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Obtaining Short Free Coincident Selection on Amorphous Films

IP.com Disclosure Number: IPCOM000085756D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Bajorek, CH: AUTHOR [+2]

Abstract

A procedure has been devised for making coincident-current selection systems for a bubble-supporting device, whereby electrical shorts between the current-carrying selectors and the bubble material beneath them are diminished, if not eliminated.

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Obtaining Short Free Coincident Selection on Amorphous Films

A procedure has been devised for making coincident-current selection systems for a bubble-supporting device, whereby electrical shorts between the current-carrying selectors and the bubble material beneath them are diminished, if not eliminated.

In a coincident-current selection procedure, all the magnetoresistive sensors in each column of individual chips on a silicon wafer are fed into the same sense amplifier. It is customary, when using such a design, to connect sensors in parallel rather than in series; such a series connection would cause the generation of a large voltage drop, causing breakdown in a conducting amorphous film, i.e., CdCoMo, below a protective insulating film.

On the other hand, it would be advantageous to use a series connection, particularly when the primary noise source for the sensing circuit would be due to inductive pickup in the leads to the sense amplifier. In order to permit such series connection, it would be helpful to remove that portion of the amorphous metal film surrounding each chip area. A cross section of a coincident-current selection scheme for a bubble device array is shown in the figure, wherein a silicon substrate 2 supports a layer 4 of a bubble-supporting material such as GdCoMo. Normally, the GdCoMo would be a continuous layer. However, prior to covering such GdCoMo layer 4 with a layer 6 of SiO(2), vertical and horizontal strips of GdCoMo are removed from...