US Patent 11239816 Decoupled transversely-excited film bulk acoustic resonators

Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate having parallel front and back surfaces, the back surface attached to the substrate. A decoupling dielectric layer is on the front surface of the piezoelectric plate. An interdigital transducer (IDT) is formed over the decoupling dielectric layer such that interleaved fingers of the IDT are over a portion of the piezoelectric plate suspended across a cavity formed in the substrate.