A Piezoelectric Composite Resonator Consisting of a ZnO Film on an Anisotropically Etched Silicon Substrate

Abstract

A thickness-mode piezoelectric composite resonator consisting of a ZnO film on a silicon substrate was studied. The relation between the effective electromechanical coupling factor and the ratio of the substrate thickness to the piezoelectric-film thickness was theoretically analyzed. In order to obtain a lower-order overtone composite resonator with high electromechanical coupling, a thin diaphragm structure fabricated by anisotropic etching of a silicon wafer was utilized as a substrate. An effective electromechanical coupling factor of 8.9% was experimentally obtained for the 2nd overtone mode.