Microelectromechanical device with moving element

• US 6,535,663 B1
• Filed: 07/19/2000
• Issued: 03/18/2003
• Est. Priority Date: 07/20/1999
• Status: Expired due to Fees

• Current Assignee: Memlink Ltd.
• Original Assignee: Memlink Ltd.
• Inventors: Chertkow, Igal Roberto
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/619,013
• Time in Patent Office: 972 Days
• Field of Search: 385/16, 385/17, 385/18, 385/19-24, 359/230, 359/224, 359/198, 359/199, 359/214, 359/221, 359/223, 359/226, 359/298
• US Class Current: 385/18
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81C 1/00214 Processes for the simultaneaous manufacturing of a network or an array of similar microstructural devices
• CPC Class Codes: G02B 6/3514 the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3572 Magnetic force magnetic forces controlling reflecting elements in general G02B26/085; magneto-optic devices G02F1/09
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/3578 Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/423 using guiding surfaces for the alignment
• CPC Class Codes: H01H 2001/0084 with perpendicular movement of the movable contact relative to the substrate
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]

Abstract

A microelectromechanical (MEMS) device has a substrate, and a generally planar moving element, such as a mirror, disposed in parallel to the surface of the substrate. An actuator is operatively engageable with the moving element for selectively actuating the moving element between a first position in a plane horizontal to the surface of the substrate and a second position in that plane. The MEMS device may be effectively used as an optical switch. Various different actuators can be used. Preferably, the device is fabricated using a surface micromachining process.

Claims

1. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate; and

(c) an actuator operatively engageable with the moving element for selectively moving the element between a first position in a plane horizontal to the surface of the substrate and a second position in that plane, wherein the actuator comprises;

an elastic material having a surface and positioned between the substrate and the moving element; and

an elastic wave inducer for generating a traveling elastic wave on said surface of the elastic material, the propagation of said elastic wave on said surface serving to move the moving element.

2. The MEMS device of claim 1 wherein the elastic wave inducer comprises:

a first substrate electrode, a second substrate electrode, a ground electrode coupled between the moving element and the surface of the elastic material, and circuitry for providing a first AC electric signal between the first substrate electrode and the ground electrode and a second AC electric signal between the second substrate electrode and the ground electrode, the first and second AC electric signals being out of phase with one another.

3. The MEMS device of claim 1 wherein the moving element includes a conductive component and the device further comprises:

at least one substrate electrode and circuitry for generating an electric field between the conductive component and the at least one substrate electrode to hold the moving element by means of static friction.

4. The MEMS device of claim 1 wherein the moving element includes a conductive component and the device further comprises:

a first substrate electrode, a second substrate electrode, and circuitry for generating an electric field between the first substrate electrode and the second substrate electrode;

whereby the electric field induces a further electric field between the conductive component and at least one of the first and second substrate electrodes to hold the moving element by means of static friction.

5. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate, wherein the moving element rests on static support members fixed to the substrate and has a travel path between the first and second positions; and

(c) an actuator operatively engageable with the moving element for selectively moving the element between a first position in a plane horizontal to the surface of the substrate and a second position in that plane, wherein the actuator comprises;

a plurality of elongated actuating beams spaced perpendicularly to and along an edge of the travel path of the moving element, each beam extending substantially parallel to the surface of the substrate and having a tip and a base rigidly fixed with respect to the substrate;

beam attachment means for controllably holding the moving element to the actuating beams that are located along the edge of the portion of the travel path in which the moving element is located; and

a beam tip actuator for controllably moving the actuating beams, when the moving element is being held thereto, in a desired direction along the travel path.

6. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate; and

(c) an actuator operatively engageable with the moving element for selectively moving the element from a first position in a plane horizontal to the surface of the substrate to a second position in that plane such that the path of an optical beam directed at the device is not affected by the element when the element is in the first position and is affected by the element when the element is in the second position, wherein the actuator comprises;

an elastic material having a surface and positioned between the substrate and the moving element; and

an elastic wave inducer for generating a traveling elastic wave on said surface of the elastic material, the propagation of said elastic wave on said surface serving to move the moving element.

7. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate; and

(c) an actuator operatively engageable with the moving element for selectively moving the element from a first position in a plane horizontal to the surface of the substrate to a second position in that plane such that the path of an optical beam directed at the device is not affected by the element when the element is in the first position and is affected by the element when the element is in the second position, wherein the actuator comprises;

a plurality of elongated actuating beams spaced perpendicularly to and along a travel path of the moving element, each beam having a tip and a base that is rigidly fixed with respect to the substrate; and

a beam actuator for controllably moving the actuating beams so that the beams that are positioned along the portion of the travel path in which the moving element is located intermittently engage the moving element and thereby move the moving element in a desired direction along the travel path.

8. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate, wherein the moving element rests on static support members fixed to the substrate and has a travel path between the first and second positions; and

(c) an actuator operatively engageable with the moving element for selectively moving the element from a first position in a plane horizontal to the surface of the substrate to a second position in that plane such that the path of an optical beam directed at the device is not affected by the element when the element is in the first position and is affected by the element when the element is in the second position, wherein the actuator comprises;

a plurality of elongated actuating beams spaced perpendicularly to and along an edge of the travel path of the moving element, each beam extending substantially parallel to the surface of the substrate and having a tip and a base rigidly fixed with respect to the substrate;

beam attachment means for controllably holding the moving element to the actuating beams that are located along the edge of the portion of the travel path in which the moving element is located; and

a beam tip actuator for controllably moving the actuating beams, when the moving element is being held thereto, in a de sired direction along the travel path.

9. A microelectromechanical (MEMS) device comprising:

(a) a substrate having a surface;

(b) a generally planar moving element disposed in parallel to the surface of the substrate; and

(c) an actuator operatively engageable with the moving element for selectively moving the element between a first position in a plane horizontal to the surface of the substrate and a second position in that plane, wherein the actuator comprises;

a plurality of elongated actuating beams spaced perpendicularly to and along a travel path of the moving element, each beam having a tip and a base that is rigidly fixed with respect to the substrate; and

a beam actuator for controllably moving the actuating beams so that the beams that are positioned along the portion of the travel path in which the moving element is located intermittently engage the moving element and thereby move the moving element in a desired direction along the travel path.

10. The MEMS device of claim 9 wherein the travel path is linear and has first and second edges, and wherein the plurality of actuating beams comprises:

a first set of actuating beams spaced along the first edge of the travel path; and

a second set of actuating beams spaced along the second edge of the travel path, the beam actuator controllably moving the tips of the beams in the first set synchronously with the tips of the beams in the second set.

11. The MEMS device of claim 10 wherein the moving element rests on static support members fixed to the substrate, and wherein, in each of the first and second sets, the actuating beams that are located along the edge of the portion of the travel path in which the moving element is located rotate in phase so that the intermittent engagement of the moving element by said beams in each set is simultaneous.

12. The MEMS device of claim 11 wherein the tips of the actuating beams in the first set are connected to one another by means of a first connecting support beam and the tips of the actuating beams in the second set are connected to one another by means of a second connecting support beam.

13. The MEMS device of claim 12 wherein the first and second connecting support beams are further connected to one another by means of one or more synchronizing beams.

14. The MEMS device of claim 10 wherein the tips of the first set of actuating beams are located proximate to the first edge of the travel path;

and the tips of the second set of actuating beams are located proximate to the second edge of the travel path.

15. The MEMS device of claim 14 wherein the moving element comprises wings extending from said moving element at each of the first and second edges of the travel path, and wherein the wings are operatively engageable with the tips of the actuating beams.

16. A method of fabricating the MEMS device of claim 10 using surface micromachining techniques comprising sequentially depositing and etching a plurality of material layers.

17. The method of claim 16 comprising:

depositing a first structural material layer on the surface of the substrate, and patterning and etching the first structural material layer;

depositing a first sacrificial material layer on top of the first structural material layer, and patterning and etching the first sacrificial material layer;

depositing a second structural material layer on top of the first sacrificial material layer, and patterning and etching the second structural material layer;

depositing a second sacrificial material layer on top of the second structural material layer, and patterning and etching the second sacrificial material layer;

depositing a third structural material layer on top of the second sacrificial material layer, and patterning and etching the third structural material layer; and

removing the remainder of the first and second sacrificial material layers to release the device.

18. The MEMS device of claim 10 wherein the beams are conductive and the beam actuator comprises, for each actuating beam:

a first electrode connected to the substrate and positioned vertically from said actuating beam with respect to the surface of the substrate;

a second electrode connected to the substrate and positioned horizontally from said actuating beam with respect to the surface of the substrate; and

circuitry for controllably generating a first electric field between the first electrode and said actuating beam to move the tip of said actuating beam in a vertical direction with respect to the surface of the substrate, and a second electric field between the second electrode and said actuating beam to move the tip of said actuating beam in a horizontal direction with respect to the surface of the substrate.

19. The MEMS device of claim 10 wherein, in each of the first and second sets, adjacent ones of the actuating beams that are located along the edge of the portion of the travel path in which the moving element is located rotate out of phase so that the intermittent engagement of the moving element by adjacent tips in each set is successive.

20. The MEMS device of claim 9 wherein the beams are conductive and the beam actuator comprises, for each actuating beam:

a first electrode connected to the substrate and positioned vertically from said actuating beam with respect to the surface of the substrate;

a second electrode connected to the substrate and positioned horizontally from said actuating beam with respect to the surface of the substrate; and

circuitry for controllably generating a first electric field between the first electrode and said actuating beam to move said actuating beam in a vertical direction with respect to the surface of the substrate, and a second electric field between the second electrode and said actuating beam to move said actuating beam in a horizontal direction with respect to the surface of the substrate.

21. The MEMS device of claim 9 wherein the moving element includes a conductive component and the device further comprises:

at least one substrate electrode and circuitry for generating an electric field between the conductive component and the at least one substrate electrode to hold the moving element by means of static friction.

22. The MEMS device of claim 9 wherein the moving element includes a conductive component and the device further comprises:

a first substrate electrode, a second substrate electrode, and circuitry for generating an electric field between the first substrate electrode and the second substrate electrode;

whereby the electric field induces a further electric field between the conductive component and at least one of the first and second substrate electrodes to hold the moving element by means of static friction.