Substrate structure and assembly method for reduced spatial light modulator size

• US 5,818,563 A
• Filed: 09/09/1997
• Issued: 10/06/1998
• Est. Priority Date: 07/23/1996
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Narayan, Chandrasekhar, Colgan, Evan George, Yang, Kei-Hsiung, Sanford, James Lawrence, Melcher, Robert Lee, Nakasogi, Teruhiro
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Ngo, Julie
• Application Number:
  US08/926,152
• Time in Patent Office: 392 Days
• Field of Search: 349/158, 349/160, 349/156, 349/187, 349/190, 349/153, 349/116, 349/149, 349/151, 349/152
• US Class Current: 349/158
• CPC Class Codes: G02F 1/1339 Gaskets; Spacers; Sealing of cells
• CPC Class Codes: G02F 1/136 Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit G02F1/135 takes precedence

Abstract

A spatial light modulator designed to use a minimum area on the surface of a silicon substrate. This invention comprises a silicon substrate on a back plate with a glass cover that is used to seal liquid crystal between the glass cover and the silicon substrate. Most importantly, the glue seal formed to contain the liquid crystal material is between the cover glass plate and the Si substrate on only one side and the back plate on the remaining three sides. This structure allows a smaller semiconductor substrate to be used.

Claims

1. A spatial light modulator, comprising:

a substrate structure comprising a backplate and a silicon substrate in contact with said backplate, said silicon substrate having at its surface an active array area between its edges and at least an electrical connection area at one end of said silicon substrate, and said backplate having edges which extend beyond all but said one end of said silicon substrate;

a transparent cover mounted above said substrate structure and extending beyond said active array area but not covering said electrical connection area;

electro-optic material between said transparent cover and said substrate structure over at least said active array area; and

a sealant in contact with said transparent cover and said substrate structure so as to contain said electro-optic material, said sealant being in contact with said backplate and at most three edges of the active array area on the surface of said silicon substrate including the edge between said electrical connection area and said active array area.

2. A spatial light modulator as recited in claim 1, wherein said sealant is in contact with said backplate and at most one edge of the active array area on said surface of said silicon substrate, said at most one edge being between said active array area and said electrical connection area.

3. A spatial light modulator as recited in claim 1, wherein said silicon substrate is mounted on said backplate.

4. A spatial light modulator as recited in claim 1, further comprising:

a plurality of spacers for separating said transparent cover from said silicon substrate by a fixed distance.

5. An apparatus as recited in claim 1, wherein said electro-optic material is liquid crystal.

6. An apparatus as recited in claim 1, wherein said electro-optic material is twisted nematic liquid crystal.

7. An apparatus as recited in claim 1, wherein said electro-optic material is ferro-electric liquid crystal.

8. An apparatus as recited in claim 1, wherein said electro-optic material is polymer dispersed liquid crystal.

9. An apparatus as recited in claim 1, wherein said electro-optic material is polymer stabilized cholesteric texture liquid crystal.

10. A spatial light modulator, comprising:

a substrate structure comprising a backplate and a silicon substrate in contact with said backplate, said silicon substrate having at its surface at least an electrical connection area at one edge of said silicon substrate and an active array area;

a transparent cover mounted above said substrate structure and extending beyond said active array area but not covering said electrical connection area;

electro-optic material between said transparent cover and said substrate structure over at least said active array area; and

a sealant in contact with said transparent cover and said substrate structure so as to contain said electro-optic material;

wherein said silicon substrate is recessed into said backplate.

11. An apparatus as recited in claim 10, wherein said electro-optic material is selected from the group consisting of liquid crystal, twisted nematic liquid crystal, ferro-electric liquid crystal, polymer dispersed liquid crystal, and polymer stabilized cholesteric texture liquid crystal.

12. A method of assembling a spatial light modulator, said method comprising:

forming a substrate structure by placing a silicon substrate having at its surface at least an electrical connection area at one edge and an active array area in a recess of a backplate so that a surface of said backplate and said surface of said silicon substrate are approximately coplanar;

providing a sealant between a transparent plate coated with a transparent electrical conducting material and said substrate structure such that said sealant is in contact with both said silicon substrate and said backplate; and

filling a cavity formed between said transparent plate and said silicon surface with an electro-optic material wherein said electro-optic material covers at least said active array area but not said electrical connection area.

13. A method of assembling a spatial light modulator comprising:

forming a substrate structure by placing a silicon substrate having at its surface at least an electrical connection area at one edge and an active array area on a flat backplate;

placing spacers on said backplate about said silicon substrate to form a coplanar surface large enough to accommodate a transparent plate with a conducting layer;

placing said transparent plate on said spacers to cover at least said active array area but not said electrical connection area; and

filling a cavity formed between said transparent plate and said silicon substrate with an electro-optic material, thereby forming said spatial light modulator.

14. A spatial light modulator comprising:

a substrate structure comprising a backplate and a silicon substrate in contact with said backplate, said silicon substrate having at its surface at least an electrical connection area at one edge of said silicon substrate and an active array area;

a transparent cover mounted above said substrate structure and extending beyond said active array area but not covering said electrical connection area;

electro-optic material between said transparent cover and said substrate structure over at least said active array area; and

a sealant in contact with said transparent cover and said substrate structure so as to contain said electro-optic material;

and, wherein said back plate comprises a plurality of spacers to control the distance between said top glass and said silicon substrate.

15. An apparatus as recited in claim 14, wherein said electro-optic material is selected from the group consisting of liquid crystal, twisted nematic liquid crystal, ferro-electric liquid crystal, polymer dispersed liquid crystal, and polymer stabilized cholesteric texture liquid crystal.

16. A spatial light modulator as recited in claim 14, wherein said silicon substrate is mounted on said backplate.

17. A spatial light modulator as recited in claim 14, further comprising:

a plurality of spacers for separating said transparent cover from said silicon substrate by a fixed distance.