Method and device for fabricating a release structure to facilitate bonding of mirror devices onto a substrate

• US 20060274399A1
• Filed: 06/01/2005
• Published: 12/07/2006
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Original Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Inventors: Yang, Xiao
• Granted Patent: US 7,202,989 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A method of fabricating a spatial light modulator. The method includes providing a first substrate having a mirror layer, the mirror layer having an upper surface and a lower surface. The method also includes forming a standoff structure from the first substrate, the standoff structure having an integrated surface coupled to the lower surface of the mirror layer and a bonding surface opposite the integrated surface. The standoff structure includes a centrally located base section extending from the integrated surface to the bonding surface along a first axis and a plurality of lateral extension arms extending from the base section along a second axis orthogonal to the first axis. The method further includes providing a second substrate having a bonding surface and a support surface, joining the bonding surface of the standoff structure to the bonding surface of the second substrate, and releasing a portion of the first substrate to form a torsion spring hinge coplanar with the mirror layer.

Claims

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

providing a first substrate having a mirror layer, the mirror layer having an upper surface and a lower surface;

forming a standoff structure from the first substrate, the standoff structure having an integrated surface coupled to the lower surface of the mirror layer and a bonding surface opposite the integrated surface, the standoff structure comprising;

a centrally located base section extending from the integrated surface to the bonding surface along a first axis; and

a plurality of lateral extension arms extending from the base section along a second axis orthogonal to the first axis;

providing a second substrate having a bonding surface and a support surface;

joining the bonding surface of the standoff structure to the bonding surface of the second substrate; and

releasing a portion of the first substrate to form a torsion spring hinge coplanar with the mirror layer.

2. The method of claim 1 wherein the second axis is collinear with the torsion spring hinge.

3. The method of claim 2 further comprising releasing a portion of the mirror layer to form a micro-mirror, wherein the torsion spring hinge is aligned with a diagonal of the micro-mirror.

4. The method of claim 1 wherein the first substrate and the standoff structure are fabricated from a single piece of material.

5. The method of claim 4 wherein the single piece of material is a silicon wafer.

6. The method of claim 5 wherein the silicon wafer is a single crystal silicon wafer.

7. The method of claim 1 wherein a reflective surface is coupled to the upper surface of the mirror layer.

8. The method of claim 7 wherein the reflective surface is deposited on the upper surface of the mirror layer.

9. The method of claim 1 wherein the releasing step comprises an etching step that removes material from a portion of the mirror layer and a portion of the standoff structure initially in contact with the portion of the mirror layer.

10. A support structure for a spatial light modulator, the support structure comprising:

a central mounting section coupled to a first substrate at a first surface and to a mirror structure at a second surface, a distance from the first surface to the second surface defined by a first height;

two sets of lateral extension arms, each set extending in opposite directions from the central mounting section, wherein each set of extension arms comprises at least two arms coupled to the first surface, the extension arms defined by a length measured from the central mounting section, a width measured perpendicular to the length, and a second height measured parallel to the first height, wherein the first height is greater than the second height.

11. The support structure of claim 10 wherein one lateral extension arm of each set is parallel to a second extension arm of the set.

12. The support structure of claim 10 wherein the second height is substantially uniform over the length of the lateral extension arms.

13. The support structure of claim 10 wherein a separation distance between the two lateral extension arms making up each set of lateral extension arms, the separation distance being measured along the width of the extension arms, is equal to the width of a torsion spring hinge coplanar with the mirror structure.

14. The support structure of claim 10 wherein the mirror structure, the central mounting section, and the two sets of lateral extension arms are fabricated from a single piece of material.

15. The support structure of claim 14 wherein the single piece of material is a silicon wafer.

16. A standoff structure adapted to support a micro-mirror structure, the standoff structure comprising:

a centrally located base section coupled to an electrode substrate and extending to a first height above the electrode substrate, the base section adapted to support a micro-mirror structure; and

a plurality of extension arms coupled to the base section and extending away from the base section in a lateral direction and extending to a second height above the electrode substrate, wherein the plurality of extension arms are separated by a separation distance.

17. The standoff structure of claim 16 wherein the base section is coupled to the electrode substrate using a substrate bonding process.

18. The standoff structure of claim 16 wherein the standoff structure and the micro-mirror structure are fabricated from a silicon substrate.

19. The standoff structure of claim 16 wherein the micro-mirror structure comprises a torsion beam having a width equal to the separation distance.

20. The standoff structure of claim 16 wherein the first height is greater than the second height.