MEMS DEVICES REQUIRING NO MECHANICAL SUPPORT

• US 20090147343A1
• Filed: 12/07/2007
• Published: 06/11/2009
• Est. Priority Date: 12/07/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Kogut, Lior, Tung, Ming-Hau, Tung, Yeh-Jiun
• Granted Patent: US 7,715,079 B2
• Time in Patent Office: Days
• US Class Current: 359/254
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• 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 are described having movable layers that are mechanically isolated. The movable layers are electrically attractable such that they can be selectively moved between a top and bottom electrode through application of a voltage. In interferometric modulators, the movable layers are reflective such that an optically resonant cavity is formed between the layer and a partially reflective layer, thereby providing a display pixel that can be turned on or off depending on the distance between the reflective layers in the resonant cavity.

Claims

1. An electromechanical device, comprising:

a first electrode;

a second electrode, wherein a gap is present between the first and second electrodes; and

a mechanically isolated electrically attractable member positioned within the gap, wherein the electrically attractable member is movable within the gap between a first position closer to the first electrode than the second electrode and a second position closer to the second electrode than the first electrode.

2. The electromechanical device of claim 1, comprising a charge transfer element configured to change a charge of the electrically attractable member.

3. The electromechanical device of claim 2, wherein the charge transfer element comprises one or more electrical contacts.

4. The electromechanical device of claim 3, wherein the electrically attractable member does not contact the one or more electrical contacts at a third position between the first and second electrodes.

5. The electromechanical device of claim 3, where the charge transfer element comprises at least one electrical contact positioned to contact the electrically attractable member when it is in the first position, and at least one other electrical contact positioned to contact the electrically attractable member when it is in the second position.

6. The electromechanical device of claim 2, wherein the charge transfer element comprises an electrically conductive coupling connecting the electrically attractable member to a driving circuit.

7. The electromechanical device of claim 2, wherein the charge transfer element comprises a conductive post along which the electrically attractable member is configured to move.

8. The electromechanical device of claim 1, wherein the electrically attractable member is charged.

9. The electromechanical device of claim 1, comprising a post positioned within the gap, wherein the electrically attractable member comprises an opening through which the post extends.

10. The electromechanical device of claim 1, wherein at least one surface of the electrically attractable member is substantially reflective.

11. The electromechanical device of claim 1, wherein the first electrode is partially reflective.

12. The electromechanical device of claim 1, wherein the first electrode and electrically attractable member form an interferometric modulator.

13. The electromechanical device of claim 1, comprising a fourth electrode coplanar with the first electrode and a fifth electrode coplanar with the second electrode, wherein the first and second electrodes are positioned to overlap with a substantial portion of a first portion of the electrically attractable member and the fourth and fifth electrodes are positioned to overlap with a substantial portion of a second portion of the electrically attractable member.

14. A display, comprising an array of electromechanical devices according to claim 1.

15. The display of claim 14, further comprising:

a processor that is in electrical communication with the array of electromechanical devices, said processor being configured to process image data; and

a memory device in electrical communication with said processor.

16. The display of claim 15, further comprising:

a first controller configured to send at least one signal to the array of electromechanical devices; and

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

17. The display of claim 15, further comprising an image source module configured to send said image data to said processor.

18. The display of claim 17, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

19. The display of claim 15, further comprising an input device configured to receive input data and to communicate said input data to said processor.

20. A method of moving an electrically attractable member between two positions in an electromechanical device, the method comprising:

providing an electrically attractable member in contact with a first electrode;

applying a first voltage between a second electrode and the electrically attractable member such that the electrically attractable member moves toward the second electrode; and

breaking contact between the electrically attractable member and the first electrode, wherein the electrically attractable member retains enough charge to continue moving toward the second electrode.

21. The method of claim 20, further comprising:

contacting the electrically attractable member with a third electrode;

applying a second voltage between a fourth electrode and the electrically attractable member such that the electrically attractable member moves toward the fourth electrode; and

breaking contact between the electrically attractable member and the third electrode, wherein the electrically attractable member retains enough charge to continue moving toward the fourth electrode.

22. The method of claim 20, wherein breaking contact between the electrically attractable member and the first electrode comprises breaking an electrical contact between the electrically attractable member and a driving circuit.

23. The method of claim 20, wherein the movement of the electrically attractable member causes the breaking.

24. The method of claim 20, comprising changing a charge in the electrically attractable member.

25. The method of claim 24, wherein changing the charge is accomplished by the contact of the electrically attractable member with the first electrode.

26. A method of tilting an electrically attractable member in an electromechanical device, the method comprising:

applying a first voltage between a first planar electrode and a mechanically isolated electrically attractable member such that a force is applied between a first portion of the mechanically isolated electrically attractable member and the first electrode; and

applying a second voltage between a second planar electrode and the mechanically isolated electrically attractable member such that a force is applied between a second portion of the mechanically isolated electrically attractable member and the second electrode, wherein a gap is present between the planes of the first and second electrodes and wherein the first electrode is positioned to overlap with a substantial portion of the first portion of the mechanically isolated electrically attractable member and the second electrode is positioned to overlap with a substantial portion of the second portion of the mechanically isolated electrically attractable member such that when the first and second voltages are applied, the mechanically isolated electrically attractable member tilts relative to the planes of the first and second electrodes.

27. A method of manufacturing an electromechanical device, comprising:

depositing a first electrode layer;

depositing a first sacrificial layer over the first electrode layer;

depositing a second electrode layer over the first sacrificial layer;

etching the second electrode layer to create substantially isolated regions of the second electrode layer;

depositing a second sacrificial layer over the second electrode layer such that the isolated regions of the second electrode layer are substantially surrounded by sacrificial material;

depositing a third electrode layer over the second sacrificial layer; and

removing the sacrificial layers to mechanically isolate the substantially isolated regions of the second electrode layer.

28. The method of claim 27, comprising depositing a dielectric layer between the first electrode layer and the first sacrificial layer.

29. The method of claim 27, comprising depositing a dielectric layer between the first sacrificial layer and the second electrode layer.

30. The method of claim 27, comprising depositing a dielectric layer between the second electrode layer and the second sacrificial layer.

31. The method of claim 27, comprising depositing a dielectric layer between the second sacrificial layer and the third electrode layer.

32. The method of claim 27, wherein after removing the sacrificial layers, the substantially isolated regions of the second electrode layer are mechanically isolated from other structures in the electromechanical device.