U.S. patent application number 15/354337 was filed with the patent office on 2018-05-17 for optical sensor.
The applicant listed for this patent is VisEra Technologies Company Limited. Invention is credited to Chin-Chuan HSIEH, Kuo-Feng LIN.
Application Number | 20180138329 15/354337 |
Document ID | / |
Family ID | 60048676 |
Filed Date | 2018-05-17 |
United States Patent
Application |
20180138329 |
Kind Code |
A1 |
LIN; Kuo-Feng ; et
al. |
May 17, 2018 |
OPTICAL SENSOR
Abstract
An optical sensor includes a sensing layer, a color filter, and
a grid structure. The sensing layer includes a photodiode. The
color filter includes a lower portion disposed on the sensing
layer, and an upper portion disposed on the lower portion. The
upper portion includes a bottom surface connected to the lower
portion, a first inclined surface inclined relative to the bottom
surface, and a second inclined surface that is opposite to the
first inclined surface and inclined relative to the bottom surface.
The grid structure surrounds the upper portion. Between the first
inclined surface and the bottom surface is a first acute angle, and
between the second inclined surface and the bottom surface is a
second acute angle.
Inventors: |
LIN; Kuo-Feng; (Kaohsiung
City, TW) ; HSIEH; Chin-Chuan; (Hsin-Chu City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VisEra Technologies Company Limited |
Hsin-Chu City |
|
TW |
|
|
Family ID: |
60048676 |
Appl. No.: |
15/354337 |
Filed: |
November 17, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/14621 20130101;
H01L 31/02162 20130101; H01L 31/02164 20130101; H01L 27/1464
20130101; H01L 27/14623 20130101; H01L 27/14645 20130101; H01L
31/02327 20130101; H01L 27/14627 20130101 |
International
Class: |
H01L 31/0232 20060101
H01L031/0232 |
Claims
1. An optical sensor, comprising: a sensing layer comprising a
photodiode; a first color filter comprising a first lower portion
disposed on the sensing layer, and a first upper portion disposed
on the first lower portion, wherein the first upper portion
comprises a first bottom interface connected to the first lower
portion, a first inclined surface inclined relative to the first
bottom interface, and a second inclined surface opposite to the
first inclined surface and inclined relative to the first bottom
interface; a shading structure surrounding the first lower portion;
and a grid structure surrounding the first upper portion, wherein
the grid structure comprises a first grid layer disposed on the
shading structure, a second grid layer disposed on the first grid
layer, and a third grid layer disposed on the second grid layer,
wherein a refractive index of the first grid layer is greater than
a refractive index of the second grid layer, and a refractive index
of the second grid layer is greater than a refractive index of the
third grid layer, wherein between the first inclined surface and
the first bottom interface is a first acute angle, and between the
second inclined surface and the first bottom interface is a second
acute angle.
2. The optical sensor as claimed in claim 1, wherein the first
acute angle and the second acute angle are in a range from about 65
degrees to 89 degrees.
3. The optical sensor as claimed in claim 1, wherein the first
acute angle is equal to the second acute angle.
4. The optical sensor as claimed in claim 1, wherein the first
inclined surface and the second inclined surface are symmetrically
arranged about a symmetry plane of the first color filter.
5. The optical sensor as claimed in claim 1, wherein the first
upper portion further comprises a top surface opposite to the first
bottom interface, and the first upper portion narrows gradually
from the first bottom interface to the top surface.
6. The optical sensor as claimed in claim 1, wherein a cross
section of the first upper portion has a trapezoidal shape, and the
cross section of the first upper portion is perpendicular to the
first bottom interface and the first inclined surface.
7. The optical sensor as claimed in claim 1, wherein the first
lower portion and the first upper portion are formed as a single
piece, and comprise the same materials.
8. (canceled)
9. (canceled)
10. The optical sensor as claimed in claim 1, wherein cross
sections of the first grid layer and the second grid layer are
V-shaped.
11. The optical sensor as claimed in claim 1, wherein the materials
of the first grid layer, the second grid layer, and the third grid
layer are different.
12. The optical sensor as claimed in claim 1, wherein a thickness
of the first color filter is greater than 1 um.
13. An optical sensor, comprising: a sensing layer comprising a
photodiode; a first color filter comprising a first lower portion
disposed on the sensing layer, and a first upper portion disposed
on the first lower portion, wherein the first upper portion
comprises a first bottom interface connected to the first lower
portion, a first inclined surface inclined relative to the first
bottom interface, and a second inclined surface opposite to the
first inclined surface and inclined relative to the first bottom
interface; and a grid structure surrounding the first upper
portion; wherein between the first inclined surface and the first
bottom interface is a first acute angle, and between the second
inclined surface and the first bottom interface is a second acute
angle, wherein the first color filter further comprises a first
dome portion, disposed on the first upper portion, comprises an
arched top surface, wherein the first lower portion, the first
upper portion and the dome portion are formed as a single piece,
and comprise the same materials.
14. The optical sensor as claimed in claim 13, further comprising:
a second color filter comprising a second lower portion disposed on
the sensing layer, and a second upper portion disposed on the
second lower portion, wherein the second upper portion comprises a
second bottom interface connected to the second lower portion, and
a third inclined surface inclined relative to the second bottom
interface, a third color filter comprising a third lower portion
disposed on the sensing layer, and a third upper portion disposed
on the third lower portion, wherein the third upper portion
comprises a third bottom interface connected to the third lower
portion, and a fourth inclined surface inclined relative to the
third bottom interface, wherein between the third inclined surface
and the second bottom interface is a third acute angle, between the
fourth inclined surface and the third bottom interface is a fourth
acute angle, the first acute angle is greater than the third acute
angle, and the third acute angle is greater than the fourth acute
angle.
15. The optical sensor as claimed in claim 14, wherein the first
color filter is a blue color filter, the second color filter is a
green color filter, and the third color filter is a red color
filter.
16. The optical sensor as claimed in claim 14, wherein the first
color filter further comprises a first dome portion disposed on the
first upper portion, the second color filter further comprises a
second dome portion disposed on the second upper portion, and the
third color filter further comprises a third dome portion disposed
on the third upper portion.
17. The optical sensor as claimed in claim 16, wherein a height of
the first dome portion relative to the first upper portion is
greater than a height of the second dome portion relative to the
second upper portion, and a height of the second dome portion
relative to the second upper portion is greater than a height of
the third dome portion relative to the third upper portion.
18. The optical sensor as claimed in claim 16, wherein heights of
the first dome portion relative to the first upper portion, the
second dome portion relative to the second upper portion, and the
third dome portion relative to the third upper portion is in a
range from about 50 nm to 150 nm.
19. The optical sensor as claimed in claim 14, further comprising
an anti-reflection film disposed on the first upper portion, the
second upper portion and the third upper portion, wherein a
thickness of the anti-reflection film is in a range from about 100
nm to 250 nm.
20. The optical sensor as claimed in claim 19, wherein a thickness
of the anti-reflection film over the first upper portion is greater
than a thickness of the anti-reflection film over the second upper
portion, and a thickness of the anti-reflection film over the
second upper portion is greater than a thickness of the
anti-reflection film over the third upper portion.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present disclosure relates to an optical sensor, and in
particular to an optical sensor with color filters.
Description of the Related Art
[0002] An optical sensor, such as a spectrum sensor or an image
sensor, is configured to detect light or capture an image from an
object. The optical sensor is generally mounted on an electrical
device, such as a spectrum meter or a camera.
[0003] FIG. 1 is a schematic view of a conventional optical sensor
B1. The optical sensor includes a sensing layer B10, color filters
B20, and microlenses B30. The sensing layer B10 includes
photodiodes B11 to sense light beams, and covert the light beams
into electrical signals. The color filters B20 are disposed on the
sensing layer B10, and the cross sections of the color filters B20
are rectangular. The microlens B30 are disposed on the color
filters B20, and configured to focus the light beams to the
photodiodes B11.
[0004] However, with the development of electrical devices, it has
been requested that the electrical device be as thin as possible,
and that the manufacturing cost of the electrical device be
decreased. Therefore, the thickness of the conventional optical
sensor B1 needs to be decreased to correspond to the thickness of
the electrical device. Consequently, it is desirable that a
solution for improving optical sensors be provided.
BRIEF SUMMARY OF THE INVENTION
[0005] The present disclosure provides an optical sensor with less
thickness and a lower manufacturing cost.
[0006] The present disclosure provides an optical sensor including
a sensing layer, a first color filter, and a grid structure. The
sensing layer includes a photodiode. The first color filter
includes a first lower portion disposed on the sensing layer, and
an first upper portion disposed on the first lower portion. The
first upper portion includes a first bottom surface connected to
the first lower portion, a first inclined surface inclined relative
to the first bottom surface, and a second inclined surface opposite
to the first inclined surface and inclined relative to the first
bottom surface.
[0007] The grid structure surrounds the first upper portion.
Between the first inclined surface and the first bottom surface is
a first acute angle, and between the second inclined surface and
the first bottom surface is a second acute angle.
[0008] In some embodiments, the first acute angle and the second
acute angle are in a range from about 65 degrees to 89 degrees. In
some embodiments, the first acute angle is equal to the second
acute angle. The first inclined surface and the second inclined
surface are symmetrically arranged about the plane of symmetry of
the first color filter.
[0009] In some embodiments, the first upper portion further
includes a top surface opposite to the first bottom surface, and
the first upper portion narrows gradually from the first bottom
surface to the top surface.
[0010] In some embodiments, a cross section of the first upper
portion has a trapezoidal shape, and the cross section of the first
upper portion is perpendicular to the first bottom surface and the
first inclined surface.
[0011] In some embodiments, the first lower portion and the first
upper portion are formed as a single piece, and are made of the
same materials.
[0012] In some embodiments, a shading structure surrounds the first
lower portion, and the grid structure is disposed on the shading
structure.
[0013] In some embodiments, the grid structure includes a first
grid layer disposed on the shading structure, a second grid layer
disposed on the first grid layer, and a third grid layer disposed
on the second grid layer. The refractive index of the first grid
layer is greater than the refractive index of the second grid
layer, and the refractive index of the second grid layer is greater
than the refractive index of the third grid layer.
[0014] In some embodiments, the cross sections of the first grid
layer and the second grid layer are V-shaped. The materials of the
first grid layer, the second grid layer, and the third grid layer
are different. In some embodiments, a thickness of the first color
filter is greater than 1 um.
[0015] In some embodiments, the first color filter further includes
a first dome portion disposed on the first upper portion, and the
first dome portion includes an arched top surface. The first lower
portion, the first upper portion and the dome portion are formed as
a single piece, and comprise the same materials.
[0016] In some embodiments, the color filter further includes a
second color filter and a third color filter. The second color
filter includes a second lower portion disposed on the sensing
layer, and a second upper portion disposed on the second lower
portion. The second upper portion includes a second bottom surface
connected to the second lower portion, and a third inclined surface
inclined relative to the second bottom surface.
[0017] The third color filter includes a third lower portion
disposed on the sensing layer, and a third upper portion disposed
on the third lower portion The third upper portion includes a third
bottom surface connected to the third lower portion, and a fourth
inclined surface inclined relative to the third bottom surface.
Between the third inclined surface and the second bottom surface is
a third acute angle. Between the fourth inclined surface and the
third bottom surface is a fourth acute angle. The first acute angle
is greater than the third acute angle, and the third acute angle is
greater than the fourth acute angle.
[0018] In some embodiments, the first color filter is a blue color
filter, the second color filter is a green color filter, and the
third color filter is a red color filter.
[0019] In some embodiments, the first color filter further includes
a first dome portion disposed on the first upper portion. The
second color filter further includes a second dome portion disposed
on the second upper portion. The third color filter further
includes a third dome portion disposed on the third upper
portion.
[0020] In some embodiments, the height of the first dome portion
relative to the first upper portion is greater than the height of
the second dome portion relative to the second upper portion. The
height of the second dome portion relative to the second upper
portion is greater than the height of the third dome portion
relative to the third upper portion.
[0021] In some embodiments, the heights of the first dome portion
relative to the first upper portion, the second dome portion
relative to the second upper portion, and the third dome portion
relative to the third upper portion is in a range from about 50 nm
to 150 nm.
[0022] In some embodiments, an anti-reflection film disposed on the
first upper portion, the second upper portion and the third
portion. The thickness of the anti-reflection film is in a range
from about 100 nm to 250 nm.
[0023] In some embodiments, the thickness of the anti-reflection
film over the first upper portion is greater than a thickness of
the anti-reflection film over the second upper portion. The
thickness of the anti-reflection film over the second upper portion
is greater than the thickness of the anti-reflection film over the
third upper portion.
[0024] In conclusion, the optical sensor does not need to include
conventional microlenses depending on the structure of the color
filters. Therefore, the thickness and the manufacturing cost of the
optical sensor are decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
[0026] FIG. 1 is a schematic view of a conventional optical sensor
B1.
[0027] FIG. 2 is a schematic view of an optical sensor in
accordance with some embodiments of the present disclosure.
[0028] FIG. 3 is wavelength vs. QE spectrum diagram of the optical
sensor of the present disclosure and a conventional optical sensor
with microlenses.
[0029] FIG. 4A is an electrical field distribution diagram in a
cross section of the optical sensor of the present disclosure
resulted from a simulation to illuminate the optical sensor of the
present disclosure with a light beam wavelength of 530 nm using an
FDTD (Finite-difference time-domain) simulation method.
[0030] FIG. 4B is an electrical field distribution diagram in a
cross section of a conventional optical sensor resulted from a
simulation to illuminate the conventional optical sensor with a
light beam wavelength of 530 nm using the same FDTD simulation
method.
[0031] FIG. 5A shows acute angle vs. SNR 10 diagrams of the optical
sensor and the conventional optical sensor in accordance with some
embodiments of the present disclosure.
[0032] FIG. 5B shows acute angle vs. G-Sensitivity diagrams of the
optical sensor and the conventional optical sensor in accordance
with some embodiments of the present disclosure.
[0033] FIG. 6 is incident angle vs. QE spectrum diagram of the
optical sensor emitted by a 530 nm incident light beam of the
present disclosure and a conventional optical sensor with
microlenses.
[0034] FIG. 7 is a schematic view of an optical sensor in
accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0035] The following disclosure provides many different
embodiments, or examples, for implementing different features of
the present disclosure. Specific examples of components and
arrangements are described below to simplify the present
disclosure. For example, the formation of a first feature over or
on a second feature in the description that follows may include
embodiments in which the first and second features are formed in
direct contact, and may also include embodiments in which
additional features may be formed between the first and second
features, such that the first and second features may not be in
direct contact.
[0036] In addition, the present disclosure may repeat reference
numerals and/or letters in the various examples. This repetition is
for the purpose of simplicity and clarity and does not in itself
dictate a relationship between the various embodiments and/or
configurations discussed. Furthermore, the shape, size, and
thickness in the drawings may not be drawn to scale, or the
drawings may be otherwise simplified for clarity of discussion, as
they are intended merely for illustration.
[0037] It should be understood that additional operations can be
provided before, during, and after the method, and some of the
operations described can be replaced or eliminated for other
embodiments of the method.
[0038] FIG. 2 is a schematic view of an optical sensor 1 in
accordance with some embodiments of the present disclosure. The
optical sensor 1 is configured to sense light beams, and covert the
light beams into electrical signals.
[0039] In some embodiments, the optical sensor 1 is a CMOS
(Complementary Metal-Oxide-Semiconductor) sensor. In some
embodiments, the optical sensor 1 is a BSI (backside illumination)
CMOS sensor. In some embodiments, the optical sensor 1 is an image
sensor configured to capture an image. The image sensor can be
applied to an imaging apparatus, such as a digital camera.
[0040] In some embodiments, the optical sensor 1 is a spectrum
sensor configured to detect the spectrum of an object. The spectrum
sensor can be applied to a spectrum meter.
[0041] The optical sensor 1 includes a sensing layer 10, color
filters 20, a shading structure 30, a grid structure 40, and an
anti-reflection film 50. The sensing layer 10 extends along a
reference plane P1. The sensing layer 10 is configured to detect
incident light beams according to the light beams falling on the
sensing layer 10.
[0042] The sensing layer 10 may include all of the following
elements, but the sensing layer 10 does not necessarily include all
of the following elements, as long as the object of the sensing
layer 10 is achieved. The sensing layer 10 includes a substrate 11
and photodiodes 12. In some embodiments, the sensing layer 10
further includes another component or layer (not shown in figures),
such as electrical circuits underneath of the photodiodes 12 and a
passivation layer configured to protect the electrical
circuits.
[0043] The photodiodes 12 are disposed in the substrate 11, and
arranged in an array at the reference plane P1. Each of the
photodiodes 12 is configured to sense light beams and generate
electrical signals according to the intensity of the light beams
falling thereon. In some embodiments, an image can be generated
according to the electrical signals by a process chip (not shown in
figures).
[0044] The color filters 20 are disposed on the sensing layer 10.
In some embodiments, the color filters 20 are wave-guided color
filters. Each of the color filters 20 is located over one of the
photodiodes 12 in a stacking direction D1. The stacking direction
D1 is perpendicular to the sensing layer 10 and the reference plane
P1. The color filters 20 are arranged in an array on a plane
parallel to the reference plane P1. The thickness of the color
filters 20 is greater than 1 um.
[0045] Each of the color filters 20 allows a predetermined range of
wavelengths of light beam to pass through. In some embodiments,
color filters 20 include red color filters, green color filters,
and blue color filters. For example, the red color filters allow
wavelengths of a light beam in a range from 620 nm to 750 nm (red
light) to pass to the photodiodes 12. The green color filters allow
wavelengths of a light beam in a range from 495 nm to 570 nm (green
light) to pass to the photodiodes 12. The blue color filters allow
wavelengths of a light beam in a range from 476 nm to 495 nm (blue
light) to pass to the photodiodes 12.
[0046] The color filters 20 include lower portions 21 and upper
portions 22. The lower portions 21 are disposed on the sensing
layer 10, and the upper portions 22 are disposed on the lower
portions 21. The lower portion 21 and the upper portion 22 are
formed as a single piece, and include the same materials.
[0047] The shading structure 30 is disposed on the sensing layer
10. The shading structure 30 surrounds and is connected to the
lower portions 21. The shading structure 30 is arranged on a plane
parallel to the reference plane P1. In some embodiments, the
shading structure 30 has a transmittance lower than 30%. The
shading structure 30 is configured to shield a light beam from
passing through. Therefore, the quantity of the light beam in one
color filter 20 transmitted to an adjacent color filter 20 is
decreased.
[0048] The grid structure 40 is disposed on the shading structure
30. The grid structure 40 surrounds and is connected to the upper
portions 22. The grid structure 40 is arranged on a plane parallel
to the reference plane P1. The grid structure 40 includes bottom
tips 44 connected to the shading structure 30, and top surfaces 45
connected to the anti-reflection film 50. In some embodiments, the
top surfaces 45 of the grid structure 40 are flat planes.
[0049] The grid structure 40 has transmittances greater than 80% or
90%. The grid structure 40 is configured to reflect the light beam
in the color filters 20 toward the photodiodes 12.
[0050] In some embodiments, the refractive indexes of the grid
structure 40 and/or the shading structure 30 is lower than the
refractive index of the color filters 20, and thus the color
filters 20, the grid structure 40, and/or the shading structure 30
forms a light pipe structure to guide light beams to the
photodiodes 12.
[0051] In some embodiments, the refractive index of the grid
structure 40 is in a range from about 1.2 to 1.5. The shading
structure 30 includes a refractive index in a range from about 1.3
to 1.9. The refractive index of the color filters 20 is in a range
from about 1.7 to 3.2.
[0052] The anti-reflection film 50 is disposed on the upper
portions 22 and the grid structure 40. The anti-reflection film 50
is configured to decrease the reflection of the light beam
transmitted to the optical sensor 1. In some embodiments, the
anti-reflection film 50 is a flat structure, parallel to the
sensing layer 10. The thickness of the anti-reflection film 50 is
in a range from about 100 nm to 250 nm.
[0053] As shown in FIG. 2, the cross section of the lower portion
21 has a rectangular shape. The cross section of the upper portion
22 has a trapezoidal shape. The cross section of the shading
structure 30 includes rectangular shapes. The cross section of the
grid structure 40 includes triangular shapes.
[0054] The described cross sections are perpendicular to the
reference plane P1, the reference plane P2, the bottom surface 221,
and the sensing layer 10. In some embodiments, the described cross
sections are perpendicular to the inclined surface 223, and/or the
inclined surface 224.
[0055] Each of the upper portions 22 includes a bottom surface 221,
a top surface 222, an inclined surface 223, and an inclined surface
224. In some embodiments, the bottom surfaces 221, the top surfaces
222, the inclined surfaces 223, and/or the inclined surfaces 224
are flat surface.
[0056] The bottom surfaces 221 are connected to the lower portions
21. In some embodiments, the bottom surfaces 221 and the top
surfaces of the shading structure 30 are located in a reference
plane P2 parallel to the reference plane P1.
[0057] The top surface 222 is opposite to the bottom surface 221,
and parallel to the bottom surface 221. The top surface 222 is
connected to the anti-reflection film 50. The area of the bottom
surface 221 is greater than the area of the top surface 222. The
upper portion 22 narrows gradually from the bottom surface 221 to
the top surface 222.
[0058] The inclined surface 223 is inclined relative to the bottom
surface 221. The inclined surface 224 is opposite to the inclined
surface 223, and inclined relative to the bottom surface 221. The
inclined surface 223 and the inclined surface 224 are symmetrically
arranged about the symmetry plane P3 of the color filter 20. The
symmetry plane P3 is located at the center of the color filter 20,
and parallel to the bottom surface 221.
[0059] Between the inclined surface 223 and the bottom surface 221
are an acute angle A1, and between the inclined surface 224 and the
bottom surface 221 are an acute angle A2. The acute angle A1 and
the acute angle A2 are in a range from about 65 degrees to 89
degrees. In this embodiment, the acute angle A1 is equal to the
acute angle A2.
[0060] The distances between the inclined surface 223 and the
inclined surface 224 are gradually decreased from the bottom
surface 221 to the top surface 222. The distances are measured in a
direction parallel to the bottom surface 221.
[0061] Depending on the structures and designs of the color filters
20 and the grid structure 40, the light beam emitted to the optical
sensor 1 is greatly guided to the photodiodes 12. In this
embodiment, the conventional microlenses can be omitted in the
optical sensor 1. By omitting the conventional microlenses, the
thickness and the manufacturing cost of the optical sensor 1 is
decreased.
[0062] FIG. 3 is wavelength vs. QE spectrum diagram of the optical
sensor 1 of the present disclosure and a conventional optical
sensor with microlenses. In this case, the acute angles A1 and A2
of the optical sensor 1 are 78 degrees, for example. In FIG. 3,
light beams with different wavelengths are emitted on red color
filters, green color filters, and blue color filters.
[0063] As shown in FIG. 3, the sensitivity of the optical sensor 1
of the present disclosure is improved according to the QE (Quantum
Efficiency) spectrum. The QE peaks of the optical sensor 1 are
increased in comparison with the conventional optical sensor with
microlenses. In addition, the optical cross talk of the optical
sensor 1 is decreased in comparison with the conventional optical
sensor.
[0064] As shown in FIGS. 4A, in the optical sensor 1 of the present
disclosure, the electric field intensity is more observable in a
region of the green color filter 20b and the sensing layer 10 under
the green color filter 20b. Moreover, the electrical field
distribution in a region of an adjacent color filter 20, such as a
red color filter or a blue color filter, and the sensing layer 10
under the adjacent color filter 20 is extremely low. Therefore, the
optical cross talk of the optical sensor 1 is decreased. In
addition, the reflection of the color filters 20 is low, and the
standing wave effect of the color filters 20 is low. According to
the fact that the electric field passing through the green color
filters 20b and the underlying sensing layers 10 is deeper and more
vertical as shown in FIG. 4A, the green color filters 20b and the
underlying sensing layers 10 have high photo flux.
[0065] As shown in FIG. 4B and compared to FIG. 4A, in the
conventional optical sensor, the electric field passing through the
green color filters and the underlying sensing layers (at the left
side of the dashed line in FIG. 4B) is shallower and does not pass
through the sensing layers vertically as that shown in FIG. 4A.
That means the green color filters and the underlying sensing
layers 10 in the conventional optical sensor have lower photo flux.
Further, in a region adjacent to the green color filter, such as a
red color filter or a blue color filter (at the right side of the
dashed line in FIG. 4B), the electric field distribution is denser
than that shown in FIG. 4A. That means the conventional optical
sensor suffer more seriously from optical cross talk. As a result,
according to the optical sensor 1 of the present disclosure, the QE
can be increased and the optical cross talk in the optical sensor 1
can be decreased.
[0066] FIG. 5A shows acute angle vs. SNR 10 diagrams of the optical
sensor 1 and the conventional optical sensor in accordance with
some embodiments of the present disclosure. SNR (Signal-to-Noise
Ratio) at low illumination is a key performance of an image sensor
(optical sensor). The low illumination is an environment
represented in a low light environment, such as an overcast
environment, nightfall environment, and indoor environment. In
application, when SNR is controlled at a predetermined value, the
corresponding illumination level is expected to be as minimal as
possible to yield the acceptable image. In general, when SNR=10,
the image generated by the optical sensor is acceptable. Hence, SNR
10 has been used as a performance metric of SNR at low illumination
conditions. SNR 10 stands for the illuminance (lux) where a target
SNR=10 is reached after white balance and color correction. As
shown in FIG. 5A, when SNR 10 (illuminance, lux) is lower, the
optical sensor 1 can generate image quality of SNR=10 under a lower
illumination environment. When the acute angle A1 and the acute
angle A2 are greater than 65 degrees, the SNR 10 of the optical
sensor 1 of the present disclosure is greater than the conventional
optical sensor. Therefore, under the same low illumination
condition, the quality of the image generated by the optical sensor
1 of the present disclosure is better than the quality of the image
generated by the conventional optical sensor.
[0067] FIG. 5B shows acute angle vs. G-Sensitivity diagrams of the
optical sensor 1 and the conventional optical sensor in accordance
with some embodiments of the present disclosure. When the acute
angle A1 and A2 are greater than 65 degrees, the G-Sensitivity of
the optical sensor 1 of the present disclosure is greater than the
conventional optical sensor.
[0068] FIG. 6 is incident angle vs. QE spectrum diagram of the
optical sensor 1 emitted by a 530 nm incident light beam of the
present disclosure and a conventional optical sensor with
microlenses. The QE G-peak of the optical sensor 1 is improved in
comparison with the conventional optical sensor when the incident
angle of the 530 nm light beam is in a range from about 0 degrees
to 30 degrees. The QE R-peak and the QE B-peak of the optical
sensor 1 are also improved in comparison with the conventional
optical sensor when the incident angle of the 530 nm incident light
beam is in a range from about 0 degrees to 30 degrees.
[0069] Therefore, the optical sensor 1 may have a great performance
depending on the structures and the designs of the color filters
20. Conventional microlenses may not be needed in the optical
sensor 1.
[0070] FIG. 7 is a schematic view of an optical sensor 1 in
accordance with some embodiments of the present disclosure. The
grid structure 40 includes at least two grid layers stacked on each
other, and includes at least two different materials. In this
embodiment, the grid structure 40 includes a first grid layer 41, a
second grid layer 42, and a third grid layer 43. The first grid
layer 41 is disposed on the shading structure 30. The second grid
layer 42 is disposed on the first grid layer 41. The third grid
layer 43 is disposed on the second grid layer 42.
[0071] The materials of the first grid layer 41, the second grid
layer 42, and the third grid layer 43 are different. In some
embodiments, the refractive index of the first grid layer 41 is
greater than the refractive index of the second grid layer 42. The
refractive index of the second grid layer 42 is greater than the
refractive index of the third grid layer 43. In some embodiments,
the cross sections of the first grid layer 41, and the second grid
layer 42 are V-shaped. The cross section of the third grid layer 43
is triangular. The cross sections are perpendicular to the bottom
surface 221.
[0072] Depending on the structures and designs of the grid
structure 40, the light beam emitted to the optical sensor 1 is
greatly guided emitted to the photodiodes 12.
[0073] In some embodiments, the color filters 20 include color
filter 20a, 20b and 20c. The color filters 20a are blue color
filters. The color filters 20b are green color filters. The color
filters 20c are red color filters.
[0074] The inclined surface 223a of the upper portion 22a of the
color filter 20a is inclined relative to the bottom surface 221a.
Between the inclined surface 223a and the bottom surface 221a is an
acute angle A3. The inclined surface 223b of the upper portion 22b
of the color filter 20b is inclined relative to the bottom surface
221b. Between the inclined surface 223b and the bottom surface 221b
is an acute angle A4.
[0075] The inclined surface 223c of the upper portion 22c of the
color filter 20c is inclined relative to the bottom surface 221c.
Between the inclined surface 223c and the bottom surface 221c is an
acute angle A5. The acute angle A3 is greater than the acute angle
A4. The acute angle A4 is greater than the acute angle A5. The
acute angles A3, A4 and A5 are in a range from about 65 degrees to
89 degrees.
[0076] Depending on the described acute angles A3, A4 and A5 of the
color filters 20, the quantity of the light beam in guided into the
color filter 20a is greater than the quantity of the light beam in
guided in the color filter 20b. The quantity of the light beam in
guided into the color filter 20b is greater than the quantity of
the light beam in guided in the color filter 20c. Therefore, the
image generated by the optical sensor 1 can be improved by
adjusting the acute angles A3, A4 and A5 of the color filters
20.
[0077] The color filters 20 further include dome portions 23
disposed on the upper portions 22. Each of the dome portions 23
includes an arched top surface 231. Therefore, the dome portions 23
are functioned as the conventional microlens. The dome portions 23
can focus light beams to the photodiodes 12. Depending on the
structures and designs of the dome portions 23, the light beam
emitted to the optical sensor 1 is greatly guided emitted to the
photodiodes 12.
[0078] In some embodiments, the color filter 20a further includes a
dome portion 23a disposed on the upper portion 22a. The color
filter 20b further includes a dome portion 23b disposed on the
upper portion 22b. The color filter 20c further includes a dome
portion 23c disposed on the upper portion 22c. The height of the
dome portion 23a relative to the upper portion 22a is greater than
the height of the dome portion 23b relative to the upper portion
22b. The height of the dome portion 23b relative to the upper
portion 22b is greater than the height of the dome portion 23c
relative to the upper portion 22c. The heights of the dome portion
23a, 23b and 23c are in a range from about 50 nm to 150 nm.
[0079] By the heights of the dome portions 23, the quantity of the
light beam in guided into the color filter 20a is greater than the
quantity of the light beam in guided in the color filter 20b. The
quantity of the light beam in guided into the color filter 20b is
greater than the quantity of the light beam in guided in the color
filter 20c. The image generated by the optical sensor 1 can be
improved by adjusting the heights of the dome portions 23.
[0080] In some embodiments, the thickness of the anti-reflection
film 50 over the upper portion 22a is greater than the thickness of
the anti-reflection film 50 over the upper portion 22b. The
thickness of the anti-reflection film 50 over the upper portion 22b
is greater than the thickness of the anti-reflection film 50 over
the upper portion 22c.
[0081] By the thicknesses of the anti-reflection film 50, the
quantity of the light beam in guided into the color filter 20a is
greater than the quantity of the light beam in guided in the color
filter 20b. The quantity of the light beam in guided into the color
filter 20b is greater than the quantity of the light beam in guided
in the color filter 20c. The image generated by the optical sensor
1 can be improved by adjusting the thickness of the anti-reflection
film 50.
[0082] In conclusion, the optical sensor does not need to include
conventional microlenses depending on the structure of the color
filters. Therefore, the thickness and the manufacturing cost of the
optical sensor are decreased.
[0083] The features disclosed may be combined, modified, or
replaced in any suitable manner in one or more disclosed
embodiments, but are not limited to any particular embodiments.
[0084] While the invention has been described by way of example and
in terms of preferred embodiment, it is to be understood that the
invention is not limited thereto. On the contrary, it is intended
to cover various modifications and similar arrangements (as would
be apparent to those skilled in the art). Therefore, the scope of
the appended claims should be accorded the broadest interpretation
so as to encompass all such modifications and similar
arrangements.
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