Multi-layer, self-aligned vertical combdrive electrostatic actuators and fabrication methods

• US 20020005976A1
• Filed: 03/14/2001
• Published: 01/17/2002
• Est. Priority Date: 03/24/2000
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Behin, Behrang, Pannu, Satinderpall
• Granted Patent: US 6,744,173 B2
• Time in Patent Office: Days
• US Class Current: 359/254
• CPC Class Codes: B81B 2201/033 Comb drives
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 2203/0181 See-saws
• CPC Class Codes: B81B 2203/058 Rotation out of a plane 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 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: B81C 1/00214 Processes for the simultaneaous manufacturing of a network or an array of similar microstructural devices
• CPC Class Codes: B81C 1/00396 Mask characterised by its composition, e.g. multilayer masks
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• 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 6/3524 the optical element being refractive
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• 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 6/359 of the position of the moving element itself during switching, i.e. without monitoring the switched beams
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49156 : with selective destruction of conductive paths

Abstract

A multi-layer vertical comb-drive actuator includes a first comb structure having a plurality of first comb fingers and a second comb structure having a plurality of second comb fingers, wherein the first and second comb fingers are substantially interdigitated. The first and second comb fingers may include two or more stacked conductive layers electrically isolated from each other by an insulating layer or an air gap. Alternatively, either the first or second comb fingers may include only one conductive layer. An application of a voltage between the first and second comb fingers causes the second comb structure to move relative to the first comb structure. The present invention includes a 2D-gimble configuration to rotate a movable element along two axis.

Claims

1. A multi-layer vertical comb-drive actuator comprising:

a) a first comb structure having a plurality of first comb fingers; and

b) a second comb structure having a plurality of second comb fingers, wherein the second comb structure is positioned such that the second comb fingers are interdigitated and self aligned with the first comb fingers;

wherein one or more of the first and second comb fingers includes at least one first conductive layer and at least one second conductive layer, wherein the first and second conductive layers are electrically isolated from each other.

2. The multi-layer vertical comb-drive actuator of claim 1 wherein the first and second conductive layers are electrically isolated by an insulating layer.

3. The multi-layer vertical comb-drive actuator of claim 1 wherein the first and second conductive layers are isolated by an air gap.

4. The multi-layer vertical comb-drive actuator of claim 1, wherein one or more of the first comb fingers include first and second conductive layers.

5. The multi-layer vertical comb-drive actuator of claim 4, wherein one or more of the second comb fingers of the second comb structure has at least one first conductive layer that is substantially aligned with the first conductive layer of the first comb fingers of the first comb structure.

6. The multi-layer vertical comb-drive actuator of claim 5, wherein an application of a voltage between the second conductive layers of the first comb fingers and the first conductive layers of second comb fingers causes relative movement between the first and second comb structures.

7. The multi-layer vertical comb-drive actuator of claim 5, wherein the second comb fingers further comprise a second conductive layer, wherein the first and second conductive layer of the second comb fingers are electrically isolated from each other.

8. The multi-layer vertical comb-drive actuator of claim 7, wherein the first and second conductive layers of the second comb fingers are electrically isolated by an insulating layer.

9. The multi-layer vertical comb-drive actuator of claim 7, wherein the first and second conductive layers of the second comb fingers are electrically isolated by an air gap.

10. The multi-layer vertical comb-drive actuator of claim 7, wherein an application of a voltage between the first conductive layer of the first comb fingers and the second conductive layer of the second comb fingers causes the second comb structure to move relative to the first comb structure.

11. The multi-layer vertical comb-drive actuator of claim 7, wherein an application of a voltage between the second conductive layer of the first comb fingers and the first conductive layer of the second comb fingers causes the second comb structure to move relative to the first comb structure.

12. The multi-layer vertical comb-drive actuator of claim 1, wherein the second comb structure has one or more second comb fingers comprising the first and the second conductive layers.

13. The multi-layer vertical comb-drive actuator of claim 12, wherein the first comb structure and the second comb structure are fabricated from a common substrate containing the first and second conducting layers.

14. The multi-layer vertical comb-drive actuator of claim 12, wherein an application of a voltage between the first conductive layers of the first comb fingers and the second conductive layers of the second comb fingers causes the second comb structure to move relative to the first comb structure.

15. The multi-layer vertical comb-drive actuator of claim 1 further comprising a means for measuring a capacitance between the first comb fingers and the second comb fingers.

16. The multi-layer vertical comb-drive actuator of claim 15 further comprising a feedback mechanism coupled to the capacitance measuring means for controlling a position of the second comb structure.

17. The multi-layer vertical comb-drive actuator of claim 1 further comprising a rotating element mechanically coupled to the second comb structure.

18. The multi-layer vertical comb drive actuator of claim 17, wherein the rotatable element is mechanically coupled to a substrate by a flexure.

19. The multi-layer vertical comb-drive actuator of claim 17 further comprising:

a) a frame mechanically coupled to the rotatable flexure and hence the rotating element;

b) a second rotatable flexure disposed along a second axis and mechanically engaged with the frame;

c) a third comb structure having a one or more third comb fingers; and

d) a fourth comb structure having one or more fourth comb fingers, wherein the fourth comb structure is positioned such that the fourth comb fingers of the fourth comb structure are interdigitated with the third fingers of the third comb structure;

wherein one or more of the third and fourth comb structures have one or more comb fingers including at least one first and at least one second conductive layers, wherein the first and second conductive layers are electrically isolated from each other.

20. The multi-layer vertical comb-drive actuator of claim 19, wherein the first and second conductive layers are electrically isolated by an insulating layer.

21. The multi-layer vertical comb-drive actuator of claim 19, wherein the first and second conductive layers are electrically isolated by an air gap.

22. The multi-layer vertical comb drive actuator of claim 19, wherein the first, second, third and fourth comb structures are substantially co-planar.

23. The multi-layer vertical comb-drive actuator of claim 19, wherein the axis and the second axis are substantially orthogonal.

24. The multi-layer vertical comb-drive actuator of claim 19, wherein the second rotatable flexure is attached to a substrate.

25. The actuator of claim 19 wherein the first comb structure is mechanically coupled to the frame and wherein the fourth comb structure is mechanically coupled to the frame.

26. The multi-layer vertical comb-drive actuator of claim 19, wherein one or more of the third comb fingers include the first and second conductive layers.

27. The multi-layer vertical comb-drive actuator of claim 26, wherein one or more of the fourth comb fingers has at least one first conductive layer aligned with the first conductive layer one or more of the third comb fingers.

28. The multi-layer vertical comb-drive actuator of claim 27, wherein an application of a voltage between the second conductive layer of the third comb fingers of and the first conductive layer of fourth comb fingers causes the fourth comb structure to move relative to the third comb structure, thereby causing the rotating element to rotate about the second axis.

29. The multi-layer vertical comb-drive actuator of claim 28, wherein one or more of the fourth comb fingers includes a second conductive layer aligned with the second conductive layer of the third comb structure, wherein the first and second conductive layers of the fourth comb fingers are electrically isolated from each other.

30. The multi-layer vertical comb-drive actuator of claim 29, wherein the first and second conductive layers of the fourth comb fingers are electrically isolated by an insulating layer.

31. The multi-layer vertical comb-drive actuator of claim 29, wherein the first and second conductive layers of the fourth comb fingers are electrically isolated by an air gap.

32. The multi-layer vertical comb-drive actuator of claim 29, wherein an application of a voltage between the first conductive layers of the third comb fingers and the second conductive layer of the fourth comb fingers causes the fourth comb structure to move relative to the third comb structure, thereby causing the rotating element to rotate about the second axis.

33. The multi-layer vertical comb-drive actuator of claim 19, wherein the fourth comb structure has one or more fourth comb fingers comprising the first and the second conductive layers.

34. The multi-layer vertical comb-drive actuator of claim 33, wherein the third comb structure has one or more first comb fingers comprising at least one first conductive layer in aligned with the first conductive layers of the fourth comb fingers.

35. The multi-layer vertical comb-drive actuator of claim 34, wherein an application of a voltage between the first conductive layers of the third comb fingers and the second conductive layers of the fourth comb fingers causes the fourth comb structure to move relative to the third comb structure, thereby causing the rotating element to rotate about the second axis.

36. The multi-layer vertical comb-drive actuator of claim 19 further comprising a means for measuring a capacitance between the third comb fingers of the and the fourth comb fingers.

37. The multi-layer vertical comb-drive actuator of claim 36 further comprising a feedback mechanism coupled to the capacitance measuring means.