Piezoelectric device

• US 8,450,904 B2
• Filed: 07/13/2011
• Issued: 05/28/2013
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Iwamoto, Takashi, Kando, Hajime
• Primary Examiner(s): San Martin, J.
• Application Number:
  US13/181,546
• Publication Number:
  US 20110266918A1
• Time in Patent Office: 685 Days
• Field of Search: 310/313
• US Class Current: 310/313.R
• CPC Class Codes: H03H 3/08 for the manufacture of resonators or networks using surface acoustic waves
• CPC Class Codes: H03H 9/02992 Details of bus bars, contact pads or other electrical connections for finger electrodes
• CPC Class Codes: H03H 9/059 consisting of mounting pads or bumps
• CPC Class Codes: H03H 9/25 Constructional features of resonators using surface acoustic waves devices for manipulating acoustic surface waves in general G10K11/36
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A piezoelectric device includes IDT electrodes and solves various problems resulting from the IDT electrodes. The piezoelectric device has a configuration in which a piezoelectric thin-film and a support are bonded together such that the piezoelectric thin-film is supported by the support. IDT electrodes and interconnect electrodes are provided on a surface of the piezoelectric thin-film that is located on the support side. The piezoelectric thin-film includes a region in which the IDT electrodes are provided and on which no support is provided but an opening is formed. This allows the IDT electrodes and the piezoelectric thin-film and the IDT electrode-formed region of the piezoelectric thin-film to not be in contact with the support, thereby defining a membrane including only the piezoelectric thin-film and the IDT electrodes as elements, the piezoelectric thin-film and the IDT electrodes being disposed therein and being important for properties of the piezoelectric device.

Claims

1. A piezoelectric device comprising:

a support;

a piezoelectric thin-film including opposed main surfaces and being supported by the support on a support side of the piezoelectric thin-film;

IDT electrodes located on the support side of the piezoelectric thin-film to define an IDT electrode region; and

a space located over the IDT electrode region of the piezoelectric thin-film that is located on the support side such that the IDT electrodes are not in contact with the support;

wherein

the piezoelectric thin-film is configured such that vibration displacements are generated on both of the opposed main surfaces of the piezoelectric thin-film when a charge is applied to the IDT electrodes; and

the IDT electrodes are located only on the support side of the piezoelectric thin-film such that no IDT electrodes are disposed on a side of the piezoelectric thin-film opposite to the support side.

2. The piezoelectric device according to claim 1, wherein a thickness of the support is greater than a thickness of the piezoelectric thin-film.

3. The piezoelectric device according to claim 1, wherein the support is made of one of Si, glass, or a piezoelectric material.

4. The piezoelectric device according to claim 1, wherein the support is made of a piezoelectric material having a linear expansion coefficient substantially equal to a linear expansion coefficient of the piezoelectric thin-film.

5. The piezoelectric device according to claim 1, wherein the support is disposed directly adjacent to the space such that no structural elements are disposed between the support and the space.