Proof-mass with supporting structure on integrated circuit-MEMS platform and method of fabricating the same

• US 20100147076A1
• Filed: 01/04/2010
• Published: 06/17/2010
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: Brett M. Diamond, Jan E. Vandemeer, Kaigham J. Gabriel, Matthew A. Zeleznik
• Original Assignee: Brett M. Diamond, Jan E. Vandemeer, Kaigham J. Gabriel, Matthew A. Zeleznik
• Inventors: Diamond, Brett M., Zeleznik, Matthew A., Gabriel, Kaigham J., Vandemeer, Jan E.
• Granted Patent: US 8,094,980 B2
• Time in Patent Office: Days
• US Class Current: 73/514.320
• 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 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, the at least one spring and the at least one bottom electrode further defining 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 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.

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

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

18. The device according to claim 15, wherein 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.

19. The device according to claim 18, wherein the at least one conductive layer functions as the at least one top electrode.

20. The device according to claim 15, wherein the change in initial capacitance is sensed by the drive/sense circuitry.

21. The device according to claim 15, wherein the sense/drive circuitry senses movement of the suspended proof-mass along at least one of the x-, y-, and z-directions.

22. The device according to claim 15, wherein the sense/drive circuitry senses changes in inertia of the suspended proof-mass along at least one of the x-, y-, and z-directions.

23. The device according to claim 15, wherein the sense/drive circuitry senses tilting of the suspended proof-mass along at least one of the x-, y-, and z-directions.

24. The device according to claim 1, wherein a force is applied to the suspended proof-mass in at least one of the x-, y-, and z-directions by creation of an electrostatic potential between the at least one top electrode and the at least one bottom electrode.

25. The device according to claim 24, wherein the force applied to the proof-mass causes the proof-mass to move in at least one of the x-, y-, and z-directions.

26. The device according to claim 24, wherein the force applied to the proof-mass causes the proof-mass to tilt along at least one of the x-, y-, and z-directions.

27. The device according to claim 24, wherein the drive/sense circuitry generates the electrostatic potential between the at least one top electrode and the at least one bottom electrode.

28. The device according to claim 24, wherein the drive/sense circuitry generates the electrostatic potential between the at least one conductive layer and the at least one bottom electrode.

29. The device according to claim 24, further comprising:

at least one input port in optical communication with the proof-mass; and

at least one output port in optical communication with the proof-mass;

wherein the proof-mass directs light waves from at least one input port to at least one output port.

30. The device according to claim 29, wherein the device is an optical switch.

31. The device according to claim 30, wherein the drive/sense circuitry generates the electrostatic potential between the at least one top and bottom electrodes.

32. The device according to claim 30, wherein the device is one of a plurality employed in an array.

33. The device according to claim 30, wherein the proof-mass foams at least one reflective mirror.

34. The device according to claim 30, wherein the proof-mass forms at least one partially reflective mirror.

35. The device according to claim 30, wherein the proof-mass forms at least one diffraction grating.

36. The device according to claim 30, wherein the proof-mass is transparent to at least one wavelength of light.

37. The device according to claim 30, further comprising at least one optical coating disposed on the proof-mass.

38. The device according to claim 37, wherein the at least one optical coating forms at least one reflective mirror.

39. The device according to claim 37, wherein the at least one optical coating forms at least one partially reflective mirror.

40. The device according to claim 37, wherein the at least one optical coating forms at least one diffraction grating.

41. The device according to claim 37, wherein the at least one optical coating is transparent to at least one wavelength of light.

42. The device according to claim 1, wherein a force is applied to the suspended proof-mass in at least one of the x-, y-, and z-directions by creation of an electrostatic potential between the at least one conductive layer and the at least one bottom electrode.

43. The device according to claim 42, wherein the force applied to the proof-mass causes the proof-mass to move in at least one of the x-, y-, and z-directions.

44. The device according to claim 42, wherein the force applied to the proof-mass causes the proof-mass to tilt along at least one of the x-, y-, and z-directions.