Modeling and simulation on film bulk acoustic resonator with silicon oxide temperature-compensated layer

The property of temperature-frequency drift has an effect on the passband ripples, center frequency and insertion loss of film bulk acoustic resonator (FBAR) filters, reducing the reliability of its electrical application. A temperature-frequency drift simulation of a typical Mo/AlN/Mo 3-layered FBAR is achieved using finite element analysis software ANSYS, and the simulated temperature coefficient of frequency is about －3510－6/℃ within the temperature range ［－50 ℃, 150 ℃］. By adding a SiO2 temperature compensated layer with positive temperature coefficient in the FBAR stacked films structure, the effects of the compensated layer thickness on temperature-frequency drift, resonant frequency and electromechanical coupling are analyzed. The simulated temperature-frequency coefficient of the FBAR stack with a SiO2 temperature compensated layer, which is composed of Mo/AlN/SiO2/Mo multi-layer films, is about 0.87210－6/℃, which shows significantly improved temperature stability compared to that without the temperature compensated layer.