Support structure for MEMS device and methods therefor

• US 20070019922A1
• Filed: 07/21/2006
• Published: 01/25/2007
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Kothari, Manish, Sasagawa, Teruo, Ganti, SuryaPrakash, Sampsell, Jeffrey
• Granted Patent: US 7,534,640 B2
• Time in Patent Office: Days
• US Class Current: 385/147
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/0307 Anchors
• CPC Class Codes: B81C 1/00595 Control etch selectivity
• CPC Class Codes: B81C 2201/0136 by doping limited material regions
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C

Abstract

A microelectromechanical systems device having support structures formed of sacrificial material that is selectively diffused with a dopant material or formed of a selectively oxidized metal sacrificial material. The microelectromechanical systems device includes a substrate having an electrode formed thereon. Another electrode is separated from the first electrode by a cavity and forms a movable layer, which is supported by support structures formed of a diffused or oxidized sacrificial material.

Claims

1. A method of making a microelectromechanical systems device, comprising:

providing a substrate having a first electrode formed over the substrate;

forming at least one support structure of the device by forming a metal sacrificial material over the first electrode layer and oxidizing some portions of the sacrificial material.

forming a movable layer over the sacrificial material after forming the at least one support structure; and

creating a cavity between the substrate and the movable layer.

2. The method of claim 1, wherein creating the cavity comprises selectively removing unoxidized portions of the sacrificial material after forming the movable layer.

3. The method of claim 2, wherein selectively removing comprises etching unoxidized portions of the sacrificial material with an etchant selected from the group consisting of:

a source of fluorine, NH₄OH, H₃PO₄, Cl₂ plasma, and PAN (phosphoric acetic nitric) etchant.

4. The method of claim 2, wherein selectively removing comprises etching unoxidized portions of the sacrificial material with XeF₂.

5. The method of claim 1, oxidizing comprises masking some portions of the sacrificial material before oxidizing unmasked portions of the sacrificial material.

6. The method of claim 1, wherein oxidizing comprises anodizing some portions of the sacrificial material.

7. The method of claim 6, wherein anodizing comprises masking some portions of the sacrificial material before anodizing unmasked portions of the sacrificial material.

8. The method of claim 1, wherein the metal comprises aluminum.

9. The method of claim 1, wherein the metal is selected from the group consisting of aluminum, magnesium, tantalum, titanium, and molybdenum.

10. The method of claim 1, wherein creating the cavity comprises selectively removing unoxidized portions of the sacrificial material after forming the mechanical layer by plasma etching.

11. The method of claim 1, wherein creating the cavity allows the movable layer to be movable.

12. The method of claim 1, wherein the microelectromechanical systems device is an interferometric modulator.

13. The method of claim 12, wherein the movable layer comprises a mirror layer.

14. The method of claim 1, wherein the microelectromechanical systems device comprises:

a display;

a processor that is in electrical communication with said display, said processor being configured to process image data;

a memory device in electrical communication with said processor.

15. The method of claim 14, wherein the microelectromechanical systems device further comprises:

a driver circuit configured to send at least one signal to said display.

16. The method of claim 15, wherein the microelectromechanical systems device further comprises:

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

17. The method of claim 14, wherein the microelectromechanical systems device further comprises:

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

18. The method of claim 15, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

19. The method of claim 14, wherein the microelectromechanical systems device further comprises:

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

20. An unreleased interferometric modulator device, comprising:

a substrate;

a first electrode formed over the substrate;

a layer formed over the first electrode, wherein the layer comprises a sacrificial portion formed of a metal and a support portion, wherein the support portion is an oxide of the metal; and

a movable layer over the layer.

21. The unreleased interferometric modulator device of claim 20, wherein the movable layer comprises an electrode.

22. The unreleased interferometric modulator device of claim 20, wherein the movable layer comprises a mirror layer.

23. The unreleased interferometric modulator device of claim 20, wherein the support portion is resistant to an etchant selected from the group consisting of:

a source of fluorine, NH₄OH, H₃PO₄, Cl₂ plasma, and PAN (phosphoric acetic nitric) etchant.

24. The unreleased interferometric modulator device of claim 23, wherein the sacrificial portion can be etched by an etchant selected from the group consisting of:

a source of fluorine, NH₄OH, H₃PO₄, Cl₂ plasma, and PAN (phosphoric acetic nitric) etchant.

25. The unreleased interferometric modulator device of claim 20, further comprising a second electrode layer, wherein at least a portion of the layer is positioned between the first electrode and the movable layer.

26. The unreleased interferometric modulator device of claim 25, wherein the movable layer comprises a mechanical layer attached to a second electrode layer.

27. A method of making a microelectromechanical systems device, comprising:

providing a substrate having a first electrode layer formed over the substrate;

forming at least one support structure by forming a sacrificial material over the first electrode layer and anodizing selected portions of the sacrificial material; and

creating a cavity between the first electrode layer and a second electrode layer.

28. The method of claim 27, further comprising depositing the sacrificial material over the first electrode layer before forming the second electrode layer over the sacrificial material, wherein creating the cavity comprises selectively removing the sacrificial material in unanodized portions after forming the second electrode layer.

29. The method of claim 27, wherein the sacrificial material comprises a metal selected from the group consisting of aluminum, tantalum, titanium, and molybdenum.

30. The method of claim 27, wherein the sacrificial material comprises molybdenum.

31. The method of claim 27, wherein the sacrificial material comprises silicon.

32. The method of claim 27, wherein creating a cavity comprises etching unanodized portions of the sacrificial material with an etchant selected from the group consisting of:

a source of fluorine, NH₄OH, H₃PO₄, Cl₂ plasma, and PAN (phosphoric acetic nitric) etchant.

33. The method of claim 27, wherein creating a cavity comprises etching unanodized portions of the sacrificial material with XeF₂.

34. The method of claim 27, wherein creating a cavity comprises masking some portions of the sacrificial material before anodizing the selected portions of the sacrificial material, wherein the selected portions are unmasked portions of the sacrificial material.

35. The method of claim 27, wherein the mocroelectromechanical device is an interferometric modulator.

36. The method of claim 35, wherein the second electrode layer comprises a mirror layer.

37. A method of making an interferometric modulator device, comprising:

providing a substrate having a first electrode layer formed over the substrate;

depositing a sacrificial material over the first electrode layer; and

forming at least one support structure of the device by selectively diffusing a dopant material into the sacrificial material.

38. The method of claim 37, further comprising:

forming a movable layer over the sacrificial material after forming the at least one support structure; and

creating a cavity between the substrate and the movable layer.

39. The method of claim 37, wherein the substrate comprises a material selected from the group consisting of sapphire and quartz.

40. The method of claim 37, wherein forming at least one support structure comprises patterning the dopant material over the sacrificial material.

41. The method of claim 40, wherein patterning comprises:

depositing the dopant material over the sacrificial material; and

selectively etching the dopant material.

42. The method of claim 40, wherein patterning comprises:

masking the first electrode layer; and

depositing the dopant material over the sacrificial material after masking.

43. The method of claim 37, wherein selectively diffusing comprises subjecting the device to a temperature of at least 600°

C.

44. The method of claim 37, wherein the sacrificial material comprises silicon and the dopant material comprises a material selected from the group consisting of oxygen, aluminum, zinc, copper, gold, platinum, and sodium.

45. The method of claim 41, wherein the dopant material comprises a material that is resistant to an etchant used for selectively etching.

46. The method of claim 37, wherein the dopant material is a solid.

47. An unreleased interferometric modulator device, comprising:

a substrate;

a first electrode formed over the substrate;

a layer formed over the first electrode, wherein the layer comprises a sacrificial portion formed of a material and a support portion, wherein the support portion comprises the material doped with a dopant material; and

a movable layer over the layer.

48. The device of claim 47, wherein the substrate comprises a material selected from the group consisting of sapphire and quartz.

49. The device of claim 47, wherein the dopant material is a solid.

50. The device of claim 47, wherein the material of the sacrificial material is selectively etchable with respect to the support portion.

51. A method of making an interferometric modulator device, comprising:

providing a substrate having a first electrode layer formed over the substrate;

depositing a sacrificial material over the first electrode layer; and

forming at least one support structure of the device by selectively implanting ions into the sacrificial material and using a laser to anneal implanted portions of the sacrificial material.

52. The method of claim 51, further comprising forming a patterned mask over the sacrificial material before forming the at least one support structure.

53. The method of claim 51, wherein the ions comprise oxygen ions.

54. The method of claim 51, wherein the ions comprise carbon ions.

55. The method of claim 51, wherein the ions comprise nitrogen ions.