Micromirror array device with electrostatically deflectable mirror plates

• US 7,394,140 B2
• Filed: 04/19/2005
• Issued: 07/01/2008
• Est. Priority Date: 05/13/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Heureux, Peter H, Huibers, Andrew, Patel, Satyadev, Spindt, Chris
• Primary Examiner(s): Smoot; Stephen W
• Application Number:
  US11/110,184
• Publication Number:
  US 20050196896A1
• Time in Patent Office: 1,169 Days
• Field of Search: 257/436
• US Class Current: 257/436
• 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: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

Disclosed herein is a micromirror array device that comprises an array of reflective deflectable mirror plates each being associated with one single addressing electrode to be deflected to an ON state angle. A light transmissive electrode is disposed proximate to the mirror plates for deflecting the mirror plates to a non-zero OFF angle. The mirror plates are arranged in the array with a center-to-centre distance of 10.17 microns or less.

Claims

1. A micromirror array device, comprising:

first and second substrates bonded together with a gap therebetween;

an array of mirror plates within the gap;

an array of addressing electrodes on the second substrate and proximate to the mirror plates for electrostatically deflecting the mirror plates towards the second substrate;

an electrode on the first substrate for electrostatically deflecting the mirror plates towards the first substrate; and

wherein a center-to-center distance between the adjacent mirror plates is from 4.38 to 10.17 microns.

2. The device of claim 1, wherein each mirror plate is associated with one single addressing electrode for being addressed and deflected.

3. The device of claim 2, wherein the center-to-center distance between the adjacent mirror plates is from 4.38 to 9.34 microns.

4. The device of claim 2, the array of mirror plates has a diagonal from 0.55 inch to 0.8 inch.

5. The device of claim 4, wherein the array of mirror plates has a diagonal around 0.7 inch.

6. The device of claim 2, wherein the array of mirror plates comprises at least 1280 mirror plates along a length of the array.

7. The device of claim 1, wherein a gap between the adjacent mirror plates is 0.5 micron or less.

8. The device of claim 7, wherein the gap between the adjacent mirror plates is from 0.15 to 0.5 micrometer or less.

9. The device of claim 1, wherein the center-to-center distance between adjacent mirror plates is from 8.07 to 10.16 micrometers.

10. The device of claim 1, wherein the center-to-center distance between adjacent mirror plates is from 6.23 to 9.34 micrometers.

11. The device of claim 1, wherein the first substrate is transmissive to visible light;

and wherein the second substrate is a semiconductor substrate.

12. The device of claim 11, wherein the mirror plates are formed on the first substrate;

and wherein the addressing electrodes are on the second substrate.

13. The device of claim 12, wherein each mirror plate is attached to a deformable hinge,;

and the deformable hinge is held on the first substrate by a post formed on the first substrate.

14. The device of claim 13, wherein the mirror plate is attached to the deformable hinge at an attachment point such that the attachment point is away from the geometric center of the mirror plate.

15. The device of claim 13, wherein the mirror plate is attached to the deformable hinge such that the rotation axis of the mirror plate is parallel to but offset from a diagonal of the mirror plate when viewed from the top as the mirror plate is parallel to the first substrate.

16. The device of claim 1, wherein an addressing electrode of the array of addressing electrodes is extended beyond the furthest edge of the mirror plate when viewed from the lop of the mirror plate as the mirror plate is parallel to the first substrate.

17. The device of claim 1, wherein the electrode on the first substrate is transmissive to the visible light.

18. The device of claim 17, wherein the electrode on the first substrate is in a form of a continuous film, a frame, a grid, a strip, or a pad.

19. The device of claim 17, wherein the first substrate further comprises an anti-reflection optical film.

20. The device of claim 19, wherein the first substrate further comprises a light absorbing or blocking mask.

21. The device of claim 20, wherein the light absorbing or blocking mask is in a form of a frame disposed around the circumference of a major surface of the first substrate.

22. The device of claim 1, wherein the electrode on the first substrate is associated with all micromirrors in the micromirror array.

23. The device of claim 22, wherein the electrode is a multilayered structure that comprises an electrically conductive and electrically non-conductive material.

24. The device of claim 23, wherein the electrically conductive material comprises an indium-tin-oxide.

25. The device of claim 23, wherein the electrically non-conductive material comprises a silicon oxide.

26. The device of claim 25, wherein the electrically non-conductive material further comprises TiOx.

27. The device of claim 25, wherein the electrically non-conductive material further comprises NbOx.

28. The device of claim 1, wherein each mirror plate is associated with a stopping mechanism for limiting a rotation of the mirror plate when the mirror plate is rotated to a desired angle.

29. The device of claim 28, wherein the first substrate is a portion of light transmissive wafer;

and wherein the two wafers are bonded together with an intermediate spacer disposed therebetween.

30. The device of claim 1, wherein the second substrate is a portion of a semiconductor wafer having a set of electrode dies formed thereon, wherein each electrode die comprising an array of addressing electrodes.

31. The device of claim 1, wherein the first and second substrates are bonded with a sealing material that comprises a sealing ball.

32. The device of claim 1, wherein the first and second substrates are bonded with a sealing material that comprises an electrically conductive material.

33. The device of claim 32, wherein the electrically conductive material comprises an epoxy that is filled with an electrically conductive element.

34. The device of claim 33, wherein the electrically conductive element is silver.

35. The device of claim 33, wherein the electrically conductive element is gold.

36. The device of claim 33, wherein the electrically conductive element is chromium.

37. The device of claim 32, wherein the electrically conductive material is electrically connected to the electrode on the first substrate.

38. The device of claim 32, wherein the electrically conductive material is electrically connected to the mirror plates.

39. The device of claim 32, wherein the electrode on the first substrate further comprises an insulating layer.

40. The device of claim 1, further comprising:

an electrically conductive spring disposed between the first and second substrates, wherein the electrically conductive spring is electrically connected to the electrode on the first substrate.

41. The device of claim 1, further comprising:

an electrically conductive spring disposed between the first and second substrates, wherein the electrically conductive spring is electrically connected to the mirror plates.

42. The device of claim 1, wherein the second substrate is disposed on a package substrate.

43. The device of claim 42, wherein the package substrate is bonded to the first substrate.

44. The device of claim 43, wherein the package substrate is bonded to a package cover that is light transmissive.

45. The device of claim 44, wherein the package cover and package substrate are hermetically sealed leaving a space therebetween;

and wherein the space has a pressure of 1 atmosphere or less.

46. The device of claim 43, further comprising:

a getter disposed.

47. The device of claim 43, further comprising:

a lubricant disposed.

48. The device of claim 1, further comprising:

a light absorbing mask for absorbing incident light.

49. The device of claim 48, wherein the light absorbing mask is disposed on the first substrate.

50. The device of claim 48, wherein the light absorbing mask is disposed on the second substrate.

51. The device of claim 1, wherein the mirror plates are derived from a single crystal material.

52. The device of claim 51, wherein the single crystal material is a single crystal silicon.

53. The device of claim 1, wherein the mirror plates are formed on the second substrate on which the addressing electrodes are formed.

54. A micromirror array device, comprising:

an array of deflectable reflective mirror plates on a first substrate;

an array of addressing electrodes disposed proximate to and associated with the mirror plates for electrostatically deflecting the mirror plates in a first direction;

a light transparent electrode disposed proximate to the mirror plates for rotating the mirror plates in a second direction other than the first direction; and

wherein a center-to-center distance between the adjacent mirror plates is from 4.38 to 10.17 microns.

55. A projection system, comprising:

an illumination system producing an incident light;

a spatial light modulator comprising a micromirror array device of claim 54 for modulating the incident light;

a projection lens for projecting the modulated incident light onto a display target; and

the display target.

56. The system of claim 55, wherein the illumination system further comprises:

a light source;

a light pipe; and

a color filter comprising a set of color segments.

57. The system of claim 56, wherein the lightpipe is disposed between the light source and the color filter on the propagation path of the illumination light.

58. The system of claim 56, wherein the lightpipe is disposed after both of the light source and the color filter on the propagation path of the illumination light.

59. An assembly, comprising:

first and second wafers;

a plurality of mirror dies each comprising an array of reflective deflectable mirror plates disposed between the first and second wafers;

a plurality of electrode dies on the second wafer with each electrode die comprising an array of addressing electrodes for deflecting the mirror plates towards the second wafer;

a plurality of electrodes disposed on the first wafer for deflecting the mirror plates towards the first wafer; and

wherein a center-to-center distance between adjacent mirror plates in each die is from 4.38 to 10.16 microns.

60. The assembly of claim 59, wherein the mirror dies are on the first wafer that is transmissive to visible light.

61. The assembly of claim 59, wherein the mirror dies are the same as the electrode dies with the addressing electrodes and mirror plates formed on the second substrate.