SPATIAL LIGHT MODULATOR WITH MULTI-LAYER LANDING STRUCTURES

• US 20080196814A1
• Filed: 03/26/2008
• Published: 08/21/2008
• Est. Priority Date: 10/13/2005
• Status: Active Grant

• Current Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Original Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Inventors: Yang, Xiao
• Granted Patent: US 8,066,890 B2
• Time in Patent Office: Days
• US Class Current: 156/60
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

A method of fabricating a spatial light modulator. The method includes providing a first substrate including a first bonding surface, forming a first layer coupled to the bonding surface, wherein the first layer is characterized by a first set of material parameters, and forming a second layer coupled to the first layer, wherein the second layer is characterized by a second set of material parameters. The method also includes patterning the first layer and the second layer to form a plurality of landing structures extending to a first distance from the bonding surface of the first substrate. The method further includes providing a second substrate including a second bonding surface, joining the first bonding surface of the first substrate to the second bonding surface of the second substrate, and forming a plurality of moveable mirrors from the second substrate. During operation, the moveable mirrors make contact with the second layer.

Claims

1. A method of fabricating a spatial light modulator, the method comprising:

providing a first substrate including a first bonding surface;

forming a first layer coupled to the bonding surface, the first layer characterized by a first set of material parameters;

forming a second layer coupled to the first layer, the second layer characterized by a second set of material parameters;

patterning the first layer and the second layer to form a plurality of landing structures extending to a first distance from the bonding surface of the first substrate;

providing a second substrate including a second bonding surface;

joining the first bonding surface of the first substrate to the second bonding surface of the second substrate; and

forming a plurality of moveable mirrors from the second substrate, wherein the moveable mirrors make contact with the second layer during operation of the spatial light modulator.

2. The method of claim 1 wherein the first layer comprises an aluminum layer.

3. The method of claim 1 wherein the second layer comprises a titanium nitride layer.

4. The method of claim 1 wherein the first set of material parameters comprises an elastic modulus less than a predetermined value.

5. The method of claim 4 wherein the predetermined value is 70 GPa.

6. The method of claim 1 wherein the second set of material parameters comprises a hardness measure less than a predetermined value.

7. The method of claim 6 wherein the predetermined value is 2,000 kg/mm² measured using the Knoop hardness test.

8. The method of claim 1 wherein the plurality of moveable mirrors are coplanar with a torsion beam formed from the second substrate.

9. A method of fabricating a spatial light modulator, the method comprising:

providing an electrode substrate comprising a first surface;

forming a multi-level electrode coupled to the first surface of the electrode substrate;

forming a plurality of composite landing structures coupled to the first surface of the electrode substrate and electrically isolated from the multi-level electrode;

forming a spacer structure coupled to the first surface of the electrode substrate;

providing a mirror substrate;

bonding the mirror substrate to the spacer structure of the electrode substrate;

fabricating a mirror plate from a portion of the mirror substrate, wherein the mirror plate comprises a reflective surface and a contact surface; and

fabricating a flexible hinge from the portion of the mirror substrate, wherein the flexible hinge is coupled to the mirror plate and the contact surface of the mirror plate makes contact with at least one of the plurality of composite landing structures upon activation of the multi-level electrode.

10. The method of claim 9 wherein the plurality of composite landing structures comprise a first layer fabricated from a first material and a second layer fabricated from a second material.

11. The method of claim 10 wherein the first material is characterized by a value of Young'"'"'s modulus less than 70 GPa.

12. The method of claim 11 wherein the first material comprises aluminum.

13. The method of claim 10 wherein the second material is characterized by a value of hardness greater than 2,000 kg/mm² measured on the Knoop hardness scale.

14. The method of claim 13 wherein the second material comprises titanium nitride.

15. The method of claim 9 wherein the plurality of multi-level electrodes comprise a layered structure of aluminum, titanium nitride, tungsten, aluminum, and titanium nitride.

16. The method of claim 9 wherein the flexible hinge is a torsion spring hinge.

17. The method of claim 16 wherein a longitudinal axis of the torsion spring hinge is aligned with a diagonal of the mirror plate.

18. A method of fabricating a spatial light modulator, the method comprising:

providing a first substrate comprising a first surface;

forming a plurality of multi-level electrodes coupled to the first surface of the first substrate, each of the plurality of multi-level electrodes adapted to provide an electrostatic force in response to a control signal;

forming a plurality of multi-layer landing structures coupled to the first surface of the first substrate, each of the multi-layer landing structures comprising;

a first material characterized by a value of Young'"'"'s modulus less than 70 GPa, and

a second material characterized by a value of hardness greater than 2,000 kg/mm² measured on the Knoop hardness scale;

forming a plurality of standoff structures coupled to the first surface of the first substrate; and

forming a plurality of mirror structures, each of the mirror structures coupled to at least one of the plurality of standoff structures and adapted to rotate in response to the electrostatic force.

19. The method of claim 18 wherein the plurality of mirror structures comprise a mirror plate and a coplanar torsion beam.

20. The method of claim 18 wherein the first material comprises aluminum and the second material comprises titanium nitride.