# US 2022/0045262 A1 · Piezoelectric device

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- Number: US 2022/0045262 A1
- Document ID: US20220045262A1
- Status: Published application
- Kind: A1
- Application number: 17/507,858
- Filed: 2021-10-22
- Published: 2022-02-10
- Earliest claimed: 2019-05-17
- Assignees: Murata Manufacturing Co., Ltd.
- Applicants: Murata Manufacturing Co., Ltd.
- Inventors: Yutaka KISHIMOTO; Shinsuke IKEUCHI; Masayuki SUZUKI; Fumiya KUROKAWA
- Web page: https://patentgrep.com/patent/US20220045262A1

## CPC

- H10N 30/708: {Intermediate layers, e.g. barrier, adhesion or growth control buffer layers}
- H10N 30/01: Manufacture or treatment
- H10N 30/082: by etching, e.g. lithography
- H10N 30/2042: {Cantilevers, i.e. having one fixed end}
- H10N 30/306: {Cantilevers}
- H10N 30/871: {Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes}
- H10N 30/877: {Conductive materials}
- H10N 30/853: Ceramic compositions
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A piezoelectric device includes a base portion and an upper layer on an upper side of and supported by the base portion. The upper layer includes a membrane portion that does not overlap with the base portion in plan view. The membrane portion includes at least one piezoelectric layer sandwiched by electrode layers from a top and a bottom thereof. An intermediate layer is between a lower electrode and the base portion. The intermediate layer includes one or more individual layers, and an individual layer exposed as a lower surface of the membrane portion among the one or more individual layers includes a bent portion, which extends from the lower surface of the membrane portion to a lateral wall, on a boundary between a portion defining and functioning as the lower surface of the membrane portion and a portion overlapping with the base portion.

## Claims

### Claim 1

A piezoelectric device comprising:
a base portion; and
an upper layer on an upper side of the base portion and supported by the base portion; wherein
the upper layer includes a membrane portion that does not overlap with the base portion in plan view;
the membrane portion includes at least one piezoelectric layer sandwiched by electrode layers from a top and a bottom thereof;
an intermediate layer is between one of the electrode layers and the base portion, the one of the electrode layers being provided on a lower side of a lowest piezoelectric layer among the at least one piezoelectric layer; and
the intermediate layer includes one or more individual layers, and an individual layer exposed as a lower surface of the membrane portion among the one or more individual layers includes a bent portion, the bent portion extending from the lower surface of the membrane portion to a lateral wall in a sectional view, on a boundary between a portion defining and functioning as the lower surface of the membrane portion and a portion overlapping with the base portion.

### Claim 2 (depends on 1)

The piezoelectric device according to claim 1, wherein the lateral wall is inclined.

### Claim 3 (depends on 1)

The piezoelectric device according to claim 1, wherein at least one layer among the one or more individual layers is mainly made of silicon oxide.

### Claim 4 (depends on 1)

The piezoelectric device according to claim 1, wherein the membrane portion is configured to utilize a bending vibration.

### Claim 5 (depends on 1)

The piezoelectric device according to claim 1, wherein the intermediate layer exposed as a lower surface of the membrane portion among the one or more individual layers is a seed layer.

### Claim 6 (depends on 1)

The piezoelectric device according to claim 1, wherein the intermediate layer includes a single layer which is a seed layer.

### Claim 7 (depends on 6)

The piezoelectric device according to claim 6, wherein the seed layer includes at least one of AlN, ZnO, and PZT.

### Claim 8 (depends on 1)

The piezoelectric device according to claim 1, wherein the membrane portion is divided into a plurality of regions by a slit.

### Claim 9 (depends on 8)

The piezoelectric device according to claim 8, wherein the slit has an X shape.

### Claim 10 (depends on 1)

The piezoelectric device according to claim 1, wherein the intermediate layer includes a first SiO2 layer, a Si layer, and a second SiO2 layer.

### Claim 11 (depends on 10)

The piezoelectric device according to claim 10, wherein the second SiO2 layer includes the bent portion.

### Claim 12 (depends on 1)

The piezoelectric device according to claim 1, wherein the one of the electrode layers being provided on a lower side of a lowest piezoelectric layer among the at least one piezoelectric layer includes Mo or W.

### Claim 13 (depends on 1)

The piezoelectric device according to claim 1, wherein the intermediate layer includes a SiO2 layer and a Si layer.

### Claim 14 (depends on 13)

The piezoelectric device according to claim 13, wherein the Si layer includes the bent portion.