Image sensor and method of fabricating the same

• US 20060214249A1
• Filed: 03/27/2006
• Published: 09/28/2006
• Est. Priority Date: 03/28/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nam, Jung-Hyun, Jung, Jong-Wan
• Granted Patent: US 7,579,637 B2
• Time in Patent Office: Days
• US Class Current: 257/432
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/1463 Pixel isolation structures

Abstract

An image sensor and a method of fabricating the image sensor are provided. The image sensor includes a semiconductor substrate having a first conductivity type, a deep well having a second conductivity type. The deep well is formed at a predetermined depth in the semiconductor substrate to divide the semiconductor substrate into a first conductivity type upper substrate area and a lower substrate area. The image sensor further includes a plurality of unit pixels integrating charges corresponding to incident light and comprising first conductivity type ion-implantation areas. The first conductivity type ion-implantation areas are separated from one another. Moreover, at least one unit pixel among the plurality of unit pixels further comprises the first conductivity type upper substrate area that is positioned under a first conductivity type ion-implantation area included in the unit pixel. Further, the at least one unit pixel among the plurality of unit pixels extends beyond the first conductivity type ion-implantation area and is electrically isolated from first conductivity type ion-implantation areas included in adjacent unit pixels of the plurality of unit pixels.

Claims

1. An image sensor comprising:

a semiconductor substrate having a first conductivity type;

a deep well having a second conductivity type, the deep well being formed at a predetermined depth in the semiconductor substrate to divide the semiconductor substrate into a first conductivity type upper substrate area and a lower substrate area; and

a plurality of unit pixels integrating charges corresponding to incident light and comprising first conductivity type ion-implantation areas said first conductivity type ion-implantation areas are separated from one another, at least one unit pixel among the plurality of unit pixels further comprising the first conductivity type upper substrate area that is positioned under a first conductivity type ion-implantation area included in the unit pixel, extends beyond the first conductivity type ion-implantation area and is electrically isolated from first conductivity type ion-implantation areas included in adjacent unit pixels of said plurality of unit pixels.

2. The image sensor of claim 1, wherein the at least one unit pixel integrates charges corresponding to incident light having a longest wavelength of incident light into the plurality of unit pixels.

3. The image sensor of claim 1, wherein the first conductivity type ion-implantation areas are defined by a second conductivity type first isolation well.

4. The image sensor of claim 1, wherein the plurality of unit pixels comprise a red unit pixel, a green unit pixel, and a blue unit pixel which integrate charges corresponding to incident light having a wavelength in a red region, incident light having a wavelength in a green region, and incident light having a wavelength in a blue region, and wherein the at least one unit pixel is the red unit pixel.

5. The image sensor of claim 4, wherein each of the green and blue unit pixels comprises only a first conductivity type ion-implantation area.

6. The image sensor of claim 4, wherein the first conductivity type upper substrate area included in the red unit pixel is wider than the first conductivity upper substrate included in each of the green and blue unit pixels.

7. The image sensor of claim 6, wherein the first conductivity type upper substrate area included in the green unit pixel is wider than the first conductivity type upper substrate area included in the blue unit pixel.

8. The image sensor of claim 4, wherein the red, green, and blue unit pixels are arranged in a Bayer type color filter array.

9. The image sensor of claim 1, wherein the first conductivity type ion-implantation areas are isolated in units of unit pixels by a second isolation well having the second conductivity type.

10. The image sensor of claim 9, wherein the second isolation well having the second conductivity type has substantially the same depth as or is deeper than the first conductivity type ion-implantation areas.

11. The image sensor of claim 9, wherein the first conductivity type upper substrate area at least partially overlaps with the second isolation well.

12. A method of fabricating an image sensor, comprising:

providing a semiconductor substrate having a first conductivity type;

forming a deep well having a second conductivity type at a predetermined depth in the semiconductor substrate to divide the semiconductor substrate into a first conductivity type upper substrate area and a lower substrate area; and

forming a plurality of unit pixels integrating charges corresponding to incident light and comprising first conductivity type ion-implantation areas, said first conductivity type ion-implantation areas are separated from one another such that at least one unit pixel among the plurality of unit pixels further comprises the first conductivity type upper substrate area that is positioned under a first conductivity type ion-implantation area included in the unit pixel, extends beyond the first conductivity type ion-implantation area and is electrically isolated from first conductivity type ion-implantation areas included in adjacent unit pixels of said plurality of unit pixels.

13. The method of fabricating an image sensor of claim 12, wherein the at least one unit pixel integrates charges corresponding to incident light having a longest wavelength of incident light into the plurality of unit pixels.

14. The method of fabricating an image sensor of claim 12, wherein the first conductivity type ion-implantation areas are defined by a second conductivity type first isolation well.

15. The method of fabricating an image sensor of claim 12, wherein the plurality of unit pixels comprise a red unit pixel, a green unit pixel, and a blue unit pixel which integrate charges corresponding to incident light having a wavelength in a red region, incident light having a wavelength in a green region, and incident light having a wavelength in a blue region, and wherein the at least one unit pixel is the red unit pixel.

16. The method of fabricating an image sensor of claim 15, wherein each of the green and blue unit pixels comprises only a first conductivity type ion-implantation area.

17. The method of fabricating an image sensor of claim 15, wherein the first conductivity type upper substrate area included in the red unit pixel is wider than the first conductivity type upper substrate area included in each of the green and blue unit pixels.

18. The method of fabricating an image sensor of claim 17, wherein the first conductivity type upper substrate area included in the green unit pixel is wider than the first conductivity type upper substrate area included in the blue unit pixel.

19. The method of fabricating an image sensor of claim 15, wherein the red, green, and blue unit pixels are arranged in a Bayer type color filter array.

20. The method of fabricating an image sensor of claim 12, wherein the first conductivity type ion-implantation areas are isolated in units of unit pixels by a second isolation well having the second conductivity type.

21. The method of fabricating an image sensor of claim 20, wherein the second isolation well having the second conductivity type has substantially the same depth as or is deeper than the first conductivity type ion-implantation areas.

22. The method of fabricating an image sensor of claim 20, wherein the first conductivity type upper substrate area at least partially overlaps with the second isolation well.