation and removal of the copper from the etchant and regeneration of the etchant making the same available for further use. The etchant used comprises complexed cupric ions as an oxidant. In practice, the etchant is used to etch copper until the dissolved copper concentration reaches a predetermined point, typically from 10 to 24 ounces per gallon of solution. At this point, the etchant is circulated in a loop where it is treated to precipitate dissolved copper, the precipitate is removed and the etchant is returned to the etching apparatus for further use.

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.

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.

Process for forming a metal oxide pattern

Abstract: A process for forming a pattern of metal oxide on a substrate wherein a metal oxide is selectively formed or etched in accordance with a thermal pattern. In one embodiment, selected portions of a uniform layer of substantially amorphous metal oxide are converted to a more crystalline form by heat and remaining amorphous oxide portions are removed by chemical etching to form the pattern. In another embodiment, a metal-organic compound precursor of the metal oxide is thermally decomposed on the substrate in accordance with the pattern. A novel vapor etching process, and a novel sputtering process for forming amorphous metal oxide, are disclosed.

Zum einfluss von temperprozessen auf widerstandsschwankungen in siliziumeinkristallen

Abstract: Striations in semiconductor silicon have been detected even after extreme annealing (e.g. 500 hr at 1230°C or 72 hr at 1400°C) by chemical etching as well as by electrical measurements of the resistivity profile. The result can be understood in the light of recent values for the diffusion coefficient of phosphorus in silicon.

Semiconductor devices manufacture

Abstract: SEMICONDUCTOR STRUCTURES HAVING MULTI-LAYER METAL CONDUCTORS FORMED ON THE SURFACE OF THE SEMICONDUCTOR DEVICES AND HAVING EXCESS METAL BETWEEN THE CONDUCTORS REMOVED BY SPUTTER ETCHING IN AN ATMOSPHERE WHICH PRODUCES OXIDATION OF ONE OF THE METAL LAYERS OF SAID CONDUCTORS. THE METAL COMPOUND MASK THUS FORMED INHIBITS THE ETCHING PROCESS IN THE REGIONS WHERE THE OIDIZED LAYER IS EXPOSED AND PROTECTS THE ACTIVE COMPONENTS BENEATH THE LAYER. THE OXIDIZED PORTIONS OF THE MASKING LAYER ARE THEN REMOVED BY A SUITABLE SOLVENT OR ETCH. A CHEMICAL ETCHING METAL COMPOUND MASK MAY BE FORMED OF A METAL AND THE SEMICONDUCTOR MATERIAL FOR SEPARATING THE CHIPS FROM THE WAFER BY ANISOTROPIC ETCHING.

Fabrication of thin film devices

Abstract: A process is described for the fabrication of devices in which thin films of tungsten are etched by a chemical procedure. This chemical procedure involves the use of ferricyanide as the oxidizing agent contained in an aqueous solution. The solution also contains a substance with an affinity for protons to promote the etching reaction. The pH of the etching solution is between 7 and 10 but can be higher if desired. Such etching solutions not only yield etching rates of practical interest, but are usable with photoresists which are ordinarily attacked at high pH. In cases where enhanced etching resolution and uniformity is of particular importance, a special procedure is described which involves spraying the etchant and spinning the sample.

Manufacture of printing elements by a photoresist chemical etching system

Abstract: THIS PROCESS COMPRISES THE USE OF TWO DISSIMILAR PHOTORESIST IMAGES. THE TOP PHOTORESIST IMAGE IS SUPERIMPOSED OVER AND EXTENDS BEYOND THE BOTTOM PHOTORESIST IMAGE. THE TOP PHOTORESIT IMAGE FUNCTIONS AS A RESIT WHILE ACID ETCHING A PATTERN WHICH IS LARGER THAN REQUIRED. THE TOP PHOTORESIST IMAGE IS THEN REMOVED. THE BOTTOM PHOTORESIST IMAGE REMAINS IN PLACE AND FUNCTIONS AS A RESIST WHILE ACID ETCHING THE FINAL AND WELL-DEFINED PATTERN.

Chemical etching of gadolinium-gallium garnet substrates

Abstract: The etching of mechanically polished gadolinium-gallium garnet substrates by phosphoric acid, sulphuric acid and sulphuric-oxalic acid mixture was investigated in order to find an etchant which would remove the damaged surface layer and provide a substrate surface suitable for liquid phase epitaxial growth of magnetic garnets. Optimum surface properties were obtained when substrates were etched for 10 sec in phosphoric acid which had been maintained for 1 to 2 h at temperatures of 350 or 400°C. The disadvantage of this etchant is that it increases the surface roughness of the substrate. Surface smoothness was retained when substrates were etched in sulphuric acid; however, this acid revealed residual scratch marks introduced into the platelet during mechanical polishing. The sulphuric-oxalic acid mixture and phosphoric acid at 160° C revealed defects due to coring, faceting and scratch marks.

The effects of chemical etching on the magnetic properties of permalloy films

Abstract: 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete.

Formation d'images photolytiques sur les macrocristaux d'halogénure de plomb

Abstract: The preparation and some properties of large lead halide crystals are described. The photolysis of these crystals was followed by chemical etching (photosolubilization), showing that the rate of solubilization decreases if the crystal is exposed in the presence of oxygen.

Etching of group III-V semiconductors

Abstract: Group III-V compound semiconductor devices with attached gold conductor areas are etched using a basic ferricyanide etchant. The etchant is an aqueous solution containing ferricyanide ions in a concentration from 0.8 molar to 1.2 molar and sodium or potassium hydroxide in a concentration from 0.3 molar to 1.5 molar. This etchant rapidly removes the semiconductor material leaving smooth surfaces, while leaving the gold conductors and areas protected by oxide layers essentially intact. The use of titanium layers as etching masks, deposited for example by evaporating or sputtering through a removable mask, is also disclosed.

Photoelectric emission from GexSi1-x mixed crystals

Abstract: Photoemission of mixed crystalline GexSi1-x samples was studied. Thin epitaxial layers on Si substrates were prepared by gaseous transport process. Measurements were made in 10−9 torr UHV on atomic clean surfaces prepared by chemical etching and heat treatment in vacuum. The quantum efficiency, threshold of photoemission, work function, electron affinity and energy distribution of photoelectrons excited by 4–6.2 eV photons were determined. A gradual shift of characteristics with composition was observed. The work function (surface Fermi level) of the samples, determined by the retarding field method of Hughes, corresponded to the bulk Fermi level.

Process for etching polymeric films

Abstract: A process for etching a film of two polymeric materials is disclosed. The eligible polymeric films are mutually miscible before imaging or etching. Prior to etching, the films are imaged by phase separation. This imaging is accomplished by contacting the films with appropriate solvents. The imaged areas are etched by contact with a liquid such as water or alcohol. The etched films produced by the process of this invention can be employed as a display device or as a printing element.