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The mechanical properties of freestanding electroplated Cu thin films

Published online by Cambridge University Press:  01 June 2006

Y. Xiang ,
T.Y. Tsui  and
J.J. Vlassak
Y. Xiang
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
T.Y. Tsui
Affiliation:
Texas Instruments, Inc., Dallas, Texas 75243
J.J. Vlassak*
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
*
a) Address all correspondence to this author. e-mail: vlassak@esag.deas.harvard.edu
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Abstract

The plane-strain bulge test is used to investigate the mechanical behavior of freestanding electroplated Cu thin films as a function of film thickness and microstructure. The stiffness of the films increases slightly with decreasing film thickness because of changes in the crystallographic texture and the elastic anisotropy of Cu. Experimental stiffness values agree well with values derived from single-crystal elastic constants and the appropriate orientation distribution functions. No modulus deficit is observed. The yield stress of the films varies with film thickness and heat treatment as a result of changes in the grain size of the films. The yield stress follows typical Hall-Petch behavior if twins are counted as distinct grains, indicating that twin boundaries are effective barriers to dislocation motion. The Hall-Petch coefficient is in good agreement with values reported for bulk Cu. Film thickness and crystallographic texture have a negligible effect on the yield stress of the films.

Keywords

CuFilmStress/strain relationship
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 6 , June 2006 , pp. 1607 - 1618
Copyright
Copyright © Materials Research Society 2006

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References

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