Microelectromechanical systems electret microphone

Patent metadata

Field	Value
Publication number	US-9736594-B2
Application number	US-201414561843-A
Country	US
Kind code	B2
Filing date	Dec 5, 2014
Priority date	Dec 5, 2014
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Microelectromechanical systems (MEMS) electret acoustic sensors or microphones, devices, systems, and methods are described. Exemplary embodiments employ electret comprising an inorganic dielectric material such as silicon nitride in MEMS electret acoustic sensors or microphones. Provided implementations include variations in electret acoustic sensor or microphone configuration and recharging of the electret.

First claim

What is claimed is:

1. A device, comprising:
a first electrode associated with a microelectromechanical systems (MEMS) electret acoustic sensor;
a second electrode associated with the MEMS electret acoustic sensor; and
an electret comprising an inorganic dielectric material, disposed on or associated with the first electrode or the second electrode, that stores a charge to provide a potential difference between the first electrode and the second electrode associated with the MEMS electret acoustic sensor.

2. The device of claim 1 , further comprising:
a charging component configured to recharge the electret based at least in part on a predetermined rate of decay of the potential difference.

3. The device of claim 2 , wherein the charging component is further configured to determine the charge on the electret based on the potential difference.

4. The device of claim 3 , wherein the charging component is further configured to charge the electret based at least in part on a determination that the potential difference is less than a predetermined threshold.

5. The device of claim 1 , wherein the first electrode comprises a stationary electrode comprising the electret.

6. The device of claim 5 , wherein the stationary electrode comprises a perforated backplate.

7. The device of claim 1 , wherein the second electrode comprises a movable membrane comprising the electret.

8. The device of claim 7 , wherein the movable membrane comprises a diaphragm consisting of the electret.

9. The device of claim 1 , wherein the inorganic dielectric material comprises at least one material selected from groups of materials comprising nitrides of silicon, oxides of silicon, nitrides of aluminum, or oxides of aluminum.

10. The device of claim 1 , wherein the first electrode comprises the electret and the second electrode comprises another electret.

11. A method, comprising:
forming an electret comprising an inorganic dielectric material on or associated with a first electrode or a second electrode associated with a microelectromechanical systems (MEMS) electret microphone; and
charging the electret to provide a potential difference between the first electrode and the second electrode associated with the MEMS electret microphone.

12. The method of claim 11 , further comprising:
recharging the electret based at least in part on at least one of a predetermined rate of decay of the potential difference, a fixed time interval, a determination that the potential difference is less than a predetermined threshold, or a sensed mode of operation of a device associated with the MEMS electret microphone.

13. The method of claim 11 , wherein the forming the electret comprises forming the electret comprising at least one material selected from groups of materials comprising nitrides of silicon, oxides of silicon, nitrides of aluminum, or oxides aluminum.

14. The method of claim 11 , wherein the forming the electret comprises forming the electret on a stationary electrode comprising the first electrode.

15. The method of claim 11 , wherein the forming the electret comprises forming the electret on a perforated backplate comprising the first electrode.

16. The method of claim 11 , wherein the forming the electret comprises forming the electret on a movable membrane comprising the second electrode.

17. The method of claim 11 , wherein the forming the electret comprises forming the electret as a diaphragm comprising the second electrode.

18. A system, comprising:
a microelectromechanical systems (MEMS) electret acoustic sensor comprising:
a first electrode;
a second electrode;
an electret comprising an inorganic dielectric material, disposed on or associated with the first electrode or the second electrode, that stores a charge to provide a potential difference between the first electrode and the second electrode; and

a charging component configured to intermittently recharge the electret.

19. The system of claim 18 , wherein the first electrode comprises a stationary electrode and the second electrode comprises a movable membrane.

20. The system of claim 18 , wherein the charging component is further configured to recharge the electret based at least in part on at least one of a predetermined rate of decay of the potential difference, a fixed time interval, a determination that the potential difference is less than a predetermined threshold, a sensed mode of operation of a device associated with the MEMS electret acoustic sensor.

Assignees

• Invensense Inc

Inventors

• Khenkin Aleksey S
• Daneman Mike

Classifications

• H04R19/016 Primary

  for microphones · CPC title

• B81B3/00

  Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes (B81B5/00 takes precedence) · CPC title

• H04R31/003

  for diaphragms or their outer suspension · CPC title

• H04R2201/003

  Mems transducers or their use · CPC title

• B81B3/0086

  Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage · CPC title