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Thin Film Bubble Domain Sensors Using Single Level Metallurgy

IP.com Disclosure Number: IPCOM000087221D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 89K

Publishing Venue

IBM

Related People

Cohen, MS: AUTHOR

Abstract

A process is described for providing a thin-film magnetoresistive sensor for detection of magnetic bubble domains, using single level metallurgy. The process can be used where the magnetic bubble domain film is a nonconductive material, and gold (rather than an insulator) provides the nonmagnetic spacing between the magnetic propagation elements and the bubble domain film. The gold conductive layer can be used as a conductor for the transfer gates in a bubble domain device, which provides high efficiency transfer gates. In the following description, a process will be illustrated in which gold is deposited before magnetic materials are deposited. However, the process can be used to provide the thin-film sensor for other conductor/magnetic material configurations.

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Thin Film Bubble Domain Sensors Using Single Level Metallurgy

A process is described for providing a thin-film magnetoresistive sensor for detection of magnetic bubble domains, using single level metallurgy. The process can be used where the magnetic bubble domain film is a nonconductive material, and gold (rather than an insulator) provides the nonmagnetic spacing between the magnetic propagation elements and the bubble domain film. The gold conductive layer can be used as a conductor for the transfer gates in a bubble domain device, which provides high efficiency transfer gates. In the following description, a process will be illustrated in which gold is deposited before magnetic materials are deposited. However, the process can be used to provide the thin-film sensor for other conductor/magnetic material configurations.

In Fig. 1, the thin-film magnetoresistive sensor is separate from the columns of chevron propagation elements that are used to move stripped-out bubble domains. Although the sensor is shown as weaving through the chevrons, this is schematic only. In the present process, it is important only to keep the propagation chevrons electrically isolated from the sensor.

Figs. 2A-2E illustrate the process. A bubble domain film 10 has a thin plating base layer 12 deposited on it, after which a resist layer 14 is applied, exposed and developed to leave the structure of Fig. 2A. A layer 16 of gold is then plated through the resist mask as shown in Fig. 2B. After plating, electrical contact is made to the sensor and to the surrounding area and the thin plating base 12 surrounding the sensor element (now covered with gold) is burned out, as illustrated in Fig. 2B. This leaves the sensor electrically isolated from the rest of the plating base. Since the gold layer is relatively thick and of higher conductivity than the plating base, it will be nearly equipotential, so that the burn-o...