CMOS ultrasonic transducers and related apparatus and methods

Patent metadata

Field	Value
Publication number	US-9499392-B2
Application number	US-201414172383-A
Country	US
Kind code	B2
Filing date	Feb 4, 2014
Priority date	Feb 5, 2013
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

CMOS Ultrasonic Transducers and processes for making such devices are described. The processes may include forming cavities on a first wafer and bonding the first wafer to a second wafer. The second wafer may be processed to form a membrane for the cavities. Electrical access to the cavities may be provided.

First claim

What is claimed is:

1. A method comprising:
depositing a first conductive layer on a silicon wafer;
depositing a second conductive layer on the first conductive layer;
depositing a first layer of SiO 2 on the second conductive layer;
etching at least one cavity in the first layer of SiO 2 , a bottom surface of the at least one cavity corresponding to the second conductive layer;
depositing a second layer of SiO 2 on the first layer of SiO 2 ;
planarizing the second layer of SiO 2 ;
bonding a second wafer comprising silicon to the silicon wafer with a fusion bond;
thinning a backside of the second wafer distal the at least one cavity to form a membrane over the at least one cavity; and
depositing a third conductive layer on the membrane.

2. The method of claim 1 , wherein the first conductive layer comprises aluminum.

3. The method of claim 1 , wherein the second conductive layer comprises TiN.

4. The method of claim 1 , wherein depositing the first layer of SiO 2 is performed via TEOS.

5. The method of claim 1 , wherein the method does not involve any steps performed at higher than 450° C.

6. The method of claim 1 , wherein the silicon wafer has a complementary metal oxide semiconductor (CMOS) circuit formed therein, and wherein the method further comprises electrically connecting the third conductive layer to the CMOS circuit.

Assignees

• Butterfly Network Inc

Inventors

• Rothberg Jonathan M
• Fife Keith G
• Ralston Tyler S
• Charvat Gregory L
• Sanchez Nevada J

Classifications

• B81B7/0077

  Other packages not provided for in groups B81B7/0035 - B81B7/0074 · CPC title

• B81B2203/0315

  Cavities · CPC title

• B81B3/0021 Primary

  Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00) · CPC title

• B81C2203/0735

  Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit · CPC title

• G10K11/18

  Methods or devices for transmitting, conducting or directing sound (G10K11/02, G10K11/36 take precedence) · CPC title