Proof-mass with supporting structure on integrated circuit-MEMS platform

• US 7,640,805 B2
• Filed: 12/18/2006
• Issued: 01/05/2010
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: Akustica Incorporated
• Original Assignee: Akustica Incorporated
• Inventors: Diamond, Brett M., Gabriel, Kaigham J., Vandemeer, Jan E., Zeleznik, Matthew A.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US11/640,345
• Publication Number:
  US 20080142914A1
• Time in Patent Office: 1,114 Days
• Field of Search: 735/143.2, 735/143.8, 735/141.8, 361/280
• US Class Current: 73/514.32
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 2203/0742 Interleave, i.e. simultaneously forming the micromechanical structure and the CMOS circuit

Abstract

Provided is a micro-electromechanical-system (MEMS) device including a substrate; at least one semiconductor layer provided on the substrate; a circuit region including at least one chip containing drive/sense circuitry, the circuit region provided on the at least one semiconductor layer; a support structure attached to the substrate; at least one elastic device attached to the support structure; a proof-mass suspended by the at least one elastic device and free to move in at least one of the x-, y-, and z-directions; at least one top electrode provided on the at least one elastic device; and at least one bottom electrode located beneath the at least one elastic device such that an initial capacitance is generated between the at least one top and bottom electrodes, wherein the drive/sense circuitry, proof-mass, supporting structure, and the at least one top and bottom electrodes are fabricated on the at least one semiconductor layer.

Claims

1. A micro-electromechanical-system (MEMS) device, comprising:

a substrate;

at least one semiconductor layer provided on the substrate;

a circuit region including at least one chip containing drive/sense circuitry, the circuit region provided on the at least one semiconductor layer;

a support structure attached to the substrate;

at least one elastic device attached to the support structure;

a proof-mass suspended by the at least one elastic device and free to move in at least one of the x-, y-, and z-directions;

at least one top electrode provided on the at least one elastic device; and

at least one bottom electrode located beneath the at least one elastic device such that an initial capacitance is generated between the at least one top and bottom electrodes;

wherein;

the initial capacitance between the at least one top electrode and the at least one bottom electrode changes in response to a force applied to the proof-mass;

the change in initial capacitance results from a change in the area of overlap between the at least one top electrode and the at least one bottom electrode; and

the drive/sense circuitry, proof-mass, supporting structure, and the at least one top and bottom electrodes are fabricated on the at least one semiconductor layer.

2. The device according to claim 1, wherein the MEMS device is a single monolithic die.

3. The device according to claim 1, wherein the circuit region includes silicon, metal, and oxide layers.

4. The device according to claim 1, wherein a top surface of the proof-mass includes at least one metal layer and at least one oxide layer.

5. The device according to claim 1, further including at least one spring suspending the proof-mass and anchored to the substrate.

6. The device according to claim 5, wherein the at least one spring and the at least one bottom electrode further define an air gap separating the at least one spring from the at least one bottom electrode.

7. The device according to claim 5, wherein the at least one spring includes one of a serpentine loop, mesh pattern, crab-leg flexure, folded flexure, or simple beam.

8. The device according to claim 5, wherein the at least one spring includes at least one mechanical layer and at least one conductive layer.

9. The device according to claim 8, wherein the at least one conductive layer functions as the at least one top electrode.

10. The device according to claim 8, wherein the at least one mechanical layer connects the proof-mass to the substrate while suspending the at least one top electrode above the at least one bottom electrode.

11. The device according to claim 10, wherein the at least one mechanical layer further includes at least one insulating layer that electrically isolates the at least one conductive layer from the at least one top electrode.

12. The device according to claim 10, wherein the at least one mechanical layer further includes at least one insulating layer that electrically isolates the at least one top electrode from the at least one bottom electrode.

13. The device according to claim 1, further comprising at least one over-travel stop disposed at an edge of the proof-mass and anchored to the substrate.

14. The device according to claim 13, wherein the at least one over-travel stop is disposed over a portion of the proof-mass.

15. The device according to claim 1, wherein the change in initial capacitance results additionally from a change in the distance between the at least one top electrode and the at least one bottom electrode.

16. The device according to claim 15, wherein at least one conductive layer functions as the at least one top electrode.

17. The device according to claim 1, wherein at least one conductive layer functions as the at least one top electrode.

18. The device according to claim 1, wherein the change in initial capacitance is sensed by the drive/sense circuitry.

19. The device according to claim 1, wherein the drive/sense circuitry senses movement of the suspended proof-mass along at least one of the x-, y-, and z-directions.

20. The device according to claim 1, wherein the drive/sense circuitry senses changes in inertia of the suspended proof-mass along at least one of the x-, y-, and z-directions.

21. The device according to claim 1, wherein the drive/sense circuitry senses tilting of the suspended proof-mass along at least one of the x-, y-, and z-directions.

22. A micro-electromechanical-system (MEMS) device, comprising:

a substrate;

a circuit region including at least one chip containing drive/sense circuitry;

a support structure attached to the substrate;

at least one elastic device attached to the support structure;

a proof-mass suspended by the at least one elastic device and free to move in at least one of the x-, y-, and z-directions;

at least one top electrode provided on the at least one elastic device; and

at least one bottom electrode located beneath the at least one elastic device such that an initial capacitance is generated between the at least one top and bottom electrodes;

wherein;

the initial capacitance between the at least one top electrode and the at least one bottom electrode changes in response to a force applied to the proof-mass;

the change in initial capacitance results from a change in the area of overlap between the at least one top electrode and the at least one bottom electrode; and

the drive/sense circuitry, proof-mass, supporting structure, and the at least one top and bottom electrodes are fabricated one of directly and indirectly on the substrate.