Mechanical and Piezoelectric Behavior of Thin Film PZT Composites for MEMS Applications
The elastic and failure mechanical properties, the d31 piezoelectric coefficient and the effect of applied stress on the hysteresis curves of freestanding PZT composite films, comprised of SiO2, Pt, PZT and Pt, were measured from microscale tension specimens. The d31 coefficient was measured from the out-of-plane deflection of biased PZT specimens with dimensions similar to those of MEMS components. An analytical solution for the bending of a multilayered piezoelectric beam was used to compute a first estimate of d31 as 176±27 pm/V. The field induced inplane stress hysteresis loops were asymmetric at small in-plane stresses becoming of similar magnitude as the applied stress was increased beyond 300 MPa. Similarly, the intersection of the hysteresis loops shifted from negative to positive electric field at stresses larger than 150 MPa. The applied stress resulted in reduction of the hysteresis magnitude due to mechanical constraints imposed on 90° domain switching. The effect of high in-plane stress on domain switching was also the reason for the hysteretic non-linear stress-strain curves that were recorded for unbiased PZT films.
KeywordsResidual Stress Piezoelectric Coefficient Domain Switching Multilayer Beam Piezoelectric Behavior
Unable to display preview. Download preview PDF.
- 1.Polcawich, R., Judy, D., Pulskamp, J., Trolier-McKinstry, S., Dubey, M., “Advances in Piezoelectrically Actuated RF MEMS Switches and Phase Shifters”, Microwave Symposium IEEE/MTT-S International, pp. 2083-2086, 2007Google Scholar
- 4.Zhou, J., McMcollough, T., Mantell, S., Zurn, S., “Young's Modulus Measurement of Thin Film PZT”, Proceedings of 13 biennial Microelectronics symposium, pp. 153-157, 1999Google Scholar
- 7.Yagnamurthy, S., Chasiotis, I., Lambros, J., Polcawich, R., Pulskamp, J., Dubey, M., “Mechanical Properties of PZT Films and their Composites for RF-MEMS”, Proceedings of Society of Experimental Mechanics, Orlando, June 2008Google Scholar
- 11.Ong, R.J., Berfield, T.A., Sottos, N.R., Payne, D.A., “Sol-Gel derived Pb(Zr,Ti)O3 thin films: Residual stress and electrical properties”, Journal of the European Ceramic Society, 25, pp. 2247-2251, 2005Google Scholar
- 12.Berfield, T.A., Ong, R.J., Payne, D.A., Sottos, N.R., “Residual stress effects on piezoelectric response of sol-gel derived lead zirconate titanate thin films”, Journal of Applied Physics, 101 (2), 024102, 2007Google Scholar
- 17.Jaffe, B., Cook, W.R., Jaffe, H., “Piezoelectric Ceramics”, Academic Press London and Newyork, 1971Google Scholar