Image sensor having internal reflector in color filter
An image sensor includes a first unit. The first unit includes a first photodiode having a first dimension, a second photodiode disposed adjacent the first photodiode and having a second dimension that is greater than the first dimension, a first color filter overlapping the first photodiode and the second photodiode, and a first internal reflector disposed in the first color filter and overlapping the first photodiode. The first internal reflector has an inclined light receiving surface inclined from a top surface of the first color filter toward the second photodiode, and a refraction index of the first internal reflector is smaller than a refraction index of the first color filter.
1 . An image sensor comprising:
a first unit comprising:
a first photodiode having a first dimension;
a second photodiode disposed adjacent the first photodiode and having a second dimension that is greater than the first dimension;
a first color filter overlapping the first photodiode and the second photodiode, wherein the first color filter continuously covers an entire top surface of the first photodiode and an entire top surface of the second photodiode, without an inner grid in the first color filter, wherein the first unit comprises a first grid surrounding the first color filter; and
a first internal reflector disposed in the first color filter and overlapping the first photodiode, wherein the first internal reflector has an inclined light receiving surface inclined from a top surface of the first color filter toward the second photodiode, and a refraction index of the first internal reflector is smaller than a refraction index of the first color filter, wherein the first internal reflector has an angle θ 1 between the inclined light receiving surface and the first photodiode, and wherein the angle θ 1 satisfies:
0.3
*
H
1
0.5
*
W
2
+
W
1
≤
tan
θ
1
≤
H
1
W
1
,
in which H 1 is a height of the first grid, W 1 is the first dimension of the first photodiode, and W 2 is the second dimension of the second photodiode.
2 . The image sensor of claim 1 , wherein a difference between the refraction index of the first internal reflector and the refraction index of the first color filter is greater than 0.2.
3 . The image sensor of claim 1 , wherein a ratio of a height of the first internal reflector to a height of the first grid is from 0.3 to 1.
4 . The image sensor of claim 1 , wherein the first internal reflector has a fifth dimension, and the fifth dimension is greater than the first dimension of the first photodiode and is smaller than a sum of the first dimension of the first photodiode and half of the second dimension of the second photodiode.
5 . The image sensor of claim 1 , wherein the first internal reflector overlaps a portion of the second photodiode.
6 . The image sensor of claim 1 , wherein the first internal reflector comprises a transparent organic material.
7 . The image sensor of claim 1 , wherein the first internal reflector is a triangle prism, and a dimension of the first internal reflector is greater than a dimension of the first photodiode and is smaller than a sum of the dimension of the first photodiode and half of a dimension of the second photodiode.
8 . The image sensor of claim 1 , further comprising a second unit, the second unit comprising:
a third photodiode having a third dimension;
a fourth photodiode disposed adjacent the third photodiode and having a fourth dimension that is greater than the third dimension;
a second color filter overlapping the third photodiode and the fourth photodiode; and
a second internal reflector disposed in the second color filter and overlapping the third photodiode, wherein the second internal reflector has an inclined light receiving surface inclined from a top surface of the second color filter toward the fourth photodiode, a refraction index of the second internal reflector is smaller than a refraction index of the second color filter, and a transparency of the second internal reflector is different from a transparency of the first internal reflector.
9 . The image sensor of claim 8 , wherein a difference between the refraction index of the second internal reflector and the refraction index of the second color filter is greater than 0.2.
10 . The image sensor of claim 8 , wherein the second unit comprises a second grid surrounding the second color filter, wherein a ratio of a height of the second internal reflector to a height of the second grid is from 0.3 to 1.
11 . The image sensor of claim 8 , wherein the second internal reflector has a sixth dimension, and the sixth dimension is greater than the third dimension of the third photodiode and is smaller than a sum of the third dimension of the third photodiode and half of the fourth dimension of the fourth photodiode.
12 . The image sensor of claim 8 , wherein the second unit comprises a second grid surrounding the second color filter, wherein the second internal reflector has an angle θ 2 between the inclined light receiving surface and the third photodiode.
13 . The image sensor of claim 12 , wherein the angle θ 2 satisfies:
0.3
*
H
1
0.5
*
W
4
+
W
3
≤
tan
θ
2
≤
H
1
W
3
,
in which H 1 is a height of the second grid, W 3 is the third dimension of the third photodiode, and W 4 is the fourth dimension of the fourth photodiode.
14 . The image sensor of claim 8 , wherein the second color filter extends continuously from the third photodiode to the fourth photodiode.
15 . The image sensor of claim 8 , wherein an extinction coefficient of the second internal reflector is from 0.1 to 0.3.
16 . The image sensor of claim 8 , wherein the second internal reflector is a triangle prism.
17 . The image sensor of claim 8 , wherein the second internal reflector overlaps a portion of the fourth photodiode.
18 . An image sensor comprising:
a first unit comprising:
a first photodiode having a first dimension;
a second photodiode disposed adjacent the first photodiode and having a second dimension that is greater than the first dimension;
a first color filter overlapping the first photodiode and the second photodiode, wherein the first color filter continuously covers an entire top surface of the first photodiode and an entire top surface of the second photodiode, without an inner grid in the first color filter; and
a first internal reflector disposed in the first color filter and overlapping the first photodiode, wherein the first internal reflector has an inclined light receiving surface inclined from a top surface of the first color filter toward the second photodiode, and a refraction index of the first internal reflector is smaller than a refraction index of the first color filter; and
a second unit, the second unit comprising:
a third photodiode having a third dimension;
a fourth photodiode disposed adjacent the third photodiode and having a fourth dimension that is greater than the third dimension;
a second color filter overlapping the third photodiode and the fourth photodiode; and
a second internal reflector disposed in the second color filter and overlapping the third photodiode, wherein the second internal reflector has an inclined light receiving surface inclined from a top surface of the second color filter toward the fourth photodiode, a refraction index of the second internal reflector is smaller than a refraction index of the second color filter, and a transparency of the second internal reflector is different from a transparency of the first internal reflector.