PIEZOELECTRIC THIN FILM DEVICE AND METHOD FOR MANUFACTURING THE SAME

Abstract

In a piezoelectric thin film device of the present invention, the degree of flexibility is enhanced in selection of a piezoelectric material constituting a piezoelectric thin film and the crystal orientation in the piezoelectric thin film. A piezoelectric thin film filter, including four film bulk acoustic resonators, has a configuration where a filter section for providing a filter function of the piezoelectric thin film filter is bonded with a flat base substrate mechanically supporting the filter section via an adhesive layer. In manufacturing of the piezoelectric thin film filter, a piezoelectric thin film is obtained by performing removal processing on a piezoelectric substrate, but the piezoelectric thin film obtained by removal processing cannot independently stand up under its own weight. For this reason, a prescribed member including the piezoelectric substrate is previously bonded to the base substrate as a support prior to the removal processing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a piezoelectric thin film filter seen from the top;

FIG. 2 is a sectional pattern view along a cross section II-II of FIG. 1 seen from the front;

FIG. 3 is a sectional pattern view along a cross section III-III of FIG. 1 seen from the right;

FIG. 4 is a circuit diagram showing an electric connection state of four film bulk acoustic resonators included in the piezoelectric thin film filter;

FIG. 5 is a sectional pattern view of a film bulk acoustic resonator included in a piezoelectric thin film filter;

FIG. 6 is a sectional pattern view of the film bulk acoustic resonator included in the piezoelectric thin film filter;

FIG. 7 is a sectional pattern view showing how an assembly, formed by integrating a large number of piezoelectric thin film filters, is separated into individual piezoelectric thin film filters;

FIG. 8 is a view showing the flow of manufacture of the piezoelectric thin film filter according to Example 1;

FIG. 9 is a view showing the flow of manufacture of the piezoelectric thin film filter according to Example 1;

FIG. 10 is a sectional pattern view for explaining a depression formation process;

FIG. 11 is a sectional pattern view for explaining the depression formation process;

FIG. 12 is a sectional view showing a configuration of a conventional piezoelectric thin film device;

FIG. 13 is a sectional view showing the configuration of the conventional piezoelectric thin film device.

Claims

1. A method for manufacturing a piezoelectric thin film device that includes a single or a plurality of film bulk acoustic resonators, comprising: a production process for producing a prescribed member including a piezoelectric substrate;a bonding process for bonding the member to a support; anda removal process for performing removal processing on the piezoelectric substrate while keeping the member in the state of being bonded to the support, to obtain a piezoelectric thin film.

2. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein the removal process comprises a grinding process for performing grinding processing on the piezoelectric substrate.

3. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein the removal process comprises a polishing process for performing polishing processing on the piezoelectric substrate.

4. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein the bonding process bonds the member to the support by an adhesive agent.

5. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein the production process comprises a film formation process for forming a film that separates an excitation region of the piezoelectric thin film from the support in a prescribed region of the piezoelectric substrate which becomes a non-excitation region of the piezoelectric thin film.

6. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein the production process comprises a depression formation process for forming a depression that separates an excitation region of the piezoelectric thin film from the support in a prescribed region of the piezoelectric substrate which becomes an excitation region of the piezoelectric thin film.

7. The method for manufacturing a piezoelectric thin film device according to claim 1, further comprising a depression formation process for forming, prior to the bonding process, a depression that separates an excitation region of the piezoelectric thin film from the support in a prescribed region of the support which is opposed to the excitation region of the piezoelectric thin film.

8. The method for manufacturing a piezoelectric thin film device according to claim 1, wherein a thermal expansion coefficient of the piezoelectric thin film is the same as a thermal expansion coefficient of the support.

9. A piezoelectric thin film device that includes a single or a plurality of film bulk acoustic resonators, comprising: a prescribed member, including a piezoelectric thin film obtained by performing removal processing on a piezoelectric substrate;a support for supporting the member; andan adhesive layer for bonding the member and the substrate to each other.