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Conductor Metallization for Bubble Devices

IP.com Disclosure Number: IPCOM000083987D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+2]

Abstract

A cross-sectional view of a typical conductor pattern is shown for a high-density structure ion-implantation mask and other current-carrying functions in bubble devices. Typical fabrication steps involve vacuum deposition of Cr and Cu, where the latter serves as a plating base for Au. An overlay pattern (or conductor pattern) is defined by photolithography, and the conductor film is plated through the resist mask.

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Conductor Metallization for Bubble Devices

A cross-sectional view of a typical conductor pattern is shown for a high- density structure ion-implantation mask and other current-carrying functions in bubble devices. Typical fabrication steps involve vacuum deposition of Cr and Cu, where the latter serves as a plating base for Au. An overlay pattern (or conductor pattern) is defined by photolithography, and the conductor film is plated through the resist mask.

The last and most critical step is removal of the photoresist and etching away of the Cr-Cu layer under the resist by RF sputter etching. Since the etch rate of Au is almost an order of magnitude faster than Cr + Cu, the initial Au thickness must be greater than the desired final thickness by several factors, and this gives rise to fabrication problems. A capping layer to slow down the etching of the Au layer (or to protect it completely) during sputter etching is provided.

Two classes of capping materials are suitable, both of which are compatible with processing of these wafers: 1) Electroplated films, notably NiFe and similar alloy films. The sputter etch rate of nominal 80%Ni-20%Fe is approx.=0.1

of the Au etch rate, and about D.3 of the etch rate of

Cr+Cu. These films with nominal thickness of 1,000 Angstroms

have been successfully utilized. 2) Vacuum deposited films of low-sputtering yield materials, which are subdivided into two categories:

a) Materials for evaporation technique: Ti and V.

b) Materials...