PIEZOELECTRIC THIN-FILM RESONATOR, FILTER USING THE SAME, AND DUPLEXER USING THE SAME

摘要

PURPOSE: A piezoelectric thin-film resonator, a filter and a duplexer thereof are provided to improve Q of FBAR(Film Bulk Acoustic Resonator) by establishing a region burying a air gap or an insulator to the edge of the bottom electrode or the upper electrode. CONSTITUTION: A bottom electrode(2) is formed on a substrate(1). A piezoelectric film(3) is formed on the bottom electrode. The upper electrode(4) is formed on piezoelectric film. A air gap(8) is formed to be ranged from the inner side of the facing area to the outside in order to cover the upper electrode and a boundary between the facing area of the bottom electrode and the outside. The air gap is formed in a part of the film thickness direction of the piezoelectric film. The air gap is formed by eliminating a part of the piezoelectric film.