PIEZOELECTRIC THIN FILM RESONATOR

Abstract

A piezoelectric thin film resonator includes a substrate, and a resonator section formed above the substrate and having a first electrode layer, a piezoelectric layer and a second electrode layer in which acoustic vibration is generated in a thickness direction of the piezoelectric layer by application of an electric field to the piezoelectric layer by the first electrode layer and the second electrode layer, wherein at least one pair of sides of a plane configuration of the resonator section are in parallel with each other, and the shortest distance in a spacing between the parallel sides in the pair is less than a thickness of at least the resonance section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a piezoelectric thin film resonator in accordance with a first embodiment of the invention.

FIG. 2 is a cross-sectional view schematically showing the piezoelectric thin film resonator in accordance with the first embodiment.

FIGS. 3A and 3B are plan views schematically showing a resonator of the piezoelectric thin film resonator in accordance with the first embodiment.

FIG. 4 is a cross-sectional view schematically showing a piezoelectric thin film resonator in accordance with a second embodiment of the invention.

FIGS. 5A and 5B are plan views schematically showing a resonator of the piezoelectric thin film resonator in accordance with the second embodiment.

FIG. 6 is a cross-sectional view schematically showing a piezoelectric thin film resonator in accordance with a third embodiment of the invention.

Claims

1. A piezoelectric thin film resonator comprising: a substrate; anda resonator section formed above the substrate and having a first electrode layer, a piezoelectric layer and a second electrode layer in which acoustic vibration is generated in a thickness direction of the piezoelectric layer by application of an electric field to the piezoelectric layer by the first electrode layer and the second electrode layer,wherein at least one pair of sides of a plane configuration of the resonator section are in parallel with each other, and the shortest distance in a spacing between the parallel sides in the pair is less than a thickness of at least the resonance section.

2. A piezoelectric thin film resonator according to claim 1, wherein the shortest distance is less than the thickness of the piezoelectric layer.

3. A piezoelectric thin film resonator according to claim 1, wherein the plane configuration of the resonator section is in a quadrilateral shape having a pair of narrow sides and a pair of wide sides.

4. A piezoelectric thin film resonator according to claim 3, wherein the pair of narrow sides are not in parallel with each other.

5. A piezoelectric thin film resonator according to claim 4, wherein the plane configuration of the resonator section does not have a two-fold axis of rotation or a plane of mirror symmetry.

6. A piezoelectric thin film resonator according to claim 1, wherein the resonator section is disposed inside a free vibration region in a plan view defined by an opening section formed in the substrate.

7. A piezoelectric thin film resonator according to claim 1, further comprising an acoustic multilayer film formed above the substrate, wherein the resonator section is formed above the acoustic multilayer film, and is disposed within a region in a plane of the acoustic multilayer film.