Microphone with irregular diaphragm

• US 20070064968A1
• Filed: 06/28/2006
• Published: 03/22/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Analog Devices, Inc.
• Inventors: Weigold, Jason
• Granted Patent: US 7,961,897 B2
• Time in Patent Office: Days
• US Class Current: 381/369
• CPC Class Codes: G01L 9/0042 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 Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 31/00 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 Class Codes: H04R 31/003 for diaphragms or their outer suspension
• CPC Class Codes: H04R 7/14 corrugated, pleated or ribbed
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

A microphone is formed to have a diaphragm that is configured to improve signal to noise ratio. To that end, the microphone has a backplate having a hole therethrough, and a diaphragm movably coupled with the backplate. The diaphragm has a bottom surface (facing the backplate) with a convex portion aligned with the hole in the backplate.

Claims

1. A microphone comprising:

a backplate having a hole therethrough; and

a diaphragm movably coupled with the backplate, the diaphragm having a bottom surface facing the backplate,

the bottom surface of the diaphragm having a protruding portion substantially aligned with the hole in the backplate.

2. The microphone as defined by claim 1 wherein the diaphragm has a top surface that opposes the bottom surface, the protruding portion of the diaphragm forming a depression in the top surface.

3. The microphone as defined by claim 2 wherein the diaphragm has a thickness, the depressed portion having a maximum depth that is greater than or equal to the thickness of the diaphragm.

4. The microphone as defined by claim 1 wherein the diaphragm has a top surface that opposes the bottom surface, the portion of the top surface of the diaphragm that is aligned with the hole being substantially planar.

5. The microphone as defined by claim 1 wherein the bottom surface of the diaphragm is not planar.

6. The microphone as defined by claim 1 wherein the backplate has a plurality of holes therethrough, the diaphragm having a plurality of protruding portions that each share a vertical plane with one of the pluralities of holes.

7. The microphone as defined by claim 1 wherein the diaphragm has a plurality of dimples.

8. A MEMS microphone comprising:

a backplate having at least one hole formed therethrough; and

a diaphragm secured to the backplate,

the diaphragm having a protrusion extending toward the backplate, the protrusion substantially sharing a vertical plane with the at least one hole.

9. The MEMS microphone as defined by claim 8 wherein the diaphragm has a bottom surface that is not planar.

10. The MEMS microphone as defined by claim 8 wherein the diaphragm has a plurality of protrusions that each share a vertical plane with one of the at least one hole through the backplate.

11. The MEMS microphone as defined by claim 8 wherein the diaphragm has a wavy bottom surface.

12. The MEMS microphone as defined by claim 8 wherein the protrusion extends from a bottom surface of the diaphragm, the diaphragm also having a top surface that opposes the bottom surface, the protrusion of the diaphragm forming a depression in the top surface.

13. The MEMS microphone as defined by claim 12 wherein the diaphragm has a thickness, the protrusion having a depth that is greater than or equal to the thickness of the diaphragm.

14. The MEMS microphone as defined by claim 8 wherein the protrusion has a minimum point that is closest to the backplate, the minimum point and the at least one hole sharing the vertical plane.

15. A method of forming a MEMS device, the method comprising:

providing a backplate having a hole;

forming a diaphragm having a protruding portion on a bottom surface, the diaphragm being formed to be coupled with the backplate; and

forming a space between the diaphragm and the backplate, the diaphragm bottom surface facing the backplate, the protruding portion being substantially aligned with the hole in the backplate.

16. The method as defined by claim 15 wherein the diaphragm has a top surface that opposes the bottom surface, the protruding portion of the diaphragm forming a depression in the top surface.

17. The method as defined by claim 15 wherein the backplate has a plurality of holes therethrough, the diaphragm having a plurality of protruding portions that each share a vertical plane with one of the plurality of holes.

18. The method as defined by claim 15 wherein coupling comprises forming an insulator layer between the backplate and the diaphragm.

19. The method as defined by claim 15 wherein forming comprises using micromachining techniques.

20. The method as defined by claim 15 wherein forming comprises:

depositing a filler material within the hole of the backplate;

adding a spacer layer to a surface of filler material;

adding diaphragm material to a surface of the spacer layer; and

removing at least a portion of the filler material.