# US 10,770,646 B2 · Manufacturing method for flexible PMUT array

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,770,646 B2
- Document ID: US10770646B2
- Status: Granted
- Kind: B2
- Application number: 15/443,330
- Filed: 2017-02-27
- Published: 2017-09-07
- Granted: 2020-09-08
- Earliest claimed: 2016-03-01
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Donald William Kidwell, Jr.; Ravindra Shenoy; Jon Lasiter
- Web page: https://patentgrep.com/patent/US10770646B2

## CPC

- H10N 30/01: Manufacture or treatment
- A61B 8/4483: {characterised by features of the ultrasound transducer}
- H10N 30/06: Forming electrodes or interconnections, e.g. leads or terminals
- H10N 30/074: by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
- H10N 30/08: Shaping or machining of piezoelectric or electrostrictive bodies
- H10N 30/2047: {Membrane type}
- H10N 30/708: {Intermediate layers, e.g. barrier, adhesion or growth control buffer layers}
- H10N 30/872: {Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices}
- H10N 30/875: {Further connection or lead arrangements, e.g. flexible wiring boards, terminal pins}
- H10N 30/886: {Additional mechanical prestressing means, e.g. springs}
- H10N 39/00: Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
- B06B 1/0622: {on one surface}
- Y10T 29/42: Piezoelectric device making
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Techniques and structures are provided for manufacturing a flexible PMUT array. In one embodiment, a piezoelectric micromechanical ultrasonic transducer (PMUTs) array comprises a plurality of PMUTs, where each PMUT in the flexible array of PMUTs includes: a first polymer layer configured to support the PMUT, a mechanical layer configured to provide planarization to the PMUT, a first electrode, a second electrode, a piezoelectric layer configured to separate the first electrode and the second electrode, patterns on the first electrode, the piezoelectric material, and the second electrode configured to route electrical signals, and a cavity configured to adjust a frequency response of the PMUT.

## Claims

### Claim 1

A method of forming a flexible array of piezoelectric micromechanical ultrasonic transducers, comprising:
providing a carrier configured to support the flexible array of piezoelectric micromechanical ultrasonic transducers (PMUTs);
providing a release layer configured to adhere the flexible array of PMUTs to the carrier;
forming the flexible array of PMUTs over the release layer, comprising
for each PMUT in the flexible array of PMUTs,
laminating a first polymer layer configured to support the PMUT;
depositing a sacrificial material configured to pattern a cavity of the PMUT;
depositing a mechanical layer, wherein the mechanical layer includes a planarization layer configured to provide chemical mechanical planarization to the PMUT, or a mechanical membrane configured to provide stiffness to the PMUT and frequency response adjustment;
depositing a first electrode configured to be coupled to a circuit ground plane;
depositing a piezoelectric layer configured to separate the first electrode and a second electrode;
depositing the second electrode configured to be coupled to a signal; and
creating patterns on the first electrode, the piezoelectric material, and the second electrode configured to route control signals of the PMUT; and
removing the release layer to separate the flexible array of PMUTs from the carrier.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
depositing a passivation layer configured to encapsulate the first electrode, the piezoelectric layer and the second electrode;
etching contact vias configured to access the first electrode and the second electrode; and
depositing pads and/or a redistribution layer configured to route electrical signals to the first electrode and the second electrode.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
forming the cavity configured to adjust a frequency response of the PMUT.

### Claim 4 (depends on 3)

The method of claim 3, further comprising:
laminating a second polymer layer configured to encapsulate the first electrode, the piezoelectric layer and the second electrode; and
forming pattern vias configured to support signal access through the redistribution layer.

### Claim 5 (depends on 2)

The method of claim 2, further comprising:
laminating a second polymer layer configured to encapsulate the first electrode, the piezoelectric layer and the second electrode;
forming pattern vias configured to support signal access through the redistribution layer; and
separating the PMUT from the carrier.

### Claim 6 (depends on 5)

The method of claim 5, further comprising:
drilling a release via in the first polymer layer; and
forming the cavity configured to adjust a frequency response of the PMUT by removing the sacrificial material using the release via.

### Claim 7 (depends on 6)

The method of claim 6, further comprising:
laminating a fourth polymer layer configured to enclose the cavity.

### Claim 8 (depends on 2)

The method of claim 2, further comprising:
laminating a second polymer layer configured to encapsulate the first electrode, the piezoelectric layer and the second electrode;
patterning contact vias configured to access the first electrode and the second electrode; and
depositing pads and/or a redistribution layer configured to route electrical signals to the first electrode and the second electrode.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
forming the cavity configured to adjust a frequency response of the PMUT.

### Claim 10 (depends on 8)

The method of claim 8, further comprising:
laminating a third polymer layer configured to protect the PMUT;
forming pattern vias configured to support signal access through the redistribution layer;
separating the PMUT from the carrier;
drilling a release via in the first polymer layer; and
forming the cavity configured to adjust a frequency response of the PMUT by removing the sacrificial material using the release via.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
laminating a fourth polymer layer configured to enclose the cavity.

### Claim 12 (depends on 9)

The method of claim 9, further comprising:
laminating a third polymer layer configured to protect the PMUT; and
forming pattern vias configured to support signal access through the redistribution layer.