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Effect of CU and SI in Aluminum on Stress Change and on TiAl3 Formation in Al Alloy/TI Bilayer Films During Annealing

Published online by Cambridge University Press:  21 February 2011

Dirk D. Brown ,
Paul R. Besser ,
John E. Sanchez Jr. ,
Matt A. Korhonen  and
Che-Yu Li
Dirk D. Brown
Affiliation:
Advanced Process Development, Advanced Micro Devices, Sunnyvale, CA 94088 Cornell University, Department of Materials Science and Engineering, Ithaca, NY 14850
Paul R. Besser
Affiliation:
Advanced Process Development, Advanced Micro Devices, Sunnyvale, CA 94088
John E. Sanchez Jr.
Affiliation:
Advanced Process Development, Advanced Micro Devices, Sunnyvale, CA 94088
Matt A. Korhonen
Affiliation:
Cornell University, Department of Materials Science and Engineering, Ithaca, NY 14850
Che-Yu Li
Affiliation:
Cornell University, Department of Materials Science and Engineering, Ithaca, NY 14850
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Abstract

Interconnect metallizations used in advanced integrated circuits typically use an Al-alloy sputterdeposited onto a Ti barrier layer. The Ti and Al react above ∼ 400°C to form TiAl3, which affects the stress evolution of the metal stack during thermal cycling. This paper describes results of thin film experiments performed on Ti/Al-alloy bilayer films. Two Al alloys were studied: Al-I%Cu and Al-0.5%Cu-1%Si. The rate of TiAl3 formation at 430°C was determined for both alloys and used to relate TiAl3 formation to the stress evolution of the film stacks during thermal cycling. The dominant effect of the TiAl3 intermetallic formation on stress arises from a change in the stress-temperature behavior of the film stack, due to a change in the yield behavior, effective modulus, and thermal expansion coefficient of the stack. The presence of Si in the Al-alloy markedly reduces both the rate of TiAl3 formation and the resulting change in composite stress.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 356: Symposium B2 – Thin Films: Stresses and Mechanical Properties V , 1994 , 471
Copyright
Copyright © Materials Research Society 1995

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