Simulation of ZnO based film bulk acoustic resonator by modified Butterworth-Van Dyke model

Film bulk acoustic resonator model was investigated. This model was based on piezoelectric resonator formula and Butterworth-Van Dyke (BVD) model. Through simulation, the influences of piezoelectric film thickness and materials property and top electrode area on FBAR performance were studied. In the extended equivalent BVD model both the piezoelectric and the electrode layers were considered, and they have influence on resonant frequency and mass load effect. The modified BVD model includes equivalent capacitance and inductance of piezoelectric film and of top electrode layer, equivalent capacitance of bottom electrode layer, and equivalent capacitance and inductance of mass load film. Through this model the mass load effect can be proved close to the experimental data. Therefore, FBAR can be exploited as an acoustic-wave mass microbalance sensor. The theoretical predictions of resonant frequency and mass load effect were approximate well with the measurement results of ZnO based FBAR. The proposed model can be readily used in the FBAR design of micro-mass load sensor.