Image sensor including isolation region for removing photocharges
An image sensing device is provided to include a first photoelectric conversion element and a second photoelectric conversion element that are arranged adjacent to each other; a first isolation region located between the first and second photoelectric conversion elements and configured to receive a voltage to generate an electric field to attract photocharges from the first or second photoelectric conversion element; and a second isolation region separated from the first isolation region, the second isolation region located between the first and second photoelectric conversion elements and structured to include an insulation material to block photocharges from moving between the first and second photoelectric conversion elements.
1. An image sensor comprising:
a first photoelectric conversion element and a second photoelectric conversion element that are arranged adjacent to each other and doped with first conductive-type impurities, each of the first photoelectric conversion element and the second photoelectric conversion element configured to generate photocharges in response to incident light;
a floating diffusion region configured to store the photocharges from the first photoelectric conversion element and doped with the first conductive-type impurities;
a transfer transistor coupled between the first photoelectric conversion element and the floating diffusion region and overlapping with the floating diffusion region;
a first isolation region located between the first photoelectric conversion element and the second photoelectric conversion element to isolate the first and second photoelectric conversion elements and disposed apart from the floating diffusion region and the transfer transistor, and doped with the first conductive-type impurities, and configured to receive a voltage; and
a second isolation region separated from the first isolation region, the second isolation region located between the first photoelectric conversion element and the second photoelectric conversion element and structured to include an insulation material; and
a guide region disposed between a bottom surface of the first isolation region and a top surface of the second isolation region, and doped with second conductive-type impurities.
2. The image sensor according to claim 1 , wherein the first conductive-type is N-type and the second conductive-type is P-type.
3. The image sensor according to claim 1 , wherein:
the first isolation region is located to be in contact with one surface of a substrate in which the first photoelectric conversion element and the second photoelectric conversion element are included.
4. The image sensor according to claim 3 , wherein the second isolation region is located in the substrate to be further away from the one surface of the substrate.
5. The image sensor according to claim 4 , wherein:
the second isolation region is formed to be deeply etched in a vertical direction from another surface opposite to the one surface of the substrate to the one surface of the substrate.
6. The image sensor according to claim 1 , wherein the voltage corresponds to a power-supply voltage.
7. The image sensor according to claim 1 , wherein:
the voltage is applied to the first isolation region during a photocharge accumulation period in which each of the first photoelectric conversion element and the second photoelectric conversion element generates and accumulates photocharges.
8. The image sensor according to claim 1 , wherein the guide region is arranged to extend to a lower portion of the bottom surface of the first isolation region and a lower portion of the top surface of the second isolation region, the guide region structured to have a higher doped impurity density than surrounding areas to improve isolation between the first and second photoelectric conversion elements.
9. The image sensor according to claim 1 further comprising:
a well region formed to surround the first photoelectric conversion element and the second photoelectric conversion element, and configured to be in contact with the first isolation region and the second isolation region, and doped with the second conductive-type impurities.
10. The image sensor according to claim 9 , wherein:
the guide region has a higher doping density than the well region.
11. An image sensor comprising:
first to fourth photoelectric conversion elements formed in a first (2×2) matrix structure, and doped with first conductive-type impurities, each of the first to fourth photoelectric conversion element configured to generate photocharges in response to receiving incident light;
fifth to eighth photoelectric conversion elements formed in a second (2×2) matrix structure adjacent to the first (2×2) matrix structure, and doped with the first conductive-type impurities, each of the fifth to eighth photoelectric conversion elements configured to generate photocharges in response to receiving incident light;
a first isolation region disposed at a center portion of a third (2×2) matrix structure formed by the first, the second, the fifth and the sixth photoelectric conversion elements, and doped with the first conductive-type impurities, and configured to receive a voltage to generate an electric field to attract photocharges from the first, the second, the fifth and the sixth photoelectric conversion elements; and
a second isolation region disposed under the first isolation region, and structured to include an insulation material;
a first floating diffusion region disposed at a center portion of the first (2×2) matrix structure and apart from the first isolation region, and configured to store the photocharges received from the first to fourth photoelectric conversion elements, and doped with the first conductive-type impurities;
a second floating diffusion region disposed at a center portion of the second (2×2) matrix structure and apart from the first isolation region, and configured to store the photocharges received from the fifth to eighth photoelectric conversion elements, and doped with the first conductive-type impurities;
a transfer transistor coupled between the first photoelectric conversion element and the first floating diffusion region, wherein the transfer transistor overlaps with the first floating diffusion region and is disposed apart from the first isolation region;
a guide region disposed between a bottom surface of the first isolation region and a top surface of the second isolation region, and doped with second conductive-type impurities.
12. The image sensor according to claim 11 , wherein:
the first photoelectric conversion element and the second photoelectric conversion element are configured to share the first floating diffusion region.
13. The image sensor according to claim 11 , wherein the voltage corresponds to a power-supply voltage.
14. The image sensor according to claim 11 , wherein:
the second isolation region is formed to be deeply etched in a vertical direction from a second surface opposite to a first surface of a substrate including the first isolation region to the first surface of the substrate.
15. The image sensor according to claim 11 , further comprising: a well region surrounding the first to fourth photoelectric conversion elements and doped with the second conductive-type impurities.
16. The image sensor according to claim 15 , wherein the guide region has a higher doping density than the well region.