Interferometric modulator with internal polarization and drive method

• US 20060274398A1
• Filed: 06/03/2005
• Published: 12/07/2006
• Est. Priority Date: 06/03/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chou, Chen-Jean
• Granted Patent: US 7,460,292 B2
• Time in Patent Office: Days
• US Class Current: 359/247
• CPC Class Codes: B81B 3/0035 Constitution or structural means for controlling the movement of the flexible or deformable elements
• 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

In one embodiment of the invention, a method of creating an internal dipole moment in an interferometric light modulating device is disclosed. In certain embodiments, the method comprises applying heat and an electrical field to a dielectric layer of an interferometric light modulating device. Prior to implementation of this method, the dielectric layer has mobile charges or comprises random dipoles. After application of this method, however, those random dipoles are substantially aligned, thereby inducing a fixed dipole moment in the dielectric layer. The electric field creates the dipole moment in the dielectric layer and the heat helps increase the speed of the process by supplying additional activation energy. Having a dielectric layer with an induced dipole moment provides an internal voltage source that provides at least a portion of the voltage required to operate the interferometric light modulating device. The induced dipole moment also reduces the possibility of an uncontrolled shift of charge within the device during operation.

Claims

1. A method of forming a microelectromechanical systems (MEMS) device having a first electrode and a second electrode, the method comprising:

providing a first layer located between the first and second electrodes; and

applying heat to the first layer while applying a first voltage across the first and second electrodes.

2. The method of claim 1, wherein said first layer is configured to store a non-zero dipole moment after applying heat to the first layer while applying a first voltage across the first and second electrodes, wherein the non-zero dipole moment continues to exist when no voltage is applied across the first and second electrodes.

3. The method of claim 2, further comprising providing a second layer that is at least partially reflective of light, a third layer that is substantially reflective of light, the third layer in operable proximity to the second layer, wherein the second and third layers are configured to define a gap therebetween, the second layer comprising the first electrode, the third layer comprising the second electrode, wherein the third layer is movable with respect to the second layer upon application of a second voltage across the first and second electrodes.

4. The method of claim 3, wherein the first voltage applied across the first and second electrodes has a magnitude greater than a magnitude of a third voltage necessary to move the third layer an amount sufficient to substantially close the gap between the second layer and the third layer.

5. The method of claim 3, wherein providing a first layer comprises sputtering the first layer over the second layer.

6. A MEMS device formed by the method of claim 2.

7. The MEMS device of claim 6, wherein the method further comprises providing a second layer that is at least partially reflective of light, a third layer that is substantially reflective of light, the third layer in operable proximity to the second layer, wherein the second and third layers are configured to define a gap therebetween, the second layer comprising the first electrode, the third layer comprising the second electrode, wherein the third layer is movable with respect to the second layer upon application of a second voltage across the first and second electrodes, wherein the first voltage applied across the first and second electrodes has a magnitude greater than a magnitude of a third voltage necessary to move the third layer an amount sufficient to substantially close the gap between the second layer and the third layer.

8. The method of claim 1, further comprising cooling the first layer while maintaining the first voltage across the first and second electrodes.

9. The method of claim 1, wherein the first layer has a net-zero dipole moment prior to inducing the non-zero dipole moment within the first layer.

10. The method of claim 1, wherein applying heat comprises increasing a temperature of the first layer to at least 50 degrees Celsius.

11. The method of claim 1, wherein applying heat comprises increasing the temperature of the first layer to at least 70 degrees Celsius.

12. The method of claim 1, wherein the first layer comprises a dielectric material.

13. The method of claim 1, wherein the first layer comprises a ferroelectric material.

14. The method of claim 1, wherein the first layer comprises SiO_x, wherein x is less than 2.

15. The method of claim 1, wherein the first layer comprises silicon nitride.

16. The method of claim 1, wherein the first layer comprises material selected from a group comprising:

silicon oxide, silicon nitride, nitrided SiO₂, titanium oxide, semi-insulating polycrystalline silicon, and oxy-nitride.

17. A microelectromechanical systems (MEMS) device, comprising:

a first electrode;

a second electrode; and

a first layer located between the first and second electrodes, the first layer comprising a non-zero dipole moment when no voltage is applied across the first and second electrodes.

18. The MEMS device of claim 17, wherein the first layer comprises a dielectric material.

19. The MEMS device of claim 17, wherein the first layer comprises a ferroelectric material.

20. The MEMS device of claim 17, wherein the first layer comprises SiO_x, wherein x is less than 2.

21. The MEMS device of claim 17, wherein the first layer comprises silicon nitride.

22. The MEMS device of claim 17, wherein the first layer comprises material selected from a group comprising:

silicon oxide, silicon nitride, nitrided SiO₂, titanium oxide, semi-insulating polycrystalline silicon, and oxy-nitride.

23. The MEMS device of claim 17, further comprising a second layer that is at least partially reflective of light and a third layer that is substantially reflective of light, the third layer in operable proximity to the second layer, the second layer comprising the first electrode, the third layer comprising the second electrode, wherein the third layer is movable with respect to the second layer upon application of a voltage across the first and second electrodes.

24. The MEMS device of claim 23, wherein the first layer is sputtered over the second layer.

25. The MEMS device of claim 17, further comprising:

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.

26. The display system as recited in claim 25, 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.

27. The display system as recited in claim 25, further comprising:

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

28. The display system as recited in claim 27, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

29. The display system as recited in claim 25, further comprising:

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

30. A microelectromechanical systems (MEMS) device, comprising:

a first electrode;

a second electrode; and

means for providing a non-zero dipole moment between the first and second electrodes when no voltage is applied across the first and second electrodes.

31. The MEMS device of claim 30, further comprising a first layer that is at least partially reflective of light and a second layer that is substantially reflective of light, the second layer in operable proximity to the first layer, the first layer comprising the first electrode, the second layer comprising the second electrode, wherein the second layer is movable with respect to the first layer upon application of a voltage across the first and second electrodes.

32. A method of providing an operating voltage to a microelectromechanical systems (MEMS) device, comprising:

providing a first layer comprising a first electrode;

providing a second layer comprising a second electrode, wherein the second layer is movable with respect to the first layer upon application of a voltage between the first and second electrodes;

providing a third layer disposed between the first and second layers, wherein third layer comprises a non-zero dipole moment when no voltage is applied across the first and second electrodes;

providing the first layer with a first voltage potential;

providing the second layer with a second voltage potential, wherein the second voltage potential is greater in magnitude than the first voltage potential, and wherein the operating voltage comprises the first and second voltage potentials and a third voltage potential provided by the non-zero dipole moment of the insulating material.

33. The method of claim 32, wherein the combined magnitude of the third voltage potential and the first voltage potential substantially equals the magnitude of the second voltage potential.

34. The method of claim 32, wherein the first and third voltage potentials are negative and the second voltage potential is positive, and wherein the first and second voltage potentials are asymmetric.

35. A microelectromechanical systems (MEMS) device, comprising:

a first layer, wherein the first layer is configured to receive a first voltage;

a second layer, wherein the second layer is configured to receive a second voltage; and

a third layer between the first and second layers, wherein the third layer is configured to provide a third voltage, wherein the first, second, and third voltages together substantially equal a predetermined voltage.

36. The MEMS device of claim 35, wherein the third layer comprises a material configured to provide the third voltage when no voltage is applied across the first and second layers.