Integrated lens system for image sensor and method for manufacturing the same

• US 7,215,479 B1
• Filed: 02/10/2006
• Issued: 05/08/2007
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Bakin, Dmitry
• Primary Examiner(s): Sugarman; Scott J.
• Assistant Examiner(s): Collins; Darryl J.
• Application Number:
  US11/350,772
• Time in Patent Office: 452 Days
• Field of Search: 359/664, 359754-792
• US Class Current: 359/664
• CPC Class Codes: G02B 13/005 having spherical lenses only
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 7/027 the lens being in the form of a sphere or ball

Abstract

A lens system including a first substantially hemispherical lens, a second spherical lens and a third substantially hemispherical lens. The lenses are held together by a bonding material such as epoxy, which may also include a light absorbing dye. The invention also relates to a low-cost method of manufacturing the lens system out of glass, using low cost glass ball lenses to create the hemispherical lenses.

Claims

1. A lens system comprising:

a first lens comprising a convex surface and a substantially planar surface;

a second lens, which is substantially spherical in shape;

a third lens comprising a convex surface and a substantially planar surface; and

a first support structure which supports one portion of the second lens to the convex surface of the first lens and another portion of the second lens to the planar surface of the third lens.

2. The lens system of claim 1, further comprising:

a fourth lens, which is substantially spherical in shape;

a fifth lens comprising a convex surface and a substantially planar surface; and

a second support structure which supports one portion of the fourth lens to the convex surface of the third and another portion of the fourth lens to the planar surface of the fifth lens.

3. The lens system of claim 1, wherein the support structure is a first bonding material which is annularly formed around the second lens, the first bonding material being formed in a first section and a second section, the first and second sections being different.

4. The lens system of claim 2, wherein the support structure is a second bonding material which is annularly formed around the fourth lens, the second bonding material being formed in a third section and a fourth section, the fourth and fifth sections being different.

5. The lens system of claim 1, further comprising a flat plate optical element coupled to the substantially planar surface of the first lens.

6. The lens system of claim 5, wherein the flat plate element is a cover glass of a digital imager device.

7. The lens system of claim 3, wherein the second lens is a ball lens and a refractive index of the second lens is less than a refractive index of the first bonding material.

8. The lens system of claim 7, wherein the second lens comprises crown glass.

9. The lens system of claim 1, wherein the first lens is substantially hemispherical.

10. The lens system of claim 9, wherein the first lens comprises a material with a higher refractive index than a refractive index of the second lens.

11. The lens system of claim 10, wherein the material comprising the first lens comprises at least one of glass, quartz, rutile, sapphire, and fused silica.

12. The lens system of claim 1, wherein the third lens is substantially hemispherical.

13. The lens system of claim 12, wherein the third lens comprises a material with a higher refractive index than a refractive index of the second lens.

14. The lens system of claim 13, wherein the material comprising the third lens comprises at least one of glass, quartz, rutile, sapphire, and fused silica.

15. The lens system of claim 1, wherein the first lens comprises a heavy flint and serves as a field flattener.

16. The lens system of claim 3, wherein the first bonding material is epoxy.

17. The lens system of claim 3, wherein the first bonding material comprises a light absorbing dye in at least one of the first section and the second section of the first bonding material.

18. The lens system of claim 17, wherein the first bonding material comprises a light absorbing dye in both the first section and the second section of the first bonding material.

19. The lens system of claim 4, wherein the fourth lens is a ball lens and a refractive index of the fourth lens is less than a refractive index of the second bonding material.

20. The lens system of claim 19, wherein the fourth lens comprises crown glass.

21. The lens system of claim 2, wherein the fifth lens is substantially hemispherical.

22. The lens system of claim 21, wherein the fifth lens comprises a material with a higher refractive index than a refractive index of the fourth lens.

23. The lens system of claim 22, wherein the material comprising the fifth lens comprises at least one of glass, quartz, rutile, sapphire, and fused silica.

24. The lens system of claim 4, wherein the second bonding material is epoxy.

25. The lens system of claim 4, wherein the second bonding material comprises a light absorbing dye in at least one of the third section and the fourth section of the second bonding material.

26. The lens system of claim 24, wherein the second bonding material comprises a light absorbing dye in both the third section and the fourth section of the second bonding material.

27. An imager system comprising:

a first lens comprising a convex surface and a substantially planar surface coupled to a cover glass of a digital imager device, the first lens having a first refractive index;

a second lens, substantially spherical in shape, a portion of which is coupled to the convex surface of the first lens, the second lens being a crown glass ball lens and having a second refractive index;

a third lens comprising a convex surface and a substantially planar surface, the substantially planar surface of the third lens coupled to another portion of the second lens, the third lens having a third refractive index, wherein the second refractive index is lower than the first and third refractive indices;

a support structure which serves to couple the first, second, and third lenses; and

an imager for capturing an image through the imager lens system, wherein the imager lens system comprises the first, second and third lenses.

28. The imager system of claim 27, wherein the support structure is a bonding material.

29. The imager system of claim 27, wherein the imager lens system further comprises:

a fourth lens, substantially spherical in shape a portion of which is coupled to the convex surface of the third lens, the fourth lens being a crown glass ball lens; and

a fifth lens comprising a convex surface and a substantially planar surface, the substantially planar surface of the firth lens coupled to another portion of the fourth lens, and wherein the support structure further serves to couple the third, fourth, and fifth lenses.

30. An imager system comprising:

a digital image-capture device comprising a sensor surface having a plurality of micro-lenses associated with a plurality of photosensors; and

a lens system comprising;

a first lens comprising a convex surface and a substantially planar surface;

a second lens, which is substantially spherical in shape;

a third lens comprising a convex surface and a substantially planar surface; and

a support structure which supports one portion of the second lens to the convex surface of the first lens and another portion of the second lens to the planar surface of the third lens;

wherein the digital-image capture device and the lens system are optically aligned with a layer of air between them.

31. The imager system of claim 30, wherein the support structure is a first bonding material which is annularly formed around the second lens, the first bonding material being formed in a first section and a second section, the first and second sections being different.

32. The imager system of claim 30, wherein the lens system further comprises:

a fourth lens, which is substantially spherical in shape;

a fifth lens comprising a convex surface and a substantially planar surface; and

a second supporting structure which supports one portion of the fourth lens to the convex surface of the third lens and another portion of the fourth lens to the planar surface of the fifth lens.

33. The imager system of claim 32, wherein the support structure is a second bonding material which is annularly formed around the fourth lens, the second bonding material being formed in a third section and a fourth section, the third and fourth sections being different.

34. The imager system of claim 31, wherein the second lens is a ball lens and a refractive index of the second lens is less than a refractive index of the first bonding material.

35. The imager system of claim 30, wherein the first lens is substantially hemispherical and comprises a material with a higher refractive index than a refractive index of the second lens.

36. The imager system of claim 30, wherein the third lens is substantially hemispherical and comprises a material with a higher refractive index than a refractive index of the second lens.

37. The imager system of claim 30, wherein the first lens comprises a heavy flint and serves as a field flattener.

38. The imager system of claim 31, wherein the first bonding material is epoxy.

39. The imager system of claim 31, wherein the first bonding material comprises a light absorbing dye in at least one of the first section and the second section of the first bonding material.

40. The imager system of claim 33, wherein the second bonding material comprises and light absorbing dye in at least one of the third section and the fourth section of the second bonding material.

41. An image capture module comprising:

a semiconductor die;

a pixel array included on the semiconductor die, for capturing an image; and

a lens system, through which the imager views an image, the lens system optically aligned with the pixel array and comprising;

a first lens comprising a convex surface and a substantially planar surface;

a second lens, which is substantially spherical in shape;

a third lens comprising a convex surface and a substantially planar surface; and

a first bonding material that bonds one portion of the second lens to the convex surface of the first lens and another portion of the second lens to the planar surface of the third lens, wherein the first bonding material surrounds the second lens.

42. The image capture module of claim 41, further comprising:

a lens assembly comprising a housing which supports a lens barrel containing the lens system.

43. The image capture module of claim 41, further comprising:

bump pad connectors located adjacent to the edges of a top surface of the semiconductor die;

a conductive film adjacent to the bump pad connectors;

a flex tape adjacent to the conductive film, the flex tape including electrical traces and an opening through which light may travel to the pixel array; and

a connector adjacent and electrically connected to the flex tape.

44. A method of producing an imager lens system comprising:

providing a cover glass adjacent an imager surface;

providing a first lens adjacent the cover glass, wherein the first lens comprises a convex surface and a substantially planar surface;

providing a second lens adjacent the first lens, wherein the second lens is substantially spherical in shape and wherein the convex surface of the first lens is coupled to one portion of the second lens;

providing a third lens adjacent the second lens, wherein the third lens comprises a convex surface and a substantially planar surface and wherein the planar surface of the third lens is coupled to another portion of the second lens; and

coupling the first, second and third lenses together.

45. The method of claim 44, further comprising injecting a first bonding material around the first, second and third lenses to bond the lenses, while maintaining an optical path through the first, second and third lenses.

46. The method of claim 44, further comprising:

providing a fourth lens adjacent the third lens wherein the fourth lens is substantially spherical in shape and wherein the convex surface of the third lens is coupled to one portion of the fourth lens;

providing a fifth lens adjacent the fourth lens, wherein the fifth lens comprises a convex surface and a substantially planar surface and wherein the planar surface of the fifth lens is coupled to another portion of the fourth lens; and

coupling the third, fourth and fifth lenses together.

47. The method of claim 46 further comprising injecting a second bonding material around the third, fourth, and fifth lenses to bond the lenses while maintaining an optical path through the first, second, third, fourth and fifth lenses.

48. The method of claim 44, wherein the cover glass is provided at a predetermined distance from the imager surface by means of posts of the predetermined distance incorporated into the imager surface.

49. The method of claim 44, wherein the substantially planar surface of the first lens is coupled with the cover glass.

50. The method of claim 45, wherein the first bonding material is epoxy.

51. The method of claim 50, wherein the epoxy is ultraviolet cured.

52. The method of claim 50, wherein the epoxy is temperature cured.

53. The method of claim 45, wherein the first bonding material comprises a light absorbing dye.

54. The method of claim 47, wherein the second bonding material is epoxy.

55. The method of claim 54, wherein the epoxy is ultraviolet cured.

56. The method of claim 55, wherein the epoxy is temperature cured.

57. The method of claim 47, wherein the second bonding material comprises a light absorbing dye.

58. The method of claim 44, wherein the second lens is provided from a glass ball lens manufacturing process.

59. The method of claim 44, wherein the first and third lenses are provided from ball lenses ground and polished on one side to a predetermined thickness.

60. The method of claim 59, wherein the grinding and polishing is done by a chemical mechanical polishing process.

61. The method of claim 59, wherein a plurality of ball lenses is placed in an array holder to allow for simultaneous grinding and polishing of the plurality of ball lenses.

62. The method of claim 61, wherein the array holder holding the plurality of ball lenses is placed between large plates and simultaneously ground and polished to the predetermined thickness.

63. The method of claim 62, wherein the predetermined thickness of the lenses is controlled with posts and end-point detectors installed between the plates.