MEMS cavity-coating layers and methods

• US 8,164,815 B2
• Filed: 06/07/2010
• Issued: 04/24/2012
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Londergan, Ana R., Natarajan, Bangalore R., Gousev, Evgeni, Webster, James Randolph, Heald, David
• Primary Examiner(s): Mack, Ricky
• Assistant Examiner(s): Tra, Tuyen
• Application Number:
  US12/795,294
• Publication Number:
  US 20100245979A1
• Time in Patent Office: 687 Days
• Field of Search: 359/290, 359/291, 359/292, 359/245, 359/248, 359/254, 359/260, 359/223, 359/224
• US Class Current: 359/237
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• 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

Devices, methods, and systems comprising a MEMS device, for example, an interferometric modulator, that comprises a cavity in which a layer coats multiple surfaces. The layer is conformal or non-conformal. In some embodiments, the layer is formed by atomic layer deposition (ALD). Preferably, the layer comprises a dielectric material. In some embodiments, the MEMS device also exhibits improved characteristics, such as improved electrical insulation between moving electrodes, reduced stiction, and/or improved mechanical properties.

Claims

1. An optical interferometric modulator comprising:

an optical stack comprising a partial reflector and a primary dielectric layer,

a reflective layer movable relative to the optical stack;

a cavity defined by the optical stack and the reflective layer; and

a supplemental conformal dielectric layer as part of an optical dielectric layer within the cavity, wherein the supplemental dielectric layer has a thickness of at least about 10 Å

over each of the primary dielectric layer and the reflective layer within the cavity, the optical dielectric layer including the primary dielectric layer and the supplemental dielectric layer over both the optical stack and the reflective layer, wherein the thickness of the supplemental dielectric layer affects the optical properties of the interferometric modulator, and wherein a total thickness of the optical dielectric layer depends upon the thicknesses of the supplemental dielectric layer and the primary dielectric layer.

2. The optical interferometric modulator of claim 1, further comprising a deformable layer coupled to the reflective layer.

3. The optical interferometric modulator of claim 1, wherein the supplemental conformal dielectric layer comprises at least one of SiO₂ and Al₂O₃.

4. The optical interferometric modulator of claim 1, wherein the thickness of the supplemental conformal dielectric layer is from about 50 Å

to about 400 Å

.

5. The optical interferometric modulator of claim 1, wherein the thickness of the optical dielectric layer is less than about 100 nm.

6. The optical interferometric modulator of claim 1, wherein the supplemental dielectric layer over the reflective layer reduces the reflectivity of the reflective layer by about 5%.

7. A display comprising an array of optical interferometric modulators each like the optical interferometric modulator of claim 1, further comprising:

a seal circumscribing the optical interferometric modulator; and

a backplate secured to the seal.

8. An apparatus comprising:

the display of claim 7;

a processor that is configured to communicate with said display, said processor being configured to process image data; and

a memory device that is configured to communicate with said processor.

9. The apparatus of claim 8, further comprising a driver circuit configured to send at least one signal to the display.

10. The apparatus of claim 9, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

11. The apparatus of claim 8, further comprising an image source module configured to send said image data to said processor.

12. The apparatus of claim 11, wherein the image source module comprises at least one, of a receiver, transceiver, and transmitter.

13. The apparatus of claim 8, further comprising an input device configured to receive input data and to communicate said input data to said processor.

14. The optical interferometric modulator of claim 1, wherein the thickness of the supplemental conformal dielectric layer is from about 100 Å

to about 250 Å

.

15. An optical interferometric modulator comprising:

a means for partially reflecting light;

a movable means for actuating the optical interferometric modulator and for reflecting light; and

a supplemental dielectric means for covering both the means for partially reflecting light and a facing surface of the movable means, wherein the supplemental dielectric means and the means for partially reflecting light cooperate to define an optical dielectric means for establishing an optical path length and reflected wavelength maximized by optical interference, wherein a thickness of the supplemental dielectric means affects the optical properties of the interferometric modulator.

16. An electromechanical systems device comprising:

a substrate comprising a first face;

a deformable layer comprising a first face and a second face;

a variably-sized cavity comprising opposite internal surfaces defined by the first face of the substrate and the first face of the deformable layer;

a plurality of openings in the deformable layer; and

a dielectric layer in the cavity formed over the first face of the substrate and the first face of the deformable layer, wherein the dielectric layer is thicker over a plurality of locations on the first face of the substrate opposite from the openings in the deformable layer than over another location on the first face of the substrate.

17. The electromechanical systems device of claim 16, wherein the dielectric layer is additionally formed over the second face of the deformable layer.

18. The electromechanical systems device of claim 16, further comprising a movable conductor disposed in the cavity and secured to the deformable layer, wherein the movable conductor comprises a surface proximal to the substrate, and a portion of the dielectric layer is formed over the surface of the movable conductor proximal to the substrate.