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Elimination of the Halo Effect Associated with Anodized Aluminum Lines

IP.com Disclosure Number: IPCOM000080229D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Schmid, GE: AUTHOR

Abstract

When a pattern of conductive lines is produced by selective anodic oxidation of aluminium (Al), the formation of "halos" of unoxidized Al between adjacent lines can be avoided by raising the bath temperature from room temperature (25 degrees C) to 50 degrees C.

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Elimination of the Halo Effect Associated with Anodized Aluminum Lines

When a pattern of conductive lines is produced by selective anodic oxidation of aluminium (Al), the formation of "halos" of unoxidized Al between adjacent lines can be avoided by raising the bath temperature from room temperature (25 degrees C) to 50 degrees C.

It was found that whenever a narrow area between adjacent conductive lines is anodized, a prolongation of the oxidation time from 2 to 20 min is necessary to completely transform the Al to aluminium oxide (Al(2)O(3)). Oxidation times of that length are not only a disadvantage in rationalized production but can create serious problems, because the masking material on the Al has only a temporarily limited adherence.

More serious is the fact that if the distance between adjacent lines is <5 mu,even a longer oxidation time fails to remove the "halos" of unoxidized Al entirely. The consequence of this is shortcircuiting between the conductive lines.

This problem is eliminated by a higher bath temperature during oxidation. This measure has the additional advantage that the oxidation time is reduced, and that the step between the surface of the Al(2)O(3) and the surface of the Al is reduced.

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