METHOD FOR FABRICATING SINGLE CRYSTAL PIEZOELECTRIC RF RESONATORS AND FILTERS WITH IMPROVED CAVITY DEFINITION

A method of fabricating an FBAR filter device including an array of resonators, each resonator comprising a single crystal piezoelectric film sandwiched between a first metal electrode and a second metal electrode, wherein the first electrode is supported by a support membrane over an air cavity, the air cavity embedded in a silicon dioxide layer over a silicon handle, with through-silicon via holes through the silicon handle and into the air cavity, the side walls of said air cavity in the silicon dioxide layer being defined by perimeter trenches that are resistant to a silicon oxide etchant.