Flexural plate wave excitation using bulk modes

Abstract

In this paper we present theoretical analysis and experimental verification of a method to excite standing flexural plate waves on silicon nitride thin films by using piezoelectric plates (PZT-4) attached to silicon bulk substrates. It is cost effective and compatible with membranes produced by any IC-process. In this method, the bulk modes of the silicon substrate are coupled to the membrane modes. Finite Element Method is used to analyze the longitudinal mode coupled to the membrane mode, and laser interferometer is used to measure the out-of-plane displacement of the membrane. The experimental results verified the mode shape of coupled longitudinal-membrane mode predicted by FEM calculated results, and further demonstrated that many bulk modes can be coupled to membrane modes.