Resonant Inc.
TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATORS WITH TWO-LAYER ELECTRODES WITH A WIDER TOP LAYER

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 piezoelectric plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm. The interleaved fingers comprise a first layer adjacent the diaphragm and a second layer over the first layer opposite the diaphragm, the second layer having a greater width than the first layer.