Imaging device

Patent metadata

Field	Value
Publication number	US-2016163897-A1
Application number	US-201514948190-A
Country	US
Kind code	A1
Filing date	Nov 20, 2015
Priority date	Dec 3, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

To provide an imaging device equipped with a photodiode, which is capable of enhancing both of a capacity and sensitivity.
In an area of a P-type well in which a photodiode is formed, a P-type impurity region is formed from the surface of the P-type well to a predetermined depth. Further, an N-type impurity region is formed to extend to a deeper position. N-type impurity regions and P-type impurity regions respectively extending in a gate width direction from a lower part of the N-type impurity region to a deeper position so as to contact the N-type impurity region are alternately arranged in a plural form along a gate length direction in a form to contact each other.

First claim

1 . An imaging device comprising:
a semiconductor substrate having a main surface; an element forming area of a first conductivity type defined by an element isolation area formed in the semiconductor substrate; an electrode unit extending in a first direction so as to cross the element forming area in a form to divide the element forming area into a first area and a second area; and a photoelectric conversion unit formed in the first area, the photoelectric conversion unit including: a first impurity region of a first conductivity type formed from the surface of the element forming area to a first depth, a second impurity region of a second conductivity type formed from the first depth to a second depth deeper than the first depth so as to contact the first impurity region, a third impurity region of a first conductivity type extending in the first direction and formed from the second depth to a position deeper than the second depth in a form to contact the second impurity region, and a fourth impurity region of a second conductivity type extending in the first direction and formed from the second depth to a position deeper than the second depth in a form to contact the second impurity region, and the third impurity region and the fourth impurity region being alternately arranged in a plural form along a second direction orthogonal to the first direction in a form to contact each other.

2 . The imaging device according to claim 1 ,
wherein the first conductivity type is a p type, and wherein the second conductivity type is an n type.

3 . The imaging device according to claim 2 ,
wherein the third impurity region extends in the first direction with a first width, wherein the fourth impurity region extends in the first direction with a second width, and wherein assuming that the first width is X P , the second width is X N , the dielectric constant of silicon is ε Si , the elementary charge quantity is q, the impurity concentration of the third impurity region is N A , the impurity concentration of the fourth impurity region is N D , and a depletion potential for depleting the third impurity region and the fourth impurity region is V dep2 , the first width is set based on the following equation:

X
N

=

8


ɛ
si

q



N
A

N
D



(

N
D

+

N
A

)



V

dep



2

,

(
1
)

and
the second width is set based on the following equation:

X
P

-

8


ɛ
si

q



N
D

N
A



(

N
D

+

N
A

)



V

dep



2

(
2
)

4 . The imaging device according to claim 3 ,
wherein assuming that a depletion potential for depleting the second impurity region is V dep1 , the impurity concentration of the element forming area, the impurity concentration of the first impurity region, the impurity concentration of the second impurity region, the impurity concentration of the third impurity region, and the impurity concentration of the fourth impurity region are adjusted in such a manner that V dep1 >V dep2 .

5 . The imaging device according to claim 1 ,
wherein the impurity concentration of the third impurity region is set higher than the impurity concentration of the element forming area, and wherein the impurity concentration of the fourth impurity region is set lower than the impurity concentration of the second impurity region.

6 . An imaging device comprising:
a semiconductor substrate having a main surface; an element forming area of a first conductivity type defined by an element isolation area formed in the semiconductor substrate; an electrode unit extending in a first dir

Assignees

• Renesas Electronics Corp

Inventors

• Sakai Atsushi
• Eikyu Katsumi

Classifications

• H10F39/8063

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• H10F39/8033

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• H10F39/8027

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