STICTION MITIGATION WITH INTEGRATED MECH MICRO-CANTILEVERS THROUGH VERTICAL STRESS GRADIENT CONTROL

• US 20100128337A1
• Filed: 11/21/2008
• Published: 05/27/2010
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Tung, Yeh-Jiun
• Granted Patent: US 7,859,740 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: B81B 3/0059 Constitution or structural means for controlling the movement not provided for in groups B81B3/0037 - B81B3/0056
• 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

Abstract

The present disclosure relates to the mitigation of stiction in MEMS devices. In some embodiments, a MEMS device may be provided with one or more restoration features that provide an assisting mechanical force for mitigating stiction. The restoration feature may be implemented as one or more deflectable elements, where the deflectable elements may have various configurations or shapes, such as a chevron, cross, and the like. For example, the restoration feature can be a cantilever that deflects when at least one component comes into contact or proximity with another component. Multiple restoration features also may be employed and placed strategically within the MEMS device to maximize their effectiveness in mitigating stiction.

Claims

1. A micro-electromechanical (MEMS) device, said device comprising:

a first component;

a second component movable relative to the first component in a first direction; and

at least one restoration feature, on the second component, that applies a restoring force to the second component in a second direction opposite to the first direction and comprises at least one deflecting portion that borders an opening through the second component and extends towards the first component when the first and second components are apart from each other.

2. The MEMS device of claim 1, wherein the at least one deflecting portion comprises a cantilever.

3. The MEMS device of claim 2, wherein the cantilever curls toward the first component when the second component and the first component are apart from one another.

4. The MEMS device of claim 1, wherein the at least one deflecting portion comprises a plurality of leaves that extend towards the first component.

5. The MEMS device of claim 4, wherein the plurality of leaves curl toward the first component when the second component and the first component are apart from one another.

6. The MEMS device of claim 1, wherein the opening through the second component comprises a generally chevron-like shape.

7. The MEMS device of claim 1, wherein the opening through the second component comprises a generally cross-like shape.

8. The MEMS device of claim 1, wherein the at least one deflecting portion comprises a generally rectangular shape.

9. The MEMS device of claim 1, wherein the at least one deflecting portion has a curved edge.

10. The MEMS device of claim 1, further comprising at least one restoration feature, on the first component, that applies a second restoring force to the second component in the second direction.

11. The MEMS device of claim 1, wherein the at least one restoration feature comprises a plurality of restoration features on the second component.

12. The MEMS device of claim 1, wherein the at least one restoration feature is at at least one location that minimizes a probability of stiction between the first and second component.

13. The MEMS device of claim 1, wherein the MEMS device is an interferometric modulator.

14. The MEMS device of claim 13, wherein the first component comprises a substrate having a partially reflective layer and the second component comprises a reflective layer.

15. The MEMS device of claim 14, wherein the reflective layer is deformable to move in the first direction.

16. The MEMS device of claim 14, wherein the second component further comprises a deformable layer coupled to the reflective layer, the deformable layer configured to move in the first direction.

17. The MEMS device of claim 1, wherein the opening comprises an etch hole through the second component.

18. The MEMS device of claim 1, wherein the second component is coupled to the first component by one or more support structures and wherein the at least one restoration feature is positioned on the second component at least a threshold distance from the one or more support structures.

19. The MEMS device of claim 1, further comprising:

a display;

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

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

20. The MEMS device of claim 19, further comprising a driver circuit configured to send at least one signal to the display.

21. The MEMS device of claim 20, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

22. The MEMS device of claim 19, further comprising an image source module configured to send the image data to the processor.

23. The MEMS device of claim 22, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

24. The MEMS device of claim 19, further comprising an input device configured to receive input data and to communicate the input data to the processor.

25. The MEMS device of claim 1, wherein the at least one restoration feature is placed to minimize stiction between the second component and other portions of the MEMS device.

26. A micro-electromechanical (MEMS) apparatus comprising:

means for partially reflecting light;

means for reflecting light, wherein the reflecting means is movable in a first direction relative to the partially reflecting means; and

means for applying a restoring force to the reflecting means, the restoring means on the reflecting means, the restoring force in a second direction opposite to the first direction, the restoring means bordering an opening through the reflecting means and extending towards the partially reflecting means when the partially reflecting means and the reflecting means are apart from each other.

27. The MEMS apparatus of claim 26, wherein the partially reflecting means comprises a substrate.

28. The MEMS apparatus of claim 26, wherein the reflecting means comprises a reflective layer.

29. The MEMS apparatus of claim 26, wherein the restoring means comprises a cantilever that curls towards the partially reflecting means.

30. The MEMS apparatus of claim 26, wherein the restoring means comprises a plurality of cantilevers that curl towards the partially reflecting means.

31. The MEMS apparatus of claim 26, wherein the restoring means minimizes stiction between the partially reflecting means and the reflecting means.

32. A method of fabricating a microelectromechanical systems (MEMS) device, comprising:

forming an electrode layer over a substrate;

depositing a sacrificial layer over the electrode layer;

depositing a reflective layer over the sacrificial layer;

forming a plurality of support structures, said support structures extending through the sacrificial layer;

depositing a mechanical layer over the plurality of support structures; and

patterning the mechanical layer to faun at least one restoration feature at etch holes in the mechanical layer.

33. The method of claim 32, wherein depositing the mechanical layer comprises depositing the mechanical layer with a stress gradient in a direction generally perpendicular to the mechanical layer.