CMOS ultrasonic transducers and related apparatus and methods

Patent metadata

Field	Value
Publication number	US-12569880-B2
Application number	US-202318523949-A
Country	US
Kind code	B2
Filing date	Nov 30, 2023
Priority date	Feb 5, 2013
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

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 for forming a complementary metal oxide semiconductor ultrasonic transducer, the method comprising:
removing a portion of a first layer disposed over a first wafer including an electrode structure and a conductive pillar, wherein the removal of the portion of the first layer exposes a surface of the conductive pillar; depositing a second layer over the first layer and the exposed surface of the conductive pillar; forming a cavity in the second layer over the electrode structure, the cavity having a sidewall formed from the second layer; and bonding a second wafer to the second layer to form a membrane over the cavity, wherein the second wafer and the second layer are doped with the same dopant.

2 . The method according to claim 1 , wherein the first layer is formed from an insulating material.

3 . The method according to claim 1 , wherein the second layer is formed from at least one of silicon, amorphous silicon, or polysilicon.

4 . The method according to claim 1 , wherein at least a portion of the second wafer is formed from at least one of silicon, amorphous silicon, or polysilicon.

5 . The method according to claim 1 , wherein the same dopant is at least one of nitrogen or phosphorus.

6 . The method according to claim 1 , wherein removing the portion of the first layer includes etching.

7 . The method according to claim 1 , wherein the second wafer includes a plurality of layers.

8 . The method according to claim 7 , wherein at least one layer of the plurality of layers of the second wafer and the second layer are doped with the same dopant.

9 . The method according to claim 1 , wherein the first wafer further includes processing circuitry configured to:
actuate the membrane to transmit an ultrasound wave; and detect a received ultrasound wave based on vibration of the membrane.

10 . A complementary metal oxide semiconductor (CMOS) ultrasonic transducer, comprising:
a first wafer including an electrode structure and a conductive pillar; a first layer disposed over the first wafer such that a surface of the conductive pillar is exposed through the first layer; a second layer disposed over the first layer and an exposed surface of the conductive pillar, the second layer having a cavity disposed over the electrode structure, the cavity having a sidewall formed from the second layer; and a second wafer bonded to the second layer forming a membrane over the cavity, wherein the second wafer and the second layer are doped with the same dopant.

11 . The CMOS ultrasonic transducer according to claim 10 , wherein the first layer is formed from an insulating material.

12 . The CMOS ultrasonic transducer according to claim 10 , wherein the second layer is formed from at least one of silicon, amorphous silicon, or polysilicon.

13 . The CMOS ultrasonic transducer according to claim 10 , wherein at least a portion of the second wafer is formed from at least one of silicon, amorphous silicon, or polysilicon.

14 . The CMOS ultrasonic transducer according to claim 10 , wherein the same dopant is at least one of nitrogen or phosphorus.

15 . The CMOS ultrasonic transducer according to claim 10 , wherein the second wafer includes a plurality of layers.

16 . The CMOS ultrasonic transducer according to claim 15 , wherein at least one layer of the plurality of layers of the second wafer and the second layer are doped with the same dopant.

17 . The CMOS ultrasonic transducer according to claim 10 , wherein the first wafer further includes processing circuitry configured to:
actuate the membrane to transmit an ultrasound wave; and detect a received ultrasound wave based on vibration of the membrane.

Assignees

• Bfly Operations 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

• G10K9/12

  electrically operated · CPC title

• B81C2203/0771

  Stacking the electronic processing unit and the micromechanical structure · CPC title

• B81C2203/0735

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

• B81C2203/0118

  Bonding a wafer on the substrate, i.e. where the cap consists of another wafer · CPC title