Patent ID: 7649304

Claim:
A piezoelectric resonator comprising: a substrate including first and second main surfaces; and a laminated thin film including a first thin film portion and a second thin film portion, the first thin film portion being disposed on the first main surface of the substrate and supported by the substrate, the second thin film portion being spaced apart from the first main surface of the substrate and acoustically isolated from the substrate; wherein the second thin film portion of the laminated thin film includes a piezoelectric thin film, a first electrode disposed on one main surface of the piezoelectric thin film, and a second electrode disposed on another main surface of the piezoelectric thin film and being larger than the first electrode, and a portion in which the first and second electrodes overlap each other with the piezoelectric thin film disposed therebetween defines a piezoelectric vibrating portion; the piezoelectric resonator further comprising: a mass adding film disposed around the first electrode and on at least one portion of an outer region of the first electrode extending outward from a periphery of the piezoelectric vibrating portion; and a step forming film disposed on the first electrode and arranged within the periphery of the piezoelectric vibrating portion with a gap therebetween; wherein the second electrode is arranged so as to extend beyond the piezoelectric vibrating portion to a region in which the mass adding film is disposed.