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Nanoindentation of Au and Pt/Cu thin films at elevated temperatures

Published online by Cambridge University Press:  03 March 2011

Alex A. Volinsky*
Affiliation:
University of South Florida, Department of Mechanical Engineering, Tampa, Florida 33620
Neville R. Moody
Affiliation:
Sandia National Laboratories, Livermore, California 94550
William W. Gerberich
Affiliation:
University of Minnesota, Department of Chemical Engineering and Materials Science, Minneapolis, Minnesota 55455
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

This paper describes the nanoindentation technique for measuring sputter-deposited Au and Cu thin films’ mechanical properties at elevated temperatures up to 130 °C. A thin, 5-nm Pt layer was deposited onto the Cu film to prevent its oxidation during testing. Nanoindentation was then used to measure elastic modulus and hardness as a function of temperature. These tests showed that elastic modulus and hardness decreased as the test temperature increased from 20 to 130 °C. Cu films exhibited higher hardness values compared to Au, a finding that is explained by the nanocrystalline structure of the film. Hardness was converted to the yield stress using both the Tabor relationship and the inverse method (based on the Johnson cavity model). The thermal component of the yield-stress dependence followed a second-order polynomial in the temperature range tested for Au and Pt/Cu films. The decrease in yield stress at elevated temperatures accounts for the increased interfacial toughness of Cu thin films.

Type
Articles
Copyright
Copyright © Materials Research Society 2004

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