Residual stresses in Pt bottom electrodes for sol-gel derived lead zirconate titanate thin films

Residual stresses in Pt bottom electrodes for MEMS multilayer structures comprised of PZT thin films were investigated by measuring the changes in radius of wafer curvature. The Pt bottom electrodes were compressive under sputtering but changed to tension after the subsequent annealing of PZT film. This tension increased with the increase in the thickness of PZT film. Furthermore, when the PZT film was chemically etched the stresses in the Pt bottom electrodes decreased compared with after the first coating of PZT film. Therefore, the stresses in Pt bottom electrodes were changed due to the subsequent PZT coating. Thermal stress and other factors like lattice parameters, crystallite dimension and diffusion, are thought to contribute the change in the stresses.