MEMS device and process

Patent metadata

Field	Value
Publication number	US-10111021-B2
Application number	US-201715660508-A
Country	US
Kind code	B2
Filing date	Jul 26, 2017
Priority date	Jul 28, 2016
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

The application describes a MEMS transducer in which first and second conductive elements of a capacitor are both provided on the membrane. The membrane is shaped that the first and second conductive elements are displaced relative to each other when the flexible membrane deflects in response to a pressure differential across the membrane. For example the membrane may be corrugated.

First claim

The invention claimed is:

1. A MEMS transducer comprising:
a flexible membrane provided with an electrode pair, the electrode pair comprising first and second conductive elements,
wherein the flexible membrane is shaped such that the first and second conductive elements are displaced relative to each other when the flexible membrane deflects in response to a pressure differential across the membrane,
and wherein the first and second conductive elements are provided on the flexible membrane such that a non-planar portion of the flexible membrane extends between them.

2. A MEMS transducer as claimed in claim 1 , wherein the membrane is shaped to define at least one ridge and/or groove.

3. A MEMS transducer as claimed in 2 , wherein each ridge or groove comprises a pair of first and second side-walls, the conductive elements of the electrode pair(s) being provided on said side-walls.

4. A MEMS transducer as claimed in claim 3 , wherein the first side-wall of said ridge is provided with one of said first and second conductive elements and the second side-wall of the same ridge is provided with the other of said first and second conductive elements.

5. A MEMS transducer as claimed in claim 2 , wherein each ridge/groove comprises a peak and wherein the conductive elements of the electrode pairs are provided on the peaks of the ridges and/or grooves of the flexible membrane.

6. A MEMS transducer as claimed in claim 2 , wherein the membrane is shaped to include a series of alternate ridges and grooves.

7. A MEMS transducer as claimed in claim 2 , the membrane comprising at least two ridges or at least two grooves, wherein one of said first and second conductive elements is provided on one said ridge/groove, which is a first ridge/groove, and the other of said first and second conductive elements is provided on another said ridge/groove which is adjacent to said first ridge/groove.

8. A MEMS transducer as claimed in claim 1 , comprising a plurality of electrode pairs.

9. A MEMS transducer as claimed in claim 8 wherein the plurality of electrode pairs form a single set of electrode pairs and wherein the transducer is arranged/operable to provide a single output signal representing the change in capacitance between first and second conductive elements of the single set of electrode pairs.

10. A MEMS transducer as claimed in claim 8 , wherein the plurality of electrode pairs form first and second sets of electrode pairs, and wherein the transducer is arranged/operable to provide corresponding first and second output signals representing the change in capacitance between first and second conductive elements of each respective set.

11. A MEMS transducer as claimed in claim 1 , wherein a bias voltage is applied to one or more of the conductive elements of an electrode pair.

12. A MEMS transducer comprising
a flexible membrane formed of a plurality of ridges and/or grooves,
wherein the ridges and/or grooves are provided with at least one electrode pair, each electrode pair comprising a first and second conductive element,
and wherein the first and second conductive elements of a given electrode pair are displaced relative to each other when the flexible membrane deflects in response to a pressure differential across the membrane,
and wherein the first and second conductive elements are provided on the flexible membrane such that a non-planar portion of the flexible membrane extends between them.

13. A MEMS transducer according to claim 1 , wherein the conductive elements comprise a ceramic or metal material.

14. A MEMS transducer as claimed in claim 8 wherein the first conductive elements of the plurality of electrode pairs are connected together at a first electrical node and the second conductive elements of each of the plurality of electrode pairs are connected together at a different second electrical node to provide a single composite electrode pair.

15. A MEMS transducer as claimed in claim 1 , further comprising a cover and/or a backplate.

16. A MEMS transducer as claimed in claim 1 , wherein the flexible membrane is supported in a fixed relation relative to a substrate.

17. A MEMS transducer as claimed in claim 1 , wherein the flexible membrane comprises a crystalline or polycrystalline material, such as silicon nitride.

18. A MEMS transducer as claimed in claim 1 , wherein said transducer comprises a capacitive sensor such as a microphone or a speaker.

19. A MEMS transducer as claimed in claim 18 further comprising readout circuitry on a common semiconductor substrate, wherein the readout circuitry may comprise analogue and/or digital circuitry.

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

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Deas James Thomas
• Cargill Scott Lyall

Classifications

• B81B3/0021 Primary

  Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00) · CPC title

• H04R19/005 Primary

  using semiconductor materials · CPC title

• B81B2201/0257

  Microphones or microspeakers · CPC title

• B81B2203/04

  Electrodes · CPC title

• B81B3/0072

  For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers · CPC title