Single crystal piezoelectric rf resonators and filters

Abstract

A filter package comprising an array of piezoelectric films comprising an array of mixed single crystals that each comprise doped Aluminum Nitride, typically AlGaN or ScAlN, that is sandwiched between an array of lower electrodes and an array of upper electrodes comprising metal layers and silicon membranes with cavities thereover: the array of lower electrodes being coupled to an interposer with a first cavity between the array of lower electrodes and the interposer; the array of silicon membranes having a known thickness and attached over the array of upper electrodes with an array of upper cavities, each upper cavity between a silicon membrane of the array and a common silicon cover; each upper cavity aligned with a piezoelectric film, an upper electrode and silicon membrane, the upper cavities having side walls comprising SiO; the individual piezoelectric films, their upper electrodes and silicon membranes thereover being separated from adjacent piezoelectric films, upper electrodes and silicon membranes by a passivation material.