Hinge structures for micro-mirror arrays

• US 6,952,302 B2
• Filed: 02/12/2003
• Issued: 10/04/2005
• Est. Priority Date: 08/11/2000
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Duboc, Robert M. Jr., Patel, Satyadev R., Doan, Jonathan C.
• Primary Examiner(s): Sugarman, Scott J.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US10/365,951
• Publication Number:
  US 20040156089A1
• Time in Patent Office: 965 Days
• Field of Search: 359/291, 359/290, 359/295, 359/298, 359/237, 359/223, 359/224, 348/770
• US Class Current: 359/291
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A method and spatial light modulator are provided herein. The spatial light modulator has a higher resolution and an increased fill factor. The spatial light modulator also provides an increased contrast ratio. Furthermore, the spatial light modulator of the present invention can be operated in the absence of polarized light and that has improved electro-mechanical performance and robustness with respect to manufacturing. A method and its alternative are disclosed herein by the present invention for manufacturing the spatial light modulator.

Claims

1. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating relative to the substrate by the hinge, the hinge comprising:

a top metal layer comprising a metal that is an elemental metallic substance or an alloy or a metalloid;

a bottom metal layer comprising a metal that is an elemental metallic substance or an alloy or a metalloid; and

an intermediate ceramic layer between the top and bottom metal layers.

2. The device of claim 1, wherein the top metal layer comprises an early transition metal.

3. The device of claim 2, wherein the early transition metal is a compound or alloy of titanium.

4. The device of claim 1, wherein the bottom metal layer comprises an early transition metal.

5. The device of claim 4, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

6. The device of claim 1, wherein the ceramic layer is silicon oxide, silicon carbide or silicon nitride.

7. The device of claim 1, wherein the intermediate ceramic layer has a resistivity higher than 629 10₁₂ μ

Ω

·

cm.

8. The device of claim 1, wherein the top metal layer has a resistivity lower than 100,000 μ

Ω

·

cm.

9. The device of claim 1, wherein the bottom metal layer has a resistivity lower than 100,000 μ

Ω

·

cm.

10. The device of claim 1, wherein the top metal layer has a higher selectivity to a gas-phase etchant than the intermediate ceramic layer, and wherein the bottom metal layer has a higher selectivity to a spontaneous chemical vapor phase etchant than the intermediate ceramic layer.

11. The device of claim 10, wherein the gas-phase etchant is xenon difluoride.

12. The device of claim 1, wherein the top metal layer comprises a material with a higher creep rate than the intermediate ceramic layer over the operating temperature of the plate, and wherein the bottom metal layer comprises a material with a higher creep rate than the intermediate layer over the operating temperature of the plate.

13. The device of claim 1, wherein the top layer and the bottom layer comprise the same material.

14. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating relative to the substrate by the hinge, the hinge comprising:

a top layer comprising a material with a creep rate at an operating temperature of the plate;

an intermediate layer comprising a material with a creep rate lower than that of the top layer; and

a bottom layer comprising a material with a creep rate higher than that of the intermediate layer.

15. The hinge of claim 14, wherein the top layer comprises a metal, metal alloy, or metal compound.

16. The hinge of claim 14, wherein the top layer comprises an early transition metal.

17. The hinge of claim 16, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

18. The hinge of claim 16, wherein the bottom metal layer comprises a metal, metal alloy, or metal compound.

19. The hinge of claim 16, wherein the bottom layer comprises an early transition metal.

20. The hinge of claim 19, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

21. The hinge of claim 16, wherein the intermediate layer comprises silicon oxide or silicon carbide or silicon nitride.

22. The hinge of claim 16, wherein the intermediate layer has resistivity higher than 10¹² μ

Ω

·

cm.

23. The hinge of claim 16, wherein the top layer has resistivity lower than 100,000 μ

Ω

·

cm.

24. The hinge of claim 16, wherein the bottom layer has resistivity lower than 100,000 μ

Ω

·

cm.

25. The hinge of claim 16, wherein the top layer has a higher resistance to a gas-phase etchant than the intermediate layer, and the bottom layer has a higher selectivity to a gas-phase etchant than the intermediate layer.

26. The hinge of claim 25, wherein the spontaneous chemical vapor phase etchant is xenon difluoride.

27. The hinge of claim 16, wherein the top layer and the bottom layer are the same.

28. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating relative to the substrate by the hinge, the hinge comprising:

a conductive top layer with a resistivity less than 100,000 μ

Ω

·

cm;

an insulator intermediate layer with a resistivity greater than 100,000 μ

Ω

·

cm; and

a conductive bottom layer with a resistivity less than 100,000 μ

Ω

·

cm.

29. The hinge of claim 28, wherein the top layer comprises a metal, metal alloy, or metal compound.

30. The hinge of claim 28, wherein the top layer comprises an early transition metal.

31. The hinge of claim 30, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

32. The hinge of claim 28, wherein the bottom layer comprises a metal, metal alloy, or metal compound.

33. The hinge of claim 28, wherein the bottom layer comprises an early transition metal.

34. The hinge of claim 33, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

35. The hinge of claim 28, wherein the intermediate layer comprises silicon oxide or silicon carbide or silicon nitride.

36. The hinge of claim 28, wherein the top layer has a higher selectivity to a gas-phase etchant than the intermediate layer, and wherein the bottom layer has a higher selectivity to a gas-phase etchant than the intermediate layer.

37. The hinge of claim 36, wherein the gas-phase etchant is xenon difluoride.

38. The hinge of claim 28, wherein the intermediate layer has a lower creep rate than the top layer and the bottom layer.

39. The hinge of claim 28, wherein the top layer and the bottom layer are the same.

40. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating along the hinge, the hinge comprising:

a top layer with a resistance to a gas-phase etchant;

an intermediate layer with a lower resistance than the top layer to the gas-phase etchant; and

a bottom layer with a higher resistance than the intermediate layer to the gas-phase etchant.

41. The hinge of claim 40, wherein the top layer comprises a metal, metal alloy, or metal compound.

42. The hinge of claim 40, wherein the top layer comprises an early transition metal.

43. The hinge of claim 42, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

44. The hinge of claim 40, wherein the bottom metal layer comprises a metal, metal alloy, or metal compound.

45. The hinge of claim 40, wherein the bottom layer comprises an early transition metal.

46. The hinge of claim 45, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

47. The hinge of claim 40, wherein the intermediate layer comprises silicon oxide or silicon carbide or silicon nitride.

48. The hinge of claim 40, wherein the intermediate layer has resistivity higher than 10¹² μ

Ω

·

cm.

49. The hinge of claim 40, wherein the top layer has resistivity lower than 100,000 μ

Ω

·

cm.

50. The hinge of claim 40, wherein the bottom layer has resistivity lower than 100,000 μ

Ω

·

cm.

51. The hinge of claim 40, wherein the gas-phase etchant is xenon difluoride.

52. The hinge of claim 40, wherein the intermediate layer has a lower creep rate than the top layer and the bottom layer.

53. The hinge of claim 40, wherein the top layer and the bottom layer are the same.

54. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating relative to the substrate by the hinge, the hinge comprising:

a top ceramic layer;

a bottom ceramic layer; and

an intermediate conducting layer between the top ceramic layer and bottom ceramic layer.

55. The hinge of claim 54, wherein the intermediate metal layer comprises an early transition metal.

56. The hinge of claim 55, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

57. The hinge of claim 54, wherein the top ceramic layer comprises silicon oxide or silicon carbide or silicon nitride.

58. The hinge of claim 54, wherein the bottom ceramic layer comprises silicon oxide or silicon carbide or silicon nitride.

59. The hinge of claim 54, wherein the top ceramic layer has resistivity higher than 10¹² μ

Ω

·

cm.

60. The hinge of claim 54, wherein the intermediate conducting layer has resistivity lower than 100,000 μ

Ω

·

cm.

61. The hinge of claim 54, wherein the bottom ceramic layer has resistivity higher than 10¹² μ

Ω

·

cm.

62. The hinge of claim 54, wherein the top ceramic layer has a higher resistance to a spontaneous chemical vapor phase etchant than the intermediate layer, and wherein the bottom ceramic layer has a higher resistance to a gas-phase etchant than the intermediate layer.

63. The hinge of claim 62, wherein the gas-phase etchant is xenon difluoride.

64. The hinge of claim 54, wherein the intermediate conducting layer comprises a material that is more susceptible to creep than the material comprising the top ceramic layer and the bottom ceramic layer.

65. The hinge of claim 54, wherein the top layer and the bottom layer are the same.

66. A micro-mirror device comprising a micro-mirror plate attached to a hinge for rotating relative to the substrate by the hinge, the hinge comprising:

a top layer with a creep rate at the device operating temperature;

an intermediate layer with a creep rate higher than that of the top layer; and

a bottom layer with a creep rate lower than the intermediate layer.

67. The hinge of claim 66, wherein the intermediate layer comprises a metal, metal alloy, or metal compound.

68. The hinge of claim 66, wherein the intermediate layer comprises an early transition metal.

69. The hinge of claim 68, wherein the early transition metal is an elemental titanium, a compound or alloy of titanium.

70. The hinge of claim 66, wherein the top layer comprises silicon oxide or silicon carbide or silicon nitride.

71. The hinge of claim 66, wherein the bottom layer comprises silicon oxide or silicon carbide or silicon nitride.

72. The hinge of claim 66, wherein the top layer has resistivity higher than 10¹² μ

Ω

·

cm.

73. The hinge of claim 66, wherein the intermediate layer has resistivity lower than 100,000 μ

Ω

·

cm.

74. The hinge of claim 66, wherein the bottom layer has resistivity higher than 10¹² μ

Ω

·

cm.

75. The hinge of claim 66, wherein the top layer has a higher resistance to a spontaneous chemical vapor phase etchant than the intermediate layer, and wherein the bottom layer has a higher resistance to a spontaneous chemical vapor phase etchant than the intermediate layer.

76. The hinge of claim 75, wherein the gas-phase etchant is xenon difluoride.

77. The hinge of claim 66, wherein the top layer and the bottom layer are the same.