Lamb wave resonator and preparation method thereof, filter and communication equipment

The invention discloses a Lamb wave resonator, a preparation method thereof, a filter and communication equipment. The Lamb wave resonator comprises a sacrificial layer arranged on a substrate; the piezoelectric layer is arranged on the sacrificial layer, and the sacrificial layer is provided with a cavity; the interdigital electrode is arranged on the piezoelectric layer, and a device area formed by projection of the interdigital electrode in the stacking direction falls into the cavity; the release hole penetrates through the piezoelectric layer and is communicated with the cavity; the barrier wall is embedded into the piezoelectric layer and the sacrificial layer, and the barrier wall encloses a device area. Electric signals provided by the interdigital electrodes can excite sound waves under the piezoelectric effect of the piezoelectric layer. The cavity can limit propagation of sound waves on one side of the piezoelectric layer, and therefore it is guaranteed that more sound waves can be used for frequency selection of electric signals. According to the Lamb wave resonator, the supporting surface used for supporting the piezoelectric layer is independently formed at the end, away from the substrate, of the sacrificial layer, the flatness of the supporting surface is good, and therefore the bonding strength of the piezoelectric layer and the sacrificial layer is good, and the Lamb wave resonator has good structural stability.