Image Sensor with Decreased Optical Interference Between Adjacent Pixels

• US 20120068294A1
• Filed: 09/22/2011
• Published: 03/22/2012
• Est. Priority Date: 09/12/2005
• Status: Active Grant

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Inventors: Lee, Won-Ho, Cho, Dong-Heon
• Granted Patent: US 8,698,266 B2
• Time in Patent Office: Days
• US Class Current: 257/435
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

An image sensor with decreased optical interference between adjacent pixels is provided. An image sensor, which is divided into a pixel region and a peripheral region, the image sensor including a photodiode formed in a substrate in the pixel region, first to Mth metal lines formed over the substrate in the pixel region, where M is a natural number greater than approximately 1, first to Nth metal lines formed over a substrate in the peripheral region, where N is a natural number greater than M, at least one layer of dummy metal lines formed over the Mth metal lines but formed not to overlap with the photodiode, and a microlens formed over the one layer of the dummy metal lines to overlap with the photodiode.

Claims

1. An image sensor comprising:

a plurality of pixels, each including;

a photodiode; and

a dummy metal line;

wherein the dummy metal lines in adjacent pixels of the plurality of pixels combine to form a light shield.

2. The image sensor of claim 1, wherein each dummy metal line is positioned in a corner area of its corresponding pixel.

3. The image sensor of claim 1, wherein the plurality of pixels includes four pixels.

4. The image sensor of claim 1, wherein the light shield forms an amorphous shape.

5. The image sensor of claim 4, wherein the light shield is symmetric about its diagonal axis and symmetric about at least one of its horizontal axis or its vertical axis.

6. The image sensor of claim 4, wherein the light shield is symmetric about its diagonal axis and asymmetric about at least one of its horizontal axis or its vertical axis.

7. The image sensor of claim 4, wherein the light shield is asymmetric about its diagonal axis and symmetric about at least one of its horizontal axis or its vertical axis.

8. The image sensor of claim 4, wherein the light shield is asymmetric about its diagonal axis and asymmetric about at least one of its horizontal axis or its vertical axis.

9. The image sensor of claim 4, wherein the light shield includes a dummy metal line having an amorphous shape and a dummy metal line having a geometric shape.

10. The image sensor of claim 4, wherein the light shield includes an amorphous portion and a geometric portion.

11. The image sensor of claim 1, wherein the light shield forms a geometric shape.

12. The image sensor of claim 11, wherein the light shield forms at least one of a square, a rectangle, a cross, a rhombus, or a shape including at least one curve.

13. The image sensor of claim 12, wherein the light shield forms a square.

14. The image sensor of claim 12, wherein the light shield forms a rectangle.

15. The image sensor of claim 12, wherein the light shield forms a cross.

16. The image sensor of claim 12, wherein the light shield forms a rhombus.

17. The image sensor of claim 12, wherein the light shield forms a shape including at least one curve.

18. The image sensor of claim 11, wherein the light shield is symmetric about its diagonal axis and symmetric about at least one of its horizontal axis or its vertical axis.

19. The image sensor of claim 11, wherein the light shield is symmetric about its diagonal axis and asymmetric about at least one of its horizontal axis or its vertical axis.

20. The image sensor of claim 11, wherein the light shield is asymmetric about its diagonal axis and symmetric about at least one of its horizontal axis or its vertical axis.

21. The image sensor of claim 11, wherein the light shield is asymmetric about its diagonal axis and asymmetric about at least one of its horizontal axis or its vertical axis.

22. The image sensor of claim 1, wherein at least one of the dummy metal lines forms an amorphous shape.

23. The image sensor of claim 1, wherein at least one of dummy metal lines forms a geometric shape.

24. The image sensor of claim 23, wherein at least one of the dummy metal lines forms at least one of a square, a rectangle, an “

L”

shape, a triangle, or a shape including at least one curve.

25. The image sensor of claim 24, wherein the at least one of the dummy metal lines forms a square.

26. The image sensor of claim 24, wherein the at least one of the dummy metal lines forms a rectangle.

27. The image sensor of claim 24, wherein the at least one of the dummy metal lines forms an “

L”

shape.

28. The image sensor of claim 24, wherein the at least one of the dummy metal lines forms a triangle.

29. The image sensor of claim 24, wherein the at least one of the dummy metal lines forms a shape including at least one curve.

30. The image sensor of claim 1, wherein at least one of the pixels includes a horizontal axis, a vertical axis, a diagonal axis, and a plurality of dummy metal lines.

31. The image sensor of claim 30, wherein the plurality of dummy metal lines in the at least one pixel include different shapes.

32. The image sensor of claim 30, wherein the plurality of dummy metal lines in the at least one pixel include similar shapes.

33. The image sensor of claim 32, wherein the plurality of dummy metal lines in the at least one pixel include different orientations of shapes of the plurality of dummy metal lines.

34. The image sensor of claim 32, wherein the plurality of dummy metal lines in the at least one pixel include similar orientations of shapes of the plurality of dummy metal lines.

35. The image sensor of claim 30, wherein the dummy metal lines of the plurality of dummy metal lines are collectively:

symmetric about at least one of the horizontal axis or the vertical axis; and

symmetric about the diagonal axis.

36. The image sensor of claim 30, wherein the plurality of dummy metal lines of the plurality of dummy metal lines are collectively:

symmetric about at least one of the horizontal axis or the vertical axis; and

asymmetric about the diagonal axis.

37. The image sensor of claim 30, wherein the plurality of dummy metal lines of the plurality of dummy metal lines are collectively:

asymmetric about at least one of the horizontal axis or the vertical axis; and

symmetric about the diagonal axis.

38. The image sensor of claim 30, wherein the plurality of dummy metal lines of the plurality of dummy metal lines are collectively:

asymmetric about at least one of the horizontal axis or the vertical axis; and

asymmetric about the diagonal axis.

39. The image sensor of claim 30, wherein at least one of the dummy metal lines in the at least one pixel is located along at least one side of the at least one pixel.

40. The image sensor of claim 39, wherein at least two of the dummy metal lines in the at least one pixel are located along at least two sides of the at least one pixel.

41. The image sensor of claim 40, wherein the at least two of the dummy metal lines in the at least one pixel have different widths.

42. The image sensor of claim 39, wherein the at least one pixel includes four sides, and wherein the dummy metal lines are located along each of the four sides.

43. The image sensor of claim 30, wherein the at least one of the pixels includes four corner regions.

44. The image sensor of claim 43, wherein a dummy metal line is located in each of the four corner regions.

45. The image sensor of claim 44, wherein the dummy metal lines located in each of the four corner regions have a similar shape and a similar orientation.

46. The image sensor of claim 44, wherein the dummy metal lines located in each of the four corner regions have similar shapes, and wherein at least one of the dummy metal lines located in at least one of the corner regions has a different orientation.

47. The image sensor of claim 44, wherein at least one of the dummy metal lines located in at least one of the corner regions has a different shape.

48. The image sensor of claim 47, wherein each of the dummy metal lines disposed in the four corner regions have different shapes.

49. An image sensor pixel comprising:

a photodiode in a pixel region of the image sensor pixel;

a metal line in the pixel region configured to connect the image sensor pixel to at least one of a logic circuit or a power line; and

a first dummy metal line in the pixel region and positioned to block a light from outside of the pixel region from impinging on the photodiode.

50. The image sensor pixel of claim 49, further comprising a dielectric positioned between the metal line and the first dummy metal line;

and

wherein the metal line, the first dummy metal line, and the dielectric form a capacitor.

51. The image sensor pixel of claim 50, wherein the capacitor forms a circuit with elements in a peripheral region of the image sensor pixel.

52. The image sensor pixel of claim 49, wherein the first dummy metal line comprises a via contact including a top surface and a bottom surface.

53. The image sensor pixel of claim 52, wherein the bottom surface of the first dummy metal line is adjacent to the metal line.

54. The image sensor pixel of claim 53, wherein the top surface of the first dummy metal line is not adjacent to another dummy metal line or the metal line.

55. The image sensor pixel of claim 52, further comprising a second dummy metal line positioned above the first dummy metal line.

56. The image sensor pixel of claim 55, wherein the second dummy metal line is positioned directly above the first dummy metal line.

57. The image sensor pixel of claim 55, wherein the second dummy metal line comprises a via contact including a bottom surface adjacent to the first dummy metal line.

58. The image sensor pixel of claim 52, further comprising:

a lower layer including the photodiode, wherein the photodiode is positioned in a center area of the pixel region and not in a right area or a left area of the pixel region;

a pre-metal dielectric layer positioned above the lower layer and including, in the pixel region, a dielectric;

a first metal line layer positioned above the pre-metal dielectric layer and including, in the pixel region, a plurality of metal lines and a dielectric;

a first dummy metal line layer positioned above the first metal line layer and including, in the pixel region, a plurality of dummy metal lines and a dielectric;

wherein the plurality of metal lines in the first metal line layer and the plurality of metal lines in the first dummy metal line layer are positioned in the right area or the left area of the pixel region and are not substantially positioned in the center area of the pixel region.

59. The image sensor pixel of claim 58, wherein:

the lower layer includes, in a peripheral region of the image sensor pixel, a portion of a transistor;

the pre-metal dielectric layer includes, in the peripheral region, a portion of the transistor and a dielectric;

the first metal line layer includes, in the peripheral region, a plurality of metal lines and a dielectric; and

the first dummy metal line layer includes, in the peripheral region, a plurality of metal lines and a dielectric.

60. An image sensor pixel comprising:

a peripheral region including;

a first layer comprising a first peripheral region metal line;

a second layer positioned above the first layer and comprising a second peripheral region metal line; and

a via contact connecting the first peripheral region metal line with the second peripheral region metal line; and

a pixel region including;

the first layer comprising a first pixel region metal line;

the second layer positioned above the first layer; and

a via contact positioned between the first pixel region metal line and the second layer;

wherein the via contact in the pixel region comprises a dummy metal line positioned to block a light from outside of the pixel region.