US 12,765,108 B2 · Photodiode structure, preparation method and circuit structure

Abstract

A novel photodiode structure, a preparation method and a circuit structure are provided. The novel photodiode structure includes a substrate having a first doping type, a functional doping area having a second doping type, a surface doping area having the first doping type, and an auxiliary doping area having the second doping type. By forming a non-uniformly doped functional doping area, the present disclosure forms a self-built potential difference in the functional doping area and drives the moving direction of the photogenerated carriers. The photogenerated carriers may be accelerated by the potential difference, so that the collected carriers will directly enter the subsequent circuit through the transport gate. In addition, the loop shape of the auxiliary doping area can increase the area of receiving charges, in a result, the auxiliary doping area can receive the transported carriers faster, thereby further enhancing the transport efficiency of the photogenerated carriers.

Claims18

Dependent claims

A novel photodiode structure, comprising:

a substrate having a first doping type, wherein the substrate has a first doping concentration;
a functional doping area having a second doping type and formed in the substrate, wherein the functional doping area has a non-uniform doping concentration distribution, wherein a doping concentration of the functional doping area increases linearly along a horizontal direction;
a surface doping area having the first doping type and formed in the functional doping area from a top surface of the functional doping area, wherein the surface doping area has a second doping concentration;
a gate structure disposed on the substrate;
and
an auxiliary doping area having the second doping type and formed in the functional doping area, wherein the auxiliary doping area connects the gate structure to the functional doping area and is spaced by an interval from the surface doping area, wherein the auxiliary doping area has a doping concentration greater than a doping concentration of the functional doping area, wherein the horizontal direction points from the surface doping area toward the auxiliary doping area.

3 more elements

A method for preparing a novel photodiode structure, comprising:

providing a substrate having a first doping type, wherein the substrate comprises a first surface and a second surface opposite to the first surface, and the substrate has a first doping concentration;
forming a functional doping area having a second doping type in the substrate from the first surface, wherein the functional doping area has a non-uniform doping concentration distribution, wherein a doping concentration of the functional doping area increases linearly along a horizontal direction;
wherein the functional doping area is formed by:
preparing a mask plate on the substrate, and performing ion implantation based on the mask plate to form the functional doping area, wherein a plurality of nested openings each with a loop shape is formed in the mask plate, wherein a dimension of each of the plurality of nested openings is set according to a concentration at a corresponding position of the each of the plurality of nested openings, wherein a concentration distribution function of a position x of the plurality of nested openings is:
C
⁡
(
x
)
=
∫
1
l
⁢
π
⁢
∫
x
-
w
i
x
+
w
i
e
-
(
x
-
x
i
L
)
2
⁢
C
0
⁢
dx
≈
∑
i
=
1
n
C
0
⁢
1
l
⁢
π
⁢
∫
x
-
w
i
x
+
w
i
e
-
(
x
-
x
i
l
)
2
⁢
C
0
⁢
dx
,
wherein C0 represents a concentration of implanted ions, xi represents a position of the center of the ith opening of the plurality of nested openings, l represents a characteristic length of a diffusion process of each of the plurality of nested openings, and
l
=
x
n
-
x
1
n
-
1
,
a width of the ith opening of the plurality of nested openings, and
w
i
=
l
2
⁢
C
⁡
(
x
i
)
C
0
.
forming a surface doping area having the first doping type and formed in the functional doping area from the top surface, wherein the surface doping area has a second doping concentration;
forming a gate structure on the first surface of the substrate;
and
forming an auxiliary doping area having the second doping type in the functional doping area from the first surface, wherein the auxiliary doping area connects the gate structure to the functional doping area and is spaced by an interval from the surface doping area, wherein the auxiliary doping area has a doping concentration greater than a doping concentration of the functional doping area, wherein the horizontal direction points from the surface doping area toward the auxiliary doping area.

108 more elements

Dependencies are inferred from the claim text.

Photodiode structure, preparation method and circuit structure

Life of this patent

Photodiode structure, preparation method and circuit structure

Life of this patent

Abstract

Claims18