Transversely-excited film bulk acoustic resonators with solidly mounted resonator (smr) pedestals

An acoustic resonator comprising:

• a substrate;
• a piezoelectric layer;
• an acoustic Bragg reflector between the substrate and the piezoelectric layer;
• a plurality of pedestals disposed between the acoustic Bragg reflector and the piezoelectric layer, the plurality of pedestals configured such that spaces are defined between adjacent pedestals of the plurality of pedestals and between the piezoelectric layer and the Bragg reflector;
• and
• an interdigital transducer (IDT) having a plurality of interleaved fingers the piezoelectric layer.

A filter device comprising:

• a plurality of acoustic resonators, at least one of the plurality of resonators having:
• a substrate having a top surface;
• a piezoelectric layer having a front surface and a back surface;
• an interdigital transducer (IDT) on the front surface of the piezoelectric layer;
• and
• an acoustic Bragg reflector between the top surface of the substrate and the back surface of the piezoelectric layer, the acoustic Bragg reflector comprising two or more layers,
• wherein at least one layer of the two or more layers of the acoustic Bragg reflector forms a plurality of pedestals that support the back surface of the piezoelectric layer, and
• wherein spaces are defined between adjacent pedestals of the plurality of pedestals.