Image sensor
An image sensor is provided. The image sensor includes: a semiconductor substrate including a first surface and a second surface, which are opposite to each other; a photoelectric conversion region in the semiconductor substrate; a vertical transfer gate, which extends into the semiconductor substrate from the first surface toward the photoelectric conversion region; a floating diffusion region, which is provided in the semiconductor substrate, is spaced apart from the vertical transfer gate, and is an n-type impurity region; and a second impurity region, which is provided between the vertical transfer gate and the floating diffusion region and is a p-type impurity region.
1 . An image sensor, comprising:
a semiconductor substrate comprising a first surface and a second surface, which are opposite to each other;
a photoelectric conversion region in the semiconductor substrate;
a vertical transfer gate, which extends into the semiconductor substrate from the first surface toward the photoelectric conversion region;
a floating diffusion region, which is provided in the semiconductor substrate, is spaced apart from the vertical transfer gate, and is an n-type impurity region;
a second impurity region, which is provided between the vertical transfer gate and the floating diffusion region and is a p-type impurity region;
a first contact metal on the vertical transfer gate; and
a second contact metal on the floating diffusion region,
wherein a distance along a horizontal direction from an edge of an upper portion of the vertical transfer gate to a center axis of the second contact metal is greater than ½ of a distance along the horizontal direction from a center axis of a lower portion of the vertical transfer gate to the edge of the upper portion of the vertical transfer gate.
2 . The image sensor of claim 1 , further comprising a third impurity region between the second impurity region and the floating diffusion region,
wherein a p-type impurity concentration of the third impurity region is lower than a p-type impurity concentration of the second impurity region, and
wherein a width of the second impurity region is greater than a width of the third impurity region.
3 . The image sensor of claim 1 , further comprising:
deep trench isolations, which extend in parallel and define a pixel region,
wherein a distance from a center axis of the first contact metal to the center axis of the second contact metal is greater than ⅓ of a pixel length that is a distance between the deep trench isolations.
4 . The image sensor of claim 1 , further comprising a first impurity region, which is provided between the photoelectric conversion region and the second impurity region, and is adjacent to the vertical transfer gate,
wherein a p-type impurity concentration of the first impurity region is higher than a p-type impurity concentration of the second impurity region, and
wherein a height of the second impurity region is higher than a height of the first impurity region.
5 . The image sensor of claim 1 , wherein, in a single pixel region, the lower portion of the vertical transfer gate comprises a plurality of gate structures.
6 . The image sensor of claim 5 , further comprising deep trench isolations, which extend in parallel and delimit pixel regions,
wherein a distance between two of the plurality of gate structures is shorter than ⅕ of a pixel length, which is a distance between the deep trench isolations.
7 . The image sensor of claim 1 , wherein the vertical transfer gate has an L shape in a plan view.
8 . The image sensor of claim 1 , wherein the vertical transfer gate has a ring shape in a plan view, and
wherein the floating diffusion region is enclosed by the ring-shaped vertical transfer gate.