Patent ID: 7795692

Claim:
A resonator comprising: a substrate; and a resonating unit divided into an active region that causes resonances and a non-active region that does not cause resonances, and having a first electrode, a piezoelectric film, and a second electrode layered in turn on the substrate, wherein each of the first electrode and the second electrode have an active region portion and a non-active region portion, at least one of the first and the second electrodes is formed, so that at least a portion of the non-active region portion of the at least one of the first and the second electrodes has a thickness different from that of the active region portion of the at least one of the first and the second electrodes, respectively, the active region is a portion of the resonator in which all of the first electrode, the piezoelectric film, and the second electrode are overlapped in a vertical direction over an air cavity, a non-active region is another portion of the resonator where the piezoelectric film and the second electrode are overlapped outside of the active region in the vertical direction of the resonator, and the piezoelectric film is disposed on the first electrode and the air cavity, so that the air cavity at an upper surface thereof is covered by the piezoelectric film and the air cavity at side surfaces thereof is covered by piezoelectric film, the air cavity being surrounded by the piezoelectric film.