# US 2009/0260960 A1 · Switch for use in microelectromechanical systems (mems) and mems devices incorporating same

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- Number: US 2009/0260960 A1
- Document ID: US20090260960A1
- Status: Published application
- Kind: A1
- Application number: 12/106,364
- Filed: 2008-04-21
- Published: 2009-10-22
- Earliest claimed: 2008-04-21
- Assignees: FormFactor, Inc.
- Inventors: John K. Gritters; Eric D. Hobbs; Sangtae Park; Jun Jason Yao
- Web page: https://patentgrep.com/patent/US20090260960A1

## CPC

- 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)
- H01H 1/0036: {Switches making use of microelectromechanical systems [MEMS] (for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009)}
- H01H 59/0009: {making use of micromechanics}
- H01H 2001/0047: {operable only by mechanical latching}
- H01H 2001/0052: {Special contact materials used for MEMS}
- H01H 2001/0078: {with parallel movement of the movable contact relative to the substrate}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)

## 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

### Claim 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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 1)

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.

### Claim 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.

### Claim 10 (depends on 9)

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

### Claim 11 (depends on 9)

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

### Claim 12 (depends on 9)

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

### Claim 13 (depends on 9)

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.

### Claim 14 (depends on 9)

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.

### Claim 15 (depends on 14)

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

### Claim 16 (depends on 14)

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

### Claim 17 (depends on 9)

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

### Claim 18 (depends on 9)

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

### Claim 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.

### Claim 20 (depends on 19)

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

### Claim 21 (depends on 19)

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.

### Claim 22 (depends on 21)

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.

### Claim 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.

### Claim 24 (depends on 23)

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

### Claim 25 (depends on 23)

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.

### Claim 26 (depends on 23)

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.

### Claim 27 (depends on 23)

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.

### Claim 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.

### Claim 29 (depends on 28)

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.

### Claim 30 (depends on 29)

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

### Claim 31 (depends on 30)

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

### Claim 32 (depends on 30)

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.

### Claim 33 (depends on 28)

The actuator of claim 28, further comprising:
at least one gap closing actuator coupled between the first and second gap closing actuators.

### Claim 34 (depends on 28)

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.

### Claim 35 (depends on 34)

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.

### Claim 36 (depends on 28)

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.

### Claim at position 37

37-72. (canceled)