Origin of Compressive Residual Stress in Alkoxide Derived PbTiO3 Thin Film on Si Wafer

In this paper, we describe the estimation of residual stress in the alkoxide-derived lead titanate (PTO) thin film on Si substrate by X-ray diffraction (XRD) and Raman analyses. The residual stress that was estimated by XRD and Raman analyses was compressive, and the values obtained by both methods were nearly the same. The residual stress in the PTO thin film increased with decreasing film thickness. We also attempted to calculate the theoretical stress in PTO thin films with random orientation. From the theoretical calculations, the thermal stress that comes from the difference in the thermal expansion coefficient between the Si substrate and the PTO film is calculated to be tensile. On the other hand, the phase transition stress is calculated to be compressive. In addition, this compressive phase transition stress canceled out the tensile thermal stress.