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Memory Devices With Controlled Edge Slopes

IP.com Disclosure Number: IPCOM000092311D
Original Publication Date: 1968-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Raacke, KH: AUTHOR [+2]

Abstract

In the fabrication of magnetic film memory devices by vacuum evaporation or electroplating, magnetic flux closure in the devices is difficult to obtain. This is because a fine line, e.g., 3 mils wide, with a sloped cross-section is very hard to produce. Such fine lines with sloped cross-sections suitable for magnetic memory devices can be produced by electrochemical machining.

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Memory Devices With Controlled Edge Slopes

In the fabrication of magnetic film memory devices by vacuum evaporation or electroplating, magnetic flux closure in the devices is difficult to obtain. This is because a fine line, e.g., 3 mils wide, with a sloped cross-section is very hard to produce. Such fine lines with sloped cross-sections suitable for magnetic memory devices can be produced by electrochemical machining.

In the electrochemical machining process, an electrode, having a shape related to the desired slope to be produced, is positioned a short distance, e.g., one mm. or less, from the line to be machined. Both electrode and substrate are immersed in a bath of an electrolyte, preferably with low throwing power, such as sodium chlorate or sodium nitrate. A suitable electrical current, which can be either DC current or RF current, is passed through the system. The shaped electrode is then moved along the vacuum evaporated or electroplated line upon which a slope is desired. The shape of the sloped cross-section thus produced is a function of the electrode shape, the electrolyte used, the current density, and the rate the electrode is moved along the line.

Electrochemical machining is a much faster process than the sputter etching process and it results in reproducible and controllable slopes on fine lines. In many cases, the use of photoresist or other masking materials is eliminated when the electrochemical machining process is utilized.

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