Multi-level digital micromirror device

• US 5,583,688 A
• Filed: 12/21/1993
• Issued: 12/10/1996
• Est. Priority Date: 12/21/1993
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hornbeck, Larry J.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US08/171,303
• Time in Patent Office: 1,085 Days
• Field of Search: 359/290, 359/291, 359/292, 359/846, 359/214, 359/223, 359/224, 359/230
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

An improved hidden hinge digital micromirror device, and method of making the same, having hinges 424 attached to a yoke 428 which limits the rotation of the device mirror 430. In one embodiment, the mirror 430 is supported by a center support post 416 attached to two torsion hinges 424 by a landing hinge yoke 428. The ends of the torsion hinges 424 are attached to two support posts 426 which hold the hinges 424 above the substrate 400 and allow the hinges 424 to twist in a torsional fashion. The device is fabricated using two sacrificial spacer layers 404, 414 which are removed to allow the mirror 430 to rotate.

Claims

1. A method of fabricating an array of rotatable elements, each said element individually rotatable into at least two states, said method comprising the steps of:

providing a substrate for supporting all of said elements in said array;

constructing a supporting structure between said substrate and said elements, comprising at least two hinges, and at least one hinge yoke, said hinges connecting said substrate and said hinge yoke, said hinge yoke connected to said elements;

maintaining said elements in a plane separate from the plane of said substrate and said hinge yoke, wherein when said elements are rotated, said hinge yoke rotates with said elements and limits the rotation of said elements by contacting said substrate.

2. The method of claim 1 further comprising the step of constructing address electrodes for providing signals to control the rotation of said elements.

3. The method of claim 1 further comprising the step of constructing address electrodes for providing signals to control the rotation of said elements, wherein said address electrodes are supported away from said substrate.

4. The method of claim 1 further comprising the step of constructing address electrodes for providing signals to control the rotation of said elements, wherein said address electrodes are supported away from said substrate, said address electrodes constructed in the same plane as said at least two hinges.

5. The method of claim 1 further comprising the step of fabricating a bias/reset bus, said bias/reset bus constructed on said substrate and electrically connected to said elements.

6. The method of claim 1 further comprising the step of fabricating control circuitry in said substrate, said control circuitry operable to control the rotation of said elements.

7. The method of claim 1 further comprising the step of varying the size of said hinge yoke from one said element to another said element.

8. The method of claim 1 said hinge yoke having a tip, wherein said at least two hinges and said hinge yoke tip are patterned simultaneously.

9. The method of claim 1 wherein said array is a spatial light modulator of an image display system.

10. The method of claim 1 wherein said array is a spatial light modulator of a printer system.

11. A digital micromirror device comprising:

a substrate;

at least one mirror element;

at least one hinge yoke connected to said at least one mirror element;

at least two hinges between said substrate and said hinge yoke, said hinges supporting said at least one mirror element and allowing said at least one mirror element to rotate relative to said substrate, wherein said hinge yoke limits said rotation of said at least one mirror element.

12. The device of claim 11 further comprising address electrodes for providing signals to control the rotation of said at least one mirror element.

13. The device of claim 11 further comprising address electrodes for providing signals to control the rotation of said at least one mirror element, wherein said address electrodes are supported away from said substrate.

14. The device of claim 11 further comprising address electrodes for providing signals to control the rotation of said at least one mirror element, wherein said address electrodes are supported away from said substrate, and said address electrodes are in the same plane as said at least two hinges.

15. The device of claim 11 further comprising a bias/reset bus, said bias/reset bus constructed on said substrate and electrically connected to said at least one mirror element.

16. The device of claim 11 further comprising control circuitry in said substrate, said control circuitry operable to control the rotation of said at least one mirror element.

17. The device of claim 11 wherein said device has more than one mirror element and the size of said hinge yoke is varied from one said mirror element to another.

18. The device of claim 11 wherein said hinge yoke includes a tip, and wherein said at least two hinges and said hinge yoke tip are patterned simultaneously.

19. The device of claim 11 wherein said device is a spatial light modulator in an image display system.

20. The device of claim 11 wherein said device is a spatial light modulator in a printer system.

21. A digital micromirror device comprising:

a substrate;

at least one mirror element;

at least one hinge yoke connected to said at least one mirror element;

at least two hinges disposed along a hinge axis, said hinges supporting said at least one mirror element away from said substrate and allowing said at least one mirror element to rotate about said hinge axis;

at least one landing electrode disposed between said at least one mirror element and said substrate, wherein said hinge yoke limits said rotation of said at least one mirror element; and

at least one address electrode disposed between said at least one mirror element and said substrate such that said at least one landing electrode is between said at least one address electrode and said hinge axis.

22. The device of claim 21 wherein said at least one address electrode is supported away from said substrate.

23. The device of claim 21 wherein said at least one address electrode is in the same plane as said at least two hinges.

24. The device of claim 21 further comprising a bias/reset bus, said bias/reset bus constructed on said substrate and electrically connected to said at least one mirror element.

25. The device of claim 21 further comprising a bias/reset bus, wherein said at least one landing electrode forms a portion of said bias/reset bus.

26. The device of claim 21 further comprising control circuitry in said substrate, said control circuitry operable to control the rotation of said at least one mirror element.

27. The device of claim 21 wherein said device has more than one mirror element and the size of said hinge yoke is varied from one said mirror element to another.

28. A method of fabricating a digital mirror device comprising:

providing a substrate, said substrate including address circuitry;

depositing a first spacer layer on said substrate, said first spacer layer patterned to define hinge support posts and address electrode support posts;

constructing said hinge support posts;

constructing said address electrode support posts;

establishing deformable torsion hinges on said first spacer layer, wherein said deformable hinges are connected to said hinge support posts and to a hinge yoke;

establishing address electrodes on said first spacer layer, said address electrodes connected to said address electrode support posts;

depositing a second spacer layer on said substrate, said second spacer layer patterned to define mirror support posts on said hinge yoke;

establishing a plurality of mirrors on said second spacer layer, said mirrors connected to said mirror support posts; and

removing said first and second spacer layers, wherein said mirrors may rotate by deforming said hinges, said hinge yoke for limiting the rotation of said mirrors.

29. A digital micromirror device comprising:

a substrate;

an array of mirror elements;

a plurality of hinge yokes, at least one of said hinge yokes connected to each of said mirror elements in said array of mirror elements;

a plurality of hinges, each of said hinges connected between said substrate and one of said hinge yokes, each of said hinges supporting one of said mirror elements in said may of mirror elements and allowing said mirror elements to rotate relative to said substrate wherein said hinge yokes limit said rotation of said mirror elements in said array of mirror elements.

30. The device of claim 29 further comprising a plurality of address electrodes for controlling said rotation of said mirror elements in said array of mirror elements.

31. The device of claim 30 wherein said address electrodes are supported away from said substrate.

32. The device of claim 31 wherein said address electrodes are supported in the same plane as said plurality of hinges.

33. The device of claim 29 further comprising a bias/reset bus supported by said substrate and electrically connected to said array of mirror elements.

34. The device of claim 29 further comprising control circuitry in said substrate, said control circuitry operable to control the rotation of said array of mirror elements.

35. The device of claim 29 wherein the size of said plurality of hinge yokes is varied from one mirror element to another.

36. The device of claim 29 wherein each of said hinge yokes includes a tip, wherein said hinges and said hinge yoke tips are patterned simultaneously.

37. The device of claim 29 wherein said device is a spatial light modulator in an image display system.

38. The device of claim 29 wherein said device is a spatial light modulator in a printer system.