Piezoelectric unimorph microcantilevers for measuring direct and converse piezoelectric coefficients

In this study, we propose a new piezoelectric measurement method using unimorph microcantilevers to evaluate precise values of direct and converse piezoelectric coefficients for piezoelectric microelectromechanical system applications. We fabricated unimorph microcantilevers comprising 3-μm-thick polycrystalline Pb(Zr,Ti)O3 (PZT) thin films on a 20-μm-thick silicon (Si) layer. The converse piezoelectric coefficient was measured as |e31,f| = 3.9–5.8 C/m2, which was in good agreement with the measurement results of PZT thin films without microfabrication. The direct piezoelectric properties of the PZT microcantilevers were measured at the resonance frequency of each microcantilever, and |e31,f| was ∼2 C/m2, which was consistent with previous reports on the piezoelectric properties of a PZT thin film on Si. Since the measurement results included the effects of the stress condition and microfabrication damage, the measurement method of this study can evaluate the actual piezoelectric coefficient of piezoelectric properties in microdevice structures.