Mems acoustic sensor comprising a non-perimeter flexible member

Patent metadata

Field	Value
Publication number	US-2016264398-A1
Application number	US-201514642693-A
Country	US
Kind code	A1
Filing date	Mar 9, 2015
Priority date	Mar 9, 2015
Publication date	Sep 15, 2016
Grant date	—

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 substantially 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 spring coupled to a connecting structure, wherein the connecting structure is disposed between the backplate and the diaphragm, and the spring design determines the change in the distance between the diaphragm and the backplate.

2 . The MEMS acoustic sensor of claim 1 , wherein the backplate comprises the spring.

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

4 . The MEMS acoustic sensor of claim 1 , wherein the diaphragm comprises the spring.

5 . The MEMS acoustic sensor of claim 1 , wherein the backplate comprises the 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 substantially permanently connected to the stationary portion and disposed to protect the diaphragm.

10 . The MEMS acoustic sensor of claim 1 , 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 substantially 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 spring coupled to a post structure, wherein the post structure is disposed between the backplate and the diaphragm, and the spring 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 the spring.

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

16 . The method of claim 13 , wherein the backplate comprises the post structure.

17 . The method of claim 13 , wherein the diaphragm comprises the post structure.

18 . A method for fabricating a microelectromechanical system (MEMS) acoustic sensor, comprising:
forming a diaphragm disposed substantially 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 spring coupled to a post structure, wherein the post structure is disposed between the backplate and the diaphragm, and the spring is disposed so as to damp the change in the distance between the diaphragm and the backplate.

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

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

21 . The method of claim 18 , wherein the forming the diaphragm disposed substantially parallel to a backplate comprises forming the backplate comprising the post structure.

22 . The method of claim 18 , wherein the forming the diaphragm disposed substantially parallel to a backplate comprises forming the diaphragm comprising the post structure.

Assignees

• Invensense Inc

Inventors

• Bharatan Sushil
• Cagdaser Baris

Classifications

• B81B2203/0163

  Spring holders · CPC title

• B81B3/007 Primary

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

• B81C1/00658

  Treatments for improving the stiffness of a vibrating element · CPC title

• G01L9/0072 Primary

  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