Study on AIN-based hybrid bulk acoustic wave resonator with low temperature coefficient of frequency

In this paper, we study the device physics and device structure design for hybrid bulk acoustic wave resonator (hybrid resonator), which is a new type bulk acoustic resonator formed by the combination of traditional film bulk acoustic wave resonator (FBAR) and solidly mounted resonator (SMR) device structure by Mason model. The simulation results indicate that, compared with temperature-compensated FBAR (TC-FBAR), the input impedance ratio (Ra/Rr) is increased by 120%, and the effective electromechanical coefficient (Kt2) is improved by 45%. Moreover, we study the impact of number of metal/SiO2 Bragg reflectors on the performance of hybrid resonators, and find that hybrid resonator with single Bragg reflector exhibits the best performance. Our simulation results indicate that AlN-based hybrid resonator is very promising for the design of high frequency filters, oscillators and sensors with low temperature coefficient of frequency.