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Electroforming Film Patterns for Interconnections

IP.com Disclosure Number: IPCOM000094046D
Original Publication Date: 1966-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Caswell, HL: AUTHOR

Abstract

This technique is for electroforming film pattern for interconnections. In known techniques, where a substrate is coated with a film of gold and photoresist, the latter is removed where interconnection leads are desired ad gold is electroformed into the exposed area to build up a desired thickness of such metal. The problem with this technique is that the adherence of the photoresist is rarely good enough to prevent the formation of whisker growth between adjacent interconnection lines. The following double-masking technique solves the problem of whisker growth and permits a higher density of interconnection lines than heretofore possible.

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Electroforming Film Patterns for Interconnections

This technique is for electroforming film pattern for interconnections. In known techniques, where a substrate is coated with a film of gold and photoresist, the latter is removed where interconnection leads are desired ad gold is electroformed into the exposed area to build up a desired thickness of such metal. The problem with this technique is that the adherence of the photoresist is rarely good enough to prevent the formation of whisker growth between adjacent interconnection lines. The following double-masking technique solves the problem of whisker growth and permits a higher density of interconnection lines than heretofore possible.

In drawing A a substrate 1 is initially coated over the whole of a surface with a deposition of nichrome 2 and gold 3. Photoresist 9 such as KPR* is applied and retained only where an interconnection is desired. The gold is then removed from the remaining area exposing the nichrome. The nichrome is then oxidized in the H(2)O(2) at 60 degrees C for 10 minutes forming a layer of nichrome oxide 5 as in drawing B.

Layer 5 is then coated with a layer 6 of KPR to provide a mask everywhere except on interconnection 7 which is built up by a subsequent electroforming of gold. The adherence of the photoresist to the nichrome oxide prevents the development of whiskers between interconnections. In addition, if the photoresist lifts off the nichrome, the nichrome oxide stops plating from occ...