Image sensing device
An image sensing device includes a photoelectric conversion element disposed in a substrate and configured to convert incident light into photocharges indicative of the incident light, a plurality of transistors structured to process the photocharges generated by the photoelectric conversion element, a first isolation structure disposed adjacent to one side of the photoelectric conversion element and structured to vertically extend from a first surface of the substrate to a first depth, and a second isolation structure disposed adjacent to another side of the photoelectric conversion element and structured to extend from the first surface to a second depth, wherein the first depth is greater than the second depth, and wherein the first isolation structure is disposed to overlap a gate electrode of at least one of the plurality of transistors.
1 . An image sensing device comprising:
a photoelectric conversion element disposed in a substrate and configured to convert incident light into photocharges indicative of the incident light;
a plurality of transistors structured to process the photocharges generated by the photoelectric conversion element;
a first isolation structure disposed adjacent to one side of the photoelectric conversion element and structured to vertically extend from a first surface of the substrate to a first depth; and
a second isolation structure disposed adjacent to another side of the photoelectric conversion element and structured to extend from the first surface to a second depth,
wherein the first depth is greater than the second depth,
wherein the first isolation structure is disposed to overlap a gate electrode of at least one of the plurality of transistors and a channel region disposed under the gate electrode, and
wherein the channel region is disposed between the first isolation structure and the gate electrode.
2 . The image sensing device according to claim 1 , wherein the plurality of transistors includes at least one of:
a transfer transistor configured to transfer the photocharges to a floating diffusion node;
a reset transistor configured to reset the floating diffusion node;
a drive transistor configured to generate an electrical signal corresponding to an electric potential of the floating diffusion node; or
a selection transistor configured to selectively output the electrical signal of the drive transistor as a pixel signal.
3 . The image sensing device according to claim 2 , wherein:
a gate electrode of the drive transistor is disposed to overlap the first isolation structure.
4 . The image sensing device according to claim 3 , wherein:
a gate electrode of the transfer transistor, a gate electrode of the reset transistor, and a gate electrode of the selection transistor is disposed without overlapping the first isolation structure.
5 . The image sensing device according to claim 3 , wherein:
a gate electrode of the selection transistor is disposed to overlap the second isolation structure.
6 . The image sensing device according to claim 3 , wherein:
a length of the first isolation structure is identical to a distance between a first terminal and a second terminal of the drive transistor.
7 . The image sensing device according to claim 1 , wherein:
a distance between the first isolation structure and a second surface facing the first surface is shorter than a distance between the second isolation structure and the second surface.
8 . The image sensing device according to claim 1 , wherein:
each of the first isolation structure and the second isolation structure is disposed at a boundary between a pixel including the photoelectric conversion element and another pixel adjacent to the pixel.
9 . The image sensing device according to claim 8 , wherein:
the first isolation structure and the second isolation structure are disposed to surround the pixel including the photoelectric conversion element.
10 . The image sensing device according to claim 1 , wherein each of the first isolation structure and the second isolation structure includes:
an electrode configured to receive a bias voltage; and
an insulation layer configured to electrically isolate the electrode and an impurity region of the substrate from each other.
11 . The image sensing device according to claim 10 , wherein:
the bias voltage is a negative voltage.
12 . The image sensing device according to claim 1 , wherein:
the plurality of transistors includes a n-channel metal-oxide-semiconductor (NMOS) transistor including a gate electrode overlapping the first isolation structure.