Transversely-excited film bulk acoustic resonator fabrication using wafer-to-wafer bonding

Abstract

An acoustic resonator device is formed using a wafer-to-wafer bonding process by etching recesses into a first surface of a piezoelectric substrate, a depth of the recesses greater than a target piezoelectric membrane thickness; then wafer-to-wafer bonding the first surface of the piezoelectric substrate to a handle wafer using a releasable bonding method. The piezoelectric substrate is then thinned to the target piezoelectric membrane thickness to form a piezoelectric plate and at least one conductor pattern is formed on the thinned piezoelectric plate. The side of the thinned piezoelectric plate having the conductor pattern is bonded to a carrier wafer using a metal-to-metal wafer bonding process and the handle wafer is removed.