Capacitive Micromachined Ultrasonic Transducer

• US 20070167812A1
• Filed: 12/19/2006
• Published: 07/19/2007
• Est. Priority Date: 09/15/2004
• Status: Active Grant

• Current Assignee: Sonetics Ultrasound, Inc.
• Original Assignee: Sonetics Ultrasound, Inc.
• Inventors: Rich, Collin, Lemmerhirt, David
• Granted Patent: US 8,658,453 B2
• Time in Patent Office: Days
• US Class Current: 600/459
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type

Abstract

The first integrated circuit/transducer device 36 of the handheld probe includes CMOS circuits 110 and cMUT elements 112. The cMUT elements 112 function to generate an ultrasonic beam, detect an ultrasonic echo, and output electrical signals, while the CMOS circuits 110 function to perform analog or digital operations on the electrical signals generated through operation of the cMUT elements 112. The manufacturing method for the first integrated circuit/transducer device 36 of the preferred embodiment includes the steps of depositing the lower electrode S102; depositing a sacrificial layer S104; depositing a dielectric layer S106; removing the sacrificial layer S108, followed by the steps of depositing the upper electrode S110 and depositing a protective layer on the upper electrode S112.

Claims

1. An integrated circuit/transducer device, comprising:

a substrate;

a complementary-metal-oxide-semiconductor (CMOS) circuit fabricated on the substrate;

a first capacitive micromachined ultrasonic transducer (cMUT) element fabricated on the substrate and connected to the CMOS circuit, wherein the cMUT element includes a lower electrode adapted to maintain a first electrical potential, an upper electrode adapted to maintain a second electrical potential, and a cavity between the lower electrode and the upper electrode; and

a second capacitive micromachined ultrasonic transducer (cMUT) element fabricated on the substrate, wherein the cMUT element includes a lower electrode adapted to maintain a first electrical potential, an upper electrode adapted to maintain a second electrical potential, and a cavity between the lower electrode and the upper electrode, with each of these layers corresponding to a layer used in the fabrication of the CMOS circuit;

wherein the upper electrode of the first cMUT element and the upper electrode of the second cMUT element are electronically coupled.

2. The device of claim 1 wherein the lower electrode is metal.

3. The device of claim 1 wherein the lower electrode is polysilicon.

4. The device of claim 1, further comprising a dielectric layer, wherein the upper electrode is disposed on the dielectric layer and adjacent the cavity.

5. The device of claim 4, wherein the upper electrode seals the cavity.

6. The device of claim 1 further comprising a protective layer disposed on the upper electrodes of the first cMUT element and the second cMUT element.

8. A method of producing an integrated circuit/transducer device, the method comprising the steps of:

providing a substrate;

fabricating a complementary-metal-oxide-semiconductor (CMOS) circuit on the substrate;

fabricating a capacitive micromachined ultrasonic transducer (cMUT) element on the substrate and connecting the cMUT element to the CMOS circuit, wherein the cMUT element includes a lower electrode, a dielectric layer, and a sacrificial layer located between the lower electrode and the dielectric layer, with each of these layers corresponding to a layer used in the fabrication of the CMOS circuit;

removing the sacrificial layer thereby defining a cavity between the lower electrode and the dielectric layer; and

depositing an upper electrode on the dielectric layer thereby sealing the cavity.

7. The device of claim 10 wherein the protective layer is oxynitride.

9. The method of claim 8, wherein the step of depositing an upper electrode on the dielectric layer follows the step of removing the sacrificial layer.

10. The method of claim 9, further comprising the steps of:

fabricating a second capacitive micromachined ultrasonic transducer (cMUT) element on the substrate, wherein the second cMUT element includes a lower electrode, a dielectric layer, and a sacrificial layer located between the lower electrode and the dielectric layer; and

removing the sacrificial layer of the second cMUT element thereby defining a cavity between the lower electrode and the dielectric layer;

wherein the step of depositing an upper electrode on the dielectric layer includes depositing an upper electrode on the dielectric layer of the first cMUT element and the dielectric layer of the second cMUT element.

11. The method of claim 10, wherein the upper electrode is metal.

12. The method of claim 10, further comprising the step of depositing a protective layer on the upper electrode.

13. The method of claim 12, further comprising thinning the protective layer to produce the capacitive micromachined ultrasonic transducer structure.