Browse Prior Art Database

Magnetic Storage Device

IP.com Disclosure Number: IPCOM000094862D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Bertlesen, BI: AUTHOR

Abstract

In this multilayer magnetic thin-film storage device, ground plane trap flux is eliminated and drive field requirements are reduced.

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Magnetic Storage Device

In this multilayer magnetic thin-film storage device, ground plane trap flux is eliminated and drive field requirements are reduced.

The device in drawing A includes two uniaxial anisotropic thin films 2 and 4, disposed over metal substrate 6. The easy axis of magnetization of films 2 and 4 is in substantially parallel planar relationship one to the other. Such easy axis is skewed relative to a reference plane transverse to films 2 and 4. Disposed intermediate film 2 and metal substrate 6 is metal layer 8 and silicon monoxide film 10. Intermediate films 4 and 2, is metal film 12 and silicon monoxide film 14. Drive lines 16 and 18, in quadrature one to the other, are disposed over film 4. Line 16 is electrically insulated from film 4 by polymeric material 20. Line 18 is electrically insulated from 16 by polymeric material 22.

In the device's formation, substrate 6, which serves as the conductive ground plane, is polished to a mirror finish. Thereafter chromium is deposited to form layer 8, the purpose of which is to provide adhesive bonds for the silicon monoxide film to follow. Though chromium is preferred, any metal that adheres to the substrate and forms a superficial oxide compatible with silicon monoxide is usable. Thereafter, film 10 is vacuum deposited over layer 8. The silicon monoxide overshadows the surface topography over the substrate, thus minimizing substrate influence on the resultant magnetic properties.

Magnetic film 2 is then vacuum deposited over film 10. Film 2 is preferably formed from a nickel-iron-cobalt alloy. The deposition is performed in the presence of an orienting magnetic field of the type conventionally used to induce uniaxial anisotropy. As is shown in drawing B, the magnetic field is directed at an angle to the plane of magnetic film 2' to induce an easy axis of magnetization, indicated by arrow 100. This is at an angle of +a with respect to the transverse reference plane cdef to the plane of film 2'.

Then, the substrate temperature is reduced and, without breaking vacuum, chromium film 1...