Resonant Inc.
TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATOR WITH ETCHED CONDUCTOR PATTERNS

Abstract:

An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having a back surface bonded to the substrate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate and has interleaved fingers on a diaphragm spanning a cavity in the substrate. An etch-stop layer is formed on the front surface of the piezoelectric plate between the interleaved fingers. A portion of the piezoelectric plate and the etch-stop layer form the diaphragm. The etch-stop layer is impervious to the etch process used to form the interleaved fingers. The etch-stop layer may be formed on the piezoelectric plate between but not under the interleaved fingers. In other cases, the etch-stop layer is formed on the piezoelectric plate between and under the interleaved fingers.