Resonant Inc.
SUBSTRATE PROCESSING AND MEMBRANE RELEASE OF TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATOR USING A SACRIFICIAL TUB

Abstract:

An acoustic resonator device is formed using a sacrificial layer and a front side etched cavity by forming a recess in a silicon substrate with a trap-rich top layer and filling the recess with sacrificial silicon nitride. A bonding oxide (BOX) layer is formed over the trap-rich layer and the sacrificial silicon nitride filled recess and a piezoelectric plate is bonded to the BOX layer. The sacrificial silicon nitride is then removed to form a cavity by using an etchant introduced through holes in the piezoelectric plate and BOX layer without removing the BOX layer from over the cavity.