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Measuring substrate-independent modulus of thin films

Published online by Cambridge University Press:  03 March 2011

Jennifer Hay  and
Bryan Crawford
Jennifer Hay*
Affiliation:
Agilent Technologies, Oak Ridge, Tennessee 37830
Bryan Crawford
Affiliation:
Agilent Technologies, Oak Ridge, Tennessee 37830
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Substrate influence is a common problem when using instrumented indentation (also known as nano-indentation) to evaluate the elastic modulus of thin films. Many have proposed models to be able to extract the film modulus (Ef) from the measured substrate-affected modulus, assuming that the film thickness (t) and substrate modulus (Es) are known. Existing analytic models work well if the film is more compliant than the substrate. However, no analytic model accurately predicts response when the modulus of the film is more than double the modulus of the substrate. In this work, a new analytic model is proposed. This new model is shown by finite-element analysis to be able to accurately predict composite response over the domain 0.1 < Ef/Es < 10. Finally, the new model is used to analyze experimental data for compliant films on stiff substrates and stiff films on compliant substrates.

Keywords

Elastic propertiesThin filmNano-indentation
Type
Articles
Information
Journal of Materials Research , Volume 26 , Issue 6 , 28 March 2011 , pp. 727 - 738
Copyright
Copyright © Materials Research Society 2011

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