Method of creating MEMS device cavities by a non-etching process

• US 20070155051A1
• Filed: 12/29/2005
• Published: 07/05/2007
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Wang, Chun-Ming, Sasagawa, Teruo, Lan, Jeffrey
• Granted Patent: US 7,795,061 B2
• Time in Patent Office: Days
• US Class Current: 438/107
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00047 Cavities
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2201/0111 Bulk micromachining
• 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

MEMS devices (such as interferometric modulators) may be fabricated using a sacrificial layer that contains a heat vaporizable polymer to form a gap between a moveable layer and a substrate. One embodiment provides a method of making a MEMS device that includes depositing a polymer layer over a substrate, forming an electrically conductive layer over the polymer layer, and vaporizing at least a portion of the polymer layer to form a cavity between the substrate and the electrically conductive layer. Another embodiment provides a method for making an interferometric modulator that includes providing a substrate, depositing a first electrically conductive material over at least a portion of the substrate, depositing a sacrificial material over at least a portion of the first electrically conductive material, depositing an insulator over the substrate and adjacent to the sacrificial material to form a support structure, and depositing a second electrically conductive material over at least a portion of the sacrificial material, the sacrificial material being removable by heat-vaporization to thereby form a cavity between the first electrically conductive layer and the second electrically conductive layer.

Claims

1. A method of making a microelectromechanical system (MEMS) device, comprising:

depositing a polymer layer over a substrate;

forming an electrically conductive layer over the polymer layer; and

vaporizing at least a portion of the polymer layer to thereby form a cavity between the substrate and the electrically conductive layer.

2. The method of claim 1, wherein the substrate comprises a second electrically conductive layer.

3. The method of claim 2, wherein the second electrically conductive layer comprises indium tin oxide.

4. The method of claim 1, wherein the electrically conductive layer comprises a movable layer.

5. The method of claim 1, wherein vaporizing comprises heating.

6. The method of claim 5, wherein vaporizing comprises heating to a temperature in the range of from about 200 degrees C. to about 350 degrees C.

7. The method of claim 1, wherein the electrically conductive layer comprises a metal.

8. The method of claim 1, wherein the polymer layer comprises an organic polymer.

9. The method of claim 1, wherein the substrate comprises a partially reflective layer.

10. The method of claim 1, further comprising patterning the polymer layer.

11. The method of claim 10, wherein the patterning comprises at least one of electron beam lithography and image transfer.

12. The method of claim 10, further comprising:

forming a support structure aperture in the polymer; and

depositing a non-conductive material into the support structure aperture.

13. The method of claim 1, wherein depositing the polymer layer comprises at least one of spin coating, extrusion coating, spray coating, and printing.

14. The method of claim 13, wherein printing comprises inkjet deposition.

15. An unreleased microelectromechanical system (MEMS) device, comprising:

a substrate;

a heat-vaporizable polymer over the substrate; and

an electrically conductive layer over the heat-vaporizable polymer.

16. The unreleased MEMS device of claim 15, wherein the substrate comprises a second electrically conductive layer.

17. The unreleased MEMS device of claim 16, wherein the second electrically conductive layer comprises indium tin oxide.

18. The unreleased MEMS device of claim 15, wherein the electrically conductive layer comprises a metal.

19. The unreleased MEMS device of claim 15, wherein the heat-vaporizable polymer comprises an organic polymer.

20. The unreleased MEMS device of claim 15, wherein the substrate comprises a partially reflective layer.

21. The unreleased MEMS device of claim 15, further comprising:

a nonconductive support structure arranged over the substrate and configured to support the electrically conductive layer.

22. The unreleased MEMS device of claim 21 wherein at least one of the electrically conductive layer, the substrate and the support structure comprises a material that is etchable by xenon diflouride.

23. The unreleased MEMS device of claim 15, wherein the heat vaporizable polymer is configured to vaporize upon heating to a temperature in the range of about 200 degrees C. to about 350 degrees C.

24. A method for making an interferometric modulator, comprising:

providing a substrate;

depositing a first electrically conductive material over at least a portion of the substrate;

depositing a sacrificial material over at least a portion of the first electrically conductive material;

depositing an insulator over the substrate and adjacent to the sacrificial material to form a support structure; and

depositing a second electrically conductive material over at least a portion of the sacrificial material;

the sacrificial material being removable by heat-vaporization to thereby form a cavity between the first electrically conductive layer and the second electrically conductive layer.

25. An unreleased interferometric modulator made by the method of claim 24.

26. The method of claim 24, further comprising:

vaporizing the sacrificial material thereby removing substantially all of the sacrificial material.

27. A released interferometric modulator made by the method of claim 26.

28. The method of claim 24, wherein depositing the insulator precedes depositing the sacrificial material.

29. The method of claim 24, further comprising:

forming a support structure aperture in a portion of the deposited sacrificial material; and

depositing the insulator into the support structure aperture.

30. An unreleased interferometric modulator, comprising:

a first means for reflecting light;

a second means for reflecting light;

a first means for supporting the second reflecting means; and

a second means for supporting the second reflecting means;

wherein the first supporting means comprises a sacrificial material, the sacrificial material being removable by heat-vaporization to thereby form a cavity defined by the first reflecting means, the second reflecting means, and the second supporting means.

31. The unreleased interferometric modulator of claim 30, wherein the first reflecting means is a partially reflective layer.

32. The unreleased interferometric modulator of claim 30, wherein the second reflecting means is a movable reflective layer.

33. The unreleased interferometric modulator of claim 30, wherein the first supporting means is a sacrificial layer.

34. The unreleased interferometric modulator of claim 30, wherein the second supporting means is a support post.

35. An interferometric modulator comprising:

a substrate;

a first electrically conductive material over at least a portion of the substrate;

a second electrically conductive layer separated from the first electrically conductive layer by a cavity; and

a nonconductive support structure arranged over the substrate and configured to support the second electrically conductive layer;

wherein at least one of the first electrically conductive layer, the second electrically conductive layer and the non-conductive support structure comprises a material that is etchable by xenon diflouride.

36. The interferometric modulator of claim 35, wherein the material that is etchable by xenon diflouride comprises at least one of titanium, tungsten, tantalum, molybdenum, silicon nitride, and silicon.

37. An array of interferometric modulators comprising the interferometric modulator of claim 35.

38. A display device, comprising:

an array of interferometric modulators as claimed in claim 37;

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

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

39. The display device of claim 38, further comprising:

a driver circuit configured to send at least one signal to the array.

40. The display device of claim 39, further comprising:

a controller configured to send at least a portion of the image data to the driver circuit.

41. The display device of claim 38, further comprising:

an image source module configured to send the image data to the processor.

42. The display device of claim 41, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

43. The display device of claim 38, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.