Spatial light modulator with improved light shield

• US 5,953,153 A
• Filed: 10/27/1997
• Issued: 09/14/1999
• Est. Priority Date: 10/29/1996
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Clark, Jeffrey W., Overlaur, Michael J., Groller, Herman A., Conner, James L.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): BURKE, MARGARET A
• Application Number:
  US08/958,018
• Time in Patent Office: 687 Days
• Field of Search: 359/290, 359/291, 359/295, 359/318, 359/855, 359/223, 359/224
• US Class Current: 359/298
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A spatial light modulator (10) having a micromechanical active portion (12) encompassed by a light shield (14). The light shield (14) is fabricated upon a substrate (36) and has a plurality of openings (72, and 80) to permit underlying layers of photoresist (90, 92) to be undercut from beneath the light shield. Removal of the photoresist layers provides a sufficiently flat light shield, and eliminates the possibility that particles from the photoresist layer could migrate to beneath active micromirrors (30) of the spatial light modulator (12).

Claims

1. A spatial light modulator, comprising.

a substrate;

an array of deflectable light reflecting members supported by a surface of said substrate; and

a light shield supported by said substrate on a perimeter of said array of deflectable light reflecting members.

2. The spatial light modulator as specified in claim 1, wherein said light shield is comprised of a series of members connected together to form a flat surface.

3. The spatial light modulator as specified in claim 1, wherein said deflectable light reflecting members are supported by a first support structure, and said light shield is supported by a second support structure, said second support structure structurally similar to said first support structure.

4. The spatial light modulator as specified in claim 1, wherein said light shield is supported by a support structure comprising a continuous planar member extending over said substrate, said continuous planar member having a plurality of openings defined therethrough permitting any material positioned between said continuous planar member and said substrate to be undercut therefrom.

5. The spatial light modulator as specified in claim 1, wherein at least one of said deflectable light reflecting members is electrically connected to an adjacent portion of said light shield.

6. The spatial light modulator as specified in claim 1, said light shield formed by at least one rectangular reflecting region connected to an adjacent said rectangular reflecting region.

7. The spatial light modulator as specified in claim 1, wherein said light shield and said deflectable light reflecting members are supported by said substrate in the same plane.

8. The spatial light modulator as specified in claim 1, wherein said light shield surrounds said array of deflectable light reflecting members.

9. The spatial light modulator as specified in claim 1, said array of deflectable mirror elements and said light shield each formed by a coplanar array of rectangular surfaces, said rectangular surfaces in a region forming said array of deflectable mirror elements operable to deflect, and said rectangular surfaces in a region forming said light shield not operable to deflect.

10. A method of forming a micromirror device including an active mirror array and a perimeter light shield, comprising the steps of:

depositing a spacer material on a substrate;

depositing a metal layer over said spacer material;

patterning said metal layer to form an array of deflectable mirror elements and at least one light shield on a perimeter of said array; and

undercutting said spacer material from beneath both said array and said at least one light shield.

11. The method as specified in claim 10, said step of depositing a spacer material comprising the step of depositing a photoresist.

12. The method as specified in claim 11, said undercutting step comprising removing said spacer material using a plasma etch process.

13. The method as specified in claim 10, said step of patterning said metal layer comprising the step of patterning said metal layer to form said array and said light shield surrounding said array.

14. The method as specified in claim 10, said step of patterning said metal layer comprising the step of patterning the metal layer to form an array of rectangular elements, some of said rectangular elements forming said array of deflectable mirror elements, and some of rectangular elements forming said light shield.

15. The method as specified in claim 10, said step of patterning said metal layer comprising the step of patterning the metal layer to form an array of rectangular elements, some of said rectangular elements forming said light shield being interconnected at the corners of said rectangular elements.