SWITCH FOR USE IN MICROELECTROMECHANICAL SYSTEMS (MEMS) AND MEMS DEVICES INCORPORATING SAME

• US 20090260960A1
• Filed: 04/21/2008
• Published: 10/22/2009
• Est. Priority Date: 04/21/2008
• Status: Active Grant

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Park, Sangtae, Hobbs, Eric D., Yao, Jun Jason, Gritters, John K.
• Granted Patent: US 8,138,859 B2
• Time in Patent Office: Days
• US Class Current: 200/181
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 1/60 Auxiliary means structurally associated with the switch for cleaning or lubricating contact-making surfaces cleaning by normal sliding of contacts H01H1/18, H01H1/36
• CPC Class Codes: H01H 2001/0047 operable only by mechanical latching
• CPC Class Codes: H01H 2001/0052 Special contact materials used for MEMS
• CPC Class Codes: H01H 2001/0078 with parallel movement of the movable contact relative to the substrate
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

Embodiments of the present invention provide microelectromechanical systems (MEMS) switching methods and apparatus having improved performance and lifetime as compared to conventional MEMS switches. In some embodiments, a MEMS switch may include a resilient contact element comprising a beam and a tip configured to wipe a contact surface; and a MEMS actuator having an open position that maintains the tip and the contact surface in a spaced apart relation and a closed position that brings the tip into contact with the contact surface, wherein the resilient contact element and the MEMS actuator are disposed on a substrate and are movable in a plane substantially parallel to the substrate. In some embodiments, various contact elements are provided for the MEMS switch. In some embodiments, various actuators are provided for control of the operation of the MEMS switch.

Claims

1. A MEMS switch, comprising:

a resilient contact element comprising a resilient beam and a tip configured to wipe a contact surface; and

a MEMS actuator having an open position that maintains the tip and the contact surface in a spaced apart relation and a closed position that brings the tip into contact with the contact surface, wherein the resilient contact element and the MEMS actuator are disposed on a substrate and are movable in a plane substantially parallel to the substrate.

2. The switch of claim 1, wherein the resilient contact element is coupled to the actuator.

3. The switch of claim 1, wherein the contact surface is coupled to the actuator.

4. The switch of claim 1, wherein the MEMS actuator is at least one of a comb actuator, a gap closing actuator, an angled gap closing actuator, a partitioned MEMS actuator, or a multi-stage actuator.

5. The switch of claim 1, wherein the actuator provides a contact force greater than or on the order of mN at an actuation voltage of less than or equal to about 3 Volts.

6. The switch of claim 1, wherein at least one of the contact surface or the tip comprises rhodium.

7. The switch of claim 1, wherein the actuator and the resilient contact element are lithographically formed on a common substrate.

8. The switch of claim 1, wherein the resilient contact element is part of a spring assembly having a first spring constant when deflected up to a first distance, a greater, second spring constant when deflected beyond the first distance and up to a second distance, and a greater, third spring constant when deflected beyond the second distance and up to a third distance, and wherein the spring assembly stores mechanical energy when deflected towards a contact surface that biases the spring assembly away from the contact surface.

9. A MEMS switch, comprising:

a resilient contact element comprising a beam flexible about a pivot point and a having a tip disposed proximate an end of the beam and configured to engage a contact surface; and

a MEMS actuator coupled to the resilient contact element and having an open position that maintains the tip and the contact surface in a spaced apart relation and a closed position that brings the tip into contact with the contact surface, wherein the actuator is coupled to the beam at a point remote from the pivot point, and wherein the resilient contact element and the MEMS actuator are disposed on a substrate and movable in a plane substantially parallel to the substrate.

10. The switch of claim 9, wherein operation of the actuator pulls the beam towards the actuator.

11. The switch of claim 9, wherein the actuator is coupled to the beam on the same side of the pivot point as the tip

12. The switch of claim 9, wherein the actuator is coupled to the beam on a side of the pivot point opposite the tip

13. The switch of claim 9, further comprising:

a selectively engageable locking mechanism configured to bias the tip into contact with the contact surface and wherein operation of the actuator selectively opens the switch.

14. The switch of claim 9, further comprising:

a second resilient contact element comprising a beam and a tip configured to wipe a contact surface, the resilient element and the second resilient element both coupled to the actuator.

15. The switch of claim 14, wherein actuation causes the resilient element and the second resilient element to move in the same direction.

16. The switch of claim 14, wherein actuation causes the resilient element and the second resilient element to move in opposite directions.

17. The switch of claim 9, wherein the pivot point of the beam is closer to the actuator than to the tip.

18. The switch of claim 9, wherein the pivot point of the beam is closer to the tip than to the actuator.

19. A MEMS actuator, comprising:

a comb actuator movable between an first position and a second position; and

a gap closing actuator coupled to the comb actuator, wherein opposing electrodes of the gap closing actuator are brought into operable proximity to each other when the comb actuator is in the second position.

20. The actuator of claim 19, wherein the comb actuator and the gap closing actuator are formed on a common substrate.

21. The actuator of claim 19, wherein the comb actuator and the gap closing actuator each further comprise one or more fixed electrodes and one or more movable electrodes.

22. The actuator of claim 21, further comprising:

a movable frame housing the movable electrodes; and

a spring coupled to the frame for providing a restoring force that biases the frame towards the open position.

23. A MEMS actuator, comprising:

a gap closing actuator having a plurality of first electrodes and a plurality of second electrodes disposed parallel to the first electrodes and movable in a non-normal and non-parallel direction with respect thereto.

24. The actuator of claim 23, wherein the second electrodes are constrained to move linearly.

25. The actuator of claim 23, wherein the first electrodes and second electrodes are disposed in an angled, swept back pattern with respect to an axis of motion of the actuator.

26. The actuator of claim 23, further comprising:

a plurality of third electrodes; and

a plurality of fourth electrodes disposed parallel to the third electrodes and linearly movable in a non-normal and non-parallel direction with respect thereto, the first and third electrodes fixed to a common substrate and the second and the fourth electrodes coupled together to move in unison.

27. The actuator of claim 23, further comprising:

a movable frame housing the movable electrodes and a spring coupled to the frame for providing a restoring force that biases the frame towards an open position.

28. A MEMS actuator, comprising:

a first gap closing actuator comprising a first plurality of electrodes having a first gap disposed therebetween; and

a second gap closing actuator comprising a second plurality of electrodes having a second gap disposed therebetween, the first gap closing actuator coupled to the second gap closing actuator such that the closing of the first gap partially closes the second gap.

29. The actuator of claim 28, wherein the first plurality of electrodes comprises a first fixed electrode and a first movable electrode movable with respect to the first fixed electrode, and wherein the second plurality of electrodes comprises a second fixed electrode and a second movable electrode movable with respect to the second fixed electrode.

30. The actuator of claim 29, wherein the first fixed electrode is movable with respect to the second fixed electrode.

31. The actuator of claim 30, wherein the first fixed electrode is coupled to a substrate via one or more springs.

32. The actuator of claim 30, wherein the first fixed electrode and the first movable electrode are disposed non-perpendicularly with respect to an axis of motion of the actuator.

33. The actuator of claim 28, further comprising:

at least one gap closing actuator coupled between the first and second gap closing actuators.

34. The actuator of claim 28, further comprising:

a substrate having at least one of the second plurality of electrodes fixed thereto; and

a frame housing at least some of the first and second plurality of electrodes, the frame movable with respect to the substrate.

35. The actuator of claim 34, further comprising:

a spring coupled to the frame for providing a restoring force that biases the frame towards an open position of the actuator.

36. The actuator of claim 28, wherein the MEMS actuator is disposed on a substrate, and wherein the first gap closing actuator and the second gap closing actuator of the MEMS actuator each move in a direction substantially parallel to a plane defined by the substrate.

37. -72. (canceled)