The mechanical properties of freestanding electroplated Cu thin films


*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)peer-review

102 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1607-1618
Number of pages12
JournalJournal of Materials Research
Issue number6
Early online date1 Jun 2006
Publication statusPublished - Jun 2006
Externally publishedYes

Bibliographical note

Acknowledgments: We thank M.T. Perez-Prado for assistance with XRD, W. Moberly Chan for help with the TEM work, and Y-S. Jun for use of the AFM. Helpful discussions with J.W. Hutchinson and F. Spaepen are gratefully acknowledged. This research was funded by the National Science Foundation (Grant No. DMR-0133559) and by the MRSEC at Harvard University.


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