Yield superstructure for digital micromirror device

• US 6,323,982 B1
• Filed: 05/11/1999
• Issued: 11/27/2001
• Est. Priority Date: 05/22/1998
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hornbeck, Larry J.
• Primary Examiner(s): Phan, James
• Application Number:
  US09/309,745
• Time in Patent Office: 931 Days
• Field of Search: 359/223, 359/224, 359/290-291, 359/295, 359/298, 359/198, 359/900
• US Class Current: 359/224.1
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A high-yield micromirror device and fabrication method. Address electrodes (310) and a separate mirror bias/reset conductor (312) are disposed on a substrate (304). A micromirror superstructure including torsion beam support posts (116), torsion beam hinges (120), a torsion beam yoke (114), a mirror support post (326), and a mirror (102) is fabricated above, and electrically connected to, the mirror bias/reset conductor (312) such that the torsion beam yoke (114) and mirror (102) are suspended above the address electrodes (310). A dielectric layer (328) is formed over the address electrodes (310). The dielectric layer (328), coupled with the elimination of upper address electrodes used in the prior art electrically insulates the address electrodes (310) from contact with the mirror superstructure and prevents conductive debris from shorting either the mirror superstructure or mirror bias/reset conductor (312) to the address electrodes (310).

Claims

1. A micromirror device comprising:

a substrate;

at least one address electrode supported by said substrate;

a mirror bias/reset conductor supported by said substrate;

a dielectric layer overlying said at least one address electrode;

a deformable element supported over said dielectric layer; and

a deflectable rigid member supported by said deformable element, wherein a voltage differential between said at least one address electrode and said rigid member is operable to create an electrostatic attraction between said at least one address electrode and said rigid member and to cause said deflectable rigid member to deflect toward said at least one address electrode.

2. The micromirror device of claim 1, wherein said rigid member is a hinge yoke.

3. The micromirror device of claim 1, wherein said rigid member is a mirror.

4. The micromirror device of claim 1, wherein said deformable element is a torsion hinge.

5. The micromirror device of claim 1, wherein said deformable element is a cantilever hinge.

6. The micromirror device of claim 1, said dielectric layer further overlying said mirror bias/reset conductor.

7. The micromirror device of claim 1, said dielectric layer further overlying said mirror bias/reset conductor, wherein portions of said dielectric layer are removed to allow said deflectable rigid member to contact said mirror bias/reset conductor.

8. A method of forming a micromirror device, said method comprising the steps of:

forming a mirror bias/reset conductor and address electrodes on a substrate;

forming a dielectric layer over said address electrodes; and

forming a deflectable rigid member supported by said substrate.

9. The method of claim 8, wherein said step of forming a deflectable rigid member comprises the step of forming a mirror.

10. The method of claim 8, wherein said step of forming a deflectable rigid member comprises the step of forming a hinge yoke.

11. The method of claim 8, wherein said step of forming a deflectable rigid member comprises the step of forming a mirror and a torsion hinge yoke.

12. The method of claim 8, wherein said step of forming a dielectric layer over said address electrodes comprises forming a dielectric layer over said address electrodes and said mirror bias/reset conductor.

13. The method of claim 8, further comprising the step of forming a deformable member supported by said substrate, said deflectable rigid member connected to and supported by said deformable member.

14. The method of claim 13, wherein said step of forming a deformable member comprises the step of forming a torsion hinge.

15. The method of claim 13, wherein said step of forming a deformable member comprises the step of forming a cantilever hinge.

16. The method of claim 8, further comprising the steps of:

depositing a spacer layer over said address electrodes and said mirror bias/reset conductor;

opening vias in said spacer layer;

depositing a metal in said vias; and

patterning said metal to form at least one support structure, said at least one support structure supporting said deflectable rigid member above said substrate.

17. The method of claim 16, further comprising the step of:

removing at least part of said spacer layer.

18. A method of forming a micromirror device, said method comprising the steps of:

forming a mirror bias/reset conductor and address electrodes on a substrate;

forming a dielectric layer over said address electrodes; and

forming a deflectable rigid member supported by said substrate by;

depositing a first spacer layer;

depositing at least one metal layer on said first spacer layer;

patterning said at least one metal layer to form said support structures, a deformable element, and a hinge yoke;

forming a second spacer layer over portions of said first spacer layer not covered by said support structures, said deformable element, and said hinge yoke;

depositing a third spacer layer over said second spacer layer, said support structures, said deformable element, and said hinge yoke;

opening vias through said third spacer layer to said hinge yoke; and

forming micromirrors on said third spacer layer.

19. The method of claim 18 wherein said step of forming a second spacer layer comprises the step of forming a second spacer layer over said deformable element.

20. The method of claim 18 wherein said step of depositing a third spacer layer comprises the step of depositing a planarizing third spacer layer.

21. A micromirror device comprising:

a substrate;

a first layer supported by said substrate;

a second layer spaced apart from said first layer, said second layer forming a micromirror; and

a third layer disposed between and spaced apart from said first layer and said second layer, said third layer supported by said substrate and supporting said second layer, said third layer comprising at least one deformable element and at least one hinge yoke, wherein address electrodes are formed only in said first layer.

22. The micromirror device of claim 21 further comprising a dielectric layer disposed on said address electrodes.

23. A method of forming a micromirror device, said method comprising the steps of:

forming a mirror bias/reset conductor and address electrodes on a substrate;

forming a dielectric layer over said address electrodes;

forming a hinge yoke supported above said address electrodes; and

forming a micromirror supported by said hinge yoke.

24. The method of claim 23, further comprising the step of forming a dielectric layer over said address electrodes and said mirror bias/reset conductor.

25. The method of claim 23, further comprising the step of forming a deformable member supported by said substrate, said hinge yoke connected to and supported by said deformable member.

26. The method of claim 25, wherein said step of forming a deformable member comprises the step of forming a torsion hinge.

27. The method of claim 25, wherein said step of forming a deformable member comprises the step of forming a cantilever hinge.

28. The method of claim 23, further comprising the steps of:

depositing a spacer layer over said address electrodes and said mirror bias/reset conductor;

opening vias in said spacer layer;

depositing a metal in said vias; and

patterning said metal to form said at least one support structure, said at least one support structure supporting said micromirror above said substrate.

29. The method of claim 28, further comprising the step of:

removing at least part of said spacer layer.

30. The method of claim 23, said step of forming a micromirror comprising the steps of:

depositing an inverse spacer layer, said inverse spacer layer patterned to avoid said hinge yoke;

depositing a spacer layer over said inverse spacer layer and said hinge yoke;

opening vias through said spacer layer to said hinge yoke; and

forming micromirrors on said spacer layer.