Micromirror device and method for making the same

• US 7,119,944 B2
• Filed: 02/11/2005
• Issued: 10/10/2006
• 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 X.
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US11/056,727
• Publication Number:
  US 20060056005A1
• Time in Patent Office: 606 Days
• Field of Search: 359/291, 359/292, 359/293, 359/295, 359/298, 359/214, 359/220, 359/222, 359/223, 359/224, 359/230, 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 27/1026 for use with reflective spatial light modulators
• 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 micromirror device, comprising:

a substrate;

a mirror plate;

a deformable hinge disposed in the same plane as the mirror plate and connected to the mirror plate such that the mirror plate is movable relative to the substrate;

first and second posts positioned proximate to the mirror plate for holding the mirror plate on the substrate, wherein the first and second posts are disposed such that a line connecting the first and second posts is not coincident with a diagonal of the mirror plate;

a semiconductor substrate having thereon an addressing electrode for addressing and deflecting the mirror plate, wherein the semiconductor substrate supports the first and second posts; and

wherein the mirror plate and/or the deformable hinge comprises single crystal silicon.

2. The device of claim 1, wherein the first and second posts are aligned to two opposite edges of the mirror plate.

3. The device of claim 2, wherein the hinge and mirror plate comprise a single crystal silicon.

4. The device of claim 3, wherein the mirror plate and posts are made from the same material.

5. The device of claim 4, wherein said same material from which the post and mirror plate are made is a single crystal silicon.

6. The device of claim 2, wherein each of the first and second posts comprises a major edge that is parallel to the closest edge of the mirror plate.

7. The device of claim 3, wherein the deformable hinge is parallel to a diagonal of the mirror plate.

8. The device of claim 1, wherein the deformable hinge is not parallel to any diagonal of the mirror plate.

9. The device of claim 1, further comprising a set of gaps in the plane of the mirror plate, and wherein one of the set of gaps is not perpendicular to any diagonal of the mirror plate.

10. The device of claim 1, further comprising a set of gaps in the plane of the mirror plate, wherein one of the set of gaps is not perpendicular to an illumination light incident onto the mirror plate.

11. The device of claim 1, wherein the addressing electrode is the single addressing electrode of the micromirror device for addressing and deflecting the mirror plate.

12. The device of claim 11, wherein the addressing electrode is positioned offset from the mirror plate.

13. The device of claim 12, wherein a virtual line connecting a geometric center of the mirror plate and a geometric center of the addressing electrode is not perpendicular to the surface of the mirror plate at a non-deflected state.

14. The device of claim 1, wherein the mirror plate has a thickness from 0.1 to 0.45 microns.

15. The device of claim 1, wherein the thickness is from 0.2 to 0.35 microns.

16. A spatial light modulator device, comprising:

an array of micromirror devices of claim 1.

17. The device of claim 16, wherein at least one of the micromirror of the micromirror array has at most one post directly connected thereto.

18. The device of claim 16, wherein at least one of the micromirror of the micromirror array has no post directly connected thereto.

19. The device of claim 16, wherein the top surfaces of at least two adjacent micromirror devices are connected to the semiconductor substrate with the same post.

20. A projection system, comprising:

an illumination system providing illumination light;

a spatial light modulator of claim 16;

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.

21. The system of claim 20, wherein the illumination system comprises a light source, a lightpipe, and a color filter.

22. The system of claim 20, wherein the lightpipe is positioned after the light source and color filter at a propagation path of the illumination light.

23. The system of claim 20, wherein the lightpipe is positioned between the light source and color filter.

24. The device of claim 1, wherein the hinge comprises a coating film having a coating material other than the material of the hinge.

25. The device of claim 24, wherein the coating film comprises a light blocking material.

26. The device of claim 24, wherein the coating film comprises a light absorbing material.

27. The device of claim 1, wherein the hinge comprises at least an oxidized portion.

28. The device of claim 1, wherein the hinge comprises at least a nitrided portion.

29. The device of claim 1, wherein the mirror plate comprises a light reflective coating.

30. The device of claim 29, wherein the light reflective coating comprises gold.

31. The device of claim 29, wherein the light reflective coating comprises silver.

32. The device of claim 29, wherein the light reflective coating comprises aluminum.

33. The device of claim 32, wherein the mirror plate further comprises a barrier layer between the mirror plate and aluminum coating.

34. The device of claim 29, wherein the mirror plate further comprises a balancing layer for balancing the reflective coating.

35. The device of claim 34, wherein the balancing layer is disposed on the opposite side of the mirror plate to the reflective coating.

36. The device of claim 1, further comprising a light blocking/absorbing layer on one or both of the first and second posts.

37. The device of claim 1, further comprising a packaging substrate on which the micromirror device is disposed, wherein the package substrate comprises a light absorbing layer.

38. The device of claim 37, further comprising:

a package cover bonded to the package substrate with the micromirror disposed therebetween.