PIEZOELECTRIC THIN FILM DEVICE

Abstract

The present invention is directed to improving characteristics of a piezoelectric thin film device. A piezoelectric thin film filter including four film bulk acoustic resonators has a configuration where a filter section and a base substrate are bonded to each other via an adhesive layer, the filter section including a piezoelectric thin film which cannot stand up individually under its own weight, the flat base substrate mechanically supporting the filter section. As a piezoelectric material constructing the piezoelectric thin film, it is desirable to use a single-crystal material including no grain boundary, selected from crystal, lithium niobate, lithium tantalite, lithium tetraborate, zinc oxide, potassium niobate, and langasite.

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 piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators, which comprises: a single-crystal piezoelectric thin film; anda support for supporting a prescribed member including said piezoelectric thin film.

2. The piezoelectric thin film device according to claim 1, wherein said piezoelectric thin film includes no gain boundary.

3. The piezoelectric thin film device according to claim 1, wherein a single crystal constructing said piezoelectric thin film is selected from quartz crystal, lithium niobate, lithium tantalite, lithium tetraborate, zinc oxide, potassium niobate, and langasite.