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Chrome Oxide and Copper Doped Aluminum Metallization Semiconductor Contacts

IP.com Disclosure Number: IPCOM000088649D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Grosewald, PS: AUTHOR [+4]

Abstract

This article relates to the use of a composite metallurgy of PtSi and Al-Cu as a metallurgy for semiconductor wiring. The metallurgy may be used both for forming ohmic contacts and for Schottky barrier diodes. Pure Cr interdiffuses readily with aluminum to form the Cr-Al, intermetallic. However, if the Cr is evaporated in an oxidizing ambient, such as H(2)O or O(2), a film which is a mixture of Cr and Cr(2)O(3) is formed which is significantly less reactive with Al than pure Cr. The Cr-Cr(2)O(3) film exhibits a negative temperature coefficient of resistivity unlike metals, which have a positive temperature coefficient of resistance. Typically, a partial pressure of H(2)O of approximately 3 x 10/-5/ torr is maintained in the evaporator during the entire Cr deposition.

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Chrome Oxide and Copper Doped Aluminum Metallization Semiconductor Contacts

This article relates to the use of a composite metallurgy of PtSi and Al-Cu as a metallurgy for semiconductor wiring. The metallurgy may be used both for forming ohmic contacts and for Schottky barrier diodes. Pure Cr interdiffuses readily with aluminum to form the Cr-Al, intermetallic. However, if the Cr is evaporated in an oxidizing ambient, such as H(2)O or O(2), a film which is a mixture of Cr and Cr(2)O(3) is formed which is significantly less reactive with Al than pure Cr. The Cr-Cr(2)O(3) film exhibits a negative temperature coefficient of resistivity unlike metals, which have a positive temperature coefficient of resistance. Typically, a partial pressure of H(2)O of approximately 3 x 10/-5/ torr is maintained in the evaporator during the entire Cr deposition.

This mixture is a substantially better diffusion barrier between Al and PtSi than is pure Cr. The use of this mixture also reduces the need for the incorporation of Si in the Al-Cu alloy. The use of Si necessitates sintering at 400 degrees C or more to drive it into solution with the Al-Cu. The high temperature step causes Si to diffuse into the Al-Cu film and precipitate in grain boundaries, leading to several detrimental effects, such as increased conductive stripe resistance and etching. The use of the Cr-Cr(2)O(3) film eliminates the need for the Si so that the high temperature sintering step, to drive the Si into solutio...