Micromirror array devices with light blocking areas

• US 7,265,892 B2
• Filed: 05/02/2005
• Issued: 09/04/2007
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew
• Primary Examiner(s): Ben; Loha
• Application Number:
  US11/120,814
• Publication Number:
  US 20060077525A1
• Time in Patent Office: 855 Days
• Field of Search: 359/290, 359/291, 359/295, 359/298, 359/212, 359/223, 359/224, 359/846, 359/297, 438/65, 438/66, 438/72, 438/73, 438/104, 438/107, 257/89, 257/436, 257/443, 348/771, 353/32, 353/35, 353/99, 353/30
• 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
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time

Abstract

Disclosed herein is a micromirror array device package having a light blocking area for reducing unexpected light scattering from the surfaces of the posts.

Claims

1. A method of making a micromirror array device, comprising:

providing a substrate;

forming an array of light blocking pads on the substrate;

depositing a sacrificial material on the substrate;

forming an array of mirror plates and hinges on the sacrificial material and an array of posts extending from the hinges to the substrate with at least one of the posts being supported by one of the light blocking pads; and

removing the sacrificial material such that the mirror plates are movable relative to the substrate.

2. The method of claim 1, wherein the light blocking pads are formed before depositing the sacrificial material.

3. The method of claim 2, further comprising:

depositing a layer of a light blocking material on the substrate; and

patterning the deposited light blocking layer into the light blocking pads at locations each of which corresponds to one of the surfaces of the posts.

4. The method of claim 3, wherein the sacrificial material is deposited on the patterned light blocking pads.

5. The method of claim 1, wherein the light blocking pads are formed after depositing the sacrificial material and during the step of forming the posts that further comprises:

patterning the deposited sacrificial material so as to form a plurality of post areas;

depositing the light blocking material on the patterned sacrificial material;

patterning the deposited sacrificial material such that the bottom surface of at least one of the posts areas is covered by the light blocking material.

6. The method of claim 5, wherein the sacrificial material is deposited as first and second sacrificial layers;

wherein the mirror plates are formed on the first sacrificial layer;

wherein the second sacrificial layer is deposited on the formed mirror plates;

wherein the hinges are formed on the deposited sacrificial material; and

wherein the posts are formed after depositing and patterning of the second sacrificial layer.

7. The method of claim 5, wherein at least one of the post areas has a wall that has the sacrificial material.

8. The method of claim 1, wherein the step of removing the sacrificial material comprises:

removing the sacrificial material using a spontaneous vapor phase etchant.

9. The method of claim 8, wherein the etchant comprises a noble gas halide.

10. The method of claim 9, wherein the noble gas halide comprises a xenon difluoride.

11. The method of claim 8, wherein the etchant comprises an interhalogen.

12. The method of claim 8, wherein the etchant comprises HF.

13. The method of claim 8, wherein the etchant comprises a diluent gas.

14. The method of claim 13, wherein the diluent gas is an inert gas.

15. A micromirror array device, comprising:

a substrate;

an array of light blocking pads on the substrate;

an array of mirror plates attached to an array of hinges; and

an array of posts extending from the hinges to the substrate with at least one of the posts being supported by one of the light blocking pads.

16. The device of claim 15, wherein the substrate is a glass.

17. The device of claim 15, wherein the substrate is a quartz.

18. The device of claim 15, wherein the mirror plates are derived from a single crystal.

19. The device of claim 18, wherein the single crystal is a single crystal silicon.

20. The device of claim 15, wherein the mirror plates and hinges are formed in the same plane.

21. The device of claim 15, wherein the light blocking pads each comprise a light blocking material that comprises a light absorbing material that absorbs 85% or more of the incident light.

22. The device of claim 21, wherein the light blocking material comprises a light absorbing material that absorbs 90% or more of the incident light.

23. The device of claim 21, wherein the light absorbing material comprises chromium.

24. The device of claim 21, wherein the light absorbing material comprises chromium oxide.

25. The device of claim 21, wherein the light absorbing material comprises nickel.

26. The device of claim 21, wherein the light absorbing material comprises a material that is selected from the group consisting of CrN_x, TiAl_x, and TaN_x.

27. The device of claim 21, wherein the light absorbing material comprises CN_x, CAl_xN_y, or CTi_xN_y.

28. The device of claim 21, wherein the light absorbing material comprises SiC_x.

29. The device of claim 21, wherein the light absorbing material comprises WC.

30. The device of claim 21, wherein the light absorbing material comprises TiAlCN.

31. The device of claim 21, wherein the light absorbing material comprises a TiC layer and WC layer.

32. The device of claim 21, wherein the light absorbing material comprises a C layer and WC layer.

33. The device of claim 21, wherein the light absorbing material comprises a TiAlN layer, a WC layer, and a C layer.

34. The device of claim 15, wherein the light blocking pads each comprise a light absorbing material that absorbs 99% or more of the incident light.

35. The device of claim 15, wherein the light blocking pads each comprise a light reflecting layer that reflects 85% or more of the incident light.

36. The device of claim 35, wherein the light reflecting layer comprises a silver layer.

37. The device of claim 35, wherein the light reflecting layer comprises a gold layer.

38. The device of claim 35, wherein the light reflecting layer comprises an aluminum layer.

39. The device of claim 15, wherein the light blocking pads each comprise a light reflecting layer that reflects 90% or more of the incident light.

40. The device of claim 15, further comprising:

an optical film on the substrate that is a light transmissive substrate for adjusting an optical property of the light transmissive substrate.

41. The device of claim 40, wherein the optical film comprises:

an electrically conductive layer that is transmissive to the visible light.

42. The device of claim 41, wherein the optical film further comprises:

an electrically non-conductive layer that is transmissive to the visible light.

43. The device of claim 41, wherein the electrically conductive layer comprises an indium-tin-oxide layer.

44. The device of claim 42, wherein the electrically non-conductive layer comprises a SiO_x layer.

45. The device of claim 42, wherein the electrically non-conductive layer comprises a TiO_x layer.

46. The device of claim 42, wherein the electrically non-conductive layer comprises a NbO_x layer.

47. The device of claim 15, wherein the substrate is a light transmissive substrate that further comprises an anti-reflection layer.

48. The device of claim 15, wherein not all of the surfaces of the posts contact the light blocking pads.

49. The device of claim 15, wherein all of the surfaces of the posts are covered by a light blocking or absorbing material.

50. The device of claim 15, wherein not all mirror plates are held on the substrate by a post.

51. The device of claim 15, wherein the light blocking pad has a shape of square.

52. The device of claim 15, wherein each mirror plate is attached to one of the array of hinges via hinge contact.

53. The device of claim 52, wherein the hinge contact contacts the mirror plate at a location offset away from the geometric center of the mirror plate.

54. The device of claim 53, wherein the hinge contact contacts the mirror plate at a location substantially around the geometric center of the mirror plate.

55. The device of claim 15, further comprising:

an array of addressing electrodes positioned proximate to the mirror plates for addressing and deflecting the mirror plates.

56. The device of claim 55, wherein each mirror plate is associated with only one of the addressing electrodes.

57. The device of claim 15, wherein the mirror plates are formed such that a geometric center-to-center distance between adjacent mirror plates is 10.16 microns or less.

58. The device of claim 15, wherein the mirror plates are formed such that a geometric center-to-center distance between adjacent mirror plates is from 4.38 to 10.16 microns.