Method of fabricating a free-standing microstructure

• US 20060077529A1
• Filed: 08/05/2005
• Published: 04/13/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence, Sampsell, Jeffrey B.
• Granted Patent: US 7,492,502 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

Provided is a MEMS device comprising an integrated post and deformable layer. In some embodiments, the transition between the post and deformable layer comprises substantially a single arcuate or convex surface, thereby providing a mechanically robust structure. Some embodiments provide a method for fabricating a MEMS device comprising the use of a self-planarizing sacrificial material, which provides a surface conducive to the formation of a relatively uniform deformable layer thereon.

Claims

1. A method for fabricating a microelectromechanical systems device comprising:

forming a conductive layer over a first sacrificial layer;

patterning a movable conductor from the conductive layer; and

forming a planar layer of a second sacrificial layer over the movable conductor and first sacrificial layer.

2. The method of claim 1, wherein forming the second sacrificial layer comprises reflowing the layer, non-uniform exposure of the layer, exposure of the layer at non-optimized wavelengths, under-exposure of the layer, or combinations thereof.

3. The method of claim 1, further comprising forming an opening in the first sacrificial layer prior to forming the second sacrificial layer, wherein the opening is adjacent to the movable conductor.

4. The method of claim 3, further comprising forming a first opening in the second sacrificial layer, wherein

the first opening in the second sacrificial layer is adjacent to the movable conductor;

and

the first opening in the second sacrificial layer is substantially aligned with the opening in the first sacrificial layer.

5. The method of claim 4, further comprising forming a second opening in the second sacrificial layer, wherein the second opening in the second sacrificial layer is substantially centered over the movable conductor.

6. The method of claim 4, wherein the first opening in the second sacrificial layer forms a substantially smooth step that substantially covers the movable conductor and the first sacrificial layer.

7. The method of claim 6, further comprising forming a deformable layer over the second sacrificial layer.

8. The method of claim 7, wherein the deformable layer substantially conforms to the smooth step.

9. The method of claim 7, further comprising removing substantially the entire second sacrificial layer after forming the deformable layer.

10. The method of claim 1, wherein the second sacrificial material is a self-planarizing material.

11. The method of claim 10, wherein the self-planarizing material comprises a resist, a photoresist, spin-on glass, spin-on dielectric, or combinations thereof.

12. The method of claim 1, wherein the microelectromechanical systems device is an optical modulator.

13. An interferometric modulator manufactured by the method of claim 1.

14. A microelectromechanical systems device comprising:

a movable conductor formed over a first sacrificial layer, and a planar second sacrificial layer formed over the movable conductor and the first sacrificial layer.

15. The microelectromechanical systems device of claim 14, further comprising a first opening in the first sacrificial material adjacent to the mirror.

16. The microelectromechanical systems device of claim 15, further comprising a second opening in the second sacrificial material adjacent to the mirror.

17. The microelectromechanical systems device of claim 16, further comprising a deformable layer formed over the second sacrificial material.

18. The microelectromechanical systems device of claim 14, wherein the second sacrificial layer comprises a self-planarizing material.

19. The microelectromechanical systems device of claim 18, wherein the self-planarizing material comprises a resist, a photoresist, spin-on glass, spin-on dielectric, or combinations thereof.

20. The microelectromechanical systems device of claim 14, wherein the microelectromechanical systems device is an optical modulator.

21. A method for fabricating an interferometric modulator comprising:

forming a first sacrificial layer;

forming a mirror layer over the first sacrificial layer;

patterning the reflective layer to form a mirror; and

spinning-on a second sacrificial layer over the mirror and the first sacrificial layer.

22. The method of claim 21, wherein the second sacrificial layer comprises a resist, a photoresist, spin-on glass, spin-on dielectric, or combinations thereof.

23. The method of claim 21, further comprising forming a first opening in the second sacrificial layer adjacent to the patterned conductive layer.

24. The method of claim 23, wherein the first opening in the second sacrificial layer forms a substantially smooth step that substantially covers the movable conductor and the first sacrificial layer.

25. The method of claim 24, further comprising forming a deformable layer over the second sacrificial layer.

26. The method of claim 25, wherein the deformable layer substantially conforms to the smooth step.

27. The method of claim 25, wherein the deformable layer at least partially fills the first opening in the second sacrificial layer, thereby forming a support post integrated with the deformable layer.

28. The method of claim 21, further comprising etching away the second sacrificial layer.

29. An interferometric modulator comprising:

a substrate;

a deformable layer;

a plurality of posts extending between the substrate and the deformable layer, wherein the posts and deformable layer are integrated;

an optical stack formed on the substrate proximal to the deformable layer;

a movable mirror disposed between the optical stack and the deformable layer;

a connector securing the movable mirror to the deformable layer; and

a transition between a post and the deformable layer comprising substantially a single arcuate surface.

30. An apparatus comprising:

a substrate;

a deformable layer;

means integrated with the deformable layer for supporting the deformable layer;

a movable conductor disposed between the substrate and the deformable layer;

and

a connector securing the movable conductor to the deformable layer.

31. The apparatus of claim 30, wherein the means for supporting the deformable layer comprises a plurality of posts.

32. The apparatus of claim 30, further comprising:

a display;

a processor that is in electrical communication with said display, wherein the processor is configured to process image data; and

a memory device in electrical communication with said processor.

33. The apparatus of claim 32, further comprising:

a driver circuit configured to send at least one signal to said display.

34. The apparatus of claim 33, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

35. The apparatus of claim 32, further comprising an image source module configured to send said image data to said processor.

36. The apparatus of claim 35, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

37. The apparatus of claim 32, further comprising an input device configured to receive input data and to communicate said input data to said processor.