Image sensing device

1. An image sensing device, comprising:

a first impurity region disposed in a semiconductor substrate and including impurities with a first doping polarity, the first impurity region configured to generate photocharges by performing photoelectric conversion in response to incident light;

a second impurity region disposed over the first impurity region and having impurities with a second doping polarity different from the first doping polarity, the second impurity region in contact with on some portions of the first impurity region;

a floating diffusion region disposed over the second impurity region and configurated to store the photocharges; and

a transfer gate coupled to the floating diffusion region and configured to transmit the photocharges generated by the first impurity region to the floating diffusion region,

wherein the first impurity region is arranged not in contact with the transfer gate,

wherein the first impurity region includes:

a lower impurity region disposed to be spaced apart from the second impurity region by a predetermined distance; and

an upper impurity region disposed between the lower impurity region and the second impurity region to contact with the lower impurity region and the second impurity region,

wherein the upper impurity region has an opening to expose the lower impurity region, the opening located to vertically overlap the transfer gate.

2. The image sensing device according to claim 1 , wherein:

the first impurity region is formed to contact the second impurity region in a region that is disposed below the floating diffusion region.

3. The image sensing device according to claim 1 , wherein:

the first impurity region includes a portion disposed below the transfer gate and is spaced apart from a bottom surface of the second impurity region by a predetermined distance.

4. The image sensing device according to claim 1 , wherein:

the first impurity region includes a plurality of impurity regions having different impurity densities from each other.

5. The image sensing device according to claim 1 , wherein

the lower impurity region has a first density and

the upper impurity region has a second density lower than the first density.

6. The image sensing device according to claim 1 , wherein:

the upper impurity region has a ring shape having the opening.

7. The image sensing device according to claim 5 , further comprising:

a third impurity region disposed in the lower impurity region, and having a third density higher than the first density.

8. The image sensing device according to claim 7 , wherein:

the third impurity region is disposed to vertically overlap with the transfer gate.

9. The image sensing device according to claim 1 , wherein:

the upper impurity region is located under the floating diffusion region.

10. The image sensing device according to claim 1 , wherein the transfer gate has a portion buried in the semiconductor substrate.

11. The image sensing device according to claim 10 , wherein:

a distance between the portion of the transfer gate and a top surface of the first impurity region is shorter than a distance between a bottom surface of the second impurity region and the top surface of the first impurity region.

12. The image sensing device according to claim 1 , further comprising:

a source follower transistor configured to output a signal corresponding to an amount of the photocharges stored in the floating diffusion region; and

a selection transistor configured to transmit an output signal of the source follower transistor to a column line based on a selection signal,

wherein the source follower transistor and the selection transistor are disposed over the first impurity region such that the source follower transistor and the selection transistor vertically overlap with the first impurity region.

13. An image sensing device, comprising:

a pixel array including a plurality of unit pixels and configured to provide an electrical signal corresponding to an incident light received by the pixel array,

wherein each of the plurality of unit pixels includes:

a first impurity region having first-type impurities, and configured to generate photocharges through a photoelectric conversion of the incident light; and

a second impurity region having second-type impurities different from the first-type impurities and disposed over the first impurity region,

wherein the first impurity region has a top surface having a portion distanced from the second impurity region,

wherein the first impurity region includes:

a lower impurity region disposed to be spaced apart from the second impurity region by a predetermined distance; and

an upper impurity region disposed between the lower impurity region and the second impurity region to contact with the lower impurity region and the second impurity region,

wherein the upper impurity region has a ring-shape having an opening to partially expose the lower impurity region.

14. The image sensing device according to claim 13 , wherein:

the first impurity region includes a plurality of impurity regions having different impurity densities from each other.

15. The image sensing device according to claim 13 , wherein

the lower impurity region has a first density and

the upper impurity region has a second density lower than the first density.

16. The image sensing device according to claim 15 , further comprising:

a third impurity region disposed in the lower impurity region, and having a third density higher than the first density.

17. The image sensing device according to claim 16 , wherein:

the third impurity region is disposed to vertically overlap with the opening.

18. An image sensing device, comprising:

a first impurity region disposed in a semiconductor substrate and including impurities with a first doping polarity, the first impurity region configured to generate photocharges by performing photoelectric conversion in response to incident light;

a second impurity region disposed over the first impurity region and having impurities with a second doping polarity different from the first doping polarity, the second impurity region in contact with on some portions of the first impurity region;

a floating diffusion region disposed over the second impurity region and configurated to store the photocharges; and

a transfer gate coupled to the floating diffusion region and configured to transmit the photocharges generated by the first impurity region to the floating diffusion region,

wherein the first impurity region is arranged not in contact with the transfer gate,

wherein the first impurity region comprises:

a lower impurity region having a first density, and disposed to be spaced apart from the second impurity region by a predetermined distance; and

an upper impurity region having a second density lower than the first density, and disposed between the lower impurity region and the second impurity region, wherein the upper impurity region is in contact with the lower impurity region and the second impurity region, and

wherein the upper impurity region is located under the floating diffusion region.

19. The image sensing device of claim 18 , wherein the upper impurity region has an opening to expose the lower impurity region, the opening located to vertically overlap the transfer gate.

20. The image sensing device of claim 18 , wherein:

the first impurity region is formed to contact the second impurity region in a region that is disposed below the floating diffusion region.