Capacitive sensing structure with embedded acoustic channels

• US 9,809,451 B2
• Filed: 11/16/2015
• Issued: 11/07/2017
• Est. Priority Date: 06/05/2013
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Chan, Mei-Lin, Li, Xiang, Lim, Martin
• Primary Examiner(s): YUSHINA, GALINA G
• Application Number:
  US14/942,969
• Publication Number:
  US 20160068386A1
• Time in Patent Office: 722 Days
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0127 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 Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00238 Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure
• CPC Class Codes: B81C 2203/035 Soldering
• CPC Class Codes: B81C 2203/0785 Transfer and j oin technology, i.e. forming the electronic processing unit and the micromechanical structure on separate substrates and joining the substrates
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 7/08 comprising superposed layers separated by air or other fluid
• CPC Class Codes: H10N 30/204 using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/308 Membrane type

Abstract

A MEMS device includes a dual membrane, an electrode, and an interconnecting structure. The dual membrane has a top membrane and a bottom membrane. The bottom membrane is positioned between the top membrane and the electrode and the interconnecting structure defines a spacing between the top membrane and the bottom membrane.

Claims

1. A method of manufacturing a micro-electro-mechanical system (MEMS) device comprising:

forming an electrode on top of a complementary metal-oxide-semiconductor (CMOS) wafer;

forming a moveable dual-plate membrane with top and bottom membranes on top of the electrode, the moveable dual plate membrane forming a MEMS device wafer;

forming an interconnecting structure, wherein the moveable dual-plate membrane and the interconnecting structure create a MEMS on the MEMS device wafer, the interconnecting structure being positioned between the top and bottom membranes and

bonding the CMOS wafer to the MEMS device wafer and causing electrical connection between the CMOS wafer and the MEMS device wafer, the interconnecting structure electrically connecting the top and the bottom membranes.

2. The method of claim 1, wherein the bonding comprises eutectic bonding.

3. The method of claim 1, further including forming standoffs on the MEMS wafer.

4. The method of claim 1, further including depositing polysilicon on the MEMS wafer before forming the standoffs.

5. The method of claim 1, further including forming standoffs between the bottom membrane and the electrode, the standoffs electrically connecting the bottom membrane and the electrode.

6. The method of claim 1, further including thinning the CMOS wafer.

7. The method of claim 1, wherein the forming the moveable dual-plate membrane comprising forming a top membrane and a bottom membrane.

8. The method of claim 7, further including forming perforations in the bottom membrane.

9. The method of claim 1, further including bonding a handle wafer on top of the moveable dual-plate membrane, the handle wafer including at least one acoustic port.

10. The method of claim 1, further including creating the interconnecting structure from a single crystal silicon pillar structure left over from partially consumed silicon pillars.

11. The method of claim 1, wherein the bottom membrane is made of a conductive material.

12. The method of claim 1, wherein the electrode is made of aluminum.

13. The method of claim 3, wherein the bonding step includes bonding the CMOS wafer and the MEMS device wafer by aluminum-germanium eutectic bonds through the standoff.

14. The method of claim 3, wherein the standoff is made of conductive material and a thickness of the standoff defines an electrical sensing gap between the electrode and the bottom membrane.

15. The method of claim 3, wherein the interconnecting structure is anchored through bonding to the electrode.

16. The method of claim 3, wherein the top electrode, the interconnecting structure, and the bottom membrane move up and down together, causing a gap formed between the bottom membrane and the electrode to change accordingly.

17. The method of claim 1, further including forming more than one interconnecting structure between the top and bottom membranes.

18. The method of claim 1, wherein a change of acoustic pressure causing the top membrane to move downwardly toward or upwardly away from the electrode.

19. The method of claim 1, wherein a pressure differential is formed on a left side of the top membrane by a pressure difference between a pressure on a left side of the interconnecting structure and a top of the top membrane and a pressure on the left side of the interconnecting structure and a bottom of the top membrane, while a pressure differential on a right side of the top membrane is formed by a pressure difference between a pressure on the right side of the interconnecting structure and the top of the top membrane and the pressure on the right side of the interconnecting structure and the bottom of the top membrane.