Support structure for MEMS device and methods therefor

• US 8,218,229 B2
• Filed: 02/24/2010
• Issued: 07/10/2012
• Est. Priority Date: 07/22/2005
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sasagawa, Teruo, Chui, Clarence, Kothari, Manish, Ganti, SuryaPrakash, Sampsell, Jeffrey B., Wang, Chun-Ming
• Primary Examiner(s): PINKNEY, DAWAYNE
• Application Number:
  US12/711,634
• Publication Number:
  US 20100147790A1
• Time in Patent Office: 867 Days
• Field of Search: 359290-292, 359/295, 359223-225, 359/245, 359260-263, 359/298, 359/198, 359301-303, 359317-318, 359/237, 359/242
• 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 method of making a microelectromechanical systems device, comprising:

providing a substrate having a first electrode layer formed thereon;

depositing a sacrificial layer over the first electrode layer;

forming at least one annular hole in the sacrificial layer;

filling the annular hole;

depositing a second electrode layer over the sacrificial layer after filling the annular hole; and

removing the sacrificial layer outside of the annular hole after depositing the second electrode layer to leave a portion of the sacrificial layer that supports the second electrode layer above the first electrode layer.

2. The method of claim 1, wherein filling the annular hole comprises depositing a protective material in the annular hole.

3. The method of claim 2, wherein the protective material is a self-planarizing material.

4. The method of claim 2, wherein the sacrificial layer is susceptible to etching by an etchant and the protective material is resistant to etching by the same etchant.

5. The method of claim 4, wherein the etchant is xenon difluoride.

6. The method of claim 2, wherein the sacrificial layer comprises an inorganic material.

7. The method of claim 6, wherein filling the annular hole comprises depositing a protective material in the annular hole and the inorganic material is selected from the group consisting of silicon, molybdenum, tungsten, and titanium and the protective material comprises photoresist.

8. The method of claim 1, wherein the microelectromechanical systems device is an interferometric modulator device.

9. A method of making an electromechanical systems device, comprising:

providing a substrate having a first electrode layer formed thereon;

depositing a sacrificial layer over the first electrode layer;

forming at least one annular hole in the sacrificial layer;

filling the annular hole;

depositing a second electrode layer over the sacrificial layer after filling the annular hole; and

removing the sacrificial layer outside of the annular hole after depositing the second electrode layer to leave a portion of the sacrificial layer within the filled annular hole, the portion of sacrificial layer connecting the second electrode layer to the substrate.

10. The method of claim 9, wherein filling the annular hole includes depositing a self-planarizing material in the annular hole.

11. The method of claim 9, wherein removing the sacrificial layer includes etching with an etchant and filling the annular hole includes depositing a material resistant to the etchant.

12. The method of claim 9, wherein the sacrificial layer is an inorganic material.

13. The method of claim 12, wherein the inorganic material is selected from the group consisting of silicon, molybdenum, tungsten, and titanium.

14. The method of claim 13, wherein removing the sacrificial layer includes etching with a fluorine-based etchant without removing a material filling the annular hole.