PZT Thin-Film Meso- and Micro Devices

This paper consists of three major topics. The first topic is a review of challenges encountered in PZT thin film fabrication. Currently, sol-gel processing is one of the most promising techniques to fabricate PZT thin films. There are, however, several major challenges, including crack formation, thermally unstable electrodes, and poor piezoelectric properties. The second topic reveals some innovative fabrication processes that could substantially enhance quality of PZT thin films. For example, use of dilute sealant layer and rapid thermal annealing can lead to PZT films with large crack-free area. Use of sol electrophoretic deposition can enhance piezoelectric properties and thickness of PZT films simultaneously. Use of sol electrophoresis and soft lithography can directly pattern PZT films without etching. The third topic is design considerations encountered in the development of PZT thin-film microactuators. For example, one needs to confirm that the corner frequency of the PZT RC-circuit is much higher than the lowest natural frequency of the actuator's mechanical structure, so that the bandwidth and quality factor will not be sacrificed. Also, accuracy of finite element analyses cannot be readily assumed, because uncertainties in piezoelectric constants and boundary conditions can significantly alter the predictions from the finite element analyses.