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Sputter Cleaning Method For Lowering Contact Resistance In Ta-Cr-Al/Cu Metallurgical Structure

IP.com Disclosure Number: IPCOM000048589D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Dalal, HM: AUTHOR [+4]

Abstract

In Ta-Cr-Al/Cu metallurgy, high contact resistance can be observed even after sintering at 400 degrees C. Sintering at higher temperature progressively reduces the contact resistance, but the undesirable susceptibility to metal penetration increases. In accordance with the following process, however, the sintering temperature is reduced or the sintering step can be eliminated entirely while still achieving low contact resistance.

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Sputter Cleaning Method For Lowering Contact Resistance In Ta-Cr-Al/Cu Metallurgical Structure

In Ta-Cr-Al/Cu metallurgy, high contact resistance can be observed even after sintering at 400 degrees C. Sintering at higher temperature progressively reduces the contact resistance, but the undesirable susceptibility to metal penetration increases. In accordance with the following process, however, the sintering temperature is reduced or the sintering step can be eliminated entirely while still achieving low contact resistance.

Low barrier Schottky barrier silicon diodes employ tantalum as the Schottky contact metal. Water-bled chromium-aluminum/copper metallurgy is used to establish ohmic contact to the tantalum. A resistance film is formed at the top of the tantalum film during tantalum deposition. The water-bled chromium film on the tantalum surface reacts with the resistive film and partially reduces the contact resistance. 450 degrees C sintering is normally required to lower the resistance to acceptable levels.

Sintering at any temperature can be made optional while still achieving low contact resistance by in-situ or ex-situ sputter etching the top surface of the deposited tantalum at 200-500 watts, 5-15 (Mu) degrees Ar pressure for 3-8 minutes. The Cr-Al/Cu then is deposited on the etched surface. It is possible now to bleed H(2)O vapor at higher pressures, if desired, for improved barrier effectiveness.

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