Electrostatically charged microstructures

• US 6,597,048 B1
• Filed: 04/10/2001
• Issued: 07/22/2003
• Est. Priority Date: 12/26/2000
• Status: Expired due to Fees

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Kan, Edwin C.
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US09/828,991
• Time in Patent Office: 833 Days
• Field of Search: 257/415, 257/419, 257/420, 257/315
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• CPC Class Codes: B81B 2201/033 Comb drives
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/04 Electrodes
• 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: B81B 7/008 MEMS characterised by an electronic circuit specially adapted for controlling or driving the same B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H02N 1/08 with conductive charge carrier, i.e. capacitor machines

Abstract

A process and apparatus for injecting electrostatic charges into opposing elements of MEMS structures to produce repulsing forces between the elements. These forces tend to produce controlled spacing between components to prevent sticking and to provide friction-free relative movement.

Claims

1. A microstructure incorporating floating nonvolatile electrostatic charges comprising:

first and second spaced, relatively movable microelectromechanical components, each said component including an electrically conductive or semiconductive segment capable of receiving and retaining an electrostatic charge, wherein at least one of said components is a floating gate structure; and

a source of nonvolatile electrical charges comprising an exterior floating gate operable to inject into said floating gate structure a nonvolatile floating electrostatic charge of selected polarity to produce an electrically floating electrode.

2. The microstructure of claim 1, wherein said source is variable to regulate the amount and the polarity of the electrostatic charge in said floating electrode.

3. The microstructure of claim 1 wherein said source is operable to inject nonvolatile electrostatic charges of selected polarity and amplitude into the conductive or semiconductive segments of said first and said second components.

4. The microstructure of claim 3, wherein said first component is fixed and said second component is movable.

5. The microstructure of claim 1, further including a third component incorporating a conductive or semiconductive segment and spaced from said first and second components, said first and third components being fixed and said second component being movably mounted between said first and second components, said source being operable to inject said nonvolatile floating electrostatic charge into said segment of said second component to form said electrically floating electrode.

6. The microstructure of claim 5, wherein said source is further operable to inject a nonvolatile electrostatic charges of selected polarity and amplitude into said segments of said first and third components.

17. The microstructure of claim 1, wherein said at least one of said components is rotatable with respect to the other of said components.

7. A microstructure incorporating floating nonvolatile electrostatic charges, comprising:

first, second and third spaced microelectromechanical components, each said component including an electrically conductive or semiconductive segment capable of receiving and retaining an electrostatic charge, said first and third components being fixed and said second component being movably mounted between said first and second components, and

first, second and third semiconductor devices integral with said first, second and third components and operable to inject nonvolatile electrostatic charges of selected polarity and amplitude into said segments of said first, second and third components respectively, and to produce in said second component an electrically floating electrode.

8. The microstructure of claim 7, wherein said semiconductor devices integral with said first and third components are separated from said components after charge injection.

9. The microstructure of claim 7, wherein said semiconductor devices are controllable to regulate the charges injected into their respective component segments.

10. The microstructure of claim 9, wherein each said semiconductor device is an electrically erasable programmable read-only memory device.

11. The microstructure of claim 7, wherein said second component is mounted to have a resonant frequency dependent upon the values of said electrostatic charges of said first, second and third components.

12. The microstructure of claim 7, wherein said electrostatic charges on said first, second and third components have the same polarity.

13. The microstructure of claim 7, wherein said second component has a dimension that is less than about 100 μ

m.

14. The microstructure of claim 7, wherein said third electrode is a cantilever having a first, fixed end and having a second end extending over said first and second components.

15. A microstructure incorporating floating nonvolatile electrostatic charges, comprising:

first and second spaced fixed microelectromechanical components each including an electrically conductive or semiconductive segment capable of receiving and retaining an electrostatic charge;

a third microelectromechanical component incorporating a conductive or semiconductive segment and having a first, fixed end and a second movable end extending between said first and second components;

a semiconductor source of nonvolatile electrical charges operable to inject into said segment of said third component a nonvolatile floating electrostatic charge of selected polarity to produce an electrically floating electrode, said fixed end of said third component being integral with said source.

16. The microstructure of claim 15, wherein said semiconductor device is separable from said third component.

18. A microstructure incorporating floating nonvolatile charges, comprising:

first and second spaced, relatively movable microelectromechanical components, each said component including an electrically conductive or semiconductive segment capable of receiving and retaining electrostatic charges; and

a source of nonvolatile electrical charges operable to inject into the conductive or semiconductive segment of at least one of said components a nonvolatile floating electrostatic charge of selected polarity to produce an electrically floating electrode, wherein said source is an electrically erasable programmable read-only (EEPROM) having a gate electrically connected to said segment of said second component, said EEPROM being operable to controllably inject electrostatic charges into said second component segment.

19. The microstructure of claim 18, further including a third component spaced from said first and second components, with said second component being movable between said first and third components.

20. The microstructure of claim 19, wherein said second component is released from said EEPROM following electrostatic charge injection to provide a mechanically free-floating electrode.

21. The microstructure of claim 19, wherein said EEPROM is controllable to regulate the motion of said second component with respect to said first and third components.

22. The microstructure of claim 19, further including nonvolatile electrostatic charges on said first and third components, the charges on said first, second and third components being the same polarity to produce repelling forces between said components.

23. The microstructure of claim 22, wherein said second component comprises multiple floating electrodes, each electrically connected to a corresponding EEPROM to enable each floating electrode to carry a different charge.

24. The microstructure of claim 23, wherein each of said floating electrodes has a shape selected to provide specific motion characteristics with respect to said first and third components.

25. The microstructure of claim 22, wherein said second component protrudes out of the space between said first and third components.

26. The microstructure of claim 19, wherein said second component is a membrane incorporating nanometer-scale conductive metal crystals.

27. A microstructure incorporating floating nonvolatile charges, comprising:

first and second spaced, relatively movable microelectromechanical components, each said component including an electrically conductive or semiconductive segment capable of receiving and retaining electrostatic charges; and

a source of nonvolatile electrical charges operable to inject into the conductive or semiconductive segment of at least one of said components a nonvolatile floating electrostatic charge of selected polarity to produce an electrically floating electrode, wherein said source includes a first electrically erasable programmable read-only memory (EEPROM) having a gate electrically connected to said second component, said first and second components comprising a microelectromechanical comb-type actuator, said components having multiple spaced, parallel interdigitated fingers.

28. The microstructure of claim 27, wherein each said EEPROM is connected and operable to inject repelling electrostatic charges on adjacent components.

29. A microstructure, comprising:

first and second spaced, relatively movable microelectromechanical components capable of receiving and retaining an electrostatic charge; and

first and second active controllable semiconductor devices connected to inject into a corresponding one of said first and second components nonvolatile electrostatic charges of selected amplitude and polarity.

30. The microstructure of claim 29, wherein at least one of said components incorporates nanocrystals for receiving and retaining said electrostatic charges.

31. The microstructure of claim 30, wherein each said semiconductor device is an electrically erasable programmable read-only memory (EEPROM) having a gate electrically connected to its corresponding component.

32. The microstructure of claim 31, wherein each said EEPROM is releasable from its corresponding component.

33. The microstructure of claim 29, wherein said first component is rotable with respect to said second component, and wherein said charges are of the same polarity to provide a frictionless hinge.

34. The microstructure of claim 29, wherein said first component is linearly movable with respect to said second component, and wherein said components incorporate interdigitated fingers to provide a comb structure.

35. The microstructure of claim 29, further including means for detecting the relative motion of said components.

36. The microstructure of claim 29, further including means for producing relative motion of said first component with respect to said second component.

37. The microstructure of claim 29, further including:

a third component spaced from and relatively fixed with respect to said first component, said second component being located between and relatively movable with respect to said first and third components; and

a third active controllable semiconductor device connected to inject nonvolatile electrostatic charges of selected amplitude and polarity into said third component.

38. The microstructure of claim 37, wherein said charges on said first, second and third components are selected to position said second component between said first and third components.

39. The microstructure of claim 38, wherein said semiconductor devices are electrically erasable programmable read-only memory (EEPROM) devices.

40. The microstructure of claim 39, wherein said second component comprises a movable beam incorporating nanocrystals.

41. The microstructure of claim 40, wherein said EEPROM devices are releasable from said components.

42. The microstructure of claim 41;

further including means for detecting motion of said second movable beam with respect to said first and third components.

43. The microstructure of claim 41, further including means for moving said movable beam with respect to said first and third components for generating electrical or electromagnetic waves.

44. A microstructure, comprising:

first, second and third spaced parallel microelectromechanical electrodes capable of receiving and retaining an injected nonvolatile electrostatic charge, said second electrode being located between and movable with respect to said first and third electrodes; and

at least one electrically erasable programmable read-only memory (EEPROM) device having a gate electrically connected to, and releasable from, said first, second and third electrodes and operable to inject nonvolatile electrostatic charges into said electrodes.

45. The microstructure of claim 44, wherein said electrostatic charges are of the same polarity, so that said second electrode is repelled by said first and second electrodes.

46. The microstructure of claim 45, wherein said EEPROM is operable to vary the charges on said second electrode to vary the effective mechanical properties of said second electrode.

47. The microstructure of claim 46, wherein the shape of said second electrode is,selected to provide specific mechanical resonance properties.

48. The microstructure of claim 45, wherein said second electrode is movable to generate power.

49. The microstructure of claim 44, wherein said second electrode comprises a movable beam having a thin film layer incorporating conductive nanometer-scale crystals for receiving and retaining said nonvolatile electrostatic charges.

50. The microstructure of claim 44, wherein said second electrode is mounted as a cantilever for motion between and with respect to said first and second electrodes.

51. The microstructure of claim 50, wherein said second electrode protrudes into free space with respect to said first and third electrodes, whereby motion of said second electrode produces electromagnetic wave emission.

52. The microstructure of claim 51, wherein said second electrode is an electrostatically charged membrane containing metal nanocrystals.

53. The microstructure of claim 51, wherein the electrostatic charges on said first, second and third electrodes are selected to regulate the resonant frequency of motion of said second electrode.