MEMS device and process

Patent metadata

Field	Value
Publication number	US-9926189-B2
Application number	US-201715413608-A
Country	US
Kind code	B2
Filing date	Jan 24, 2017
Priority date	Jan 28, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

The application describes MEMS transducers and associated methods of fabrication. The MEMS transducer has a flexible membrane with a vent structure comprising a moveable portion which opens in response to a differential pressure across the membrane to provide a flow path through the membrane. At least one edge of the moveable portion comprises one or more protrusions and/or recesses in the plane of the moveable portion.

First claim

The invention claimed is:

1. A MEMS transducer comprising: a flexible membrane, the flexible membrane having a vent structure comprising a moveable portion, the vent structure having an equilibrium position at which the moveable portion is substantially in plane with the rest of the membrane, wherein in response to a differential pressure across the vent structure, the moveable portion deflects away from the plane of the membrane to reveal an aperture in the membrane, and wherein at least one edge of the moveable portion comprises one or more protrusions and/or recesses in the plane of the moveable portion.

2. A MEMS transducer as claimed in claim 1 , wherein the edge of the moveable portion comprises a first adjacent edge and has a shape that substantially compliments the shape of a second adjacent edge when the vent structure is at the equilibrium position, which second adjacent edge is an adjacent edge of another moveable portion and/or an adjacent edge of the membrane.

3. A MEMS transducer as claimed in claim 2 , wherein said first and second adjacent edges are defined by a channel which extends through a membrane.

4. A MEMS transducer as claimed in claim 3 , wherein the first and second adjacent edges comprises interdigitated edges.

5. A MEMS transducer as claimed in claim 1 , wherein the edge exhibits a sinusoidal, a square-wave, a triangle-wave, or a saw-tooth shape.

6. A MEMS transducer as claimed in claim 1 , wherein the edge is serrated.

7. A MEMS transducer as claimed in claim 1 , wherein the vent structure comprises a plurality of moveable portions which are connected to the outer periphery of the aperture in the membrane and which border each other at the equilibrium position in the plane of the membrane.

8. A MEMS transducer as claimed in claim 7 , wherein first and second edges are provided on two of the plurality of moveable portions.

9. A MEMS transducer as claimed in claim 8 , wherein at the equilibrium position the first and second adjacent edges are provided at a region of the moveable portion where the most deflection of the moveable portion is expected in response to a differential pressure across the membrane.

10. A MEMS transducer as claimed in claim 1 , wherein the density of the protrusions and/or recesses varies.

11. A MEMS transducer as claimed in claim 10 , wherein a higher density of protrusions and/or recesses is provided on an edge within a region of the moveable portion where the most deflection of the moveable portion is expected in response to a pressure differential across the membrane.

12. A MEMS transducer as claimed in the claim 1 , wherein the moveable portion of the flexible membrane is defined by one or more channels running through the flexible membrane.

13. A MEMS transducer as claimed in claim 1 , wherein each internal edge that is provided with a plurality of protrusions and/or recesses, is an edge of one said moveable portion and/or is an edge of the rest of the membrane.

14. A MEMS transducer as claimed in claim 1 , wherein each moveable portion deflects to provide a flow path through the membrane.

15. A MEMS transducer as claimed in claim 1 , wherein the vent structure adopts the equilibrium position when the pressure differential across the membrane is negligible, wherein at the equilibrium position the flow path through the vent structure is at a minimum.

16. A MEMS transducer as claimed in claim 1 , wherein the flexible membrane is supported between a first volume and a second volume and wherein the flow path is between the first and second volumes.

17. A MEMS transducer as claimed in claim 1 , wherein each moveable portion is generally triangular, square or rectangular in shape.

18. A MEMS transducer as claimed in claim 1 , wherein said moveable portion is connected to the rest of the flexible membrane via a beam structure.

19. A MEMS transducer as claimed in claim 1 , comprising a back-plate structure wherein the flexible membrane is supported with respect to said back-plate structure.

20. A MEMS transducer as claimed in claim 19 wherein said back-plate structure comprises a plurality of holes through the back-plate structure.

21. A MEMS transducer as claimed in claim 1 , wherein said transducer comprises a capacitive sensor.

22. A MEMS transducer as claimed in claim 1 , wherein said transducer comprises a microphone.

23. A MEMS transducer as claimed in claim 21 , further comprising readout circuitry.

24. An integrated circuit comprising a MEMS transducer as claimed in claim 1 and readout circuitry.

25. A MEMS transducer as claimed in claim 1 , wherein the transducer is located within a package having a sound port.

26. An electronic device comprising a MEMS transducer as claimed in claim 1 .

27. An electronic device as claimed in claim 26 wherein said device is at least one of: a portable device; a battery powered device; an audio device; a computing device; a communications device; a personal media player; a mobile telephone; a games device; and a voice controlled device.

28. A MEMS transducer comprising: a flexible membrane having a vent structure, the vent structure comprising a moveable portion which is separated from the rest of the membrane by a channel which extends through the membrane and defines a pair of adjacent internal edges, wherein at least one of the internal edges is provided with one or more protrusions or recesses.

29. A MEMS transducer as claimed in claim 28 , wherein each internal edge that is provided with a plurality of protrusions and/or recesses, is an edge of one said moveable portion and/or is an edge of the rest of the membrane.

30. A MEMS transducer as claimed in claim 28 , wherein each moveable portion deflects to provide a flow path through the membrane.

31. A MEMS transducer as claimed in claim 28 , wherein the vent structure adopts the equilibrium position when the pressure differential across the membrane is negligible, wherein at the equilibrium position the flow path through the vent structure is at a minimum.

32. A MEMS transducer as claimed in claim 28 , wherein the flexible membrane is supported between a first volume and a second volume and wherein the flow path is between the first and second volumes.

33. A MEMS transducer as claimed in claim 28 , wherein each moveable portion is generally triangular, square or rectangular in shape.

34. A MEMS transducer as claimed in claim 28 , wherein said moveable portion is connected to the rest of the flexible membrane via a beam structure.

35. A MEMS transducer as claimed in claim 28 , comprising a back-plate structure wherein the flexible membrane is supported with respect to said back-plate structure.

36. A MEMS transducer as claimed in claim 35 wherein said back-plate structure comprises a plurality of holes through the back-plate structure.

37. A MEMS transducer as claimed in claim 28 , wherein said transducer comprises a capacitive sensor.

38. A MEMS transducer as claimed in claim 28 , wherein said transducer comprises a microphone.

39. A MEMS transducer as claimed in claim 37 , further comprising readout circuitry.

40. An integrated circuit comprising a MEMS transducer as claimed in claim

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Piechocinski Marek Sebastian

Classifications

• G01L9/0042 Primary

  Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms (details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively) · CPC title

• B81B7/0029

  Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025 · CPC title

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title

• H04R19/005

  using semiconductor materials · CPC title

• B81B7/0016

  Protection against shocks or vibrations, e.g. vibration damping · CPC title