Patent ID: 7230511
Filing Date: 2007-06-12
Classification: H03H

Abstract:
1. A thin film bulk acoustic resonator comprising: a piezoelectric film; a pair of electrodes between which the piezoelectric film is interposed; and a resonator portion including the electrodes and a region of the piezoelectric film between the electrodes, wherein the piezoelectric film includes an outer region extending outwards from at least a portion of a periphery of the resonator portion, and the outer region includes, in at least a portion thereof, an acoustic damping region for damping acoustic waves, and wherein the acoustic damping region, in the piezoelectric film, is composed of the same material as that of any other region of the piezoelectric film, and the acoustic damping region has a lower crystallinity than that of any other region of the piezoelectric film, and any element immediately underlying the acoustic damping region has a coarser surface than that of a lower one of the pair of electrodes of the resonator portion.