Methods and systems for controlling movement within MEMS structures

• US 20040154397A1
• Filed: 02/07/2003
• Published: 08/12/2004
• Est. Priority Date: 02/07/2003
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Johnson, Burgess R., Platt, William P.
• Granted Patent: US 6,860,151 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: Y10T 74/12 Gyroscopes

Abstract

A method for reducing undesired movements of proof masses in micro-electromechanical systems (MEMS) devices is described where the proof masses are suspended above a substrate by one or more suspensions. The method includes providing an anchor on the substrate substantially between a first proof and suspensions for the first proof mass and a second proof mass and suspensions for the second proof mass, coupling a first portion of a beam to the first proof mass, coupling a second portion of the beam to the second proof mass, and attaching a third portion of the beam to the anchor, the third portion extending between the first portion and second portion of the beam, the anchor and the third portion configured to allow for rotation about an axis perpendicular to the substrate.

Claims

1. A method for reducing undesired movements parallel to a plane of a substrate of proof masses in micro-electromechanical systems (MEMS) devices, the proof masses being suspended above the substrate by one or more suspensions, said method comprising:

providing an anchor on the substrate substantially between a first proof mass and suspensions for the first proof mass and a second proof mass and suspensions for the second proof mass;

coupling a first portion of a beam to the first proof mass;

coupling a second portion of the beam to the second proof mass; and

attaching a third portion of the beam to the anchor, the third portion extending between the first portion and second portion of the beam, the anchor and the third portion configured to allow at least a partial rotation of the third portion of the beam about an axis perpendicular to the substrate.

2. A method according to claim 1 further comprising forming the third portion of the beam at an approximate right angle to both the first portion and the second portion of the beam.

3. A method according to claim 1 wherein:

coupling a first portion of a beam comprises attaching the first portion of the beam to a suspension for the first proof mass; and

coupling a second portion of the beam comprises attaching the second portion of the beam to a respective suspension for the second proof mass.

4. A method according to claim 3 wherein:

attaching the first portion of the beam comprises attaching the first portion of the beam substantially perpendicular to the suspension; and

attaching the second portion of the beam comprises attaching the second portion of the beam substantially perpendicular to the respective suspension.

5. A method according to claim 1 wherein attaching a third portion of the beam to the anchor comprises attaching an approximate midpoint of the third portion to the anchor.

6. A method according to claim 1 wherein attaching a third portion of the beam to the anchor comprises:

attaching the first portion and the second portion of the beam to a rectangular suspension;

attaching anchoring beams to the rectangular suspension; and

attaching the anchoring beams to an anchor.

7. A method according to claim 1 wherein:

coupling a first portion of a beam comprises attaching the first portion of the beam to the first proof mass; and

coupling a second portion of the beam comprises attaching the second portion of the beam to the second proof mass.

8. A micro-electromechanical systems device comprising:

a substrate;

at least one proof mass;

at least two suspensions extending from each said proof mass;

at least one anchor contacting said substrate; and

at least one beam comprising a first portion, a second portion, and a third portion, said first portion coupled to a first said proof mass, said second portion coupled to a second said proof mass, said third portion connected to said first portion and said second portion, said third portion extending between said first and said second portions, said third portion attached to said anchor, said anchor and said third portion configured to allow at least a partial rotation of said third portion of said beam about an axis perpendicular to said substrate.

9. A device according to claim 8 wherein said third portion of each said beam is substantially perpendicular to both said first portion and said second portion of each said beam.

10. A device according to claim 8 wherein to couple said first portion of said beam to a first said proof mass and said second portion of said beam to a second said proof mass, said first portion of said beam is attached to a suspension for said first proof mass and said second portion of said beam is attached to a suspension for said second proof mass.

11. A device according to claim 10 wherein said first portion of said beam is connected to said suspension at a point between a midpoint of said suspension and an anchor point for said suspension.

12. A device according to claim 10 wherein said first portion and said second portion of each said beam extends substantially perpendicular to said suspensions.

13. A device according to claim 8 wherein to couple said first portion of said beam to a first said proof mass and said second portion of said beam to a second said proof mass, said first portion of said beam is attached to said first proof mass and said second portion of said beam is attached to said second proof mass.

14. A device according to claim 8 wherein each said anchor is connected to a substantial midpoint of said third portion of each said beam.

15. A device according to claim 8 wherein said device comprises two said proof masses.

16. A device according to claim 8 wherein each said anchor is formed as a portion of said substrate.

17. A device according to claim 8 wherein each said beam is micro-machined from a silicon wafer.

18. A device according to claim 8 wherein said third portion of said beam comprises:

a rectangular suspension attached to said first portion and said second portion of said beam; and

at least one anchoring beam attached to said rectangular suspension and configured to be attached to said anchor.

19. A device according to claim 8 wherein said device comprises at least one of a gyroscope, an inertial measurement unit, an accelerometer, a pressure sensor, and a temperature sensor.

20. A device according to claim 8 wherein said suspensions comprise folded beam suspensions.

21. An anchored support structure for a micro-electromechanical systems device, said structure comprising:

an anchor connected to a substrate; and

a beam comprising a first portion, a second portion, and a third portion, said first portion configured to be coupled to a first proof mass, said second portion configured to be coupled to a second proof mass, said third portion extending between said first portion and said second portion, said third portion attached to said anchor, said anchor and said third portion configured to allow at least a partial rotation of said third portion of said beam about an axis perpendicular to the substrate.

22. An anchored support structure according to claim 21 wherein to couple said first portion of said beam to the first proof mass and said second portion of said beam to the second proof mass, said first portion of said beam is attached to a suspension for the first proof mass and said second portion of said beam is attached to a suspension for the second proof mass.

23. An anchored support structure according to claim 22 wherein said first portion is substantially perpendicular to the suspension to which it is attached and said second portion is substantially perpendicular to the suspension to which it is attached.

24. An anchored support structure according to claim 21 wherein to couple said first portion of said beam to the first proof mass and said second portion of said beam to the second proof mass, said first portion of said beam is attached the first proof mass and said second portion of said beam is attached to the second proof mass.

25. An anchored support structure according to claim 21 wherein said beam is configured such that when said third portion pivots about said anchor, said first portion moves in a first direction, and said second portion moves in a direction opposite to the first direction.

26. An anchored support structure according to claim 21 wherein said third portion is attached to said anchor at an approximate midpoint of said third portion.

27. An anchored support structure according to claim 21 wherein said third portion comprises:

a rectangular suspension attached to said first portion and said second portion of said beam; and

at least one anchoring beam attached to said rectangular suspension and configured to be attached to said anchor.

28. A micro-electromechanical systems gyroscope comprising:

a substrate;

two proof masses;

a plurality of suspensions, a first plurality configured to suspend the first said proof mass above said substrate, and a second plurality configured to suspend the second said proof mass above said substrate; and

an anchored support structure comprising an anchor formed on said substrate and a beam, said beam comprising a first portion coupled to said first proof mass, a second portion coupled to said second proof mass, and a third portion attached to said anchor, said anchor and said third portion configured to allow at least a partial rotation of said third portion of said beam about an axis perpendicular to said substrate, said third portion extending between said first portion and said second portion.

29. A micro-electromechanical systems gyroscope according to claim 28 wherein said third portion is substantially perpendicular to said first portion and said second portion.

30. A gyroscope according to claim 28 wherein said first portion is attached substantially perpendicular to said suspension for said first proof mass and said second portion is attached substantially perpendicular to said suspension for said second proof mass.

31. A gyroscope according to claim 28 wherein said beam is configured such that when said third portion pivots about said anchor, said first portion moves in a first direction, and said second portion moves in a direction opposite to the first direction.

32. A micro-electromechanical systems gyroscope according to claim 28 wherein said third portion comprises:

a rectangular suspension attached to said first portion and said second portion of said beam; and

at least one anchoring beam attached to said rectangular suspension and configured to be attached to said anchor.

33. A micro-electromechanical systems gyroscope according to claim 28 wherein said suspensions comprise folded beam suspensions.

34. A method for correlating movement between respective proof masses in micro-electromechanical systems devices, the proof masses being suspended above a substrate by one or more suspensions, said method comprising:

mechanically connecting the first proof mass and the second proof mass; and

providing a rotational moment within the mechanical connection, the rotational moment being along an axis perpendicular to the substrate.

35. A method according to claim 34 wherein providing a rotational moment comprises pivotably anchoring a portion of the mechanical connection to the substrate.

36. A method according to claim 34 further comprising configuring the mechanical connection such that a movement in the suspension for one proof mass in a first direction substantially prevents a movement in the same direction in the suspension for the other proof mass.

37. A method according to claim 34 wherein the suspensions extend from the proof masses at a first end and are anchored to the substrate at a second end, wherein mechanically connecting the first proof mass and the second proof mass comprises attaching the mechanical connection to at least one suspension at a location between a midpoint of the suspension and an anchor point for the suspension.