Resonant Inc.
Transversely-excited film bulk acoustic resonators with electrodes having a second layer of variable width

Abstract:

There is disclosed acoustic resonators and filter devices. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having front and back surfaces, the back surface attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The interleaved fingers include a first layer having a rectangular shape adjacent the diaphragm and a second layer over the first layer opposite the diaphragm, and wherein a width of the second layer varies along a length of each finger.