MEMS microphone with low pressure region between diaphragm and counter electrode

Patent metadata

Field	Value
Publication number	US-9986344-B2
Application number	US-201514934340-A
Country	US
Kind code	B2
Filing date	Nov 6, 2015
Priority date	Jun 28, 2013
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A MEMS microphone includes a first diaphragm element, a counter electrode element, and a low pressure region between the first diaphragm element and the counter electrode element. The low pressure region has a pressure less than an ambient pressure.

First claim

What is claimed is:

1. A microelectromechanical system (MEMS) microphone comprising:
a first diaphragm element;
a second diaphragm element spaced apart from the first diaphragm element;
a low pressure region between the first diaphragm element and the second diaphragm element, the low pressure region having a pressure less than an ambient pressure;
a first counter electrode element disposed within the low pressure region; and
a ventilation hole which extends from the first diaphragm element to the second diaphragm element and is sealed off against the low pressure region, wherein the ventilation hole extends through the first counter electrode element.

2. The MEMS microphone according to claim 1 , wherein the pressure in the low pressure region is substantially a vacuum within a sealed cavity.

3. The MEMS microphone according to claim 1 , wherein the pressure in the low pressure region is less than about 50% of the ambient pressure.

4. The MEMS microphone according to claim 1 , wherein ventilation hole is formed by a channel between the first diaphragm element and the second diaphragm element.

5. The MEMS microphone according to claim 1 , wherein the first diaphragm element is electrically coupled to the second diaphragm element.

6. The MEMS microphone according to claim 1 , wherein the first diaphragm element is electrically isolated from the second diaphragm element.

7. The MEMS microphone according to claim 1 , wherein the microphone further comprises a second counter electrode element spaced apart from the first counter electrode element and disposed within the low pressure region.

8. The MEMS microphone according to claim 7 , wherein ventilation hole extends through the second counter electrode element.

9. The MEMS microphone according to claim 7 , wherein the first counter electrode element is electrically isolated from the second counter electrode element.

10. The MEMS microphone according to claim 1 , wherein the first diaphragm element has a diaphragm compliance of at least about 1 nm/Pa.

11. The MEMS microphone according to claim 1 , further comprising a hinge element coupled between the first diaphragm element and a support structure.

12. The MEMS microphone according to claim 11 , wherein the hinge element comprises a wall element configured to laterally confine the low pressure region.

13. The MEMS microphone according to claim 12 , wherein the wall element is coupled to the support structure so that the support structure participates in confining the low pressure region.

14. The MEMS microphone according to claim 12 , wherein the first counter electrode element is coupled to the support structure independently from the hinge element through at least one gap in the hinge element extending from the low pressure region to the support structure.

15. A microelectromechanical system (MEMS) microphone comprising:
a first diaphragm element;
a second diaphragm element spaced apart from the first diaphragm element;
a low pressure region disposed between the first diaphragm element and the second diaphragm element, the low pressure region having a pressure less than an ambient pressure;
a first counter electrode element disposed within the low pressure region;
a hinge element coupled between the first diaphragm element and a support structure, wherein the hinge element comprises a wall element configured to laterally confine the low pressure region; and
one or more pillars coupled between the first diaphragm element and the second diaphragm element, wherein the one or more pillars are electrically isolating.

16. The MEMS microphone of claim 15 , wherein the pressure in the low pressure region is substantially a vacuum within a sealed cavity.

17. The MEMS microphone of claim 15 , further comprises a second counter electrode element electrically isolated from the first counter electrode element and arranged in the low pressure region.

18. The MEMS microphone according to claim 15 , wherein at least two pillars of the one or more pillars are spaced apart from each other by a distance that varies between 5 μm and 20 μm.

19. The MEMS microphone of claim 15 , further comprising a third diaphragm element, the third diaphragm element having a stiffness which is less than the stiffness of the first diaphragm element or the stiffness of the second diaphragm element.

20. The MEMS microphone of claim 19 , wherein the third diaphragm element is coupled between a support structure and at least one of the first diaphragm element and the second diaphragm element.

21. The MEMS microphone of claim 20 , wherein the first counter electrode element is supported at the support structure independently from the third diaphragm element.

22. A microelectromechanical system (MEMS) microphone comprising:
a first diaphragm element;
a second diaphragm element spaced apart from the first diaphragm element;
a low pressure region disposed between the first diaphragm element and the second diaphragm element, the low pressure region having a pressure less than an ambient pressure;
a first counter electrode element disposed within the low pressure region; and
one or more pillars coupled between the first diaphragm element and the second diaphragm element, wherein the one or more pillars are electrically isolating.

Assignees

• Infineon Technologies Ag

Inventors

• Dehe Alfons
• Froemel Andreas

Classifications

• B81B2201/0264

  Pressure sensors · CPC title

• H04R23/006

  using solid state devices (solid state devices per se H10) · CPC title

• B81B2201/0257

  Microphones or microspeakers · CPC title

• H04R31/00

  Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor {(manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182)} · CPC title

• B81B3/0078

  Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075 · CPC title