# US 2014/0191619 A1 · Piezoelectric device and method for manufacturing piezoelectric device

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- Number: US 2014/0191619 A1
- Document ID: US20140191619A1
- Status: Published application
- Kind: A1
- Application number: 14/028,621
- Filed: 2013-09-17
- Published: 2014-07-10
- Earliest claimed: 2011-03-22
- Assignees: Murata Manufacturing Co., Ltd.
- Applicants: Murata Manufacturing Co., Ltd.
- Inventors: Korekiyo ITO; Takashi IWAMOTO
- Web page: https://patentgrep.com/patent/US20140191619A1

## CPC

- H10N 30/06: Forming electrodes or interconnections, e.g. leads or terminals
- H03H 3/08: for the manufacture of resonators or networks using surface acoustic waves
- H03H 9/02574: {of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate}
- H03H 9/02929: {of ageing changes of characteristics, e.g. electro-acousto-migration}
- H03H 9/14538: {Formation}
- H10N 30/067: Forming single-layered electrodes of multilayered piezoelectric or electrostrictive parts
- H10N 30/073: by fusion of metals or by adhesives
- H10N 30/8542: {Alkali metal based oxides, e.g. lithium, sodium or potassium niobates}
- H10N 30/877: {Conductive materials}
- H10W 72/012: {of bump connectors, dummy bumps or thermal bumps}
- Y10T 29/42: Piezoelectric device making
- Y10T 29/49005: Acoustic transducer
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a −C plane on a −Z axis side of the piezoelectric thin film, the −C plane on the −Z axis side of the piezoelectric thin film is etched. Thus, −Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the −Z planes of the piezoelectric thin film in the −Z axis direction such that the crystal growth plane thereof is parallel to the −Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the −Z axis direction such that the crystal growth plane thereof is parallel to the −Z planes of the piezoelectric thin film.

## Claims

### Claim 1

(canceled)

### Claim 2

A piezoelectric device comprising:
a support;
a piezoelectric thin film located on or over the support, the piezoelectric thin film being polarized along a +Z axis and a −Z axis that are crystal axes; and
an electrode located on a crystal plane of the piezoelectric thin film perpendicular to the −Z axis, the electrode including a crystal plane parallel to the crystal plane of the piezoelectric thin film.

### Claim 3 (depends on 2)

The piezoelectric device according to claim 2, further comprising a dielectric film between the support and the piezoelectric thin film.

### Claim 4 (depends on 2)

The piezoelectric device according to claim 2, wherein the electrode material is aluminum or an aluminum-based material.

### Claim 5 (depends on 3)

The piezoelectric device according to claim 3, wherein the electrode material is aluminum or an aluminum-based material.

### Claim 6 (depends on 4)

The piezoelectric device according to claim 4, wherein the electrode is arranged on the crystal plane of the piezoelectric thin film such that a (111) crystal plane of the aluminum is parallel to the crystal plane of the piezoelectric thin film.

### Claim 7 (depends on 5)

The piezoelectric device according to claim 5, wherein the electrode is arranged on the crystal plane of the piezoelectric thin film such that a (111) crystal plane of the aluminum is parallel to the crystal plane of the piezoelectric thin film.

### Claim 8 (depends on 2)

The piezoelectric device according to claim 2, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 9 (depends on 3)

The piezoelectric device according to claim 3, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 10 (depends on 4)

The piezoelectric device according to claim 4, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 11 (depends on 6)

The piezoelectric device according to claim 6, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 12

A method for manufacturing a piezoelectric device including a support and a piezoelectric thin film formed on or over the support and polarized along a +Z axis and a −Z axis that are crystal axes, the method comprising:
an etching step of, among a main surface on the +Z axis side of the piezoelectric thin film and a main surface on the −Z axis side of the piezoelectric thin film, etching the main surface on the −Z axis side of the piezoelectric thin film; and
an electrode-forming step of forming an electrode by epitaxially growing an electrode material on a crystal plane, exposed by the etching, of the piezoelectric thin film perpendicular to the −Z axis in the −Z axis direction such that a crystal growth plane thereof is parallel to the crystal plane of the piezoelectric thin film.

### Claim 13 (depends on 12)

The method for manufacturing a piezoelectric device according to claim 12, wherein the electrode material is aluminum or an aluminum-based material.

### Claim 14 (depends on 13)

The method for manufacturing a piezoelectric device according to claim 13, wherein the electrode is formed in the electrode-forming step by epitaxially growing the aluminum on the crystal plane of the piezoelectric thin film in the −Z axis direction such that a (111) crystal growth plane of the aluminum is parallel to the crystal plane of the piezoelectric thin film.

### Claim 15 (depends on 12)

The method for manufacturing a piezoelectric device according to claim 12, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 16 (depends on 13)

The method for manufacturing a piezoelectric device according to claim 13, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 17 (depends on 14)

The method for manufacturing a piezoelectric device according to claim 14, wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.

### Claim 18 (depends on 12)

The method for manufacturing a piezoelectric device according to claim 12, further comprising:
an ion implantation step of implanting an ionized element into a single-crystal piezoelectric substrate to form a region in which the concentration of the element implanted into the single-crystal piezoelectric substrate peaks; and
a splitting step of splitting off the piezoelectric thin film from the single-crystal piezoelectric substrate along the region in which the concentration of the implanted element peaks.

### Claim 19 (depends on 12)

The method for manufacturing a piezoelectric device according to claim 12, wherein the single-crystal piezoelectric substrate is a rotated Y-cut substrate.

### Claim 20 (depends on 19)

The method for manufacturing a piezoelectric device according to claim 19, wherein the single-crystal piezoelectric substrate has a cut angle of more than 90° and less than 270°.