# US 9,520,811 B2 · Capacitive micromachined ultrasonic transducer (CMUT) device with through-substrate via (TSV)

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- Number: US 9,520,811 B2
- Document ID: US9520811B2
- Status: Granted
- Kind: B2
- Application number: 13/779,376
- Filed: 2013-02-27
- Published: 2014-08-28
- Granted: 2016-12-13
- Earliest claimed: 2013-02-27
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Peter B. Johnson; Ira Oaktree Wygant
- Web page: https://patentgrep.com/patent/US9520811B2

## CPC

- B06B 1/0292: {Electrostatic transducers, e.g. electret-type}
- A61B 8/4483: {characterised by features of the ultrasound transducer}
- H02N 1/002: {Electrostatic motors}
- H02N 1/006: {of the gap-closing type (H02N1/004 takes precedence)}
- H02N 1/008: {Laterally driven motors, e.g. of the comb-drive type}
- B06B 2201/76: Medical, dental
- 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)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- H02N: ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR

## Abstract

A Capacitive Micromachined Ultrasonic Transducer (CMUT) device includes at least one CMUT cell including a first substrate having a top side including a patterned dielectric layer thereon including a thick and a thin dielectric region. A membrane layer is bonded on the thick dielectric region and over the thin dielectric region to provide a movable membrane over a micro-electro-mechanical system (MEMS) cavity. A through-substrate via (TSV) includes a dielectric liner which extends from a bottom side of the first substrate to a top surface of the membrane layer. A top side metal layer includes a first portion over the TSV, over the movable membrane, and coupling the TSV to the movable membrane. A patterned metal layer is on the bottom side surface of the first substrate including a first patterned layer portion contacting the bottom side of the first substrate lateral to the TSV.

## Claims

### Claim 1

A Capacitive Micromachined Ultrasonic Transducer (CMUT) device, comprising:
a CMUT cell including:
a substrate including a top side and a bottom side;
a dielectric layer over the top side of the substrate, the dielectric layer having a first region and a second region laterally surrounded by the first region and thinner than the first region, the first and second regions defining a cavity;
a membrane layer bonded directly on the first region of the dielectric layer and enclosing the cavity over the second region of the dielectric layer, the membrane layer including a movable membrane movable within the cavity;
a through-substrate via (TSV) penetrating the substrate, the dielectric layer, and the membrane layer, and the TSV positioned laterally away from the movable membrane, the TSV including a conductive filler extending from the bottom side of the substrate to be coplanar with the membrane layer; and
a metal layer contacting the conductive filler above the top side of the substrate, the metal layer extending laterally along the membrane layer and contacting the movable membrane.

### Claim 2 (depends on 1)

The CMUT device of claim 1, further comprising:
a dielectric passivation layer above the metal layer.

### Claim 3 (depends on 1)

The CMUT device of claim 1, further comprising:
a second CMUT cell;
a second metal layer contacting the conductive filler of the first CMUT cell below the bottom side of the substrate to couple the first CMUT cell to the second CMUT cell.

### Claim 4 (depends on 1)

The CMUT device of claim 1, wherein the membrane layer comprises a single crystal silicon material.

### Claim 5 (depends on 1)

The CMUT device of claim 1, wherein the conductive filler comprises copper and protruding from the bottom side of the substrate.

### Claim 6 (depends on 1)

The CMUT device of claim 1, wherein the substrate has a resistivity less than or equal to 0.1 Ω-cm.

### Claim 7 (depends on 1)

The CMUT device of claim 1, wherein said membrane layer is vacuum fusion bonded to the dielectric region.