An Acoustic Piezoelectric Ring-Shape Lamb Wave MEMS Resonator

This paper presents a novel micromechanical acoustic resonator based on the propagation of asymmetric Lamb wave in thin-film piezoelectric-on-silicon structure. The demonstrated structure is composed of four layers; Aluminum Nitride (AlN) as a piezoelectric layer, gold and platinum for electrodes on top and bottom of AlN layer respectively and an underlying polysilicon layer. The presented structure, composite bulk acoustic resonator (CBAR), utilizes the thickness vibration of the thin film. For studying the presented resonator, a prototype model structure is simulated and optimized at 318 MHz. The proposed electrodes are used to induce an asymmetric Lamb wave in the resonator. For this purpose, different electrode configurations are introduced and simulated in order to have less deformity in the structure. In order to achieve optimum operation in drive and sense mode, there is discussion about determination of the location of electrodes.