FBAR Resonators with Sufficient High Q for RF Filter Implementation

Abstract

Film Bulk Acoustic Wave Resonators (FBAR) at 2.6GHz using AlN piezoelectric material have been fabricated and characterized in this work. A stack of Al bottom electrode, AlN layer and top Al electrode is used to excite the thickness extensional (TE) vibration mode. The FBAR resonator has a quality factor of about 400 and the piezoelectric coupling coefficient of 4.25%, which is critical for RF filter implementation. Moreover, FBAR resonator has been designed to suppress spurious modes in order to ensure higher quality factor. Different filter topologies of ladder/lattice architecture are then explored for effective implementation using several FBAR resonators to build band-pass RF filters.