Method of fabricating a free-standing microstructure

• US 7,492,502 B2
• Filed: 08/05/2005
• Issued: 02/17/2009
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence, Sampsell, Jeffrey B.
• Primary Examiner(s): Mack; Ricky L
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/198,127
• Publication Number:
  US 20060077529A1
• Time in Patent Office: 1,292 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/298
• 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;

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

forming an opening in the first sacrificial layer prior to forming the second sacrificial layer, wherein the opening is adjacent to the movable conductor;

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; and

forming a deformable layer over the second sacrificial layer, and into the first opening in the second sacrificial layer, thereby forming an integrated deformable layer and post.

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 a second opening in the second sacrificial layer, wherein the second opening in the second sacrificial layer is substantially centered over the movable conductor.

4. The method of claim 1, 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.

5. The method of claim 4, wherein the deformable layer substantially conforms to the smooth step.

6. The method of claim 1, further comprising removing substantially the entire second sacrificial layer after forming the deformable layer.

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

8. The method of claim 7, wherein the self-planarizing material comprises a resist, a photoresist, spin-on glass, spin-on dielectric, or combinations thereof.

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

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

16. The method of claim 3, wherein forming a deformable layer over the second sacrificial layer comprises forming the deformable layer through the second opening of the second sacrificial layer, wherein the deformable layer contacts the movable conductor, thereby forming an integrated deformable layer and connector.

11. A microelectromechanical systems device comprising:

a movable conductor formed over a first sacrificial layer;

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

an opening in the first sacrificial layer adjacent to the movable conductor;

a first opening in the second sacrificial layer adjacent to the movable conductor and substantially aligned with the opening in the first sacrificial layer; and

a conductive deformable layer over the planar second sacrificial layer, comprising an integrated post extending into the first opening in the second sacrificial layer.

12. The microelectromechanical systems device of claim 11, further comprising a second opening in the second sacrificial material substantially centered over the movable conductor.

13. The microelectromechanical systems device of claim 11, wherein the second sacrificial layer comprises a self-planarizing material.

14. The microelectromechanical systems device of claim 13, wherein the self-planarizing material comprises a resist, a photoresist, spin-on glass, spin-on dielectric, or combinations thereof.

15. The microelectromechanical systems device of claim 11, wherein the microelectromechanical systems device is an optical modulator.

17. The microelectromechanical systems device of claim 12, wherein the deformable layer comprises an integrated connector extending through the second opening in the second sacrificial layer and contacting the movable conductor.