MEMS device and process

Patent metadata

Field	Value
Publication number	US-10343894-B2
Application number	US-201715676430-A
Country	US
Kind code	B2
Filing date	Aug 14, 2017
Priority date	Aug 22, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

The application describes a MEMS transducer comprising a layer of conductive material provided on a surface of a layer of membrane material. The layer of conductive material comprises first and second regions, wherein the thickness and/or the conductivity of the/each first and second regions is different.

First claim

The invention claimed is:

1. A MEMS transducer comprising
a substrate having a cavity;
a layer of membrane material provided relative to the substrate, wherein the membrane material extends over the cavity; and
a layer of conductive material provided on a surface of the layer of membrane material;
the layer of conductive material comprising at least one first region having a first thickness and a first conductivity and at least one second region having a second thickness and a second conductivity, wherein the thickness and/or the conductivity of the/each first and second regions is different and wherein at least one second region of the conductive material is provided on a region of the surface of the layer of membrane material which is laterally outside the region of the layer of membrane material which overlies the cavity.

2. A MEMS transducer as claimed in claim 1 , wherein the first region and the second region of the conductive material exhibit different thicknesses.

3. A MEMS transducer as claimed in claim 1 , wherein the first and second regions form an electrically continuous conductive layer on the surface of the membrane.

4. A MEMS transducer as claimed in claim 1 , wherein the second region of the layer of conductive material comprises first and second sub-layers of conductive material.

5. A MEMS transducer as claimed in claim 4 , wherein at least one of the sub-layers comprises a layer of conductive material having at least one opening.

6. A MEMS transducer as claimed in claim 1 , wherein at least one first region is provided on a region of the membrane which overlies the substrate cavity.

7. A MEMS transducer as claimed in claim 1 , wherein the conductive material forming the first region comprises a continuous sheet of conductive material.

8. A MEMS transducer as claimed in claim 1 , wherein the conductive material forming the first region comprises a layer of conductive material having at least one opening.

9. A MEMS transducer as claimed in claim 1 , wherein the layer of conductive material forms a membrane electrode of the transducer.

10. A MEMS transducer as claimed in claim 9 , wherein the layer of conductive material forms a conductive track which extends between the membrane electrode and a region for electrically coupling said membrane electrode to circuitry for readout.

11. A MEMS transducer as claimed in claim 10 , wherein the track is at least partially formed of at least one second region.

12. A MEMS transducer as claimed in claim 1 , wherein the layer of membrane material exhibits at least one step between a first level and a second level, and wherein at least one second region is provided on a region the layer of membrane material which includes said step.

13. A MEMS transducer as claimed in claim 1 , wherein the second region comprises one or more elements or interconnected tracks which are provided on a region of the layer of membrane material which overlies the cavity.

14. A MEMS transducer as claimed in claim 1 , wherein the first region and the second region of the conductive material exhibit different electrical conductivity.

15. A MEMS transducer as claimed in claim 14 , wherein the first region exhibits a lower electrical conductivity than the second region.

16. A MEMS transducer as claimed in claim 15 , wherein the first region comprises a conductive dielectric material.

17. A MEMS transducer as claimed in claim 14 , wherein the second region comprises a metal material or a metal alloy material.

18. A MEMS transducer as claimed in claim 1 , wherein said membrane comprises a crystalline or polycrystalline material.

19. A MEMS transducer as claimed in claim 1 , wherein the conductive layer comprises three of more regions, each region having a different thickness and/or conductance to the other regions.

20. A MEMS transducer as claimed in claim 1 wherein said transducer comprises a capacitive sensor such as a capacitive microphone.

21. A MEMS transducer as claimed in claim 20 further comprising readout circuitry wherein the readout circuitry may comprise analogue and/or digital circuitry.

22. 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

• Duffy Stephen
• Jenkins Colin Robert
• Hoekstra Tsjerk Hans

Classifications

• H04R19/005 Primary

  using semiconductor materials · CPC title

• B81B2201/0257

  Microphones or microspeakers · CPC title

• B81B2207/03

  Electronic circuits for micromechanical devices which are not application specific, e.g. for controlling, power supplying, testing, protecting · 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

• H04R19/04

  Microphones (H04R19/01 takes precedence) · CPC title