METHODS AND DEVICES FOR INHIBITING TILTING OF A MOVABLE ELEMENT IN A MEMS DEVICE

• US 20080112035A1
• Filed: 01/15/2008
• Published: 05/15/2008
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Cummings, William
• Granted Patent: US 7,663,794 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• 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

Interferometric modulators having a separable modulator architecture are disclosed having a reflective layer suspended from a flexible layer over a cavity. The interferometric modulators have one or more anti-tilt members that inhibit undesirable movement of the reflective layer, such as curling and/or tilting. The stabilization of the reflective layer by the anti-tilt members can improve the quality of the optical output of the interferometric modulators, as well as displays comprising such interferometric modulators.

Claims

1. A microelectromechanical systems (MEMS) device comprising:

a substrate;

an electrically conductive layer over the substrate;

a movable element positioned over the substrate and movable between a first position spaced from the substrate by a first distance and a second position spaced from the substrate by a second distance, the first distance being greater than the second distance, and the movable element having a first surface facing away from the substrate and a second surface facing towards the substrate;

at least one stationary member contacting the first surface of the movable element when the movable element is in the first position, wherein the at least one stationary member is configured to inhibit movement of at least a portion of the movable element when the movable element is in the first position, and further wherein the second surface of the movable element is substantially parallel to the substrate when the movable element is in the first position and the second position; and

a mechanical layer coupled to the movable element, wherein the mechanical layer exerts a force on the movable element that facilitates contact between the at least one stationary member and the first surface of the movable element when the movable element is in the first position.

2. The MEMS device of claim 1, wherein the at least one stationary member comprises a first stationary member and a second stationary member contacting the first surface of the movable element when the movable element is in the first position, and further wherein the first stationary member and the second stationary member contact the first surface of the movable element at substantially the same distance from the substrate.

3. A device comprising an array of a plurality of the MEMS devices as claimed in claim 1.

4. The device of claim 3, wherein the at least one stationary member comprises a shaft segment, a first head segment connected to the shaft segment and contacting the movable element of a first MEMS device of the plurality of MEMS devices, and a second head segment connected to the shaft segment and contacting the movable element of a second MEMS device of the plurality of MEMS devices.

5. The device of claim 4, wherein the at least one stationary member inhibits movement of at least a portion of the movable elements of each of the first and second MEMS devices in a direction generally perpendicular to the first surfaces of the movable elements when the movable elements are in the first position.

6. The device of claim 4, wherein the at least one stationary member inhibits movement of at least a portion of the movable elements of each of the first and second MEMS devices in a direction generally parallel to the first surfaces of the movable elements when the movable elements are in the first position.

7. The device of claim 4, wherein the at least one stationary member inhibits rotational movement of at least a portion of the movable elements of each of the first and second MEMS devices when the movable elements are in the first position.

8. The device of claim 1, wherein the mechanical layer comprises a first portion attached to the movable element and a second portion attached to the at least one stationary member.

9. A microelectromechanical system (MEMS) device comprising:

means for supporting at least a portion of the MEMS device;

first electrically conductive means for receiving an electrical signal, the first electrical conductive means positioned over the supporting means;

second electrically conductive means for receiving an electrical signal, the second electrical conductive means positioned over the supporting means, the second electrically conductive means movable between a first position spaced from the first electrically conductive means by a first distance and a second position spaced from the first electrically conductive means by a second distance, the first distance being greater than the second distance, wherein the second electrically conductive means has a first surface facing away from the supporting means and a second surface substantially parallel to the supporting means when the second electrically conductive means is in the first and second positions;

means for stabilizing the second electrically conductive means, the stabilizing means contacting the first surface of the second electrically conductive means when the second electrically conductive means is in the first position, wherein the stabilizing means is configured to inhibit movement of at least a portion of the second electrically conductive means when the second electrically conductive means is in the first position; and

means for exerting a force on the second electrically conductive means, the force facilitating contact between the stabilizing means and the first surface of the second electrically conductive means when the second electrically conductive means is in the first position.

10. The MEMS device of claim 9, wherein the supporting means comprises a substrate.

11. The MEMS device of claim 9, wherein the first electrically conductive means comprises a metal layer.

12. The MEMS device of claim 9, wherein the stabilizing means comprises at least one stationary member.

13. The MEMS device of claim 9, wherein the second electrically conductive means comprises a metal layer.

14. The MEMS device of claim 9, wherein the force exerting means comprises a mechanical layer.

15. A method of manufacturing a microelectromechanical system (MEMS) device comprising:

forming an electrically conductive layer over a substrate;

forming a dielectric layer over the substrate;

depositing a sacrificial layer over the electrically conductive layer and the dielectric layer;

forming a reflective element over the sacrificial layer, the reflective element having a first surface facing away from the substrate and a second surface substantially parallel to the substrate;

forming a hole through the sacrificial layer;

forming a stabilization member comprising a first portion formed in the hole and a second portion connected to the first portion, the second portion formed over at least a portion of the reflective element; and

forming a mechanical layer coupled to the reflective element, wherein the mechanical layer exerts a force on the reflective element that facilitates contact between the stabilization member and the first surface of the reflective element subsequent to removal of the sacrificial layer.

16. The method of claim 15, further comprising removing the sacrificial layer.

17. The method of claim 15, further comprising forming a second sacrificial layer over the stabilization member and the reflective element.

18. The method of claim 17, wherein the mechanical layer is formed over the second sacrificial layer.

19. The method of claim 17, further comprising removing the sacrificial layer and the second sacrificial layer.

20. A microelectromechanical system (MEMS) device comprising:

a display comprising a plurality of display elements, each display element comprising;

a substrate;

an electrically conductive layer over the substrate;

a movable element positioned over the substrate and movable between a first position spaced from the substrate by a first distance and a second position spaced from the substrate by a second distance, the first distance being greater than the second distance, and the movable element having a first surface facing away from the substrate and a second surface facing towards the substrate;

at least one stationary member contacting the first surface of the movable element when the movable element is in the first position, wherein the at least one stationary member is configured to inhibit movement of at least a portion of the movable element when the movable element is in the first position, and further wherein the second surface of the movable element is substantially parallel to the substrate when the movable element is in the first position and the second position; and

a mechanical layer coupled to the movable element, wherein the mechanical layer exerts a force on the movable element that facilitates contact between the at least one stationary member and the first surface of the movable element when the movable element is in the first position;

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

a memory device in electrical communication with the processor.

21. The MEMS device of claim 20, further comprising

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

and

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

22. A method of modulating light, the method comprising:

providing a microelectromechanical system (MEMS) device, the MEMS device comprising;

a substrate;

an electrically conductive layer over the substrate;

a movable element positioned over the substrate and movable between a first position spaced from the substrate by a first distance and a second position spaced from the substrate by a second distance, the first distance being greater than the second distance, and the movable element having a first surface facing away from the substrate and a second surface facing towards the substrate;

at least one stationary member contacting the first surface of the movable element when the movable element is in the first position, wherein the at least one stationary member is configured to inhibit movement of at least a portion of the movable element when the movable element is in the first position, and further wherein the second surface of the movable element is substantially parallel to the substrate when the movable element is in the first position and the second position; and

a mechanical layer coupled to the movable element, wherein the mechanical layer exerts a force on the movable element that facilitates contact between the at least one stationary member and the first surface of the movable element when the movable element is in the first position; and

moving the movable element between the first position and the second position.

23. A device comprising:

an array of at least two interferometric modulators, each interferometric modulator comprising;

a substrate;

an optical layer positioned over the substrate, the optical layer being at least partially transmissive to incident light;

a mirror mechanically coupled to and positioned over the substrate and movable between a first position spaced from the optical layer by a first distance and a second position spaced from the optical layer by a second distance, the first distance being greater than the second distance, and the mirror having a surface facing away from the substrate, wherein light reflected by the interferometric modulator is interferometrically modulated; and

at least one stationary member contacting the surface of the mirror when the mirror is in the first position, wherein the at least one stationary member is configured to inhibit movement of at least a portion of the mirror when the mirror is in the first position;

wherein the stationary members of the at least two interferometric modulators contact the surface of each respective mirror at a different first distance from the optical layer when the mirrors are in the first position.