Solid-state image pickup device

• US 7,701,029 B2
• Filed: 05/19/2003
• Issued: 04/20/2010
• Est. Priority Date: 05/20/2002
• Status: Expired due to Fees

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Mabuchi, Keiji
• Primary Examiner(s): Purvis; Sue
• Assistant Examiner(s): Rodela; Eduardo A
• Application Number:
  US10/440,683
• Publication Number:
  US 20030214595A1
• Time in Patent Office: 2,528 Days
• Field of Search: 257/431, 257/447, 257/460, 257/461, 257/462, 257/E31.054, 257/E31.073, 257/E31.124
• US Class Current: 257/462
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14689 MOS based technologies
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

In a rear surface incidence type CMOS image sensor having a wiring layer 720 on a first surface (front surface) of an epitaxial substrate 710 in which a photodiode, a reading circuit (an n-type region 750 and an n+ type region 760) and the like are disposed, and a light receiving plane in a second surface (rear surface), the photodiode and a P-type well region 740 on the periphery of the photodiode are disposed in a layer structure that does not reach the rear surface (light receiving surface) of the substrate, and an electric field is formed within the substrate 710 to properly lead electrons entering from the rear surface (light receiving surface) of the substrate to the photodiode. The electric field is realized by providing a concentration gradient in a direction of depth of the epitaxial substrate 710. Alternatively, the electric field can be realized by providing a rear-surface electrode 810 or 840 for sending a current.

Claims

1. A solid-state image pickup device comprising:

a semiconductor substrate including a first conductive type photoelectric converting device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

a wiring layer formed by stacking a plurality of layers of wiring including a signal line for driving said photoelectric converting device adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric converting device; and

an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side of said photoelectric converting device.

2. A solid-state image pickup device as claimed in claim 1, characterized in that:

said photoelectric converting device is a photodiode and said well region is a P-type well region.

3. A solid-state image pickup device comprising:

a semiconductor substrate including an image pickup pixel unit having a plurality of pixels each including a photoelectric converting device and a reading circuit in a two-dimensional array;

a wiring layer formed by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric convening device; and

an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric convening device from said second surface side to said first surface side entering from the light receiving plane of said semiconductor substrate to the photoelectric converting device characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

or more of the depth of said semiconductor substrate from the second surface of said semiconductor substrate.

4. A solid-state image pickup device comprising:

a semiconductor substrate including an image pickup pixel unit having a plurality of pixels each including a first conductive type photoelectric convening device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

a wiring layer formed by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric converting device; and

an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by applying a voltage to an electrode disposed over a second surface side of said semiconductor substrate.

5. A solid-state image pickup device as claimed in claim 4, characterized in that:

said electrode is a transparent electrode disposed on an entire light receiving region of each pixel in the second surface of said semiconductor substrate.

6. A solid-state image pickup device as claimed in claim 4, characterized in that:

said electrode is a metal electrode disposed so as to avoid a light receiving region of each pixel in the second surface of said semiconductor substrate.

7. A solid-state image pickup device as claimed in claim 4, characterized in that:

an electron injection preventing film is interposed between the second surface of said semiconductor substrate and said electrode.

8. A solid-state image pickup device as claimed in claim 4, characterized in that:

said semiconductor substrate is a high-resistance semiconductor substrate.

9. A solid-state image pickup device as claimed in claim 8, characterized in that:

said high-resistance semiconductor substrate is a semiconductor substrate with a P-type impurity concentration of 1013 cm<sup>−

3</sup> or less or a semiconductor substrate with an N-type impurity concentration of 1015 cm<sup>−

3</sup> or less.

10. A solid-state image pickup device as claimed in claim 4, having a well region for said photoelectric converting device, said well region being formed at the first surface side of said semiconductor substrate and not being formed in a region on a second surface side of said photoelectric converting device.

11. A solid-state image pickup device as claimed in claim 4, characterized in that:

said photoelectric converting device is a photodiode and said well region is a P-type well region.

12. A solid-state image pickup device as claimed in claim 4, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

or more of the depth of said semiconductor substrate from the second surface of said semiconductor substrate.

13. A solid-state image pickup device as claimed in claim 4, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by change in impurity concentration of said semiconductor substrate.

14. A solid-state image pickup device as claimed in claim 13, characterized in that:

said semiconductor substrate is formed by an epitaxial substrate, and said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by change in epitaxial concentration of said epitaxial substrate.

15. A method of fabricating a solid-state image pickup device, said solid-state image pickup device comprising:

providing a semiconductor substrate having an image pickup pixel unit having a plurality of pixels each including a first conductive type photoelectric converting device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

forming a wiring layer by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric convening device;

providing an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side; and

characterized in that;

said photoelectric convening device is a photodiode and said well region is a P-type well region.

16. A method of fabricating a solid-state image pickup device, said solid-state image pickup device comprising:

providing a semiconductor substrate having an image pickup pixel unit having a plurality of pixels each including a photoelectric converting device and a reading circuit in a two-dimensional array;

forming a wiring layer by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit over a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric convening device;

providing an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate such that said electric field leads photoelectrons from the light receiving plane side of said semiconductor substrate to the photoelectric converting device; and

characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

or more of the depth of said semiconductor substrate from the second surface of said semiconductor substrate.

17. A method of fabricating a solid-state image pickup device, said solid-state image pickup device comprising:

providing a semiconductor substrate having an image pickup pixel unit having a plurality of pixels each including a first conductivity type photoelectric converting device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

forming a wiring layer by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric converting device;

providing an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side; and

characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by applying a voltage to an electrode disposed at a second surface side of said semiconductor substrate.

18. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

said electrode is a transparent electrode disposed over an entire light receiving region of each pixel.

19. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

said electrode is a metal electrode disposed so as to avoid a light receiving region of each pixel at the second surface of said semiconductor substrate.

20. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

an electron injection preventing film is interposed between the second surface of said semiconductor substrate and said electrode.

21. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

said semiconductor substrate is a high-resistance semiconductor substrate.

22. A method of fabricating a solid-state image pickup device as claimed in claim 21, characterized in that:

said high-resistance semiconductor substrate is a semiconductor substrate with a P-type impurity concentration of 1013 cm<sup>−

3</sup> or less or a semiconductor substrate with an N-type impurity concentration of 1015 cm<sup>−

3</sup> or less.

23. A method of fabricating a solid-state image pickup device as claimed in claim 17, further comprising a forming a well region for said photoelectric converting device in said solid-state image pickup device, said well region being formed at the first surface side of said semiconductor substrate and not being formed in a region on a second surface side of said photoelectric converting device.

24. A method of fabricating a solid-state image pickup device as claimed in claim 23, characterized in that:

said photoelectric converting device is a photodiode and said well region is a P-type well region.

25. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

or more of the depth of said semiconductor substrate from the second surface of said semiconductor substrate.

26. A method of fabricating a solid-state image pickup device as claimed in claim 17, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by a change in impurity concentration of said semiconductor substrate.

27. A method of fabricating a solid-state image pickup device as claimed in claim 26, characterized in that:

said semiconductor substrate is formed by an epitaxial substrate, and said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by a change in epitaxial concentration of said epitaxial substrate.

28. An electronic apparatus having a solid-state image pickup device, said solid-state image pickup device comprising:

a semiconductor substrate having an image pickup pixel unit with a plurality of pixels each including a first conductivity type photoelectric converting device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

and a wiring layer formed by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric converting device, said electronic apparatus characterized in that;

said solid-state image pickup device has an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side; and

characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

of the depth of said semiconductor substrate from the second surface of said semiconductor substrate.

29. An electronic apparatus having a solid-state image pickup device, said solid-state image pickup device comprising:

a semiconductor substrate having an image pickup pixel unit with a plurality of pixels each including a first conductivity type photoelectric converting device, a well region of a second conductive type which is opposite the first conductive type located around the photoelectric converting device and a reading circuit;

and a wiring layer formed by stacking a plurality of layers of wiring including a signal line for driving said image pickup pixel unit adjacent a first surface of said semiconductor substrate, a second surface of said semiconductor substrate being a light receiving plane for said photoelectric converting device, said electronic apparatus characterized in that;

said solid-state image pickup device has an electric field generating means for generating an electric field in said semiconductor substrate in a direction of depth of said semiconductor substrate and thereby leading photoelectrons in said photoelectric converting device from said second surface side to said first surface side; and

characterized in that;

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by applying a voltage to an electrode disposed on a second surface side of said semiconductor substrate.

30. An electronic apparatus as claimed in claim 29, further comprising a well region for said photoelectric convening device in said solid-state image pickup device, said well region being formed at the first surface side of said semiconductor substrate and not being formed in a region on a second surface side of said photoelectric converting device and wherein said electrode is a transparent electrode.

31. An electronic apparatus as claimed in claim 30, characterized in that:

said photoelectric converting device is a photodiode and said well region is a P-type well region.

32. An electronic apparatus as claimed in claim 29, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate in a region having ½

or more of the depth of said semiconductor substrate from the second surface of said semiconductor substrate and wherein said electrode is a transparent electrode.

33. An electronic apparatus as claimed in claim 29, characterized in that:

said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by a change in impurity concentration of said semiconductor substrate and wherein said electrode is a transparent electrode.

34. A method of fabricating a solid-state image pickup device as claimed in claim 33, characterized in that:

said semiconductor substrate is formed by an epitaxial substrate, and said electric field generating means generates the electric field in the direction of the depth of said semiconductor substrate by a change in epitaxial concentration of said epitaxial substrate.

35. An imaging device comprising:

a substrate having a first and a second surface;

a transistor formed at said first surface;

a first conductivity type light-electricity conversion region formed at said first surface;

an electrode formed above said second surface;

wherein said imaging device has an electric field provided between the first and a second surface sides.

36. An electronic apparatus as claimed in claim 35, wherein said electrode is transparent.

37. An imaging device comprising:

a substrate having a first and a second surface;

a transistor formed on said first surface;

a first conductivity type light-electricity conversion region formed at said first surface and a second conductivity type well region located around the light-electricity conversion region;

wherein said imaging device has a drift function by which electrons are accelerated from a second surface side to a first surface side; and

said electrons are caused by radiated light from said second surface side, further comprising a transparent electrode.

38. An imaging device comprising:

a substrate having a first and a second surface;

a transistor formed on said first surface;

a first conductivity type light-electricity conversion region formed at said first surface and a second conductivity type well region located around the light-electricity conversion region;

an insulating layer formed above said second surface;

wherein said substrate has a drift region which has non-uniform impurity distribution and is formed below said light-electricity conversion region, further comprising a transparent electrode.

39. An imaging device comprising:

a substrate having a first and a second surface;

a transistor formed on said first surface;

a first conductivity type light-electricity conversion region formed at said first surface and a second conductivity type well region located around the light-electricity conversion region;

an insulating layer formed above said second surface;

wherein said substrate has a drift region which has non-uniform impurity distribution and is formed below said light-electricity conversion region; and

further comprising a transparent electrode.

40. An imaging device as claimed in claim 39, wherein said drift region is comprised of a first region and a second region whose impurity concentration is higher than that of said first region.

41. An imaging device as claimed in claim 39, wherein said drift region is comprised of a first region and a second region whose conductivity type is different from that of said first region.

42. An electronic apparatus as claimed in claim 39, further comprising:

an electrode connected to said transistor; and

wherein said electrode is formed above said first surface.