Effects of residual stress on the thin-film elastic moduli calculated from surface acoustic wave spectroscopy experiments

Published

February 23, 2005

Author(s)

R E. Kumon, Donna C. Hurley

Abstract

We have developed a method to examine how residual stress affects the values of the elastic moduli of thin films determined from surface acoustic wave spectroscopy experiments. Because the effective second-order elastic moduli in the stressed state are a function of the residual stress and second- and third-order elastic moduli, it is possible to solve for the second- and third- order elastic moduli given the effective moduli and stress. To illustrate our approach, we apply the method to the case of an elastically isotropic thin film under equibiaxial stress. The five test samples consist of TiN films deposited on crystalline Si, with each sample having a different thickness (287 to 3330 nm) and assumed equibiaxial compressive stress (5.4 to 0.5 GPa). With increasing thickness and decreasing stress, the effective second-order moduli C11 increase and C13 decrease. The second- order elastic moduli c11 and c13 and the third-order elastic moduli c111, c112, and c123 in the unstressed state are computed by fitting the model equations to the measured data. The results show how surface acoustic wave measurements may be analyzed to to obtain thin-film mechanical properties.

Citation

Thin Solid Films

Issue

484

Pub Type

Journals

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Keywords

acoustoelastic effect, elastic properties, surface acoustic waves, thin films

Citation

Kumon, R. and Hurley, D. (2005), Effects of residual stress on the thin-film elastic moduli calculated from surface acoustic wave spectroscopy experiments, Thin Solid Films, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50166 (Accessed December 3, 2024)