Fabrication and characterization of PZT thin films for micromotors

Piezoelectric membranes consisting of PbZr_xTi_1-xO₃ (PZT) films on silicon diaphragms have been fabricated, investigated, and applied for micromotors. The PZT films were deposited by sputtering and sol gel techniques. Resonance amplitudes of up to 1000 nm/V have been measured for 16 μm thick, 2 mm diameter membranes with 0.6 μm PZT. The PZT films show a preferred direction of polarization, which seems to depend on the deposition technique. Membranes of 4 mm diameter have been successfully applied as a vibrator of a micro motor, allowing for the first time the characterization of a PZT thin film micro motor. The motor could be operated with voltages as low as 1.0 Vrms, which is much less than has been obtained with ZnO micro motors and is sufficiently low for standard battery and IC supply voltages. A 100 h degradation test of frequency and amplitude has revealed a 5 % drop in amplitude, possibly due to depolarization.