Analog interferometric modulator device

• US 20060065940A1
• Filed: 06/03/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Kothari, Manish
• Granted Patent: US 8,008,736 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• 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

Disclosed is new architecture of microelectromechanical system (MEMS) device. The device has a partially reflective optical layer, a deformable mechanical layer and a mirror layer, each of which forms an independent electrode. A support post separates the optical layer from the mechanical layer. The mirror layer is located and movable between a first position and a second position, which are located between the optical layer and the mechanical layer. The mirror is spaced from the support post, and mirror is responsive to voltages applied to the three electrodes, thereby moving between the first position and the second position. By applying various combinations of voltage differences between the optical layer and the mirror, and between the mirror and the mechanical layer, the location of the mirror between the first and second positions is tunable throughout the space between the two positions. The tunable MEMS device can be used as an analog display element or analog electrical device such as a tunable capacitor. The MEMS device of the disclosed architecture can also be operated in a non-analog manner.

Claims

1. A microelectromechanical system device comprising:

a first electrode layer;

a second electrode layer;

a support structure which separates the first electrode layer from the second electrode layer;

a reflective element located and movable between a first position and a second position, the first and second positions located between the first and second electrode layers, the reflective element comprising a reflective layer and a conductive portion, the conductive portion electrically insulated from the first electrode layer and the second electrode layer, the reflective element spaced apart from the support structure; and

wherein the reflective element is responsive to voltages applied to the first electrode layer, the second electrode layer, and the conductive portion by moving between the first position and the second position.

2. The device of claim 1, wherein the conductive portion comprises the reflective layer.

3. The device of claim 1, wherein a third position is located between the first and second position, and wherein the reflective element spontaneously moves toward the first position when the reflective element is located between the first position and the third position

4. The device of claim 1, wherein the distance between the first position and the third position is about one-third of the distance between the first electrode layer and the second electrode layer.

5. The device of claim 1, wherein the first electrode layer comprises a partially reflective surface.

6. The device of claim 1, wherein the reflective element is mechanically integrated with the second electrode layer.

7. The device of claim 1, wherein the second electrode layer is deformable as the reflective element moves between the first and second positions.

8. The device of claim 7, further comprising a connection mechanically integrating the second electrode layer and the reflective element, wherein the connection is electrically insulated from the second electrode layer.

9. The device of claim 8, wherein the connection electrically connects the conductive portion to a voltage source.

10. The device of claim 1, wherein the reflective element is mechanically decoupled from the second electrode layer.

11. The device of claim 10, further comprising a connection electrically and mechanically coupled to the reflective element and passing through a hole formed in the second electrode layer, and wherein the connection does not contact the second electrode layer.

12. The device of claim 1, wherein the reflective element is capable of being substantially stationary at any position between the first and second positions.

13. The device of claim 1, further comprising a nonconductive layer between the first electrode layer and the reflective element.

14. The device of claim 1, wherein a location of the reflective element between the first and second positions is tunable by controlling voltage differences applied between the first electrode layer and the conductive portion, and between the second electrode layer and the conductive portion.

15. The device of claim 1, wherein the device comprises a tunable capacitor.

16. The device of claim 1, wherein the device comprises a tunable frequency filter for filtering a frequency component of input signals received through the first electrode layer.

17. The device of claim 1, further comprising:

a display;

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

a memory device in electrical communication with said processor.

18. The device of claim 17, further comprising:

a first controller configured to send at least one signal to said display; and

a second controller configured to send at least a portion of said image data to said first controller.

19. The device of claim 17, further comprising an image source module configured to send said image data to said processor.

20. The device of claim 19, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

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

22. A method of making a microelectromechanical system device, comprising:

providing a partially reflective layer;

forming a first sacrificial layer over the partially reflective layer;

depositing a reflective material layer over the first sacrificial layer;

selectively etching the reflective material layer to form a mirror;

forming a second sacrificial layer over the first sacrificial layer and the mirror;

depositing a mechanical layer over the second sacrificial layer;

selectively etching the mechanical layer and the second sacrificial layer to form an opening therethrough that exposes a portion of the mirror;

filling the opening with a conductive material to form a conductor electrically connected to the mirror;

selectively etching a portion of the mechanical layer surrounding the conductor to electrically insulate the conductor from the mechanical layer; and

removing the first and second sacrificial layers.

23. The method of claim 22, further comprising filling the etched portion of the mechanical layer surrounding the conductive connection with a nonconductive material, wherein the nonconductive material mechanically couples the mechanical layer and the conductive connection.

24. A microelectromechanical system device produced by a method comprising:

providing a partially reflective layer;

forming a first sacrificial layer over the partially reflective layer;

depositing a reflective material layer;

selectively etching the reflective material layer to form a mirror;

forming a second sacrificial layer over the first sacrificial layer and the mirror;

depositing a mechanical layer over the second sacrificial layer;

selectively etching the mechanical layer and the second sacrificial layer to form an opening therethrough that exposes a portion of the mirror;

filling the opening with a conductive material to form a conductor electrically connected to the mirror;

selectively etching a portion of the mechanical layer surrounding the conductor to electrically insulate the conductor from the mechanical layer; and

removing the first and second sacrificial layers.

25. A method of operating a microelectromechanical system device, the method comprising:

providing a microelectromechanical system device comprising a first electrode layer, a second electrode layer, a support structure separating the first electrode from the second electrode layer, and a reflective element located and movable between a first position and a second position, the first and second positions located between the first and second electrode layers, the reflective element comprising a conductive portion electrically isolated from the first and second electrode layers, the reflective element responsive to voltage differences applied between the first electrode layer and the conductive portion and between the second electrode layer and the conductive portion, the reflective element spaced apart from the support structure;

applying a first voltage difference between the first electrode layer and the conductive portion, thereby moving the reflective element between the first position and a third position which is located between the first and second positions; and

applying a second voltage difference between the first electrode layer and the conductive portion while applying a non-zero voltage difference between the second electrode layer and the conductive portion, thereby moving the reflective element between the third position and the second position.

26. The method of claim 25, wherein the first voltage is smaller than a threshold voltage, beyond which the reflective element moves to the second position.

27. The method of claim 25, wherein applying the first voltage difference comprises changing the first voltage difference between zero and the threshold voltage while applying a substantially zero voltage difference between the second electrode layer and the conductive portion.

28. The method of claim 27, wherein the reflective element moves toward the first electrode layer as the first voltage difference is increased.

29. The method of claim 27, wherein the reflective element moves toward the second electrode layer as the first voltage difference is decreased.

30. The method of claim 27, wherein the second voltage is greater than the threshold voltage.

31. The method of claim 25, wherein applying the second voltage difference comprises changing the second voltage difference while applying a non-zero voltage difference between the second electrode layer and the conductive portion.

32. The method of claim 25, wherein applying a non-zero voltage difference comprises changing the non-zero voltage difference.

33. The method of claim 25, wherein the reflective element is mechanically connected to the second electrode layer, and wherein the second electrode layer deforms as the reflective element moves between the first and second positions.

34. The method of claim 25, wherein the reflective element is mechanically decoupled from the second electrode layer.

35. The method of claim 25, wherein the reflective element moves substantially proportional to a change of the first voltage difference.

36. The method of claim 25, wherein the device comprises a frequency filter, and wherein the method comprises filtering a frequency component of input signals received through the first electrode layer.

37. The method of claim 25, wherein during applying the first voltage difference, a substantially zero voltage difference is applied between the second electrode layer and the conductive portion.

38. The method of claim 25, wherein during applying the first voltage difference, a non-zero voltage difference is applied between the second electrode layer and the conductive portion.

39. A method of operating a microelectromechanical system device, the method comprising

providing a microelectromechanical system device comprising a first electrode layer, a second electrode layer spaced from the first electrode layer, and a reflective element located and movable between a first position and a second position, the first and second positions located between the first and second electrode layers, the reflective element comprising a conductive portion electrically isolated from the first and second electrode layers, the reflective element responsive to voltage differences applied between the first electrode layer and the conductive portion and between the second electrode layer and the conductive portion;

applying a first voltage difference between the first electrode layer and the conductive portion, the first voltage difference less than a threshold voltage, beyond which the reflective element spontaneously moves to the second position; and

applying a second voltage difference between the first electrode layer and the conductive portion, the second voltage difference greater than the threshold voltage while applying a non-zero voltage difference between the second electrode layer and the conductive portion.

40. The method of claim 39, wherein the reflective element is mechanically decoupled from the second electrode layer.

41. The method of claim 39, wherein the reflective element is mechanically coupled to the second electrode layer, and wherein the second electrode layer deforms as the reflective element moves between the first and second positions.

42. The method of claim 39, wherein applying the first voltage difference comprises changing the first voltage difference between zero and the threshold voltage while applying a substantially zero voltage difference between the second electrode layer and the conductive portion.

43. The method of claim 39, wherein applying the second voltage difference comprises changing the second voltage difference.

44. The method of claim 39, wherein applying the non-zero voltage difference comprises changing the non-zero voltage difference.

45. The method of claim 39, wherein the device comprises a tunable capacitor, and wherein the method comprises tuning the capacitor.

46. The method of claim 39, wherein during applying the first voltage difference, a substantially zero voltage difference is applied between the second electrode layer and the conductive portion.

47. The method of claim 39, wherein during applying the first voltage difference, a non-zero voltage difference is applied between the second electrode layer and the conductive portion.