Method and apparatus for reducing microlens surface reflection

• US 20080080056A1
• Filed: 08/29/2006
• Published: 04/03/2008
• Est. Priority Date: 08/29/2006
• Status: Abandoned Application

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Li, Jiutao, Li, Jin, Boettiger, Ulrich
• Application Number:
  US11/511,206
• Publication Number:
  US 20080080056A1
• Time in Patent Office: Days
• US Class Current: 359/620
• CPC Class Codes: G02B 1/118 having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
• CPC Class Codes: G02B 13/001 Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras G02B23/243 takes precedence
• CPC Class Codes: G02B 3/0012 characterised by the manufacturing method

Abstract

A microlens has a surface with an effective index of refraction closer to the index of air than the body of the microlens to reduce reflection. Fibers protrude vertically from the surface of a microlens. For fabrication, the fibers are propelled at an adhesive layer provided over a microlens body and subjected to an electric field so that they stand vertically on the surface of the microlens. The adhesive layer is cured to hold the fibers in place.

Claims

1. A microlens comprising:

a lens body; and

a plurality of fibers each having one end secured to a surface of the microlens body.

2. The microlens of claim 1, wherein the fibers are light-transparent.

3. The micro lens of claim 1, wherein the fibers have a diameter less than about 400 nm.

4. The microlens of claim 1, wherein each of the plurality of fibers has a length in the range of about 500 nm to about 2000 nm.

5. The microlens of claim 1, wherein about 50 to less than 100 percent of the surface area of the microlens body is covered with the fibers.

6. The microlens of claim 1, further comprising an adhesive layer for fixing the plurality of fibers to the lens body.

8. The microlens of claim 1, wherein the fibers are vertically aligned on the surface.

7. The microlens of claim 7, wherein the adhesive layer is a cured adhesive layer.

9. (canceled)

10. A pixel array comprising:

a plurality of photosensors; and

a plurality of microlenses associated with the photosensors, wherein the microlenses each have a body portion and an anti-reflective surface layer on the body portion comprising a plurality of aligned fibers having ends fixed to the body portion.

11. The pixel array of claim 10, wherein the anti-reflective layer provides the microlens with an index of refraction closer to the index of refraction of air than the index of refraction of the microlens body.

12. The pixel array of claim 10, further comprising an adhesive coating on the surface of each microlens body for adhering the fibers to the surface of the body portion.

13. An imager device comprising:

a plurality of pixels formed on a substrate;

a plurality of microlenses formed over the plurality of pixels, wherein each microlens has a fiber-coated surface; and

a readout structure for reading out signals from the plurality of pixels and for providing an image based on the signals.

14. The imager device of claim 13, wherein the fiber-coated surface of the microlens comprises an adhesive coating and a plurality of vertically aligned fibers.

15-20. -20. (canceled)

21. A method of forming a pixel array, comprising:

forming a plurality of pixels on a substrate;

forming a plurality of microlenses over the plurality of pixels;

forming a plurality of vertically aligned fibers on the surface of the microlenses.

22. The method of claim 21, wherein the step of forming a plurality of fibers further comprises fixing the plurality of fibers in a vertically-oriented arrangement on the surface of each of the microlenses.

24. The method of claim 21, wherein the step of forming a plurality of fibers includes forming an adhesive coating over the plurality of microlenses and propelling the plurality of fibers in an air-stream toward the adhesive coating such that the ends of the fibers attach to the surface of the microlens.

26. The method of claim 21, wherein the step of forming a plurality of fibers includes placing the pixel array in an electric field.

27. The method of claim 26, further comprising providing the fibers with a same electrical charge on one end of the fibers such that the fibers repel each other.

23. (canceled)

25. (canceled)

28. (canceled)

29. A method of forming a microlens comprising:

providing an adhesive layer on a surface of a microlens;

providing fibers on the adhesive coating;

causing the fibers to stand vertically on the microlens; and

curing the adhesive layer.

30. The method of claim 29, wherein the step of providing an adhesive layer comprises either applying a vapor prime of adhesive material or spraying an adhesive material onto the surface of a microlens.

32. The method of claim 29, wherein the step of providing fibers comprises propelling fibers in an air- stream toward the adhesive layer.

33. The method of claim 32, wherein the step of providing fibers further includes embedding one end of each fiber into the adhesive layer.

34. The method of claim 29, wherein the step of causing the fibers to stand vertically on the microlens comprises placing the microlens in an electric field.

35. The method of claim 34, wherein the fibers are charged to a predetermined polarity by placing the microlens in the electric field.

31. (canceled)

36. (canceled)