Multiple degree of freedom micro electro-mechanical system positioner and actuator

• US 7,451,596 B2
• Filed: 01/18/2005
• Issued: 11/18/2008
• Est. Priority Date: 01/18/2005
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Culpepper, Martin L., Chen, Shih-Chi
• Primary Examiner(s): Nguyen; Hoang M
• Application Number:
  US11/037,866
• Publication Number:
  US 20060156722A1
• Time in Patent Office: 1,400 Days
• Field of Search: 60527-529, 310306-309, 359290-291
• US Class Current: 60/527
• CPC Class Codes: F03G 7/06 using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like using thermal expansion of non-vaporising liquids F01K
• CPC Class Codes: H02K 2201/18 Machines moving with multiple degrees of freedom
• CPC Class Codes: H02N 10/00 Electric motors using thermal effects motors using expansion or contraction of bodies due to heating or cooling F03G7/06

Abstract

A micro electro-mechanical system (MEMS) positioner, including an actuator and method for making the same, includes a stage formed within a first layer of semiconductor material, along with a series of beams, flexure hinges and controlled input thermal actuators. The actuators are operatively engaged with a second layer, and are selectively actuatable to effect longitudinal expansion thereof, so that relative actuation between individual ones of actuators spaced in the planar direction relative to one another is configured to generate controlled movement of the stage within the planar direction, and relative actuation between individual ones of actuators spaced orthogonally to the planar direction relative to one another is configured to generate controlled movement of the stage out of the planar direction. The relative position between the stage and the support is adjustable in each of six degrees of freedom, so that the compliant mechanism forms a quasi-static precision manipulator.

Claims

1. A micro electro-mechanical system (MEMS) positioner comprising:

a first stage extending in a planar direction within a first layer of semiconductor material;

a plurality of first beams extending in the planar direction within said first layer;

a plurality of first flexure hinges disposed within said first layer, coupled to said stage and to said beams;

a plurality of first controlled input thermal actuators extending longitudinally within said first planar layer;

said first actuators being coupled to said first beams at spaced locations thereon;

a second stage extending in a planar direction within a second layer of semiconductor material;

a plurality of second beams extending in the planar direction within said second layer;

a plurality of second flexure hinges disposed within said second layer, coupled to said second stage and to said second beams;

a plurality of second controlled input thermal actuators extending longitudinally within said second planar layer;

said second actuators being coupled to said second beams at spaced locations thereon;

said first layer being superposed with said second layer;

said first layer and said second layer being coupled to one another by an intermediary layer;

said intermediary layer extending intermittently in the planar direction, wherein said first and second layers are coupled to one another at spaced locations thereon;

each of said first and second actuators being selectively actuatable to effect longitudinal expansion thereof;

wherein relative actuation between individual ones of actuators spaced in said planar direction relative to one another is configured to generate controlled movement of said stage within the planar direction;

wherein relative actuation between individual ones of actuators spaced orthogonally to said planar direction relative to one another is configured to generate controlled movement of said stage out of the planar direction;

the relative position between said stage and said support being adjustable in each of six degrees of freedom;

wherein said compliant mechanism forms a quasi-static precision manipulator.

2. A micro electro-mechanical system (MEMS) positioner comprising:

a stage extending in a planar direction;

at least one beam extending in the planar direction;

a plurality of flexure hinges coupled to said stage and to said beams;

a plurality of controlled input thermal actuators extending longitudinally within a first planar layer;

said actuators being coupled to said at least one beam at spaced locations thereon;

a plurality of members extending longitudinally within a second planar layer;

said members being coupled to said beam at spaced locations thereon;

said first layer being superposed with said second layer;

each of said actuators being selectively actuatable to effect longitudinal expansion thereof;

wherein actuation of said actuators is configured to generate controlled movement of said stage out of the planar direction;

wherein said compliant mechanism forms a quasi-static precision manipulator.

3. The actuator assembly of claim 2, wherein:

said actuators includes first controlled input actuators;

said members includes second controlled input actuators being selectively actuatable to effect longitudinal expansion thereof;

wherein relative actuation between individual ones of actuators spaced in said planar direction relative to one another is configured to generate controlled movement of said stage within the planar direction;

wherein relative actuation between individual ones of actuators spaced orthogonally to said planar direction relative to one another is configured to generate controlled movement of said stage out of the planar direction;

the relative position between said stage and said support being adjustable in each of six degrees of freedom.

4. The positioner of claim 2, wherein said stage comprises a first stage disposed within a first layer of semiconductor material.

5. The positioner of claim 2, wherein said at least one beam comprises a first beam extending in the planar direction within said first layer.

6. The positioner of claim 5, wherein said first beam comprises a plurality of first beams disposed within said first layer.

7. The positioner of claim 6, wherein first flexure hinges are disposed within said first layer.

8. The positioner of claim 6, said actuators are coupled to said plurality of beams at spaced locations thereon.

9. The positioner of claim 2, wherein said stage comprises a second stage extending in a planar direction within a second layer of semiconductor material.

10. The positioner of claim 9, wherein said at least one beam comprises a second beam extending in the planar direction within said second layer.

11. The positioner of claim 10, wherein said second beam comprises a plurality of second beams disposed within said second layer.

12. The positioner of claim 11, a plurality of second flexure hinges disposed within said second layer, coupled to said second stage and to said second beams.

13. The positioner of claim 3, wherein said plurality of second controlled input actuators comprises thermal actuators.

14. The positioner of claim 12, wherein said second actuators are coupled to said second beams at spaced locations thereon.

15. The positioner of claim 2, wherein said first layer and said second layer are coupled to one another by an intermediary layer.

16. The positioner of claim 15, wherein said intermediary layer extends intermittently in the planar direction, so that said first and second layers are coupled to one another at spaced locations thereon.

17. The positioner of claim 3 wherein the relative position between said stage and ground is adjustable with a translational resolution in increments as small as one nanometer.

18. The positioner of claim 3 wherein the relative position between said stage and ground is adjustable with a rotational resolution in increments of less than about 5 micro radians.

19. The positioner of claim 3, having a work envelope as small as 5×

5×

2 μ

m³.

20. The positioner of claim 3, generating a force ranging from about 150 to 500 micronewtons with a work volume ranging from 5×

5×

2 to about 6×

6×

10 micrometers.

21. The positioner of claim 3, exhibiting a force/work envelope ratio of at least about 80 micronewtons of force for each micrometer of in plane work envelope.

22. The positioner of claim 3, being fabricated from a semiconductor.

23. The positioner of claim 22, being fabricated from silicon.

24. The positioner of claim 3, having a transmission ratio ranging from:

at least about 0.05;

to about 50.

25. The positioner of claim 24, having a transmission ratio ranging from:

about 0.05;

to about 0.8.

26. The positioner of claim 2, wherein said stage is coupled to flexure hinges spaced in a substantially equilateral triangular pattern.

27. The positioner of claim 26 wherein said plurality of support beams are arranged in a substantially equilateral triangular pattern.

28. The positioner of claim 3, wherein said first controlled input actuators are superposed with said second controlled input actuators.

29. The positioner of claim 3, wherein at least one of said first controlled input actuators is offset in the planar direction from a corresponding one of said second controlled input actuators.

47. A method of aligning a first component and a second component to one another, said method comprising:

using a positioner of claim 2;

fastening the first component to the stage;

grounding a second component; and

selectively activating at least one of said actuators to effect a change in position of the first component relative to the second component in at least any one of six degrees of freedom.

30. A micro electro-mechanical system (MEMS) actuator assembly comprising:

a first actuator extending longitudinally in a first planar layer of semiconductor material;

said first actuator forming an electrical pathway therethrough, having a relatively high resistance portion and a relatively low resistance portion;

a second actuator extending longitudinally in a second planar layer of semiconductor material;

said second actuator forming an electrical pathway therethrough, the pathway having a relatively high resistance portion and a relatively low resistance portion;

said first and second layers being superposed with one another;

said low resistance portions of said first and second actuators being coupled to one another;

said high resistance portions of said first and second actuators being free of one another;

each of said first and second actuators being configured for selective actuation by selectively conveying electric current therethrough, to generate thermal expansion of the relatively high resistance portions thereof;

wherein common actuation of both said first and second actuators is configured to generate movement of said actuator system within a planar direction; and

wherein actuation of one relative to the other of said first and second actuators is configured to generate controlled movement of said system out of the planar direction.

31. A micro electro-mechanical system (MEMS) actuator assembly comprising:

a thermal actuator extending longitudinally in a first planar layer;

said actuator forming an electrical pathway therethrough;

a member extending longitudinally in a second planar layer;

said first layer and said second layer being parallel to one another;

said actuator and said member being coupled to one another;

said actuator being configured for actuation by selective application of electricity thereto, to generate thermal expansion thereof;

wherein actuation of said actuator is configured to generate controlled movement of said system out of the planar direction; and

wherein said actuator has a relatively high resistance portion having a non-uniform transverse cross-section.

32. The actuator assembly of claim 31, wherein:

said actuator includes a first actuator;

said member includes a second actuator configured for actuation by selective application of electricity thereto, to generate expansion thereof;

wherein common actuation of both said first actuator and said second actuator is configured to generate movement of said actuator system within a planar direction; and

wherein actuation of one relative to the other of said first actuator and said second actuator is configured to generate controlled movement of said system out of the planar direction.

33. The actuator assembly of claim 32, wherein said first and second actuators each form an electrical pathway extending therethrough, the pathway having a relatively high resistance portion and a relatively low resistance portion, the high resistance portion being configured for thermal expansion upon selective application of electricity thereto.

34. The actuator assembly of claim 31, wherein said actuator extends longitudinally in a first planar layer of semiconductor material.

35. The actuator assembly of claim 32, wherein said second actuator extends longitudinally in a second planar layer of semiconductor material.

36. The actuator assembly of claim 32, wherein said first and second layers are superposed with one another.

37. The actuator assembly of claim 36, wherein said first and second actuators are superposed with one another.

38. The actuator assembly of claim 33, wherein said low resistance portions of said first and second actuators are coupled to one another.

39. The actuator assembly of claim 38, wherein said high resistance portions of said first and second actuators are spaced from one another.

40. The actuator assembly of claim 32, further comprising another of said first actuators.

41. The actuator assembly of claim 40, comprising a plurality of said first actuators and a plurality of said second actuators.

42. The actuator assembly of claim 32, comprising a plurality of electrical contacts coupled to said first and second actuators.

43. The actuator assembly of claim 33, wherein the relatively high resistance portions of the first and second actuators each have a non-uniform transverse cross-section.

44. The actuator assembly of claim 43, wherein the relatively high resistance portions of the first and second actuators each have a transverse cross-section that varies along the length thereof.

45. The actuator assembly of claim 44, wherein the transverse cross-section increases and then decreases along the length of the relatively high resistance portions.

46. The actuator assembly of claim 45, wherein the transverse cross-section is greater at a medial portion than at end portions of the relatively high resistance portions.

48. A method of fabricating a positioner, said method comprising:

(a) providing a semiconductor wafer having at least two device layers alternately superposed with at least two oxide layers;

(b) applying a mask layer to the uppermost device layer;

(c) etching exposed portions of the uppermost device layer;

(d) etching exposed portions of the uppermost oxide layer;

(e) removing the mask layer;

(f) applying a metallization layer onto exposed portions of the device layers;

(g) masking portions of the metallization layer, to mask a desired contact area;

(h) etching the metallization layer to remove unwanted portions thereof;

(i) removing the mask from remaining metallization to reveal contact areas;

(j) masking exposed areas of the wafer;

(k) etching exposed portions of the exposed device layer;

(l) etching exposed portions of the exposed oxide layer;

(m) etching exposed portions of exposed device layer;

(n) masking the underside of the wafer and protecting the topside of the wafer;

(o) etching the underside of the wafer to an oxide layer;

(p) applying a vaporized etchant to the wafer to remove exposed portions of oxide layer; and

(q) removing the mask.