Abstract: A filter package comprising an array of piezoelectric films sandwiched between lower electrodes and an array of upper electrodes covered by an array of silicon membranes with cavities thereover: the lower electrode being coupled to an interposer with a first cavity between the lower electrodes and the interposer; the array of silicon membranes having a known thickness and attached over the 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 SiO2; 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.

Abstract: A single crystal membrane of BaxSr(1-x)TiO3 (BST) has been fabricated for the first time using molecular beam epitaxy. The membrane typically has a thickness of 200 nm to 500 nm and the thickness may be controlled to within 1%. It may be fabricated on a sapphire wafer carrier from which it may subsequently be detached. The smoothness of the membrane has an RMS of less than 1 nm. This membrane is very promising for the next generation of RF filters.

Abstract: A method of fabricating an RF filter comprising an array of resonators comprising the steps of: Obtaining a removable carrier with release layer; Growing a piezoelectric film on a removable carrier; Applying a first electrode to the piezoelectric film; Obtaining a backing membrane on a cover, with or without prefabricated cavities between the backing film and cover; Attaching the backing membrane to the first electrode; Detaching the removable carrier; Measuring and trimming the piezoelectric film as necessary; Selectively etching away the piezoelectric layer to fabricate discrete resonator islands; Etching down through coatings and backing membrane to a silicon dioxide layer between the backing membrane and the cover to form trenches; Applying a passivation layer into the trenches and around the piezoelectric islands; Depositing a second electrode layer over the piezoelectric film islands and surrounding passivation layer; Applying connections for subsequent electrical coupling to an interposer; Selective