Micromirror devices with in-plane deformable hinge

• US 7,215,459 B2
• Filed: 02/11/2005
• Issued: 05/08/2007
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Shi, Hongqin, Huibers, Andrew, Patel, Satyadev, Simonian, Dmitri, Dunphy, James, Doan, Jonathan, Zhang, Jianglong
• Primary Examiner(s): Dang; Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US11/056,732
• Publication Number:
  US 20060056006A1
• Time in Patent Office: 816 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/220, 359/222, 359/223, 359/224, 359/230, 359/298, 359/320, 359/322
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 27/1033 having a single light modulator for all colour channels
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

Disclosed herein is a micromirror device having in-plane deformable hinge to which a deflectable and reflective mirror plate is attached. The mirror plate rotates to different angles in response to an electrostatic field established between the mirror plate and an addressing electrode associated with the mirror plate.

Claims

1. A spatial light modulation device, comprising:

an army of micromirror devices, each of which comprises;

a single crystal mirror plate;

a deformable hinge in the same plane of the mirror plate, wherein the hinge extends along a direction that is offset from said diagonal of the mirror plate, and is not parallel to any major sides of the mirror plate; and

one addressing electrode proximate to the mirror plate for deflecting the mirror plate.

2. The device of claim 1, wherein the single crystal is single crystal silicon.

3. The device of claim 2, wherein the mirror plate is substantially square having four major sides;

and wherein said diagonal is one of the two major diagonals each connecting two opposite corners of the square.

4. The device of claim 3, wherein the length of the hinge has an angle with said diagonal, said angle is from +20°

to −

20°

degrees.

5. The device of claim 3, wherein the length of the hinge has an angle with said diagonal, said angle is from +5°

to −

5°

degrees.

6. The device of claim 3, wherein the length of the hinge has an angle with a major side of the mirror plate, said angle is from +35°

to 55°

degrees.

7. The device of claim 2, wherein the deformable hinge is single crystal.

8. The device of claim 7, wherein the deformable hinge and the mirror plate are derived from the same single crystal.

9. The device of claim 8, wherein the mirror plate is held by a frame that comprises a frame wall, said frame wall being bonded to a silicon substrate having the addressing electrode formed thereon, such that the mirror plate is held above and spaced apart from the addressing electrode by the frame.

10. The device of claim 9, wherein the frame is derived from the same single crystal of the mirror plate and the deformable hinge.

11. The device of claim 2, wherein the mirror plate comprises a reflecting surface that comprises a reflective material that is aluminum, gold, and silver.

12. The device of claim 11, wherein the mirror plate further comprises a balancing layer disposed on the opposite surface of the mirror plate to the reflecting layer so as to avoid deformation of the mirror plate due to the reflecting layer.

13. The device of claim 12, wherein the balancing layer comprises a strip.

14. The device of claim 12, wherein the balancing layer comprises a frame.

15. The device of claim 12, wherein the balancing layer is a continuous film.

16. The device of claim 12, wherein the balancing layer comprises a grid.

17. The device of claim 2, wherein the mirror plate has a thickness from 0.1to 0.45 microns.

18. The device of claim 17, wherein the thickness is from 0.2 to 0.35 microns.

19. The device of claim 2, further comprising a light absorbing material that is capable of absorbing 83% or more of the light incident thereto.

20. The device of claim 19, wherein the light absorbing material is capable of absorbing 90% or more of the light incident thereto.

21. The device of claim 19, wherein the light absorbing material is on an edge of the mirror plate.

22. The device of claim 19, wherein the light absorbing material is on a top surface of the frame, said top surface is parallel to the reflecting surface of the mirror plate.

23. The device of claim 19, wherein the light absorbing material is on a frame wall of a frame;

wherein the mirror plate is held by the frame, and said frame wall being bonded to a silicon substrate having the addressing electrode formed thereon.

24. The device of claim 19, wherein the light absorbing material is on a surface of the deformable hinge.

25. The device of claim 2, wherein the hinge comprises a portion that is thinner than the mirror plate.

26. The device of claim 2, wherein the hinge comprises a mechanical enhancing layer.

27. The device of claim 26, wherein the enhancing layer comprises SiN_x.

28. The device of claim 27, wherein the enhancing layer comprises SiO_x.

29. The device of claim 27, wherein the reflecting layer is aluminum.

30. The device of claim 29, wherein the mirror plate further comprises a barrier layer between the reflecting layer and the mirror plate so as to prevent diffusion between the reflecting layer and the single crystal mirror plate.

31. The device of claim 30, wherein the reflecting layer is deposited from a sputtering target comprising Al—

Si.

32. The device of claim 2, wherein the deformable hinge comprises at least a portion that is treated with thermal oxidization.

33. The device of claim 2, wherein the deformable hinge comprises at least a portion that is thermally treated with nitride.

34. The device of claim 2, further comprising:

a package substrate; and

a package cover above the package substrate so as to form a space in which the array of micromirror devices is disposed.

35. The device of claim 34, wherein the package cover is transmissive to visible light.

36. The device of claim 34, wherein the package substrate comprises a concaved surface forming a cavity in which the array of micromirror array devices is disposed;

and wherein the package cover is bonded to the concaved surface so as to seal the micromirror array device between the package substrate and package cover.

37. The device of claim 36, wherein the package cover is hermetically bonded to the package substrate.

38. The device of claim 36, wherein the package cover is non-hermetically bonded to the package substrate.

39. The device of claim 36, further comprising:

a getter.

40. The device of claim 2, further comprising:

a lubricant for lubricating the micromirror device.

41. A projection system, comprising:

an illumination system providing illumination light;

a spatial light modulator of claim 1;

an optical element directing the illumination light onto the spatial light modulator where the illumination is modulated;

a display target on which the modulated illumination light is projected so as to produce a desired image.

42. The system of claim 41, wherein the illumination system comprises a light source, a lightpipe, and a color filter.

43. The system of claim 42, wherein the lightpipe is positioned after the light source and color filter at a propagation path of the illumination light.

44. The system of claim 42, wherein the lightpipe is positioned between the light source and color filter.

45. A spatial light modulator device, comprising:

an array of micromirror devices, each of which comprises;

a single crystal mirror plate;

a deformable hinge in the same plane of the mirror plate;

wherein the hinge is connected to the mirror plate such that the mirror plate is operable to be deflected; and

wherein the hinge comprises on a top surface of the hinge a light absorbing material that is operable to absorb 83% or more of visible light incident thereto.

46. The device of claim 45, wherein the single crystal is a single crystal silicon.

47. The device of claim 46, wherein the light absorbing material is capable of absorbing 90% or more of the visible light incident thereto.

48. The device of claim 47, wherein the light absorbing material is black nickel.

49. The device of claim 47, wherein the light absorbing material is CrN_x.

50. The device of claim 46, wherein the light absorbing material is black nickel, CrN_x, TiAlN, TaN, or a film comprising carbon.

51. The device of claim 46, wherein the hinge is thinner than the mirror plate.

52. The device of claim 46, wherein the hinge is a derived from a single crystal.

53. The device of claim 52, wherein the mirror plate and the hinge are derived from a top layer of a frame that is fabricated from the single crystal, wherein the frame comprises a frame wall.

54. The device of claim 53, wherein the mirror plate comprises a reflecting film.

55. The device of claim 54, wherein the light reflecting material is aluminum.

56. The device of claim 55, wherein the aluminum light reflecting layer is deposited from a sputtering target comprising Al—

Si.

57. The device of claim 56, wherein the enhancing layer comprises TiN_x.

58. The device of claim 56, wherein the enhancing layer comprises SiO_x.

59. The device of claim 53, wherein the mirror plate further comprises a mechanical enhancing layer.

60. The device of claim 53, wherein the mirror plate further comprises a balancing layer so as to avoid deformation of the mirror plate.

61. The device of claim 45, wherein the mirror plate is held by a frame, said frame comprising a frame wall that is bonded to a silicon substrate comprising one addressing electrode for deflecting the mirror plate.

62. The device of claim 45, wherein the mirror plate further comprises a barrier layer disposed between the top surface of the mirror plate and light reflecting layer for preventing diffusion between the mirror plate and light reflecting layer.

63. The device of claim 45, further comprising another light blocking layer capable of absorbing 83% or more of the visible light incident thereto, wherein said another light blocking layer is disposed on a component of the micromirror other than the deformable hinge.

64. A spatial light modulator device, comprising:

an array of micromirror devices, each of which comprises;

a single crystal mirror plate;

a deformable hinge in the same plane of the mirror plate;

wherein the hinge is connected to the mirror plate such that the mirror plate is operable to be deflected; and

wherein the hinge comprises on a top surface of the hinge a light absorbing material with an absorpbility higher than that of the single crystal silicon.

65. The device of claim 64, wherein the single crystal is single crystal silicon.

66. The device of claim 65, wherein the light absorbing layer is capable of absorbing 83% or more of visible light incident thereto.

67. The device of claim 65, wherein the light absorbing material is capable of absorbing 90% or more of the visible light incident thereto.

68. The device of claim 65, wherein the mirror plate and deformable hinge are derived from the same single crystal.