System and method of providing MEMS device with anti-stiction coating

• US 7,692,839 B2
• Filed: 04/29/2005
• Issued: 04/06/2010
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Cummings, William J., Gally, Brian J., Palmateer, Lauren
• Primary Examiner(s): Sugarman; Scott J
• Assistant Examiner(s): PINKNEY, DAWAYNE
• Application Number:
  US11/119,433
• Publication Number:
  US 20060077503A1
• Time in Patent Office: 1,803 Days
• Field of Search: 359/220, 359223-224, 359/237, 359/260, 359290-292, 359/295, 359/298
• US Class Current: 359/237
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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

In various embodiments of the invention, an anti-stiction coating is formed on at least one surface of an interior cavity of a MEMS device. Particular embodiments provide an anti-stiction on one or mirror surfaces of an interferometric light modulation device, also known as an iMoD in some embodiments. In other embodiments, an interferometric light modulation device is encapsulated within a package and the anti-stiction coating is applied after the package is fabricated. In one embodiment, one or more orifices are defined in the package, e.g., in a seal, a substrate or a backplate and the anti-stiction coating material is supplied into the interior of the package via the orifice(s). In one embodiment, the anti-stiction coating material includes a self-aligned (or self-assembled) monolayer. In yet another embodiment, the anti-stiction layer coating can be incorporated into a release process where a sacrificial layer of an interferometric light modulation device is etched away with the use of a gas.

Claims

1. An interferometric light modulating device, comprising:

a reflective element;

a transmissive element;

an anti-stiction coating located between said reflective element and said transmissive element and;

a sacrificial layer located between said reflective element and said transmissive element, wherein said anti-stiction coating is provided on at least a portion of said sacrificial layer.

2. The device of claim 1, further comprising a transparent substrate, wherein said substrate is adhered to a backplate with a seal to form a sealed package, and wherein said reflective element, said transmissive element and said anti-stiction coating are located within said sealed package.

3. The device of claim 2, further comprising a desiccant, wherein said desiccant is located within said sealed package.

4. The device of claim 1, wherein said anti-stiction coating comprises a self aligning monolayer.

5. The device of claim 1, wherein said anti-stiction coating is selected from the group consisting of:

teflon, perfluorodecanoic carboxylic acid, octadecyltrichlorosilane (OTS), dichlorodimethylsilane, fluoro silane, chloro-fluoro silane, methoxy silane, trichlorosilane, silicone, polystyrene, polyurethane, a block copolymer containing a hydrophobic component, polysilazane, graphite, diamond-like carbide (DLC), silicon carbide (SiC), hydrogenated diamond coating, and fluorinated DLC.

6. The device of claim 2, further comprising at least one orifice in said package.

7. The device of claim 6, wherein said at least one orifice is an orifice in said seal, said substrate or said backplate.

8. The device of claim 1, wherein said anti-stiction coating is provided on only a portion of said reflective element.

9. The device of claim 1, wherein said anti-stiction coating is provided on only a portion of said transmissive element.

10. The device of claim 1, wherein the anti-suction coating covers the entire surface of The reflective element.

11. The device of claim 1, wherein the anti-stiction coating covers the entire surface of the transmissive element.

12. The device of claim 1, wherein the anti-stiction coating covers the entire surface of the reflective element where the opticai resonance occurs.

13. The device of claim 1, wherein the anti-stiction coating covers the entire surface of the transmissive element where the optical resonance occurs.

14. An interferometric light modulating device, comprising:

a reflective element;

a transmissive element;

an anti-stiction coating located between substantially all points of said reflective element and said transmissive element which would otherwise contact one another if the anti-stiction coating were absent; and

a sacrificial layer located between said reflective element and said transmissive element, wherein said anti-stiction coating is provided on at least a portion of said sacrificial layer.

15. The device of claim 14, wherein the reflective element comprises a moveable minor.

16. The device of claim 14, wherein the transmissive element comprises a substrate comprising at least one of glass, plastic, and a transparent polymer.

17. The device of claim 14, wherein the anti-stiction coating is located within an optically resonant cavity defined by the reflective element and the transmissive element.

18. The device of claim 14, further comprising an array of reflective elements forming an array of interferometric display elements.

19. The device of claim 14, wherein the anti-stiction coating is located on the reflective element.

20. The device of claim 14, wherein the anti-stiction coating is located on the transmissive element.