Piezoelectric resonator and preparation method thereof

The invention provides a preparation method of a piezoelectric resonator, and the method comprises the steps: providing a silicon-on-insulator substrate which comprises a first insulating layer, a first silicon layer, a second insulating layer and a second silicon layer which are sequentially stacked, the silicon-on-insulator substrate is provided with an anchor point region and a main body region, the acoustic impedance of the second insulating layer is different from the acoustic impedance of the first silicon layer and the acoustic impedance of the second silicon layer, and the acoustic impedance of the first insulating layer is different from the acoustic impedance of the first silicon layer; patterning the silicon-on-insulator substrate, and forming a groove in the main body region; bonding the silicon substrate on the surface of the silicon substrate on the insulator, which is provided with the groove, so as to be matched with the groove to form a cavity; forming a driving function layer on the second s