Solid-state imaging device, manufacturing method of the same, and electronic apparatus
A solid-state imaging device includes plural photodiodes which are formed in a photodiode area of a unit pixel with no element separating area interposed therebetween and in which impurity concentrations of pn junction areas are different from each other.
1. A solid-state imaging device comprising:
a substrate with a pixel area;
a gate electrode in the pixel area;
a first photodiode in the pixel area and at one side of the gate electrode; and
a second photodiode adjacent to the first photodiode in the pixel area,
wherein,
the second photodiode is closer to the gate electrode than the first photodiode, and
the first photodiode is comprised of at least three impurity concentration regions arranged in a depth direction of the substrate, a bottom surface of the first photodiode being deeper in the substrate than a bottom surface of the second photodiode.
2. The solid-state imaging device of claim 1 , wherein:
the first photodiode has a first region of a first conductivity type, a second region of a second conductivity type opposite the first conductivity type, and a third region of the second conductivity type arranged in that order in the depth direction of the substrate, and
the second and third regions of the first photodiode have different impurity concentrations.
3. The solid-state imaging device of claim 1 , wherein:
the first photodiode has a first region of a first conductivity type, a second region of a second conductivity type opposite the first conductivity type, and a third region of the second conductivity type,
the first, second, and third regions of the first photodiode are arranged in that order in the depth direction of the substrate, and
the second region of the first photodiode has an impurity concentration that is relatively higher than that of the third region of the first photodiode.
4. The solid-state imaging device of claim 2 , wherein:
the second photodiode has a first region of the first conductivity type and a second region of the second conductivity type,
the first and second regions of the second photodiode are arranged in that order in the depth direction of the substrate,
the first region of the second photodiode has an impurity concentration that is relatively less than that of the first region of the first photodiode, and
the second region of the second photodiode has an impurity concentration that is relatively less than that of the second region of the first photodiode.
5. The solid-state imaging device of claim 1 , further comprising first sidewalls between which the gate electrode is located.
6. The solid-state imaging device of claim 1 , wherein:
the third region of the first photodiode is a charge storage region, and
the third region has an end that is aligned with an end of one of the first sidewalls such that the third region does not extend beneath the sidewall.
7. The solid-state imaging device of claim 1 , further comprising a floating diffusion region at another side of the gate electrode that is opposite to the one side.
8. The solid-state imaging device of claim 4 , further comprising a floating diffusion region at another side of the gate electrode that is opposite to the one side, wherein:
the diffusion area serves as a drain of a transistor,
the gate electrode serves as a gate of the transistor, and
the second regions of the first and second diodes serve as a source of the transistor.