Switch for use in microelectromechanical systems (MEMS) and MEMS devices incorporating same

• US 8,138,859 B2
• Filed: 04/21/2008
• Issued: 03/20/2012
• Est. Priority Date: 04/21/2008
• Status: Expired due to Fees

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Gritters, John K., Hobbs, Eric D., Park, Sangtae, Yao, Jun Jason
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): Talpalatskiy, Alexander
• Application Number:
  US12/106,364
• Publication Number:
  US 20090260960A1
• Time in Patent Office: 1,429 Days
• Field of Search: 335/78, 335/83, 200/181
• US Class Current: 335/78
• 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 comprising the contact surface 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 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 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.

4. 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.

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

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

7. 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.

18. The switch of claim 1, wherein:

the MEMS actuator comprises a movable portion that is movable between the open position and the closed position, and

the movable portion comprises the contact surface.

19. The switch of claim 18 further comprising mechanical energy storing means for storing mechanical energy as the movable portion moves from the open position to the closed position sufficient to move the movable portion from the closed position back to the open position.

20. The switch of claim 19, wherein the mechanical energy storing means comprises mechanical springs coupled to the movable portion of the MEMS actuator.

21. The switch of claim 20 further comprising a fixed structure, wherein the mechanical springs are also coupled to fixed structure.

22. The switch of claim 1, wherein the resilient beam is linear.

23. The switch of claim 1, wherein the resilient beam is non-linear.

24. The switch of claim 1, wherein the resilient beam comprises a reinforcement member.

8. 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 directly engaged with 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.

9. The switch of claim 8, wherein operation of the actuator pulls the beam towards the actuator.

10. The switch of claim 8, wherein the actuator is coupled to the beam on the same side of the pivot point as the tip.

11. The switch of claim 8, wherein the actuator is coupled to the beam on a side of the pivot point opposite the tip.

12. The switch of claim 8, 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.

13. The switch of claim 8, 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.

14. The switch of claim 13, wherein actuation causes the resilient element and the second resilient element to move in the same direction.

15. The switch of claim 13, wherein actuation causes the resilient element and the second resilient element to move in opposite directions.

16. The switch of claim 8, wherein the pivot point of the beam is closer to the actuator than to the tip.

17. The switch of claim 8, wherein the pivot point of the beam is closer to the tip than to the actuator.