# US 10,864,553 B2 · Piezoelectric transducers and methods of making and using the same

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- Number: US 10,864,553 B2
- Document ID: US10864553B2
- Status: Granted
- Kind: B2
- Application number: 15/540,008
- Filed: 2016-01-14
- Published: 2017-12-28
- Granted: 2020-12-15
- Earliest claimed: 2015-01-16
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Firas Sammoura; Sina Akhbari; Liwei Lin
- Web page: https://patentgrep.com/patent/US10864553B2

## CPC

- B06B 1/0603: {using a piezoelectric bender, e.g. bimorph}
- B06B 1/0622: {on one surface}
- H10N 30/05: Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
- H10N 30/081: by coating or depositing using masks, e.g. lift-off
- H10N 30/082: by etching, e.g. lithography
- H10N 30/2047: {Membrane type}
- H10N 30/308: {Membrane type}
- H10N 30/87: Electrodes or interconnections, e.g. leads or terminals
- H10N 30/871: {Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes}
- H10N 30/076: by vapour phase deposition
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Piezoelectric transducers are provided. The piezoelectric transducer includes a first piezoelectric layer, a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer, and a middle electrode layer disposed between the first and second piezoelectric layers, where the middle electrode layer includes an inner region and an outer region spaced apart from the inner region. Methods of making the piezoelectric transducers are also provided. The piezoelectric transducers and methods find use in a variety of applications, including devices, such as electronics devices having one or more (e.g., an array) of the piezoelectric transducers.

## Claims

### Claim 1

A piezoelectric transducer comprising:
a first piezoelectric layer;
a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer;
a middle electrode layer disposed between the first and second piezoelectric layers, wherein the middle electrode layer comprises an inner region and an outer region spaced apart from the inner region, wherein the outer region of the middle electrode layer surrounds the inner region of the middle electrode layer;
a first via configured to expose a portion of the inner region of the middle electrode layer;
a second via configured to expose a portion of the outer region of the middle electrode layer;
a bottom electrode layer disposed on a surface of the first piezoelectric layer opposite the middle electrode layer;
a support layer disposed on a surface of the bottom electrode layer opposite the first piezoelectric layer; and
a substrate on which at least a portion of the piezoelectric transducer is disposed.

### Claim 2 (depends on 1)

The piezoelectric transducer of claim 1, wherein the inner region and the outer region of the middle electrode layer are substantially coplanar.

### Claim 3 (depends on 2)

The piezoelectric transducer of claim 2, wherein the inner region of the middle electrode layer is circular.

### Claim 4 (depends on 3)

The piezoelectric transducer of claim 3, wherein the outer region of the middle electrode layer is annular.

### Claim 5 (depends on 1)

The piezoelectric transducer of claim 1, further comprising a top electrode layer disposed on a surface of the second piezoelectric layer opposite the middle electrode layer.

### Claim 6 (depends on 1)

The piezoelectric transducer of claim 1, wherein the first piezoelectric layer and the second piezoelectric layer have the same polarity.

### Claim 7 (depends on 1)

The piezoelectric transducer of claim 1, wherein the substrate comprises an opening through the substrate and a portion of the piezoelectric transducer is exposed through the opening.

### Claim 8 (depends on 1)

The piezoelectric transducer of claim 1, wherein the piezoelectric transducer has a diameter ranging from 10 μm to 5000 μm.

### Claim 9 (depends on 1)

The piezoelectric transducer of claim 1, further comprising a via exposing a portion of the bottom electrode.

### Claim 10 (depends on 1)

The piezoelectric transducer of claim 1, wherein the piezoelectric transducer is substantially planar.

### Claim 11 (depends on 1)

The piezoelectric transducer of claim 1, wherein the piezoelectric transducer is curved.

### Claim 12

A device comprising one or more piezoelectric transducers, each piezoelectric transducer comprising:
a first piezoelectric layer;
a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer;
a middle electrode layer disposed between the first and second piezoelectric layers, wherein the middle electrode layer comprises an inner region and an outer region spaced apart from the inner region, wherein the outer region of the middle electrode layer surrounds the inner region of the middle electrode layer;
a first via configured to expose a portion of the inner region of the middle electrode layer;
a second via configured to expose a portion of the outer region of the middle electrode layer;
a bottom electrode layer disposed on a surface of the first piezoelectric layer opposite the middle electrode layer;
a support layer disposed on a surface of the bottom electrode layer opposite the first piezoelectric layer; and
a substrate on which at least a portion of the piezoelectric transducer is disposed.

### Claim 13 (depends on 12)

The device of claim 12, wherein the device comprises an array of the piezoelectric transducers.

### Claim 14 (depends on 13)

The device of claim 13, wherein the array comprises 10 or more of the piezoelectric transducers.

### Claim 15

A method of directing sound waves to a target, the method comprising:
producing sound waves from a piezoelectric transducer comprising:
a first piezoelectric layer;
a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer;
a middle electrode layer disposed between the first and second piezoelectric layers, wherein the middle electrode layer comprises an inner region and an outer region spaced apart from the inner region, wherein the outer region of the middle electrode layer surrounds the inner region of the middle electrode layer;
a first via configured to expose a portion of the inner region of the middle electrode layer;
a second via configured to expose a portion of the outer region of the middle electrode layer;
a bottom electrode layer disposed on a surface of the first piezoelectric layer opposite the middle electrode layer;
a support layer disposed on a surface of the bottom electrode layer opposite the first piezoelectric layer; and
a substrate on which at least a portion of the piezoelectric transducer is disposed,
wherein the piezoelectric transducer is configured to direct the produced sound waves to the target.

### Claim 16 (depends on 15)

The method of claim 15, wherein the piezoelectric transducer further comprises a top electrode layer disposed on a surface of the second piezoelectric layer opposite the middle electrode layer.

### Claim 17 (depends on 15)

The method of claim 15, wherein the producing comprises applying voltages having opposite phase to the inner region and the outer region of the middle electrode layer.

### Claim 18 (depends on 15)

The method of claim 15, wherein the produced sound waves are ultrasound waves.