U.S. patent application number 17/504807 was filed with the patent office on 2022-02-24 for solid-state image sensor, method of manufacturing the same, and electronic device.
This patent application is currently assigned to SONY SEMICONDUCTOR SOLUTIONS CORPORATION. The applicant listed for this patent is SONY SEMICONDUCTOR SOLUTIONS CORPORATION. Invention is credited to Yukio KANEDA.
Application Number | 20220059592 17/504807 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-24 |
United States Patent
Application |
20220059592 |
Kind Code |
A1 |
KANEDA; Yukio |
February 24, 2022 |
SOLID-STATE IMAGE SENSOR, METHOD OF MANUFACTURING THE SAME, AND
ELECTRONIC DEVICE
Abstract
A more preferable pixel for detecting a focal point may be
formed by using a photoelectric converting film. A solid-state
image sensor includes a first pixel including a photoelectric
converting unit formed of a photoelectric converting film and first
and second electrodes which interpose the same from above and below
in which at least one of the first and second electrodes is a
separated electrode separated for each pixel, and a second pixel
including the photoelectric converting unit in which the separated
electrode is formed to have a planar size smaller than that of the
first pixel and a third electrode extending at least to a boundary
of the pixel is formed in a region which is vacant due to a smaller
planar size. The present disclosure is applicable to the
solid-state image sensor and the like, for example.
Inventors: |
KANEDA; Yukio; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SONY SEMICONDUCTOR SOLUTIONS CORPORATION |
Kanagawa |
|
JP |
|
|
Assignee: |
SONY SEMICONDUCTOR SOLUTIONS
CORPORATION
Kanagawa
JP
|
Appl. No.: |
17/504807 |
Filed: |
October 19, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16516871 |
Jul 19, 2019 |
11217620 |
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17504807 |
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15521718 |
Apr 25, 2017 |
10453890 |
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PCT/JP2015/079820 |
Oct 22, 2015 |
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16516871 |
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International
Class: |
H01L 27/146 20060101
H01L027/146; H04N 9/04 20060101 H04N009/04; H04N 5/369 20110101
H04N005/369 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2014 |
JP |
2014-225190 |
Claims
1. A solid-state image sensor comprising: a first pixel including a
photoelectric converting unit formed of a photoelectric converting
film and first and second electrodes, wherein the first and second
electrodes sandwich the photoelectric converting film from below
and above, respectively, wherein the first electrode is a separated
electrode that includes a first portion overlapping the first
pixel; and a second pixel including the photoelectric converting
unit, wherein a second portion of the separated electrode that
overlaps the second pixel is formed to have a planar size smaller
than a planar size of the separated electrode of the first pixel,
the second pixel including the first portion of the separated
electrode extending to a region of the second pixel which is vacant
due to the smaller planar size of the second portion of the
separated electrode.
2. The solid-state image sensor according to claim 1, wherein the
first portion of the separated electrode is connected to wiring
which supplies a fixed potential.
3. The solid-state image sensor according to claim 1, wherein the
first portion of the separated electrode is an isolated pattern
which is not connected to wiring.
4. The solid-state image sensor according to claim 1, wherein the
first pixel and the second pixel are adjacent to one another in a
row direction.
5. The solid-state image sensor according to claim 1, wherein the
first pixel and the second pixel are diagonally adjacent to one
another.
6. The solid-state image sensor according to claim 1, wherein a
third portion of the separated electrode extends between the first
and second pixels and at least one other pixel.
7. The solid-state image sensor according to claim 1, wherein the
second electrode is a contiguous electrode that overlaps the first
and second pixels.
8. The solid-state image sensor according to claim 1, wherein the
first portion of the separated electrode overlaps a boundary
between the first pixel and the second pixel and a boundary between
the second pixel and a third pixel.
9. The solid-state image sensor according to claim 8, wherein the
first pixel, the second pixel, and the third pixel are adjacent to
one another in a row direction.
10. The solid-state image sensor according to claim 9, wherein the
first portion of the separated electrode is electrically connected
to a floating diffusion region.
11. An imaging device, comprising: a solid-state image sensor
including: a first pixel including a photoelectric converting unit
formed of a photoelectric converting film and first and second
electrodes, wherein the first and second electrodes sandwich the
photoelectric converting film from below and above, respectively,
wherein the first electrode is a separated electrode that includes
a first portion overlapping the first pixel; and a second pixel
including the photoelectric converting unit, wherein a second
portion of the separated electrode that overlaps the second pixel
is formed to have a planar size smaller than a planar size of the
separated electrode of the first pixel, the second pixel including
the first portion of the separated electrode extending to a region
of the second pixel which is vacant due to the smaller planar size
of the second portion of the separated electrode.
12. The imaging device according to claim 11, wherein the first
portion of the separated electrode is connected to wiring which
supplies a fixed potential.
13. The imaging device according to claim 11, wherein the first
portion of the separated electrode is an isolated pattern which is
not connected to wiring.
14. The imaging device according to claim 11, wherein the first
pixel and the second pixel are adjacent to one another in a row
direction.
15. The imaging device according to claim 11, wherein the first
pixel and the second pixel are diagonally adjacent to one
another.
16. The imaging device according to claim 11, wherein a third
portion of the separated electrode extends between the first and
second pixels and at least one other pixel.
17. The imaging device according to claim 11, wherein the second
electrode is a contiguous electrode that overlaps the first and
second pixels.
18. The imaging device according to claim 11, wherein the first
portion of the separated electrode overlaps a boundary between the
first pixel and the second pixel and a boundary between the second
pixel and a third pixel.
19. The imaging device according to claim 18, wherein the first
pixel, the second pixel, and the third pixel are adjacent to one
another in a row direction.
20. The imaging device according to claim 19, wherein the first
portion of the separated electrode is electrically connected to a
floating diffusion region.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority to
U.S. patent application Ser. No. 16/516,871, filed Jul. 19, 2019,
which is a continuation of and claims priority to U.S. patent
application Ser. No. 15/521,718, filed Apr. 25, 2017, now U.S. Pat.
No. 10,453,890, which is a national stage application under 35
U.S.C. 371 and claims the benefit of PCT Application No.
PCT/JP2015/079820 having an international filing date of Oct. 22,
2015, which designated the United States, which PCT application
claimed the benefit of Japanese Patent Application No. 2014-225190
filed Nov. 5, 2014, the disclosures of which are incorporated
herein by reference in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a solid-state image
sensor, a method of manufacturing the same, and an electronic
device, and especially relates to the solid-state image sensor
capable of forming a more preferable pixel for detecting a focal
point by using a photoelectric converting film, the method of
manufacturing the same, and the electronic device.
BACKGROUND ART
[0003] A solid-state image sensor in which a semiconductor is used
is mounted on many devices such as a digital camera, a video
camera, a monitoring camera, a copying machine, and a fax machine.
Recently, a so-called CMOS image sensor manufactured by a
complementary metal oxide semiconductor (CMOS) process together
with a peripheral circuit is often used as the solid-state image
sensor.
[0004] There is the CMOS image sensor in which a method of using
pixels for detecting a focal point with sensitivities asymmetrical
with respect to a light incident angle is adopted as an automatic
focusing function of a camera. For example, in Patent Document 1, a
photodiode in a pixel is divided into two and one of them with a
smaller area is used for detecting a focal point as a method of
realizing the pixel for detecting a focal point.
[0005] Also, recently, an image sensor in which an organic
semiconductor and an inorganic compound semiconductor are used as a
photoelectric converting film is developed. This generally has an
element structure including the photoelectric converting film and
electrodes interposing the same from above and below in which at
least one of the upper and lower electrodes is separated for each
pixel. Herein also, a method of using the pixel for detecting a
focal point is suggested.
[0006] In Patent Document 2, an organic photoelectric converting
element also having a color filter function arranged with the same
optical path length as a silicon photodiode of a certain pixel is
divided into two in the pixel and used as a pair, and according to
this, light with different phase difference is detected and a focal
point may be detected. Patent Document 3 enables focal point
detection by using a pair of pixels provided with a light shielding
film on a light incident side in an organic photoelectric
converting element for detecting phase difference.
CITATION LIST
Patent Document
[0007] Patent Document 1: Japanese Patent Application Laid-Open No.
2012-37777 [0008] Patent Document 2: Japanese Patent Application
Laid-Open No. 2013-145292 [0009] Patent Document 3: Japanese Patent
Application Laid-Open No. 2014-67948
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0010] However, since a photoelectric converting film for detecting
a focal point also serves as color filters in Bayer arrangement in
the method of realizing in Patent Document 2, it is required to
separate the photoelectric converting film for each pixel.
Therefore, dark current due to separation of the photoelectric
converting film might be deteriorated.
[0011] In the realizing method in Patent Document 3 in which the
light shielding film is used, when a photodiode is provided on a
silicon layer below a photoelectric converting film, light received
there is also shielded and an obtained signal becomes smaller.
[0012] The present disclosure is achieved in view of such a
condition, and an object thereof is to form a more preferable pixel
for detecting a focal point by using the photoelectric converting
film.
Solutions to Problems
[0013] A solid-state image sensor according a first aspect of the
present disclosure is provided with a first pixel including a
photoelectric converting unit formed of a photoelectric converting
film and first and second electrodes which interpose the
photoelectric converting film from above and below in which at
least one of the first and second electrodes is a separated
electrode separated for each pixel, and a second pixel including
the photoelectric converting unit in which the separated electrode
is formed to have a planar size smaller than the planar size of the
separated electrode of the first pixel and a third electrode
extending at least to a boundary of the pixel is formed in a region
which is vacant due to a smaller planar size.
[0014] A method of manufacturing a solid-state image sensor
according to a second aspect of the present disclosure forms a
first pixel including a photoelectric converting unit formed of a
photoelectric converting film and first and second electrodes which
interpose the photoelectric converting film from above and below in
which at least one of the first and second electrodes is a
separated electrode separated for each pixel, and a second pixel
including the photoelectric converting unit in which the separated
electrode is formed to have a planar size smaller than the planar
size of the separated electrode of the first pixel and a third
electrode extending at least to a boundary of the pixel is formed
in a region which is vacant due to a smaller planar size.
[0015] An electronic device according to a third aspect of the
present disclosure is provided with a solid-state image sensor
including a first pixel including a photoelectric converting unit
formed of a photoelectric converting film and first and second
electrodes which interpose the photoelectric converting film from
above and below in which at least one of the first and second
electrodes is a separated electrode separated for each pixel, and a
second pixel including the photoelectric converting unit in which
the separated electrode is formed to have a planar size smaller
than the planar size of the separated electrode of the first pixel
and a third electrode extending at least to a boundary of the pixel
is formed in a region which is vacant due to a smaller planar
size.
[0016] In the first to third aspects of the present disclosure, a
first pixel including a photoelectric converting unit formed of a
photoelectric converting film and first and second electrodes which
interpose the photoelectric converting film from above and below in
which at least one of the first and second electrodes is a
separated electrode separated for each pixel, and a second pixel
including the photoelectric converting unit in which the separated
electrode formed to have a planar size smaller than the planar size
of the separated electrode of the first pixel and a third electrode
extending at least to a boundary of the pixel is formed in a region
which is vacant due to a smaller planar size are provided.
[0017] The solid-state image sensor and the electronic device may
be independent devices or may be modules incorporated in other
devices.
Effects of the Invention
[0018] According to the first to third aspects of the present
disclosure, a more preferable pixel for detecting a focal point may
be formed by using a photoelectric converting film.
[0019] Meanwhile, the effect is not especially limited to the
effects described herein; this may also any effect described in the
present disclosure.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a view illustrating a schematic configuration of a
solid-state image sensor according to the present disclosure.
[0021] FIG. 2 is a cross-sectional configuration diagram
illustrating a cross-sectional configuration of a normal pixel.
[0022] FIG. 3 is a view illustrating a planar layout of a lower
electrode of a first embodiment.
[0023] FIG. 4 is a cross-sectional configuration diagram taken
along line Y1-Y1' in FIG. 3.
[0024] FIG. 5 is a cross-sectional configuration diagram taken
along line Y2-Y2' in FIG. 3.
[0025] FIG. 6 is a view illustrating a planar layout of a lower
electrode of a second embodiment.
[0026] FIG. 7 is a cross-sectional configuration diagram taken
along line Y11-Y11' in FIG. 6.
[0027] FIG. 8 is a view illustrating a planar layout of a third
embodiment.
[0028] FIG. 9 is a cross-sectional configuration diagram taken
along line X11-X11' in FIG. 8.
[0029] FIG. 10 is a cross-sectional configuration diagram taken
along line Y21-X21' in FIG. 8.
[0030] FIG. 11 is a cross-sectional configuration diagram taken
along line Y22-Y22' in FIG. 8.
[0031] FIG. 12 is a view illustrating a variation of the third
embodiment.
[0032] FIG. 13 is a view illustrating a variation of the third
embodiment.
[0033] FIG. 14 is a cross-sectional configuration diagram of a
pixel of a fourth embodiment.
[0034] FIG. 15 is a view illustrating a layout example of color
filters.
[0035] FIG. 16 is a cross-sectional configuration diagram of a
pixel of a fifth embodiment.
[0036] FIG. 17 is a cross-sectional configuration diagram of a
pixel of a sixth embodiment.
[0037] FIGS. 18A to 18D are a view illustrating a method of
manufacturing of the first embodiment.
[0038] FIGS. 19A to 19D are a view illustrating the method of
manufacturing of the first embodiment.
[0039] FIGS. 20A to 20D are a view illustrating the method of
manufacturing of the first embodiment.
[0040] FIGS. 21A to 21D are a view illustrating the method of
manufacturing of the first embodiment.
[0041] FIGS. 22A and 22B are a view illustrating the method of
manufacturing of the first embodiment.
[0042] FIGS. 23A and 23B are a view illustrating the method of
manufacturing of the first embodiment.
[0043] FIGS. 24A and 24B are a view illustrating the method of
manufacturing of the first embodiment.
[0044] FIG. 25A and 25B are a view illustrating the method of
manufacturing of the first embodiment.
[0045] FIG. 26 is a block diagram illustrating a configuration
example of an imaging device as an electronic device according to
the present disclosure.
MODE FOR CARRYING OUT THE INVENTION
[0046] A mode for carrying out the present disclosure (hereinafter,
referred to as an embodiment) is hereinafter described. Meanwhile,
the description is given in the following order.
[0047] 1. Schematic Configuration Example of Solid-State Image
Sensor
[0048] 2. First Embodiment of Pixel (Configuration in Which Each of
Pair of Phase Difference Pixels Includes Dummy Pixel)
[0049] 3. Second Embodiment of Pixel (Configuration in Which Pair
of Phase Difference Pixels Includes Shared Dummy Pixel)
[0050] 4. Third Embodiment of Pixel (Configuration in Which Element
Separating Electrode Is Extended to Phase Difference Pixel)
[0051] 5. Fourth Embodiment of Pixel (First Configuration in Which
Photoelectric Converting Film Receives Light of All
Wavelengths)
[0052] 6. Fifth Embodiment of Pixel (Second Configuration in Which
Photoelectric Converting Film Receives Light of All
Wavelengths)
[0053] 7. Sixth Embodiment of Pixel (Third Configuration in Which
Photoelectric Converting Film Receives Light of All
Wavelengths)
[0054] 8. Manufacturing Method of First Embodiment
[0055] 9. Application Example to Electronic Device
[0056] <1. Schematic Configuration Example of Solid-State Image
Sensor>
[0057] FIG. 1 illustrates a schematic configuration of a
solid-state image sensor according to the present disclosure.
[0058] A solid-state image sensor 1 in FIG. 1 includes a pixel
array unit 3 obtained by arranging pixels 2 in a two-dimensional
manner to form a matrix on a semiconductor substrate 12 formed of
silicon (Si), for example, as a semiconductor, and a peripheral
circuit unit around the same. The peripheral circuit unit includes
a vertical driving circuit 4, a column signal processing circuit 5,
a horizontal driving circuit 6, an output circuit 7, a control
circuit 8 and the like.
[0059] The pixels 2 arranged in a two-dimensional manner to form a
matrix in the pixel array unit 3 include a normal pixel 2X which
generates a signal for generating an image and a phase difference
pixel 2P which generates a signal for detecting a focal point as
described later with reference to FIG. 3 and the like. There also
is a case in which a dummy pixel 2D is arranged adjacent to the
phase difference pixel 2P.
[0060] The vertical driving circuit 4 formed of a shift register,
for example, selects pixel driving wiring 10, supplies a pulse for
driving the pixel 2 to the selected pixel driving wiring 10, and
drives the pixels 2 in a row unit. That is to say, the vertical
driving circuit 4 sequentially selects to scan the pixels 2 in the
pixel array unit 3 in a row unit in a vertical direction and
supplies a pixel signal based on a signal charge generated
according to a light receiving amount by a photoelectric converting
unit of each pixel 2 to the column signal processing circuit 5
through a vertical signal line 9.
[0061] The column signal processing circuit 5 arranged for each
column of the pixels 2 performs signal processing such as noise
removal on the signals output from the pixels 2 of one row for each
pixel column. For example, the column signal processing circuit 5
performs the signal processing such as correlated double sampling
(CDS) for removing a fixed pattern noise specific to the pixel and
AD conversion.
[0062] The horizontal driving circuit 6 formed of a shift register,
for example, sequentially selects the column signal processing
circuits 5 by sequentially outputting horizontal scanning pulses
and outputs the pixel signal from each of the column signal
processing circuits 5 to a horizontal signal line 11.
[0063] The output circuit 7 performs predetermined signal
processing on the signals sequentially supplied from the column
signal processing circuits 5 through the horizontal signal line 11
to output through an output terminal 13. There is a case in which
the output circuit 7 merely buffers, for example, or a case in
which this performs black level adjustment, column variation
correction, and various types of digital signal processing.
[0064] The control circuit 8 receives an input clock and data which
designates an operation mode and the like, and also outputs data
such as internal information of the solid-state image sensor 1.
That is, the control circuit 8 generates a clock signal and a
control signal which serve as a reference for operation of the
vertical driving circuit 4, the column signal processing circuit 5,
the horizontal driving circuit 6 and the like on the basis of a
vertical synchronization signal, a horizontal synchronization
signal, and a master clock. The control circuit 8 then outputs the
generated clock signal and control signal to the vertical driving
circuit 4, the column signal processing circuit 5, the horizontal
driving circuit 6, and the like.
[0065] The solid-state image sensor 1 configured in the
above-described manner is a so-called column AD type CMOS image
sensor in which the column signal processing circuit 5 which
performs the CDS processing and AD conversion processing is
arranged for each pixel column.
[0066] <2. First Embodiment of Pixel>
[0067] <Cross-Sectional Configuration of Normal Pixel>
[0068] A cross-sectional configuration of a normal pixel of a
solid-state image sensor 1 is described with reference to FIG.
2.
[0069] FIG. 2 is a view illustrating the cross-sectional
configuration of a normal pixel 2X of the solid-state image sensor
1 in FIG. 1.
[0070] Photodiodes PD1 and PD2 by PN junction are formed in a depth
direction by forming second conductivity type (for example, N-type)
semiconductor regions 42 and 43 so as to be stacked in the depth
direction in a first conductivity type (for example, P-type)
semiconductor region 41 of a semiconductor substrate 12. The
photodiode PD1 including the semiconductor region 42 as a charge
accumulation region is an inorganic photoelectric converting unit
which receives blue light to perform photoelectric conversion, and
the photodiode PD2 including the semiconductor region 43 as a
charge accumulation region is an inorganic photoelectric converting
unit which receives red light to perform the photoelectric
conversion.
[0071] A plurality of pixel transistors which reads the charges
accumulated in the photodiodes PD1 and PD2 and a multi-layer wiring
layer 44 formed of a plurality of wiring layers and an interlayer
insulating film are formed on a surface side (lower side in the
drawing) of the semiconductor substrate 12. Meanwhile, the
multi-layer wiring layer 44 is not illustrated in detail in FIG. 2.
A plurality of pixel transistors is formed of four MOS transistors
which are a transfer transistor, a selection transistor, a reset
transistor, and an amplification transistor, for example.
[0072] A conductive plug 46 for extracting the charge obtained by
the photoelectric conversion by a photoelectric converting film 52
to be described later to a side of the multi-layer wiring layer 44
is formed on the semiconductor substrate 12 so as to penetrate (the
semiconductor region 41 of) the semiconductor substrate 12. An SiO2
or SiN insulating film 47 is formed on an outer periphery of the
conductive plug 46 so as to inhibit short-circuit with the
semiconductor region 41.
[0073] The conductive plug 46 is connected to a floating diffusion
unit (FD unit) 49 formed of a second conductivity type (for
example, N-type) semiconductor region in the semiconductor
substrate 12 by means of metal wiring 48 formed in the multi-layer
wiring layer 44. The FD unit 49 is a region in which the charge
obtained by the photoelectric conversion by the photoelectric
converting film 52 is temporarily held before being read. The
charge held in the FD unit 49 is output to the column signal
processing circuit 5 on a subsequent stage through the
amplification transistor and the like as is the case with the
charges generated by the photodiodes PD1 and PD2. However, the
transfer transistor required in the photodiodes PD1 and PD2 is not
required when the charge generated by the photoelectric converting
film 52 is output as a signal. Therefore, the photoelectric
conversion using the photoelectric converting film 52 has an
advantage that light receiving areas of the photodiodes PD1 and PD2
are not narrowed.
[0074] A transparent insulating film 51 formed of two or three
layers of a hafnium oxide (HfO2) film and a silicon oxide film is
formed, for example, on an interface on a rear surface side (upper
side in the drawing) of the semiconductor substrate 12.
[0075] The photoelectric converting film 52 is arranged above the
transparent insulating film 51 so as to be interposed between a
lower electrode 53a below the same and an upper electrode 53b above
the same. Out of a region in which the photoelectric converting
film 52 is formed, a region interposed between the lower electrode
53a and the upper electrode 53b is the region in which incident
light is subjected to the photoelectric conversion; the
photoelectric converting film 52, the lower electrode 53a, and the
upper electrode 53b form a photoelectric converting unit 61. As a
film which performs the photoelectric conversion on green
wavelength light, the photoelectric converting film 52 is formed of
an organic photoelectric converting material containing a rhodamine
dye, a merocyanine dye, or quinacridone, for example. The lower
electrode 53a and the upper electrode 53b are formed of an indium
tin oxide (ITO) film, an indium zinc oxide film and the like, for
example.
[0076] Meanwhile, in a case in which the photoelectric converting
film 52 is a film which performs the photoelectric conversion on
red wavelength light, an organic photoelectric converting material
containing a phthalocyanine dye may be used, for example. Also, in
a case of the film which performs the photoelectric conversion on
blue wavelength light, an organic photoelectric converting material
containing a coumarin dye, tris(8-hydroxyquinoline) aluminum
(Alq3), the merocyanine dye and the like may be used.
[0077] Although the upper electrode 53b is formed on an entire
surface so as to be shared by all the pixels, the lower electrode
53a is formed for each pixel and is connected to the conductive
plug 46 of the semiconductor substrate 12 by means of metal wiring
54 penetrating the transparent insulating film 51. The metal wiring
54 formed of materials such as tungsten (W), aluminum (Al), and
copper (Cu) is also formed in a planar direction at predetermined
depth of the transparent insulating film 51 and also serves as an
interpixel light shielding film 55 which inhibits the light from
entering an adjacent pixel.
[0078] A high refractive index layer 56 is formed of an inorganic
film such as a silicon nitride film (SiN), silicon oxynitride film
(SiON), and silicon carbide (SiC) on an upper surface of the upper
electrode 53b. Also, an on-chip lens 57 is formed above the high
refractive index layer 56. The silicon nitride film (SiN) or a
resin material such as a styrene resin, an acrylic resin, a styrene
acrylic copolymer resin, or a siloxane resin, for example, is used
as a material of the on-chip lens 57. In this pixel structure,
since a distance between the photoelectric converting film 52 and
the on-chip lens 57 is short, light incident angle dependency is
smaller in a phase difference pixel 2P, so that the high refractive
index layer 56 has an effect of enlarging a refraction angle and
improving light condensing efficiency.
[0079] In FIG. 2, three normal pixels 2X configured in the
above-described manner are arranged side by side.
[0080] The solid-state image sensor 1 in which the normal pixels 2X
formed in this manner are arranged in a two-dimensional manner is a
rear surface irradiation type CMOS solid-state image sensor in
which the light enters from a rear surface side on an opposite side
of the surface side of the semiconductor substrate 12 on which the
multi-layer wiring layer 44 is formed.
[0081] Also, the solid-state image sensor 1 is a longitudinal
direction spectral solid-state image sensor which performs the
photoelectric conversion by the photoelectric converting film 52
formed above the semiconductor substrate (silicon layer) 12 on the
green light and performs the photoelectric conversion by the
photodiodes PD1 and PD2 in the semiconductor substrate 12 on the
blue light and red light.
[0082] <Planar Layout of Lower Electrode>
[0083] FIG. 3 is a view illustrating a planar layout of the lower
electrode in the pixel array unit 3.
[0084] As illustrated in FIG. 3, out of the pixels 2 arranged in a
two-dimensional manner in the pixel array unit 3, in the normal
pixel 2X, the lower electrode 53a is formed for each pixel. The
cross-sectional view illustrated in FIG. 2 corresponds a
cross-sectional view of a portion in which the three normal pixels
2X are arranged in a horizontal direction indicated by line X1-X1'
in FIG. 3, for example.
[0085] On the other hand, the pixels 2 arranged in a
two-dimensional manner in the pixel array unit 3 include the pixel
2 including a lower electrode 53c a planar size of which is made
smaller than that of the lower electrode 53a of the normal pixel 2X
and the pixel 2 including a lower electrode 53d enlarged to a
region which is vacant due to a decrease in size of the lower
electrode 53c.
[0086] The pixel 2 including the downsized lower electrode 53c is
the phase difference pixel 2P which generates a signal for
detecting a focal point and the pixel 2 including the enlarged
lower electrode 53d is a dummy pixel 2D arranged adjacent to the
phase difference pixel 2P.
[0087] A pair (two) of the phase difference pixels 2P configured
such that sensitivities are asymmetrical with respect to a light
incident angle is arranged in the pixel array unit 3. The two phase
difference pixels 2P which form a pair are represented as a type A
phase difference pixel 2P.sub.A and a type B phase difference pixel
2P.sub.B. Also, the dummy pixel 2D arranged adjacent to the phase
difference pixel 2P.sub.A is represented as a dummy pixel 2D.sub.A
and the dummy pixel 2D arranged adjacent to the phase difference
pixel 2P.sub.B is represented as a dummy pixel 2D.sub.B.
[0088] In an example in FIG. 3, the phase difference pixel 2P.sub.A
is the pixel in which the lower electrode 53c is formed so as to
receive light only by a left side in the pixel as compared to the
normal pixel 2X, and the phase difference pixel 2P.sub.B is the
pixel in which the lower electrode 53c is formed only on a right
side in the pixel such that a photoelectric conversion region is
symmetrical to that in the phase difference pixel 2P.sub.A.
[0089] Meanwhile, although a pair of the phase difference pixel
2P.sub.A and the dummy pixel 2D.sub.A and a pair of the phase
difference pixel 2P.sub.B and the dummy pixel 2D.sub.B are arranged
so as to be adjacent in a longitudinal direction (vertical
direction) in the example in FIG. 3, they are not necessarily
arranged so as to be adjacent in the longitudinal direction. For
example, the pair of the phase difference pixel 2P.sub.A and the
dummy pixel 2D.sub.A and the pair of the phase difference pixel
2P.sub.B and the dummy pixel 2D.sub.B may be arranged with one or
more pixels interposed therebetween or arranged so as to be
adjacent in a lateral direction (horizontal direction).
[0090] Also, although the lower electrodes 53c of the phase
difference pixels 2P.sub.A and 2P.sub.B are downsized in the
lateral direction (horizontal direction) as compared to the lower
electrode 53a in the normal pixel 2X in the example in FIG. 3, they
may also be downsized in the longitudinal direction (vertical
direction). When the lower electrodes 53c of the phase difference
pixels 2P.sub.A and 2P.sub.B are downsized in the longitudinal
direction, the phase difference pixel 2P.sub.A and the dummy pixel
2D.sub.A are arranged so as to be adjacent in the longitudinal
direction and the phase difference pixel 2P.sub.B and the dummy
pixel 2D.sub.B are also arranged so as to be adjacent in the
longitudinal direction.
[0091] Furthermore, the pair of the phase difference pixels
2P.sub.A and 2P.sub.B including the lower electrodes 53c downsized
in the lateral direction and the pair of the phase difference
pixels 2P.sub.A and 2P.sub.B including the lower electrodes 53c
downsized in the longitudinal direction may be mixed in the pixel
array unit 3.
[0092] Displacement in image occurs between the pixel signal from
the phase difference pixel 2P.sub.A and the pixel signal from the
phase difference pixel 2P.sub.B because the lower electrodes 53c
are formed in different positions. It is possible to realize
automatic focusing by calculating a defocusing amount by
calculating a phase displacement amount from the displacement in
image to adjust (move) an imaging lens.
[0093] <Cross-Sectional Configuration of Phase Difference
Pixel>
[0094] FIG. 4 illustrates a cross-sectional configuration taken
along line Y1-Y1' in FIG. 3 in which one normal pixel 2X and the
pair of the phase difference pixel 2P.sub.A and the dummy pixel
2D.sub.A are included.
[0095] FIG. 5 illustrates a cross-sectional configuration taken
along line Y2-Y2' in FIG. 3 in which one normal pixel 2X and the
pair of the phase difference pixel 2P.sub.B and the dummy pixel
2D.sub.B are included.
[0096] As illustrated in FIGS. 4 and 5, the lower electrode 53c of
the phase difference pixel 2P (2P.sub.A or 2P.sub.B) is downsized
in the lateral direction (horizontal direction) as compared to the
lower electrode 53a of the normal pixel 2X and the lower electrode
53d of the dummy pixel 2D (2D.sub.A or 2D.sub.B) is extended to a
region which is vacant due to downsizing to be formed. Although an
interval in the planar direction between the lower electrode 53c of
the phase difference pixel 2P and the lower electrode 53d of the
dummy pixel 2D is set to be the same as the interval between the
lower electrodes 53a of two adjacent normal pixels 2X, they are not
necessarily the same.
[0097] In the phase difference pixel 2P and the dummy pixel 2D, the
configuration other than the lower electrodes 53c and 53d is
similar to that of the normal pixel 2X. Therefore, B signals and R
signals generated by the photodiodes PD1 and PD2 of the phase
difference pixel 2P and the dummy pixel 2D may be utilized as the
signals for generating an image.
[0098] A G signal generated by the photoelectric converting unit
61, that is to say, the photoelectric converting film 52, the upper
electrode 53b, and the lower electrode 53c of the phase difference
pixel 2P is output to the FD unit 49 through the metal wiring 54
and the conductive plug 46 to be utilized as the signal for
detecting a focal point. The G signal for generating an image of
the phase difference pixel 2P is calculated by interpolation from
the G signals of a plurality of normal pixels 2X around the phase
difference pixel 2P, for example.
[0099] On the other hand, the G signal generated by the
photoelectric converting unit 61, that is to say, the photoelectric
converting film 52, the upper electrode 53b, and the lower
electrode 53d of the dummy pixel 2D is output to the FD unit 49
through the metal wiring 54 and the conductive plug 46, but this is
discharged without being utilized. The G signal for generating an
image of the dummy pixel 2D is also calculated by the interpolation
from the G signals of a plurality of normal pixels 2X around the
dummy pixel 2D, for example.
[0100] According to the first embodiment of the phase difference
pixel 2P configured in the above-described manner, it is not
required to form a light shielding film on an upper surface of the
photoelectric converting film 52 for each color, so that it is
possible to realize the phase difference pixel while avoiding an
increase in the number of steps for forming the light shielding
film. Also, it is not required to separate the photoelectric
converting film 52 between the pixels, so that it is possible to
inhibit dark current generated when the photoelectric converting
film 52 is separated between the pixels.
[0101] Therefore, it is possible to form a more preferable phase
difference pixel 2P for detecting a focal point by using the
photoelectric converting film 52 formed on an outer side of the
semiconductor substrate 12.
[0102] Meanwhile, in the pixel structure illustrated as the first
embodiment, since the photoelectric converting film 52 performs the
photoelectric conversion on the green light, the G signal output
from the phase difference pixel 2P is used as the signal for
detecting a focal point; however, it is possible to arbitrarily
select the color of the light on which the photoelectric conversion
is performed by the photoelectric converting film 52. That is to
say, in the longitudinal direction spectral solid-state image
sensor, it is possible to appropriately determine the color of the
light on which the photoelectric conversion is performed by the
photoelectric converting film 52 formed above the semiconductor
substrate 12 and the colors of the light on which the photoelectric
conversion is performed by the photodiodes PD1 and PD2 in the
semiconductor substrate 12.
[0103] <3. Second Embodiment of Pixel>
[0104] <Planar Layout of Lower Electrode>
[0105] Next, a second embodiment is described. Meanwhile, in the
description of the second embodiment and thereafter, the
description of a portion corresponding to that in other embodiments
indicated with the same reference sign as that of the
above-described other embodiments is appropriately omitted and only
a different portion is described. A normal pixel of the second
embodiment is similar to that of the above-described first
embodiment, so that only a phase difference pixel is described.
[0106] FIG. 6 is a view illustrating a planar layout of a lower
electrode in a pixel array unit 3.
[0107] In the second embodiment, phase difference pixels 2P.sub.A
and 2P.sub.B are arranged in a linear manner with a dummy pixel 2D
interposed therebetween. That is to say, the phase difference pixel
2P.sub.A, the dummy pixel 2D, and the phase difference pixel
2P.sub.B are arranged in the pixel array unit 3 in this order.
Therefore, the dummy pixel 2D is arranged adjacent to the phase
difference pixels 2P.sub.A and 2P.sub.B; this serves as a dummy
pixel 2D.sub.A arranged adjacent to the phase difference pixel
2P.sub.A and a dummy pixel 2D.sub.B arranged adjacent to the phase
difference pixel 2P.sub.B. Such dummy pixel 2D is represented as a
dummy pixel 2D.sub.AB.
[0108] In the second embodiment, the phase difference pixel
2P.sub.A includes a lower electrode 53c formed so as to receive
light only on a left side in the pixel as in the first embodiment.
The phase difference pixel 2P.sub.B includes the lower electrode
53c only on a right side in the pixel such that a photoelectric
conversion region is symmetrical to that of the phase difference
pixel 2P.sub.A.
[0109] Then, a lower electrode 53d of the dummy pixel 2D.sub.AB
arranged in the center is extended to regions of the phase
difference pixels 2P.sub.A and 2P.sub.B which are vacant due to
downsizing of the lower electrodes 53c to be formed. In other
words, the lower electrode 53d of the dummy pixel 2D.sub.AB is
formed so as to extend to sides of the phase difference pixels
2P.sub.A and 2P.sub.B to lie across three pixels.
[0110] Meanwhile, although the phase difference pixel 2P.sub.A, the
dummy pixel 2D, and the phase difference pixel 2P.sub.B are
arranged in a linear manner in a horizontal direction in this order
in the example in FIG. 6, it is also possible to configure such
that they are arranged in a linear manner in a vertical
direction.
[0111] <Cross-Sectional Configuration of Phase Difference
Pixel>
[0112] FIG. 7 illustrates a cross-sectional configuration taken
along line Y11-Y11' in FIG. 6 including the phase difference pixel
2P.sub.A, the dummy pixel 2D.sub.AB, and the phase difference pixel
2P.sub.B.
[0113] As illustrated in FIG. 7, the lower electrodes 53c of the
phase difference pixels 2P.sub.A and 2P.sub.B are downsized in a
lateral direction (horizontal direction) as compared to a lower
electrode 53a of a normal pixel 2X and the lower electrode 53d of
the dummy pixel 2D.sub.AB is extended to the regions which are
vacant due to the downsizing to be formed.
[0114] In the phase difference pixels 2P.sub.A and 2P.sub.B, a
charge generated in a region interposed between an upper electrode
53b and the lower electrode 53c out of a region of a photoelectric
converting film 52 is accumulated in a FD unit 49. Positions in
which the lower electrodes 53c are formed in the phase difference
pixels 2P.sub.A and 2P.sub.B are symmetrical to each other.
Displacement in image occurs between pixel signals from the phase
difference pixels 2P.sub.A and 2P.sub.B because the lower
electrodes 53c are formed in different positions. It is possible to
realize automatic focusing by calculating a defocusing amount by
calculating a phase displacement amount from the displacement in
image to adjust (move) an imaging lens.
[0115] According to the second embodiment of the phase difference
pixel 2P configured in the above-described manner, it is not
required to form a light shielding film on an upper surface of the
photoelectric converting film 52 for each color, so that it is
possible to realize the phase difference pixel while avoiding an
increase in the number of steps for forming the light shielding
film. Also, it is not required to separate the photoelectric
converting film 52 between the pixels, so that it is possible to
inhibit dark current generated when the photoelectric converting
film 52 is separated between the pixels.
[0116] Therefore, it is possible to form a more preferable phase
difference pixel 2P for detecting a focal point by using the
photoelectric converting film 52 formed on an outer side of the
semiconductor substrate 12.
[0117] <4. Third Embodiment of Pixel>
[0118] <Planar Layout of Lower Electrode>
[0119] Next, a third embodiment is described.
[0120] FIG. 8 is a view illustrating a planar layout of a lower
electrode in a pixel array unit 3.
[0121] Meanwhile, in FIG. 8, a broken line indicating a boundary of
each pixel 2 illustrated in FIGS. 3 and 6 is omitted in order to
make the drawing more visible.
[0122] In the third embodiment, an element separating electrode 81
which separates pixels (elements) is formed between lower
electrodes 53a and 53c adjacent to each other. A material similar
to that of the lower electrodes 53a and 53c such as an indium tin
oxide (ITO) film and an indium zinc oxide film, for example, may be
used as a material of the element separating electrode 81. The
element separating electrode 81 is formed between the lower
electrodes 53a and 53c adjacent to each other in a vertical
direction and in a horizontal direction, so that this is formed
into a lattice shape as illustrated in FIG. 8.
[0123] Predetermined fixed potential is applied to the element
separating electrode 81. According to this, it is possible to
prevent capacity coupling between the adjacent pixels and inhibit
an after image by collecting a charge generated between the
pixels.
[0124] A phase difference pixel 2P.sub.A includes the lower
electrode 53c formed so as to receive light only on a left side in
the pixel as in the first embodiment. The phase difference pixel
2P.sub.B includes the lower electrode 53c only on a right side in
the pixel such that a photoelectric conversion region is
symmetrical to that of the phase difference pixel 2P.sub.A.
[0125] Then, the element separating electrode 81 is formed in a
region which is vacant due to downsizing of the lower electrode 53c
of the phase difference pixel 2P.sub.A so as to be extended from a
pixel boundary line. The element separating electrode 81 is formed
also in a region which is vacant due to the downsizing of the lower
electrode 53c of the phase difference pixel 2P.sub.B so as to be
extended from the pixel boundary line. That is to say, each of the
phase difference pixels 2P.sub.A and 2P.sub.B has a configuration
in which the element separating electrode 81 adjacent thereto is
extended to the region which is vacant due to the downsized lower
electrode 53c to be formed.
[0126] Positions in which the lower electrodes 53c are formed in
the phase difference pixels 2P.sub.A and 2P.sub.B configured in the
above-described manner are symmetrical to each other. Displacement
in image occurs between pixel signals from the phase difference
pixels 2P.sub.A and 2P.sub.B because the lower electrodes 53c are
formed in different positions. It is possible to realize automatic
focusing by calculating a defocusing amount by calculating a phase
displacement amount from the displacement in image to adjust (move)
an imaging lens.
[0127] Meanwhile, although the lower electrodes 53c of the phase
difference pixels 2P.sub.A and 2P.sub.B are downsized in a lateral
direction (horizontal direction) as compared to the lower electrode
53a of a normal pixel 2X in the example in FIG. 8, they may also be
downsized in a longitudinal direction (vertical direction). In this
case, the element separating electrode 81 which separates the upper
and lower lower electrodes 53a and 53c is formed so as to be
extended in the longitudinal direction in each of the phase
difference pixels 2P.sub.A and 2P.sub.B.
[0128] <Cross-Sectional Configuration of Pixel>
[0129] FIG. 9 is a cross-sectional configuration diagram taken
along line X11-X11' in FIG. 8 including two normal pixels 2X.
[0130] FIG. 10 is a cross-sectional configuration diagram taken
along line Y21-Y21' in FIG. 8 including one normal pixel 2X and one
phase difference pixel 2P.sub.A.
[0131] FIG. 11 is a cross-sectional configuration diagram taken
along line Y22-Y22' in FIG. 8 including one normal pixel 2X and one
phase difference pixel 2P.sub.B.
[0132] As illustrated in FIG. 9, in a portion in which the normal
pixels 2X are adjacent to each other, the element separating
electrode 81 is formed in a position on the pixel boundary in a
planar direction and in the same position as that of the lower
electrode 53a in a depth direction. The element separating
electrode 81 is connected to metal wiring 82 formed below the same
and predetermined fixed potential is applied to the element
separating electrode 81 through the metal wiring 82.
[0133] As illustrated in FIG. 10, in a portion in which the phase
difference pixel 2P.sub.A and the normal pixel 2X are adjacent to
each other, the element separating electrode 81 is formed in the
region which is vacant due to the downsizing of the lower electrode
53c of the phase difference pixel 2P.sub.A so as to be extended
from the pixel boundary line.
[0134] Also, as illustrated in FIG. 11, in a portion in which the
phase difference pixel 2P.sub.B and the normal pixel 2X are
adjacent to each other, the element separating electrode 81 is
formed in the region which is vacant due to the downsizing of the
lower electrode 53c of the phase difference pixel 2P.sub.B so as to
be extended from the pixel boundary line.
[0135] The extended element separating electrode 81 is connected to
the metal wiring 82 formed below the same and predetermined fixed
potential is applied to the element separating electrode 81 also in
FIGS. 10 and 11 as in FIG. 9. The charge generated by a
photoelectric converting film 52 interposed between the extended
element separating electrode 81 and an upper electrode 53b is not
connected to the FD unit 49 and is not extracted as a signal.
[0136] According to the third embodiment of the phase difference
pixel 2P configured in the above-described manner, it is not
required to form a light shielding film on an upper surface of the
photoelectric converting film 52 for each color, so that it is
possible to realize the phase difference pixel while avoiding an
increase in the number of steps for forming the light shielding
film. Also, it is not required to separate the photoelectric
converting film 52 between the pixels, so that it is possible to
inhibit dark current generated when the photoelectric converting
film 52 is separated between the pixels.
[0137] Therefore, it is possible to form a more preferable phase
difference pixel 2P for detecting a focal point by using the
photoelectric converting film 52 formed on an outer side of the
semiconductor substrate 12.
[0138] <Variation of Third Embodiment>
[0139] Although a layout is such that a normal pixel 2X is arranged
adjacent to a phase difference pixel 2P.sub.A or 2P.sub.B in a
vertical direction and in a horizontal direction in an example
illustrated in FIG. 8, the layout may also be such that the phase
difference pixels 2P.sub.A and 2P.sub.B are arranged adjacent to
each other in the vertical direction or in the horizontal direction
as illustrated in FIG. 12.
[0140] Also, although it is described that an element separating
electrode 81 is extended on the assumption that the element
separating electrode 81 is formed into a lattice shape on a pixel
boundary in the vertical direction and in the horizontal direction
in the description above, the element separating electrode 81 in
the lattice shape may be omitted as illustrated in FIG. 13. Also,
it is of course possible to configure such that the element
separating electrode 81 in the lattice shape is omitted from the
layout illustrated in FIG. 8 and only an element separating
electrode 83 having an island shape is provided. In this case,
predetermined fixed potential is applied only to the element
separating electrode 83 having the island shape. Furthermore, a
shape may be such that not an entire element separating electrode
81 in the lattice shape is omitted but only a part of the element
separating electrode 81 in the lattice shape is omitted to form a H
shape, for example.
[0141] Meanwhile, difference between the element separating
electrode 83 in the island shape illustrated in FIG. 13 and a lower
electrode 53c in an island shape of a dummy pixel 2D.sub.AB of the
second embodiment illustrated in FIG. 6 is that the former is
connected to metal wiring 82 which supplies predetermined fixed
potential and the latter is connected to a FD unit 49 which
accumulates a charge. The element separating electrode 83 in the
island shape illustrated in FIG. 13 may also have an isolated
pattern without being connected to the metal wiring 82 formed below
the same. Alternatively, it is also possible to configure such that
the element separating electrode 83 in the island shape in FIG. 13
is not connected to the metal wiring 82 formed below the same but
connected to the FD unit 49 to accumulate the charge to
discharge.
[0142] <5. Fourth Embodiment of Pixel>
[0143] <Cross-Sectional Configuration of Pixel>
[0144] Next, a fourth embodiment is described.
[0145] In the above-described first to third embodiments, each
pixel 2 receives light of all wavelengths of red (R), green (G),
and blue (B) by a photoelectric converting unit 61 and photodiodes
PD1 and PD2; however, fourth to sixth embodiments to be described
hereinafter are different in that each pixel 2 receives only light
of any of the wavelengths of red (R), green (G), and blue (B).
[0146] FIG. 14 being a cross-sectional configuration diagram of the
pixel 2 of the fourth embodiment illustrates a cross-sectional
configuration of a portion corresponding to line Y1-Y1' in FIG. 3
in which one normal pixel 2X and a pair of a phase difference pixel
2P.sub.A and a dummy pixel 2D.sub.A are included.
[0147] Comparing the cross-sectional configuration of the first
embodiment illustrated in FIG. 4 with the cross-sectional
configuration of the fourth embodiment in FIG. 14 being the
cross-sectional configuration diagrams taken along line Y1-Y1' in
FIG. 3, in FIG. 14, a photoelectric converting film 52 which
performs photoelectric conversion on green wavelength light in FIG.
4 is replaced with a photoelectric converting film 91 which
performs the photoelectric conversion on the light of all the
wavelengths of red (R), green (G), and blue (B). Also, the
photodiode PD1 which receives the blue light and the photodiode PD2
which receives the red light are not provided in a semiconductor
substrate 12.
[0148] Furthermore, in FIG. 14, a color filter 92 which transmits
the light of the wavelength of red (R), green (G), or blue (B) is
newly provided between a high refractive index layer 56 and an
on-chip lens 57.
[0149] Therefore, only the light of any of the wavelengths of red
(R), green (G), and blue (B) which passes the color filter 92
achieves the photoelectric converting film 91, so that each pixel 2
receives only the light of any of the wavelengths of red (R), green
(G), and blue (B).
[0150] Also, a rear surface irradiation type configuration in which
the photoelectric converting unit 61 and the on-chip lens 57 are
formed on a rear surface side opposite to a surface side on which a
multi-layer wiring layer 44 is formed is adopted in the first
embodiment illustrated in FIG. 4. On the other hand, in the fourth
embodiment in FIG. 14, a surface irradiation type configuration in
which the photoelectric converting unit 61 and the on-chip lens 57
are formed on the surface side of the semiconductor substrate 12,
the side on which the multi-layer wiring layer 44 is formed is
adopted.
[0151] More specifically, the multi-layer wiring layer 44 is formed
on the surface side of the semiconductor substrate 12 and a
transparent insulating film 51, a lower electrode 53a, the
photoelectric converting film 91, an upper electrode 53b, the high
refractive index layer 56 and the like are formed on an upper
surface of the multi-layer wiring layer 44.
[0152] Since the multi-layer wiring layer 44 is formed on the
surface side of the semiconductor substrate 12, the FD unit 49
which holds the charge generated by a photoelectric converting film
52 is also formed on the surface side of the semiconductor
substrate 12. Therefore, in the fourth embodiment, a conductive
plug 46 and an insulating film 47 for extracting the charge
generated by the photoelectric converting film 91 to the rear
surface side of the semiconductor substrate 12 are not
provided.
[0153] FIG. 15 is a view illustrating a layout example of the color
filters 92 illustrated so as to correspond to the planar layout in
FIG. 3.
[0154] The color filters 92 are arranged in Bayer arrangement, for
example, as illustrated in FIG. 15.
[0155] Meanwhile, although the phase difference pixel 2P.sub.A and
a phase difference pixel 2P.sub.B are the pixels which receive a
green (Gr, Gb) wavelength, the dummy pixel 2D.sub.A is the pixel
which receives a red (R) wavelength, and a dummy pixel 2D.sub.B is
the pixel which receives a blue (B) wavelength in the example in
FIG. 15, the wavelengths (colors) of the light received by the
phase difference pixel 2P and the dummy pixel 2D are not limited to
this example. However, it is desirable that the wavelength of the
light received by the phase difference pixel 2P.sub.A and the
wavelength of the light received by the phase difference pixel
2P.sub.B are the same. Also, it is possible to make the phase
difference pixels 2P.sub.A and 2P.sub.B white pixels which receive
the light of all the wavelengths by using a material which
transmits all the wavelengths in place of the color filter 92. When
the phase difference pixels 2P.sub.A and 2P.sub.B are made the
white pixels, the material used in place of the color filter 92 may
be the same material as that of the high refractive index layer 56
and the on-chip lens 57, for example.
[0156] <6. Fifth Embodiment of Pixel>
[0157] <Cross-Sectional Configuration of Pixel>
[0158] Next, a fifth embodiment is described.
[0159] FIG. 16 being a cross-sectional configuration diagram of a
pixel 2 of the fifth embodiment illustrates a cross-sectional
configuration of a portion corresponding to line Y11-Y11' in FIG. 6
in which phase difference pixels 2P.sub.A and 2P.sub.B and a dummy
pixel 2D.sub.AB interposed therebetween are included.
[0160] In the fifth embodiment, a wavelength of light received by
each pixel 2 is configured so as to be similar to that of the
fourth embodiment described with reference to FIG. 14 and an
arrangement configuration of lower electrodes 53c and 53d is
similar to that of the second embodiment described with reference
to FIG. 7.
[0161] That is to say, in FIG. 16, color filters 92 in Bayer
arrangement is formed between a high refractive index layer 56 and
an on-chip lens 57 and a photoelectric converting film 91 which
performs photoelectric conversion on light of all the wavelengths
of red (R), green (G), and blue (B) is formed between the lower
electrode 53c or 53d and an upper electrode 53b. According to this,
a photoelectric converting unit 61 of each pixel 2 receives only
the light of any of the wavelengths of red (R), green (G), and blue
(B).
[0162] Also, the phase difference pixels 2P.sub.A and 2P.sub.B are
arranged in a linear manner with the dummy pixel 2D.sub.AB
interposed therebetween. Then, the lower electrode 53d of the dummy
pixel 2D.sub.AB arranged in the center is extended to regions which
are vacant due to downsizing of the lower electrodes 53c of the
phase difference pixels 2P.sub.A and 2P.sub.B to be formed.
[0163] Also, a pixel structure of the fifth embodiment is a surface
irradiation type structure in which the photoelectric converting
unit 61 and the on-chip lens 57 are formed on a surface side of a
semiconductor substrate 12, the side on which a multi-layer wiring
layer 44 is formed.
[0164] <7. Sixth Embodiment of Pixel>
[0165] <Cross-Sectional Configuration of Pixel>
[0166] Next, a sixth embodiment is described.
[0167] FIG. 17 being a cross-sectional configuration diagram of a
pixel 2 of the sixth embodiment illustrates a cross-sectional
configuration of a portion corresponding to line Y21-Y21' in FIG. 8
in which one normal pixel 2X and one phase difference pixel
2P.sub.A are included.
[0168] In the sixth embodiment, a wavelength of light received by
each pixel 2 is configured so as to be similar to that of the
fourth embodiment described with reference to FIG. 14 and an
arrangement configuration of a lower electrode 53c and an element
separating electrode 81 is similar to that of the third embodiment
described with reference to FIG. 10.
[0169] That is to say, in FIG. 17, color filters 92 in Bayer
arrangement are formed between a high refractive index layer 56 and
an on-chip lens 57 and a photoelectric converting film 91 which
performs photoelectric conversion on light of all the wavelengths
of red (R), green (G), and blue (B) is formed between a lower
electrode 53a or 53c and an upper electrode 53b. According to this,
a photoelectric converting unit 61 of each pixel 2 receives only
the light of any of the wavelengths of red (R), green (G), and blue
(B).
[0170] Also, the element separating electrode 81 is formed between
the phase difference pixel 2P.sub.A and the normal pixel 2X, and
the element separating electrode 81 is formed in a region which is
vacant due to downsizing of the lower electrode 53c of the phase
difference pixel 2P.sub.A so as to be extended from a pixel
boundary line as illustrated in FIG. 17.
[0171] Although not illustrated, in a portion in which the normal
pixels 2X of the sixth embodiment are adjacent to each other, as in
FIG. 9, the element separating electrode 81 is formed in a position
on the pixel boundary. Also, in a portion in which a phase
difference pixel 2P.sub.B and the normal pixel 2X are adjacent to
each other, as in FIG. 11, the element separating electrode 81 is
formed in a region which is vacant due to the downsizing of the
lower electrode 53c of the phase difference pixel 2P.sub.B so as to
be extended from the pixel boundary line.
[0172] Also, a pixel structure of the sixth embodiment is a surface
irradiation type structure in which the photoelectric converting
unit 61 and the on-chip lens 57 are formed on a surface side of a
semiconductor substrate 12, the side on which a multi-layer wiring
layer 44 is formed.
[0173] In the above-described fourth to sixth embodiments also,
positions in which the lower electrodes 53c are formed in the phase
difference pixels 2P.sub.A and 2P.sub.B are symmetrical with each
other. Displacement in image occurs between pixel signals from the
phase difference pixels 2P.sub.A and 2P.sub.B because the lower
electrodes 53c are formed in different positions. It is possible to
realize automatic focusing by calculating a defocusing amount by
calculating a phase displacement amount from the displacement in
image to adjust (move) an imaging lens.
[0174] It is not required to form a light shielding film on an
upper surface of the photoelectric converting film 91 also in the
fourth to sixth embodiments, so that it is possible to realize the
phase difference pixel while avoiding an increase in the number of
steps. Also, it is not required to separate the photoelectric
converting film 91 between the pixels, so that it is possible to
inhibit dark current generated when the photoelectric converting
film 91 is separated between the pixels.
[0175] Therefore, it is possible to form a more preferable phase
difference pixel 2P for detecting a focal point by using the
photoelectric converting film 91 formed on an outer side of the
semiconductor substrate 12 also in the fourth to sixth
embodiments.
[0176] Meanwhile, although the structure illustrated as the fourth
to sixth embodiments is the surface irradiation type pixel
structure, this may also be a rear surface irradiation type pixel
structure as that of the first to third embodiments.
[0177] It is possible to change the phase difference pixels
2P.sub.A and 2P.sub.B to white pixels also in the fifth and sixth
embodiments.
[0178] Also, a lower electrode 53d of a dummy pixel 2D of the first
to third embodiments and the element separating electrode 81 of the
fourth to sixth embodiments are the electrodes extending at least
to the boundary of the pixel.
[0179] <8. Manufacturing Method of First Embodiment>
[0180] Next, a method of manufacturing a pixel 2 according to the
first embodiment illustrated in FIG. 4 is described with reference
to FIGS. 18A to 25B.
[0181] Meanwhile, in FIGS. 18A to 25B, a method of manufacturing a
power supply unit to an upper electrode 53b not illustrated in FIG.
4 is also illustrated.
[0182] First, as illustrated in FIG. 18A, photodiodes PD1 and PD2,
a conductive plug 46, a FD unit 49, a conductive plug 122 for
supplying power to the upper electrode 53b and the like are formed
in a semiconductor region 41 of a semiconductor substrate 12. An
outer periphery of the conductive plug 122 is covered with a SiO2
or SiN insulating film 123.
[0183] Also, a plurality of pixel transistors which reads charges
accumulated in the photodiodes PD1 and PD2 and a multi-layer wiring
layer 44 formed of a plurality of wiring layers and an interlayer
insulating film are formed on a surface side (lower side in the
drawing) of the semiconductor substrate 12.
[0184] Then, as illustrated in FIG. 18B, a transparent insulating
film 51A is formed to have a predetermined film thickness on an
interface on a rear surface side of the semiconductor substrate
12.
[0185] Next, as illustrated in FIG. 18C, only a region connected to
the conductive plug 46 out of the transparent insulating film 51A
formed on the interface on the rear surface side of the
semiconductor substrate 12 is opened by lithography.
[0186] Then, as illustrated in FIG. 18D, a metal material 201 such
as tungsten (W), aluminum (Al), and copper (Cu) is formed on an
entire surface of an upper side of the transparent insulating film
51A including an opened dug portion of the transparent insulating
film 51A.
[0187] The metal material 201 formed on the entire surface of the
transparent insulating film 51A is patterned with only a desired
region left by lithography as illustrated in FIG. 19A, and
according to this, an interpixel light shielding film 55 is
formed.
[0188] Furthermore, a transparent insulating film 51B is stacked
above the transparent insulating film 51A and the interpixel light
shielding film 55 as illustrated in FIG. 19B, and thereafter only a
region connected to the conductive plug 46 out of the stacked
transparent insulating film 51B is opened again by lithography as
illustrated in FIG. 19C.
[0189] Then, a metal material 202 is formed on an entire surface on
an upper side of the transparent insulating film 51B including an
opened dug portion of the transparent insulating film 51B as
illustrated in FIG. 19D, and thereafter, the metal material 202 on
a surface layer is removed by chemical mechanical polishing (CMP),
so that metal wiring 54 penetrating the transparent insulating
films 51A and 51B is formed as illustrated in FIG. 20A.
[0190] Then, an indium tin oxide (ITO) film 203, for example, is
deposited on the transparent insulating film 51B as illustrated in
FIG. 20B and is patterned with only a desired region left by
lithography, and according to this, a lower electrode 53a of a
normal pixel 2X, a lower electrode 53c of a phase difference pixel
2P.sub.A, and a lower electrode 53d of a dummy pixel 2D.sub.A are
formed as illustrated in FIG. 20C.
[0191] Furthermore, after the transparent insulating film 51C is
formed to have a predetermined film thickness on the transparent
insulating film 51B including the lower electrodes 53a, 53c, and
53d as illustrated in FIG. 20D, the transparent insulating film 51C
is removed by chemical mechanical polishing (CMP), for example,
until this has the same film thickness as that of the lower
electrode 53a and the like. As a result, as illustrated in FIG.
21A, the transparent insulating film 51 in FIG. 4 is completed by
the remained transparent insulating film 51C and the transparent
insulating films 51B and 51A below the same.
[0192] Subsequently, a photoelectric converting material 204 which
performs photoelectric conversion on green wavelength light is
formed on upper surfaces of the lower electrodes 53a, 53c, and 53d
and the transparent insulating film 51 as illustrated in FIG. 21B,
and thereafter, an indium tin oxide (ITO) film 205 is formed
thereafter, for example, as illustrated in FIG. 21C.
[0193] Then, a photoelectric converting film 52 and the upper
electrode 53b shared by the normal pixel 2X, the phase difference
pixel 2P, and the dummy pixel 2D are completed as illustrated in
FIG. 21D by etching with only a desired region left.
[0194] Subsequently, as illustrated in FIG. 22A, a highly
refractive material 206A of a nitride film and the like serving as
a high refractive index layer 56 is formed on upper surfaces of the
upper electrode 53b in a pixel region and the transparent
insulating film 51 on an outer peripheral portion of the pixel
array unit 3.
[0195] Thereafter, a contact opening 207 is formed in a place
serving as a contact portion of the upper electrode 53b and a
contact opening 208 is formed in a place serving as a contact
portion with the conductive plug 122 as illustrated in FIG.
22B.
[0196] Then, a metal material 209 such as tungsten (W) is
conformally deposited on an upper surface of the highly refractive
material 206A after the contact openings 207 and 208 are formed as
illustrated in FIG. 23A, and thereafter, this is patterned such
that only the outer peripheral portion of the pixel array unit 3 is
left as illustrated in FIG. 23B, and according to this, connection
wiring 124 which connects the conductive plug 122 to the upper
electrode 53b is completed.
[0197] Then, as illustrated in FIG. 24A, a highly refractive
material 206B of the same material as that of the highly refractive
material 206A is further formed on the highly refractive material
206A and the connection wiring 124. The stacked highly refractive
materials 206A and 206B serve as the high refractive index layer
56.
[0198] Next, after a resin material 210 being a material of the
on-chip lens 57 is further formed on an upper surface of the high
refractive index layer 56 as illustrated in FIG. 24B, a photo
resist 211 is formed into a lens shape as illustrated in FIG. 25A.
Then, the on-chip lens 57 is formed on an uppermost portion of each
pixel 2 as illustrated in FIG. 25B by etching back on the basis of
the lens-shaped photo resist 211.
[0199] The pixel 2 of the first embodiment illustrated in FIG. 4
may be manufactured in the above-described manner. Meanwhile, the
photoelectric converting unit 61 of the pixel 2 may be similarly
manufactured also in the second to sixth embodiments.
[0200] <Application Example to Electronic Device>
[0201] Application of the technology of the present disclosure is
not limited to that to a solid-state image sensor. That is to say,
the technology of the present disclosure is applicable to general
electronic devices using the solid-state image sensor as an image
capturing unit (photoelectric converting unit) such as an imaging
device such as a digital still camera and a video camera, a
portable terminal device having an imaging function, and a copying
machine using the solid-state image sensor in an image reading
unit. The solid-state image sensor may be in a form of a single
chip, or may be in a form of a module having the imaging function
obtained by packaging an imaging unit, a signal processor, or an
optical system.
[0202] FIG. 26 is a block diagram illustrating a configuration
example of the imaging device as the electronic device according to
the present disclosure.
[0203] An imaging device 300 in FIG. 26 is provided with an optical
unit 301 formed of a lens group and the like, a solid-state image
sensor (imaging device) 302 to which a configuration of the
solid-state image sensor 1 in FIG. 1 is adopted, and a digital
signal processor (DSP) circuit 303 which is a camera signal
processing circuit. The imaging device 300 is also provided with a
frame memory 304, a display unit 305, a recording unit 306, an
operation unit 307, and a power supply unit 308. The DSP circuit
303, the frame memory 304, the display unit 305, the recording unit
306, the operation unit 307, and the power supply unit 308 are
connected to one another through a bus line 309.
[0204] The optical unit 301 captures incident light (image light)
from an object and forms an image on an imaging surface of the
solid-state image sensor 302. The solid-state image sensor 302
converts an amount of the incident light the image of which is
formed on the imaging surface by the optical unit 301 to an
electric signal in pixel unit and outputs the same as a pixel
signal. The solid-state image sensor 1 in FIG. 1, that is to say,
the solid-state image sensor which includes a pixel structure of
the above-described normal pixel 2X, phase difference pixel 2P and
the like may be used as the solid-state image sensor 302.
[0205] The display unit 305 formed of a panel display device such
as a liquid crystal panel and an organic electro luminescence (EL)
panel, for example, displays a moving image or a still image imaged
by the solid-state image sensor 302. The recording unit 306 records
the moving image or the still image imaged by the solid-state image
sensor 302 in a recording medium such as a hard disk and a
semiconductor memory.
[0206] The operation unit 307 issues an operation command regarding
various functions of the imaging device 300 under operation by a
user. The power supply unit 308 appropriately supplies various
power sources serving as operation power sources of the DSP circuit
303, the frame memory 304, the display unit 305, the recording unit
306, and the operation unit 307 to supply targets.
[0207] As described above, it is possible to realize the phase
difference pixel while avoiding an increase in the number of steps
by adopting the solid-state image sensor 1 including the pixel 2
according to the above-described embodiments as the solid-state
image sensor 302. Therefore, it is possible to improve a quality of
the imaged image also in the imaging device 300 such as the video
camera, the digital still camera, and further a camera module for a
mobile device such as a cellular phone.
[0208] The embodiment of the present disclosure is not limited to
the above-described embodiments and may be variously changed
without departing from the gist of the present disclosure.
[0209] In the above-described first to third embodiments, the
longitudinal direction spectral solid-state image sensor including
one photoelectric converting layer (photoelectric converting film
52) above a semiconductor substrate 12 and including two inorganic
photoelectric converting layers (photodiodes PD1 and PD2) in the
semiconductor substrate 12 is described.
[0210] However, the technology of the present disclosure is
similarly applicable to the longitudinal direction spectral
solid-state image sensor including two photoelectric converting
layers above the semiconductor substrate 12 and including one
inorganic photoelectric converting layer in the semiconductor
substrate 12.
[0211] Also, although it is described that the organic
photoelectric converting material is used as the photoelectric
converting film 52 of the photoelectric converting unit 61 formed
above the semiconductor substrate 12 in the above-described
embodiments, it is also possible to adopt an inorganic
photoelectric converting material. The inorganic photoelectric
converting material includes crystalline silicon, amorphous
silicon, and a compound semiconductor such as a Cu--In--Ga--Se
compound (CIGS), a Cu--In--Se compound (CIS), a chalcopyrite
structure semiconductor, and GaAs, for example.
[0212] Although the planar size of the lower electrode 53c of the
phase difference pixel 2P is half the size of the lower electrode
53a of the normal pixel 2X in the above-described embodiments,
there is no limitation. It is sufficient that the sensitivities of
the photoelectric converting units 61 of the phase difference
pixels 2P are asymmetrical with respect to the light incident angle
and the photoelectric conversion regions of the phase difference
pixels 2P.sub.A and 2P.sub.B are symmetrical to each other.
[0213] Furthermore, although the upper electrode 53b forming the
photoelectric converting unit 61 is formed on the entire surface so
as to be shared by all the pixels and the lower electrode 53a is
formed for each pixel in the above-described embodiments, it is
also possible to form the upper electrode 53b for each pixel and
form the lower electrode 53a on the entire surface so as to be
shared by all the pixels. It is also possible to form both the
lower electrode 53a and the upper electrode 53b for each pixel.
[0214] Although the solid-state image sensor in which the first
conductivity type is the P-type and the second conductivity type is
the N-type, and an electron is used as a signal charge is described
in the above-described example, the present disclosure is also
applicable to the solid-state image sensor in which a positive hole
is used as the signal charge. That is, the first conductivity type
may be the N-type, the second conductivity type may be the P-type,
and the conductivity types of the above-described respective
semiconductor regions may be reversed.
[0215] Also, the technology of the present disclosure is applicable
not only to the solid-state image sensor which senses incident
light amount distribution of visible light and images as an image
but also to the general solid-state image sensor (physical amount
distribution sensing device) such as the solid-state image sensor
which images incident amount distribution of infrared rays, X-rays,
or particles as an image, or a fingerprint detecting sensor which
senses distribution of other physical amounts such as a pressure
and capacitance and images as an image in a broad sense.
[0216] The embodiment of the present disclosure is not limited to
the above-described embodiments and may be variously changed
without departing from the gist of the present disclosure.
[0217] For example, it is possible to adopt a combination of all or
some of a plurality of embodiments described above.
[0218] Meanwhile, the effects described in this specification are
illustrative only and are not limited; the effects other than those
described in this specification may also be included.
[0219] Meanwhile, the present disclosure may also have the
following configuration. [0220] (1)
[0221] A solid-state image sensor including:
[0222] a first pixel including a photoelectric converting unit
formed of a photoelectric converting film and first and second
electrodes which interpose the photoelectric converting film from
above and below in which at least one of the first and second
electrodes is a separated electrode separated for each pixel;
and
[0223] a second pixel including the photoelectric converting unit
in which the separated electrode is formed to have a planar size
smaller than the planar size of the separated electrode of the
first pixel and a third electrode extending at least to a boundary
of the pixel is formed in a region which is vacant due to a smaller
planar size. [0224] (2)
[0225] The solid-state image sensor according to (1) described
above, wherein
[0226] the third electrode is connected to a charge holding unit
which holds a charge generated by the photoelectric converting
unit. [0227] (3)
[0228] The solid-state image sensor according to (1) or (2)
described above, wherein
[0229] the third electrode is the separated electrode of an
adjacent pixel. [0230] (4)
[0231] The solid-state image sensor according to (1) or (2)
described above, wherein
[0232] the third electrode lies across three pixels including the
second pixel and an adjacent pixel. [0233] (5)
[0234] The solid-state image sensor according to (1) described
above, wherein
[0235] the third electrode is connected to wiring which supplies
fixed potential. [0236] (6)
[0237] The solid-state image sensor according to (1) or (5)
described above, wherein
[0238] the third electrode is an element separating electrode
formed between separated electrodes of adjacent pixels. [0239]
(7)
[0240] The solid-state image sensor according to (1) described
above, wherein
[0241] the third electrode is an isolated pattern which is not
connected to wiring. [0242] (8)
[0243] The solid-state image sensor according to any one of (1) to
(7) described above, wherein
[0244] the second pixel is a phase difference pixel which generates
a signal for detecting a focal point. [0245] (9)
[0246] The solid-state image sensor according to any one of (1) to
(8) described above, wherein
[0247] the photoelectric converting film is a film which performs
photoelectric conversion on light of a wavelength of a
predetermined color. [0248] (10)
[0249] The solid-state image sensor according to (9) described
above, wherein
[0250] the photoelectric converting film is a film which performs
the photoelectric conversion on green wavelength light. [0251]
(11)
[0252] The solid-state image sensor according to any one of (1) to
(10) described above, wherein
[0253] the second pixel is further provided with an inorganic
photoelectric converting unit in a semiconductor substrate, and
[0254] the inorganic photoelectric converting unit performs the
photoelectric conversion on light of a wavelength which is not
subjected to the photoelectric conversion by the photoelectric
converting unit. [0255] (12)
[0256] The solid-state image sensor according to any one of (1) to
(7) described above, wherein
[0257] the photoelectric converting film is a film capable of
performing photoelectric conversion on light of wavelengths of red,
green, and blue. [0258] (13)
[0259] The solid-state image sensor according to (12) described
above, wherein
[0260] a red, green, or blue color filter is arranged above the
photoelectric converting film, and
[0261] the photoelectric converting film performs the photoelectric
conversion on light which passes through the color filter. [0262]
(14)
[0263] A method of manufacturing a solid-state image sensor
including:
[0264] forming a first pixel including a photoelectric converting
unit formed of a photoelectric converting film and first and second
electrodes which interpose the photoelectric converting film from
above and below in which at least one of the first and second
electrodes is a separated electrode separated for each pixel,
and
[0265] a second pixel including the photoelectric converting unit
in which the separated electrode is formed to have a planar size
smaller than the planar size of the separated electrode of the
first pixel and a third electrode extending at least to a boundary
of the pixel is formed in a region which is vacant due to a smaller
planar size. [0266] (15)
[0267] An electronic device including:
[0268] a solid-state image sensor including:
[0269] a first pixel including a photoelectric converting unit
formed of a photoelectric converting film and first and second
electrodes which interpose the photoelectric converting film from
above and below in which at least one of the first and second
electrodes is a separated electrode separated for each pixel;
and
[0270] a second pixel including the photoelectric converting unit
in which the separated electrode is formed to have a planar size
smaller than the planar size of the separated electrode of the
first pixel and a third electrode extending at least to a boundary
of the pixel is formed in a region which is vacant due to a smaller
planar size.
REFERENCE SIGNS LIST
[0271] 1 Solid-state image sensor [0272] 2 Pixel [0273] 2X Normal
pixel [0274] 2P Phase difference pixel [0275] 2D Dummy pixel [0276]
3 Pixel array unit [0277] 12 Semiconductor substrate [0278] PD1,
PD2 Photodiode [0279] 41 to 43 Semiconductor region [0280] 49 FD
unit [0281] 52 Photoelectric converting film [0282] 53a Lower
electrode [0283] 53b Upper electrode [0284] 53c, 53d Lower
electrode [0285] 54 Metal wiring [0286] 56 High refractive index
layer [0287] 57 On-chip lens [0288] 61 Photoelectric converting
unit [0289] 81 Element separating electrode [0290] 82 Metal wiring
[0291] 83 Element separating electrode [0292] 91 Photoelectric
converting film [0293] 92 Color filter [0294] 300 Imaging device
[0295] 302 Solid-state image sensor
* * * * *