DESICCANT IN A MEMS DEVICE

• US 20070268581A1
• Filed: 05/17/2007
• Published: 11/22/2007
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm, Inc.
• Inventors: Palmateer, Lauren
• Granted Patent: US 8,040,587 B2
• Time in Patent Office: Days
• US Class Current: 359/512
• 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 thereon;

a backplate;

a desiccant disposed between the backplate and the substrate; and

a cover at least partially encapsulating said desiccant, wherein said desiccant is exposed or activated.

2. The device of claim 1, wherein said desiccant forms a border that at least partially surrounds said MEMS device.

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

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

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

6. The device of claim 4, wherein the seal is disposed along an outer periphery of said desiccant to seal said substrate to said backplate.

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

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

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

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

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

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

13. 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.

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

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

16. The device of claim 13, further comprising an image source module configured to send the image data to the processor.

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

18. The device of claim 13, further comprising an input device configured to receive input data and to communicate the input data to the processor.

19. A method of manufacturing a display device, comprising:

providing a substrate having a MEMS device formed thereon;

providing a backplate;

contacting the substrate and/or the backplate with a cover, wherein the cover at least partially encapsulates a desiccant;

joining the backplate to the substrate to form a package, wherein the MEMS device is encapsulated by the package; and

exposing or activating the desiccant.

20. The method of claim 19, further comprising applying a seal between the backplate and the substrate.

21. The method of claim 19, wherein the cover is configured to form a border around said MEMS device.

22. The method of claim 19, wherein said package has at least one opening.

23. The method of claim 19, wherein activating the desiccant comprises heating the desiccant.

24. The method of claim 19, wherein said cover comprises a weakened area running longitudinally along the length of said cover.

25. The method of claim 24, wherein exposing the desiccant comprises cracking said weakened area thereby exposing the desiccant.

26. The method of claim 19, further comprising heating the MEMS device to activate said seal.

27. A MEMS based device made by the method of claim 19.

28. A MEMS based device, comprising:

means for transmitting light;

means for interferometrically reflecting light through said transmitting means formed on said transmitting means;

means for encapsulating said interferometrically reflecting means; and

means for desiccating an environment surrounding said interferometrically reflecting means, said desiccating means is exposed or activated;

means for protecting said desiccating means, said protecting means is positioned between the encapsulating means and the transmitting means.

29. The device of claim 28, wherein the transmitting means comprises a substrate.

30. The device of claim 28, wherein the interferometrically reflecting means comprises an interferometric modulator array.

31. The device of claim 28, wherein the encapsulating means comprises a backplate.

32. The device of claim 28, wherein the protecting means comprises a cover.

33. The device of claim 28, wherein the desiccating means comprises a desiccant.

34. The device of claim 28, further comprising means for sealing said encapsulating means to said transmitting means.

35. The device of claim 34, wherein the sealing means comprises a seal.