The Microscopic Origin of Residual Stress for Flat Self-Actuating Piezoelectric Cantilevers

In this study, flat piezoelectric microcantilevers were fabricated under low-stress Pb(Zr(0.52)Ti(0.48))O(3) (PZT) film conditions. They were analyzed using the Raman spectrum and wafer curvature methods. Based on the residual stress analysis, we found that a thickness of 1 μm was critical, since stress relaxation starts to occur at greater thicknesses, due to surface roughening. The (111) preferred orientation started to decrease when the film thickness was greater than 1 μm. The d(33) value was closely related to the stress relaxation associated with the preferred orientation changes. We examined the harmonic response at different PZT cantilever lengths and obtained a 9.4-μm tip displacement at 3 V(p-p) at 1 kHz. These analyses can provide a platform for the reliable operation of piezoelectric microdevices, potentially nanodevice when one needs to have simultaneous control of the residual stress and the piezoelectric properties.