MEMS acoustic sensor comprising a non-perimeter flexible member

Patent metadata

Field	Value
Publication number	US-9718671-B2
Application number	US-201514642693-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Mar 9, 2015
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

A micro electro-mechanical system (MEMS) acoustic sensor is disclosed. The acoustic sensor comprises a backplate and a diaphragm. The acoustic sensor further comprises a flexible member and optional spacer member disposed between the backplate and the diaphragm resulting in a gap between the backplate and the diaphragm. The gap can vary in response to impinging pressure on the diaphragm based on the design of the flexible member and resulting in a variable capacitance between the backplate and the diaphragm. The change in the gap can result in a change in an electrical characteristic associated with the variable capacitance and can be converted to an electrical output signal corresponding to the impinging pressure on the diaphragm. The flexible member can be part of the backplate or diaphragm.

First claim

What is claimed is:

1. A microelectromechanical system (MEMS) acoustic sensor comprising:
a diaphragm disposed parallel to a backplate, the disposition effecting a variable capacitance as measured between the diaphragm and the backplate as a function of a change in a distance between the diaphragm and the backplate resulting from an interaction with an impinging pressure wave; and
a flexible spacer member having a first end and a second end opposite and distal from the first end, wherein the first end of the flexible spacer member is disposed under and adjacent to the diaphragm and wherein the second end of the flexible spacer member is disposed above and adjacent to the backplate, and wherein the flexible spacer member determines the change in the distance between the diaphragm and the backplate.

2. The MEMS acoustic sensor of claim 1 , wherein the backplate is integrated with a spring.

3. The MEMS acoustic sensor of claim 1 , wherein the diaphragm comprises a connecting structure.

4. The MEMS acoustic sensor of claim 1 , wherein the diaphragm is integrated with a spring.

5. The MEMS acoustic sensor of claim 1 , wherein the backplate comprises a connecting structure.

6. The MEMS acoustic sensor of claim 1 , further comprising a stationary portion comprising the backplate.

7. The MEMS acoustic sensor of claim 6 , wherein the stationary portion comprises an aperture.

8. The MEMS acoustic sensor of claim 7 , wherein the backplate portion of the stationary portion comprises another aperture.

9. The MEMS acoustic sensor of claim 6 , further comprising a cover structure comprising an aperture, the cover structure permanently connected to the stationary portion and disposed to protect the diaphragm.

10. The MEMS acoustic sensor of claim 2 , wherein the spring comprises an elongated portion.

11. The MEMS acoustic sensor of claim 10 , wherein the elongated portion forms a portion of the spring formed in a serpentine manner.

12. The MEMS acoustic sensor of claim 1 , employed in a mobile device.

13. A method of transducing a pressure wave characteristic, comprising:
providing a microelectromechanical system (MEMS) acoustic sensor comprising a diaphragm disposed parallel to a backplate, the diaphragm and backplate forming a variable capacitor facilitating measurement of capacitance as a function of a change in a distance between the diaphragm and the backplate resulting from an interaction with an impinging pressure wave, and a flexible spacer member disposed between the backplate and the diaphragm and having a first end and a second end distal from the first end, wherein the first end of the flexible spacer member is disposed under and adjacent to the diaphragm, and wherein the second end of the flexible spacer member is disposed above and adjacent to the backplate, and the flexible spacer member damps the change in the distance between the diaphragm and the backplate; and
measuring a change in capacitance of the variable capacitor resulting from the interaction of the impinging pressure wave.

14. The method of claim 13 , wherein the backplate comprises a spring.

15. The method of claim 13 , wherein the diaphragm comprises a spring.

16. A method for fabricating a microelectromechanical system (MEMS) acoustic sensor, comprising:
forming a diaphragm disposed parallel to a backplate, the diaphragm and backplate forming a variable capacitor facilitating measurement of capacitance as a function of a change in a distance between the diaphragm and the backplate resulting from an interaction with an impinging pressure wave; and
forming a flexible spacer member disposed between the backplate and the diaphragm and having a first end and a second end distal from the first end, wherein the first end of the flexible spacer member is disposed under and adjacent the diaphragm, and wherein the second end of the flexible spacer member is disposed above and adjacent to the backplate.

17. The method of claim 16 , wherein the forming the diaphragm disposed parallel to a backplate comprises forming the backplate comprising a spring.

18. The method of claim 16 , wherein the forming the diaphragm disposed parallel to a backplate comprises forming the diaphragm comprising a spring.

19. The method of claim 16 , wherein the forming the diaphragm disposed parallel to a backplate comprises forming the backplate comprising the flexible spacer member.

20. The method of claim 16 , wherein the forming the diaphragm disposed parallel to a backplate comprises forming the diaphragm comprising the flexible spacer member.

Assignees

• Invensense Inc

Inventors

• Bharatan Sushil
• Cagdaser Baris

Classifications

• B81B2203/0163

  Spring holders · CPC title

• G01L9/003

  using variations in capacitance · CPC title

• B81B2203/0127

  Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function · CPC title

• G01L9/0072 Primary

  using variations in capacitance · CPC title

• B81B3/007 Primary

  For controlling stiffness, e.g. ribs · CPC title