SUPPORT STRUCTURE FOR MEMS DEVICE AND METHODS THEREFOR

• US 20100149627A1
• Filed: 02/24/2010
• Published: 06/17/2010
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Wang, Chun-Ming, Sampsell, Jeffrey B., Kothari, Manish, Sasagawa, Teruo, Ganti, SuryaPrakash
• Granted Patent: US 8,149,497 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: B81B 2203/0307 Anchors
• CPC Class Codes: B81C 1/00595 Control etch selectivity
• CPC Class Codes: B81C 2201/014 by depositing an etch stop layer, e.g. silicon nitride, silicon oxide, metal
• 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
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A microelectromechanical systems device having support structures formed of sacrificial material surrounded by a protective material. The microelectromechanical systems device includes a substrate having an electrode formed thereon. Another electrode is separated from the first electrode by a cavity and forms a movable layer, which is supported by support structures formed of a sacrificial material.

Claims

1. A microelectromechanical systems device comprising:

a substrate having a first electrode layer formed thereon;

a second electrode layer spaced apart from the first electrode layer by a cavity;

at least one support structure comprising side surfaces surrounding the support structure, wherein the at least one support structure is configured to support the second electrode layer; and

a protective material surrounding the at least one support structure to laterally isolate the at least one support structure from the cavity, wherein the protective material further covers at least a portion of a top surface of the support structure, and wherein a portion of the protective material is positioned between the second electrode layer and the top surface of the support structure.

2. The microelectromechanical systems device of claim 1, wherein the at least one support structure is formed over the first electrode layer and the protective material is a self-planarizing material.

3. The microelectromechanical systems device of claim 1, wherein the protective material comprises photoresist.

4. The microelectromechanical systems device of claim 1, wherein the protective material comprises spin-on dielectric.

5. The microelectromechanical systems device of claim 1, wherein the second electrode layer is configured to be movable.

6. The microelectromechanical systems device of claim 1, wherein the protective material has a thickness in a range of about 500 Å

to one micron.

7. The microelectromechanical systems device of claim 1, wherein the at least one support structure comprises an inorganic material.

8. The microelectromechanical systems device of claim 1, wherein the at least one support structure comprises a material selected from the group consisting of silicon, molybdenum, tungsten, and titanium.

9. The microelectromechanical systems device of claim 1, wherein the first electrode layer has a dielectric top surface exposed to the cavity.

10. The microelectromechanical systems device of claim 1, wherein the second electrode layer comprises an aluminum surface exposed to the cavity.

11. The microelectromechanical systems device of claim 1, wherein the at least one support structure is selectively etchable with respect to the protective material.

12. The microelectromechanical systems device of claim 11, wherein the at least one support structure is etchable by xenon difluoride.

13. A method of making an interferometric modulator device, comprising:

providing a substrate having a first electrode layer formed over the substrate;

surrounding side surfaces of at least one support structure with a protective material while covering at least a portion of a top surface of the support structure with the protective material; and

creating a cavity between the first electrode layer and a second electrode layer after surrounding the at least one support structure.

14. The method of claim 13, further comprising:

depositing a sacrificial material over the first electrode layer before surrounding the side surfaces of the at least one support structure; and

forming the second electrode layer after surrounding the side surfaces of the at least one support structure,

wherein creating the cavity comprises selectively removing the sacrificial material outside of the protective material after forming the second electrode layer.

15. The method of claim 14, wherein the sacrificial material comprises a material selected from the group consisting of silicon, molybdenum, tungsten, titanium, and photoresist.

16. The method of claim 14, wherein surrounding the side surfaces of the at least one support structure comprises:

etching at least one annular opening in the sacrificial material after depositing the sacrificial material; and

filling the at least one annular opening with the protective material to surround the at least one support structure.

17. The method of claim 14, wherein the at least one support structure is formed from the sacrificial material.

18. The method of claim 14, wherein the support structure is formed of a material susceptible to selective removing of the sacrificial material.

19. The method of claim 14, wherein the support structure and selectively removed portions of the sacrificial material are susceptible to removal by a same etchant.

20. The method of claim 14, wherein selectively removing comprises etching using xenon difluoride.