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Process Improvement for Deposited Ohmic Contacts

IP.com Disclosure Number: IPCOM000049882D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Giddings, JJ: AUTHOR [+4]

Abstract

Circuit components which utilize tantalum as a low barrier Schottky metallurgy experience significant contact resistance when standard Purdue first level metallization (Cr, Al-Cu) is employed. The cause of contact resistance is an undefined, interfacial film produced between the tantalum and chromium which is not dispersed by subsequent sintering. By opening the shutter prior to attaining evaporation power necessary to deposit the wafer-bled chromium film on the tantalum underlayer, the contact resistance is improved without degrading the diffusion barrier characteristics of the Cr/Cr(2)O(3) layer.

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Process Improvement for Deposited Ohmic Contacts

Circuit components which utilize tantalum as a low barrier Schottky metallurgy experience significant contact resistance when standard Purdue first level metallization (Cr, Al-Cu) is employed. The cause of contact resistance is an undefined, interfacial film produced between the tantalum and chromium which is not dispersed by subsequent sintering. By opening the shutter prior to attaining evaporation power necessary to deposit the wafer-bled chromium film on the tantalum underlayer, the contact resistance is improved without degrading the diffusion barrier characteristics of the Cr/Cr(2)O(3) layer.

In the prior process for fabricating ohmic contacts, the chromium source was raised to the required evaporation power before the shutter opened. By opening the shutter prior to maximum chromium power, it is believed that disassociation of water vapor is delayed in the initial chromium film, thus providing a "dryer" chromium-tantalum interface with low contact resistance. The diffusion barrier quality of the Cr/Cr(2)O(3) is equivalent to that of the prior process, and the oxygen profile in chromium, as measured by an Auger, is the same.

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