Influence of residual stress on the determination of Young’s modulus for SiO2 thin film by the surface acoustic waves

The surface acoustic wave (SAW) technique is attractive for nondestructive mechanical determination of thin films. In this paper, the influence of residual stress on the Young's modulus determination for SiO2 thin film is discussed. The residual stress model is established by introducing the E-eff (effective elastic constants) into the ideal model. When SAWs propagate along the Si[110] and [100] direction, the dispersion curves obtained from ideal SAW model and residual stress model are compared, respectively. The ratio (Delta E-f/E-f) is used to judge the impact. The modified formula for the Young's modulus value determined by the ideal model is calculated. The scope of the application of the ideal SAW model is obtained, where the influence of residual stress could be safely ignored. This study indicates that the influence of residual stress on the determination of Young's modulus for SiO2 thin film by SAWs are small, and it can be ignored or revised. (C) 2019 The Japan Society of Applied Physics