Piezoelectric device and production method for piezoelectric device

Patent metadata

Field	Value
Publication number	US-10700262-B2
Application number	US-201715600828-A
Country	US
Kind code	B2
Filing date	May 22, 2017
Priority date	Dec 8, 2014
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A piezoelectric resonator includes a piezoelectric thin film including a functional conductor, a fixing layer provided on a principal surface of the piezoelectric thin film to define a void that overlaps a functional portion region, and a support substrate on a principal surface of the fixing layer. A sacrificial layer is provided on a principal surface of a piezoelectric substrate and the fixing layer is provided on the principal surface of the piezoelectric substrate to cover the sacrificial layer. The support substrate is attached to a surface of the fixing layer and the piezoelectric thin film is peeled from the piezoelectric substrate. The functional conductor is provided on the piezoelectric thin film, a through hole is provided in the piezoelectric thin film to straddle a boundary between the fixing layer and the sacrificial layer, and the sacrificial layer is removed by wet etching using the through hole to form the void.

First claim

What is claimed is:

1. A piezoelectric device comprising:
a piezoelectric film including a through hole provided in a thickness direction;
a functional conductor provided on the piezoelectric film;
a fixing layer provided on a principal surface of the piezoelectric film such that a void overlaps a region where the functional conductor is provided in plan view; and
a support substrate provided on a first principal surface of the fixing layer, the first principal surface being opposite to a second principal surface of the fixing layer which is a principal surface of the piezoelectric film side; wherein
the fixing layer includes a step provided in an inner wall surface of the fixing layer at a position overlapping the through hole in plan view.

2. The piezoelectric device according to claim 1 , wherein
the step is provided at a position between the second principal surface and a bottom of the fixing layer, in a direction of a thickness of the fixing layer; and
an angle of inclination of the step is different from an angle of inclination of the inner wall surface except for the step, in a cross-sectional view.

3. The piezoelectric device according to claim 1 , wherein the functional conductor includes functional conductors disposed to define an interdigital transducer.

4. The piezoelectric device according to claim 3 , wherein the multiple functional conductors are electrically connected to wiring conductors provided on a front surface of the piezoelectric film.

5. The piezoelectric device according to claim 4 , wherein the wiring conductors are provided on the front surface of the piezoelectric film to not overlap the void.

6. The piezoelectric device according to claim 4 , wherein the multiple functional conductors and the wiring conductors are made of Al, Cu, or Au.

7. The piezoelectric device according to claim 1 , wherein a plurality of the through holes are provided.

8. The piezoelectric device according to claim 7 , wherein the plurality of the through holes are provided at an outermost boundary of a periphery of the void.

9. The piezoelectric device according to claim 1 , wherein the step is located at an off-center position in the through hole.

Assignees

• Murata Manufacturing Co

Inventors

• Kishimoto Yutaka

Classifications

• H03H3/02 Primary

  for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) · CPC title

• H10N30/086

  by polishing or grinding · CPC title

• H10N30/082 Primary

  by etching, e.g. lithography · CPC title

• H10N30/202

  using longitudinal or thickness displacement combined with bending, shear or torsion displacement · CPC title

• H10N30/05

  Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes · CPC title