Complementary metal oxide semiconductor (CMOS) ultrasonic transducers and methods for forming the same

• US 9,290,375 B2
• Filed: 05/13/2015
• Issued: 03/22/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: BFLY Operations, Inc. (Butterfly Network, Inc.)
• Original Assignee: Butterfly Network, Inc.
• Inventors: Rothberg, Jonathan M., Fife, Keith G., Ralston, Tyler S., Charvat, Gregory L., Sanchez, Nevada J.
• Primary Examiner(s): Smoot, Stephen W
• Application Number:
  US14/711,145
• Publication Number:
  US 20150251896A1
• Time in Patent Office: 314 Days
• US Class Current: 1/1
• CPC Class Codes: B06B 1/02 making use of electrical energy B06B1/18, B06B1/20 take precedence
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00134 comprising flexible or deformable structures manufacture of MEMS devices for specific applications, see relevant places, e.g. gyroscopes G01C19/5719, pressure sensors G01L9/0042, accelerometers G01P15/0802, acoustic transducers or diaphragms therefor H04R31/00
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 2201/0195 the layer being unstructured
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: B81C 2203/0771 Stacking the electronic processing unit and the micromechanical structure
• CPC Class Codes: G01N 29/2406 Electrostatic or capacitive probes, e.g. electret or cMUT-probes
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H04R 19/005 using semiconductor materials

Abstract

Complementary metal oxide semiconductor (CMOS) ultrasonic transducers (CUTs) and methods for forming CUTs are described. The CUTs may include monolithically integrated ultrasonic transducers and integrated circuits for operating in connection with the transducers. The CUTs may be used in ultrasound devices such as ultrasound imaging devices and/or high intensity focused ultrasound (HIFU) devices.

Claims

1. An apparatus, comprising:

a semiconductor wafer having a complementary metal oxide semiconductor (CMOS) integrated circuit;

a conductive membrane bonded with the semiconductor wafer such that a gap exists between a bonding surface of the semiconductor wafer and a first side of the conductive membrane proximate the bonding surface of the semiconductor wafer, the conductive membrane having a second side distal the bonding surface of the semiconductor wafer; and

a conductive standoff terminating on the first side of the conductive membrane proximate the bonding surface of the semiconductor wafer without extending through the conductive membrane such that a surface of the conductive standoff forms at least part of a bonding interface between the first side of the conductive membrane and the bonding surface of the semiconductor wafer, the conductive standoff electrically connecting the conductive membrane to the CMOS integrated circuit, and

wherein the apparatus lacks an electrode that is on the second side of the conductive membrane and that overlies the cavity.

2. The apparatus of claim 1, wherein the conductive membrane is a doped silicon layer.

3. The apparatus of claim 1, wherein the conductive standoff forms a closed contour surrounding the gap.

4. The apparatus of claim 1, wherein the conductive standoff is formed of titanium nitride (TiN).

5. The apparatus of claim 1, wherein the conductive standoff is formed of a metal.

6. The apparatus of claim 1, wherein the conductive membrane has a thickness less than thirty microns.