With rapid development in mobile technology, film bulk acoustic resonators have developed in a high frequency and wide bandwidth direction.This study focuses on the technological process of back cavity etching and a lateral exciting film bulk acoustic resonator on the POI (LiNbO3/SiO2/Si).On the study of the IDT optical lithography, etching and back cavity corrosion, the critical process parameters are determined.The frequency response curve shows that resonance and antiresonance frequencies were 4 565 and 5 035 MHz, respectively.The effective electromechanical coupling coefficient was 20.86%, which is significant for research on high frequency and wide bandwidth film bulk acoustic resonators.