| abstract |
A method of manufacturing an FBAR filter device comprising an array of resonators, each resonator comprising a single crystal piezoelectric film sandwiched between first and second electrodes, wherein the first electrode is supported by a support film on an air cavity, the air cavity being embedded in a silicon dioxide layer on a silicon handle, with through silicon vias passing through the silicon handle and into the air cavity, the side walls of the air cavity in the silicon dioxide layer being defined by boundary trenches which are resistant to a silicon dioxide etchant. |