Desiccant in a MEMS device

• US 8,040,587 B2
• Filed: 05/17/2007
• Issued: 10/18/2011
• Est. Priority Date: 05/17/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Palmateer, Lauren
• Primary Examiner(s): Lester; Evelyn A.
• Application Number:
  US11/750,279
• Publication Number:
  US 20070268581A1
• Time in Patent Office: 1,615 Days
• Field of Search: 359/223, 359/224, 359290-292, 359/295, 359/298, 359/318
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2203/019 characterised by the material or arrangement of seals between parts
• 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 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B

Abstract

A package structure and method for packaging a MEMS device is described. In one embodiment, the MEMS base device can include a substrate having a MEMS device formed thereon, a backplate, an exposed or activated desiccant disposed between the backplate and the transparent substrate, and a cover at least partially encapsulating said desiccant. In another embodiment, a MEMS display device can be manufactured by contacting the substrate and/or backplate with a cover which at least partially encapsulates a desiccant, joining the backplate and the substrate to form a package, and exposing or activating the desiccant.

Claims

1. A MEMS based device, comprising:

a substrate having a MEMS device formed on an upper surface of the substrate;

a backplate having an upper surface and a lower surface;

a desiccant disposed between the backplate and the substrate and forming a border that at least partially surrounds said MEMS device; and

a cover at least partially encapsulating said desiccant, wherein said desiccant is activated or exposed to an interior of the device through the cover, and wherein the cover is sealed to the lower surface of the backplate and the upper surface of the substrate.

2. The device of claim 1, wherein said desiccant completely surrounds said MEMS device.

3. The device of claim 1, further comprising a seal surrounding said MEMS device between said substrate and said backplate.

4. The device of claim 3, wherein the seal is disposed on said cover to attach said substrate and said backplate to said cover.

5. The device of claim 3, wherein the seal is disposed along an outer periphery of said desiccant to seal said substrate to said backplate.

6. The device of claim 1, wherein said cover comprises a weakened area running longitudinally along the length of said cover.

7. The device of claim 6, wherein said weakened area faces said MEMS device.

8. The device of claim 1, wherein said cover is formed of a material that cracks when said cover is subjected to a compressive force.

9. The device of claim 1, wherein said cover comprises an opening on one side.

10. The device of claim 1, wherein said cover comprises a metal or a plastic.

11. The device of claim 1, wherein the MEMS device is an interferometric modulator array.

12. The device of claim 1, further comprising:

a processor that is in electrical communication with the array, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

13. The device of claim 12, further comprising a driver circuit configured to send at least one signal to the array.

14. The device of claim 13, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

15. The device of claim 12, further comprising an image source module configured to send the image data to the processor.

16. The device of claim 15, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

17. The device of claim 12, further comprising an input device configured to receive input data and to communicate the input data to the processor.

18. A MEMS based device, comprising:

means for transmitting light;

means for interferometrically reflecting light through said transmitting means formed on an upper surface of said transmitting means;

means for encapsulating said interferometrically reflecting means having an upper surface and a lower surface;

means for desiccating an environment surrounding said interferometrically reflecting means and forming a border that at least partially surrounds said interferometrically reflecting means, wherein said desiccating means is exposed or activated; and

means for protecting said desiccating means, said protecting means sealed to the lower surface of the encapsulating means and the upper surface of the transmitting means, and configured to expose the desiccating means to the interior of the device through the protecting means.

19. The device of claim 18, wherein the transmitting means comprises a substrate.

20. The device of claim 18, wherein the interferometrically reflecting means comprises an interferometric modulator array.

21. The device of claim 18, wherein the encapsulating means comprises a backplate.

22. The device of claim 18, wherein the protecting means comprises a cover.

23. The device of claim 18, wherein the desiccating means comprises a desiccant.

24. The device of claim 18, further comprising a seal surrounding said interferometrically reflecting means between said encapsulating means and said transmitting means.