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Amorphous Film Bubble Devices

IP.com Disclosure Number: IPCOM000086167D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+3]

Abstract

Bubble devices fabricated using amorphous magnetic films require two levels of electrical insulation. The first of these is between the amorphous bubble domain film and the propagation elements, commonly comprised of NiFe. The second level of insulation is between the propagation elements and conductors used for various circuit functions, such as generation, annihilation, and transfer gates. Sputtered insulation (such as SiO(2)) is used, where the sputtering bias is varied during deposition of the insulation.

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Amorphous Film Bubble Devices

Bubble devices fabricated using amorphous magnetic films require two levels of electrical insulation. The first of these is between the amorphous bubble domain film and the propagation elements, commonly comprised of NiFe. The second level of insulation is between the propagation elements and conductors used for various circuit functions, such as generation, annihilation, and transfer gates. Sputtered insulation (such as SiO(2)) is used, where the sputtering bias is varied during deposition of the insulation.

When insulators are sputtered, the pinhole density becomes progressively greater as the bias voltage increases. Use of high-bias voltages suggests that high resputtering occurs which contributes to pinholes. This high pinhole density in resputtered films is caused by resputtering of the underlying amorphous magnetic metal (which has a very large sputtering yield in comparison to SiO(2)) into the oxide during the early stages of SiO(2) deposition. However, highly resputtered SiO(2) films have other very desirable advantages. For instance, these resputtered SiO(2) films provide better step coverage over conductor steps and inherently better dielectric breakdown characteristics, because of densification caused by resputtering.

In order to provide good insulation over amorphous magnetic films, the initial layers of SiO(2) are deposited at zero bias up to about 500 angstroms or so. The bias is then increased to an optimum value, such...