System and method for protecting microelectromechanical systems array using back-plate with non-flat portion

• US 20060065436A1
• Filed: 03/25/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Brian Gally, Lauren Palmateer, William J. Cummings
• Inventors: Palmateer, Lauren, Cummings, William J., Gally, Brian
• Granted Patent: US 7,368,803 B2
• Time in Patent Office: Days
• US Class Current: 174/260
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: B81C 2203/0163 Reinforcing a cap, e.g. with ribs
• 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 an electronic device utilizing interferometric modulation and a package of the device. The packaged device includes a substrate, an interferometric modulation display array formed on the substrate, and a back-plate. The back-plate is placed over the display array with a gap between the back-plate and the display array. The depth of the gap may vary across the back-plate. The back-plate can be curved or have a recess on its interior surface facing the display array. Thickness of the back-plate may vary. The device may include reinforcing structures which are integrated with the back-plate.

Claims

1. An electronic device, comprising:

a substrate;

an array of microelectromechanical devices formed on the substrate;

a back-plate placed over the array and having an interior surface and an exterior surface, the interior surface of the back-plate facing the array with a gap therebetween, the exterior surface facing away from the substrate; and

wherein a distance between the interior surface of the back-plate and the substrate varies across the substrate.

2. The electronic device of claim 1, wherein the interior surface comprises a central area and a peripheral area, and wherein the distance is greater in the central area than in the peripheral area.

3. The electronic device of claim 1, wherein the back-plate is generally bowed away from the array.

4. The electronic device of claim 1, wherein the distance is measured from a point on the interior surface to a closest point of the substrate.

5. The electronic device of claim 1, wherein the interior surface is substantially smoothly curved.

6. The electronic device of claim 1, wherein the distance changes substantially abruptly at least one location on the interior surface.

7. The electronic device of claim 1, wherein the distance is substantially the same in at least a portion of the interior surface.

8. The electronic device of claim 1, wherein the back-plate has a substantially same thickness throughout.

9. The electronic device of claim 1, wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness that is generally greater in the central area than in the peripheral area.

10. The electronic device of claim 1, wherein the exterior surface of the back-plate is substantially flat, and wherein a distance between the exterior surface and the substrate is substantially the same across the substrate.

11. The electronic device of claim 1, wherein a distance between the exterior surface and the substrate substantially varies across the substrate.

12. The electronic device of claim 1, further comprising one or more reinforcing structures formed on at least one of the interior surface and the exterior surface of the back-plate.

13. The electronic device of claim 12, wherein at a location on the interior surface where a reinforcing structure is formed, the distance is measured from a distal end of the reinforcing structure to the substrate.

14. The electronic device of claim 12, wherein the distance varies over an area of the interior surface where no reinforcing structure is formed.

15. The electronic device of claim 1, wherein the back-plate comprises a protrusion extending toward the substrate along an edge of the back-plate.

16. The electronic device of claim 1, further comprises a seal located between the substrate and the interior surface along edges of the interior surface.

17. An electronic device, comprising:

a substrate;

an array of interferometric modulators formed on the substrate;

means for covering the array, wherein said means comprises an interior surface and an exterior surface, the interior surface facing the array with a gap therebetween, the exterior surface facing away from the substrate; and

wherein a distance between the interior surface of the covering means and the substrate varies across the substrate.

18. The electronic device of claim 17, wherein the covering means comprises a curved back-plate.

19. The electronic device of claim 17, wherein the covering means further comprises one or more reinforcing structures integrated thereto.

20. The electronic device of claim 17, wherein the covering means has a recess formed on the interior surface thereof.

21. The electronic device of claim 17, wherein the covering means has varying thickness.

23. The method of claim 21, wherein forming the back-plate further comprises:

providing the back-plate having the interior surface;

placing the back-plate over the array such that the interior surface faces the array; and

binding the back-plate with the substrate along a periphery of the back-plate.

24. The method of claim 23, wherein the interior surface is substantially curved.

25. The method of claim 23, wherein the interior surface is recessed in a generally central area thereof.

26. The method of claim 23, wherein the back-plate has a substantially same thickness throughout.

27. The method of claim 23, wherein the back-plate has a varying thickness.

28. The method of claim 23, wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness that is generally greater in the central area than in the peripheral area.

29. The method of claim 23, wherein the back-plate comprises a curved portion.

30. The method of claim 29, wherein providing the back-plate comprises subjecting a substantially flat panel to warping.

31. The method of claim 29, wherein providing the back-plate comprises:

providing a substantially flat panel comprising two layers, which have different heat expansion rates; and

applying heat to the substantially flat panel, thereby creating a curvature in the panel.

32. The method of claim 29, wherein providing the back-plate comprises providing a substantially flat panel comprising two layers, each layer having a heat expansion rate that is different from that of the other, wherein placing the back-plate comprises forming a layer of a thermally curable material sandwiched between the substrate and the substantially flat panel along a periphery thereof, and wherein binding the back-plate comprises applying heat sufficient to cure the thermally curable material.

22. A method of making an electronic device, comprising:

providing an intermediate device comprising a substrate and an array of microelectromechanical devices formed on the substrate; and

forming a back-plate over the array of the intermediate device with a gap between the back-plate and the array, the back-plate having an interior surface facing the array, wherein a distance between the interior surface and the substrate varies across the substrate.

33. An electronic device produced by a method comprising:

providing an intermediate device comprising a substrate and an array of microelectromechanical devices formed on the substrate; and

forming a back-plate over the array of the intermediate device with a gap between the back-plate and the array, the back-plate having an interior surface facing the array, wherein a distance between the interior surface and the substrate varies across the substrate.

34. The electronic device of claim 33, wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate comprises at least one recess in the central area.

35. The electronic device of claim 33, wherein the back-plate has a varying thickness.

36. The electronic device of claim 33, wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness that is generally smaller in the central area than in the peripheral area.

37. The electronic device of claim 36, wherein the back-plate further comprises one or more reinforcing structures in the central area.