Support post architecture for micromechanical devices

• US 5,650,881 A
• Filed: 11/02/1994
• Issued: 07/22/1997
• Est. Priority Date: 11/02/1994
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hornbeck, Larry J.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): SIKDER, MOHAMMAD YUNUS
• Application Number:
  US08/333,186
• Time in Patent Office: 993 Days
• Field of Search: 359/871, 359/872, 359/883, 359/884, 359/224, 359/295, 359/291, 359/292, 359/293, 348/771
• US Class Current: 359/871
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/0361 Tips, pillars
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G06K 15/1252 using an array of light modulators, e.g. a linear array
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A support pillar 426 for use with a micromechanical device, particularly a digital micromirror device, comprising a pillar material 422 supported by a substrate 400 and covered with a metal layer 406. The support pillar 426 is fabricated by depositing a layer of pillar material on a substrate 400, patterning the pillar layer to define a support pillar 426, and depositing a metal layer 406 over the support pillar 426 enclosing the support pillar. A planar surface even with the top of the pillar may be created by applying a spacer layer 432 over the pillars 426. After applying the spacer layer 432, holes 434 are patterned into the spacer layer to remove any spacer material that is covering the pillars. The spacer layer is then reflowed to fill the holes and lower the surface of the spacer layer such that the surface is coplanar with the tops of the support pillars 426.

Claims

1. A micromirror device comprising:

a substrate;

at least one hinge support pillar supported by said substrate, said hinge support pillar comprised of a first deep UV hardened photoresist pillar inside a first metal sheath;

at least one hinge connected to said hinge support pillar;

at least one mirror support pillar connected to said hinge, said mirror support pillar comprised of a second deep UV hardened photoresist pillar inside a second metal sheath; and

at least one mirror element supported by said mirror support pillar.

2. The micromirror device of claim 1 wherein said first metal sheath is an aluminum alloy.

3. The micromirror device of claim 1 wherein said second metal sheath is an aluminum alloy.

4. The micromirror device of claim 1 wherein said at least one hinge is an aluminum alloy.

5. The micromirror device of claim 1 wherein said at least one hinge is an aluminum alloy containing titanium.

6. The micromirror device of claim 1 wherein said at least one hinge is an aluminum alloy containing silicon.

7. The micromirror device of claim 1 wherein said at least one hinge is an aluminum alloy containing 1% silicon and 0.2% titanium.

8. The micromirror device of claim 1 wherein said at least one hinge is 600 Angstroms thick.

9. The micromirror device of claim 1 wherein said at least one mirror element is 4250 Angstroms thick.

10. The micromirror device of claim 1 wherein said first metal sheath is 4000 Angstroms thick.

11. The micromirror device of claim 1 wherein said second metal sheath is 3750 Angstroms thick.

12. The micromirror device of claim 1 wherein said first deep UV hardened photoresist pillar is 1.0 μ

m thick.

13. The micromirror device of claim 1 wherein said first deep UV hardened photoresist pillar is hardened to a temperature of 220°

C.

14. The micromirror device of claim 1 wherein said second deep UV hardened photoresist pillar is 2.2 μ

m thick.

15. The micromirror device of claim 1 wherein said second deep UV hardened photoresist pillar is hardened to a temperature of 180°

C.

16. A micromirror device comprising:

a substrate;

at least one hinge support pillar supported by said substrate, said hinge support pillar comprising a deep UV hardened photoresist pillar inside a metal sheath;

at least one hinge connected to said hinge support pillar; and

at least one mirror element supported by said at least one hinge.

17. The micromirror device of claim 16 wherein said metal sheath is an aluminum alloy.

18. The micromirror device of claim 16 wherein said at least one hinge is an aluminum alloy.

19. The micromirror device of claim 16 wherein said at least one hinge is an aluminum alloy containing titanium.

20. The micromirror device of claim 16 wherein said at least one hinge is an aluminum alloy containing silicon.

21. The micromirror device of claim 16 wherein said at least one hinge is an aluminum alloy containing 1% silicon and 0.2% titanium.

22. The micromirror device of claim 16 wherein said at least one hinge is 600 Angstroms thick.

23. A support pillar for a micromechanical device comprising:

a substrate;

a pillar material support by said substrate, said pillar material formed in the shape of the desired support pillar from deep UV hardened photoresist; and

a metal layer forming a metal sheath at least partially supported by said substrate, wherein said metal layer is formed over said pillar material such that said pillar material is inside said metal sheath.

24. The support pillar of claim 23 wherein said pillar material is deep UV hardened to a temperature of 220°

C.

25. The support pillar of claim 23 wherein said pillar material is deep UV hardened to a temperature of 180°

C.

26. The support pillar of claim 23 wherein said metal layer is an aluminum alloy.

27. The support pillar of claim 23 wherein said metal layer is 3750 Angstroms thick.

28. The support pillar of claim 23 wherein said metal layer is 4000 Angstroms thick.