阅读说明：本技术 光电转换元件和摄像装置 (Photoelectric conversion element and imaging device ) 是由 菅野雅人 齐藤阳介 于 2020-03-04 设计创作，主要内容包括：根据本发明的一个实施方案的光电转换元件包括：第一电极；与第一电极相对的第二电极；和有机光电转换层,其设置在所述第一电极与所述第二电极之间,并且包含由通式(1)表示的基于苯并噻吩并苯并噻吩的化合物作为第一有机半导体材料。(A photoelectric conversion element according to an embodiment of the present invention includes: a first electrode; a second electrode opposed to the first electrode; and an organic photoelectric conversion layer which is provided between the first electrode and the second electrode, and which contains a benzothiophene-based compound represented by general formula (1) as a first organic semiconductor material.)

1. A photoelectric conversion element comprising:

a first electrode;

a second electrode opposite to the first electrode; and

an organic photoelectric conversion layer disposed between the first electrode and the second electrode, and containing a benzothiophene-based compound represented by the following general formula (1) as a first organic semiconductor material.

[ chemical formula 1]

(R1-R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

2. The photoelectric conversion element according to claim 1, wherein the organic photoelectric conversion layer further comprises a fullerene or a fullerene derivative as the second organic semiconductor material.

3. The photoelectric conversion element according to claim 1, wherein the organic photoelectric conversion layer further contains a third organic semiconductor material.

4. The photoelectric conversion element according to claim 3, wherein the third organic semiconductor material absorbs light of any wavelength from 400nm to 700nm (inclusive).

5. The photoelectric conversion element according to claim 1, wherein the organic photoelectric conversion layer absorbs light of all wavelengths in a range from 400nm to 700nm (inclusive).

6. The photoelectric conversion element according to claim 1, wherein the first electrode comprises a plurality of electrodes.

7. The photoelectric conversion element according to claim 1, wherein a first charge blocking layer is further provided between the first electrode and the organic photoelectric conversion layer.

8. The photoelectric conversion element according to claim 1, wherein a second charge blocking layer is further provided between the organic photoelectric conversion layer and the second electrode.

9. An image pickup apparatus having a plurality of pixels each including one or more organic photoelectric conversion portions, the organic photoelectric conversion portions each comprising:

a first electrode;

a second electrode opposed to the first electrode; and

an organic photoelectric conversion layer disposed between the first electrode and the second electrode, and containing a benzothiophene-based compound represented by the following general formula (1) as a first organic semiconductor material.

[ chemical formula 2]

(R1 to R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

10. The image pickup apparatus according to claim 9, wherein one or more of the organic photoelectric conversion portions and one or more inorganic photoelectric conversion portions that perform photoelectric conversion in a wavelength band different from that of the organic photoelectric conversion portion are stacked in each of the pixels.

11. The image pickup apparatus according to claim 10,

the inorganic photoelectric conversion part is formed to be embedded in a semiconductor substrate, and

the organic photoelectric conversion portion is formed on a first surface side of the semiconductor substrate.

12. The image pickup apparatus according to claim 11, wherein the semiconductor substrate has a second surface opposite to the first surface, and a multilayer wiring layer is formed on the second surface side.

13. The image pickup apparatus according to claim 11,

the organic photoelectric conversion portion photoelectrically converts blue light, and

an inorganic photoelectric conversion portion that photoelectrically converts green light and an inorganic photoelectric conversion portion that photoelectrically converts red light are stacked in the semiconductor substrate.

14. The image pickup apparatus according to claim 9, wherein a plurality of the organic photoelectric conversion portions that perform photoelectric conversion in wavelength bands different from each other are stacked in each of the pixels.

Technical Field

The present invention relates to a photoelectric conversion element using, for example, an organic material, and an imaging device including the photoelectric conversion element.

Background

For example, patent document 1 and non-patent document 1 have described, for example, using a combination of a coumarin dye and a fullerene as a material of a photoelectric conversion layer that absorbs blue light and performs photoelectric conversion of blue light.

List of cited documents

Patent document

Patent document 1: japanese unexamined patent application publication No. 2012-129276

Non-patent document

Non-patent document 1: Jpn.J.appl.Phys., Vol.49, No.11, pp.111601.1-11601.4(2010)

Disclosure of Invention

Incidentally, it is desirable to develop a photoelectric conversion element having high external quantum efficiency and high optical sensitivity.

It is desirable to provide a photoelectric conversion element and an image pickup apparatus capable of improving external quantum efficiency and optical sensitivity.

A photoelectric conversion element according to an embodiment of the present invention includes: a first electrode; a second electrode opposite to the first electrode; and an organic photoelectric conversion layer which is provided between the first electrode and the second electrode and contains a benzothiophene-based compound represented by the following general formula (1) as a first organic semiconductor material.

[ chemical formula 1]

(R1 to R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

An image pickup apparatus according to an embodiment of the present invention includes a plurality of pixels each including one or more organic photoelectric conversion portions, and includes the photoelectric conversion element according to the above-described embodiment as the organic photoelectric conversion portion.

In the photoelectric conversion element according to the embodiment of the present invention and the image pickup device according to the embodiment of the present invention, the organic photoelectric conversion layer is formed by using the benzothienobenzothiophene-based compound represented by the above general formula (1). This results in an improvement in carrier mobility with respect to the first electrode and the second electrode which are opposed to each other with the organic photoelectric conversion layer interposed therebetween.

Drawings

Fig. 1 is a schematic cross-sectional view of a constitutional example of an image pickup element according to a first embodiment of the present invention.

Fig. 2 is a diagram showing an overall configuration of the image pickup device shown in fig. 1.

Fig. 3 is an equivalent circuit diagram of the image pickup element shown in fig. 1.

Fig. 4 is a schematic diagram of a layout of lower electrodes and transistors included in a controller of the image pickup element shown in fig. 1.

Fig. 5 is a schematic cross-sectional view of another constitutional example of the image pickup element according to the first embodiment of the present invention.

Fig. 6 is a cross-sectional view 1 for explaining a method of manufacturing the image pickup device shown in fig. 1.

Fig. 7 is a cross-sectional view of a process subsequent to fig. 6.

Fig. 8 is a cross-sectional view of a process subsequent to fig. 7.

Fig. 9 is a cross-sectional view of a process subsequent to fig. 8.

Fig. 10 is a cross-sectional view of a process subsequent to fig. 9.

Fig. 11 is a timing chart showing an operation example of the image pickup element shown in fig. 1.

Fig. 12 is a schematic cross-sectional view of a constitutional example of an image pickup element according to a second embodiment of the present invention.

Fig. 13 is a schematic cross-sectional view of a constitutional example of an image pickup element according to a third embodiment of the present invention.

Fig. 14 is a schematic cross-sectional view of a constitutional example of an image pickup element according to a fourth embodiment of the present invention.

Fig. 15 is a block diagram showing a configuration of an image pickup apparatus using the image pickup device shown in fig. 1.

Fig. 16 is a functional block diagram showing an electronic apparatus (camera) using the image pickup device shown in fig. 15.

Fig. 17 is a block diagram showing an example of a schematic configuration of the in-vivo information acquisition system.

Fig. 18 is a diagram showing an example of a schematic configuration of an endoscopic surgery system.

Fig. 19 is a block diagram showing an example of functional configurations of a camera head and a Camera Control Unit (CCU).

Fig. 20 is a block diagram showing an example of a schematic configuration of a vehicle control system.

Fig. 21 is a view for assisting in explaining an example of mounting positions of the vehicle exterior information detecting unit and the imaging unit.

Detailed description of the preferred embodiments

Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings. A description is given below of specific examples of the present invention, and the present invention is not limited to the following embodiments. Further, the present invention is not limited to the positions, sizes, size ratios, and the like of the respective components shown in the respective drawings. Note that the description will be made in the following order.

1. First embodiment

(example of photoelectric conversion element having photoelectric conversion layer containing benzothienobenzothiophene-based compound)

1-1. construction of image pickup element

1-2. method for manufacturing image pickup element

1-3. action and Effect

2. Second embodiment (example in which two organic photoelectric conversion portions are stacked on a semiconductor substrate)

3. Third embodiment (example in which the lower electrode includes an organic photoelectric conversion portion formed with a solid film)

4. Fourth embodiment (example in which three organic photoelectric conversion portions are stacked on a semiconductor substrate)

5. Application example

6. Practical application example

7. Examples of the embodiments

<1. first embodiment >

Fig. 1 shows an example of a cross-sectional configuration of an image pickup element (image pickup element 10A) according to a first embodiment of the present disclosure. Fig. 2 shows a planar configuration of the image pickup element 10A shown in fig. 1. Fig. 3 is an equivalent circuit diagram of the image sensor 10A shown in fig. 1, and corresponds to the region 100 shown in fig. 2. Fig. 4 schematically illustrates the layout of the lower electrode 21 and the transistors included in the controller of the image pickup element 10A illustrated in fig. 1. The image pickup element 10A is included in one pixel (unit pixel P) of an image pickup apparatus (image pickup apparatus 1, see fig. 17) such as a CMOS (complementary metal oxide semiconductor) image sensor used for electronic devices such as a digital camera and a video camera, for example. The image pickup element 10A according to the present embodiment includes an organic photoelectric conversion portion 20 in which a lower electrode 21, a photoelectric conversion layer 24, and an upper electrode 25 are stacked in this order. The photoelectric conversion layer 24 is formed by using a benzothiophenobenzothiophene-based compound represented by the general formula (1) described later. The organic photoelectric conversion portion 20 corresponds to a specific example of the "photoelectric conversion element" of the present invention.

(1-1. construction of image pickup device)

The image pickup element 10A is of a so-called longitudinal spectral type in which one organic photoelectric conversion portion 20 and two inorganic photoelectric conversion portions 32G and 32R are stacked in the longitudinal direction. The organic photoelectric conversion portion 20 is disposed on the first surface (back surface; surface 30S1) side of the semiconductor substrate 30. The inorganic photoelectric conversion portions 32G and 32R are formed to be embedded in the semiconductor substrate 30, and are stacked in the thickness direction of the semiconductor substrate 30. As described above, the organic photoelectric conversion portion 20 includes the photoelectric conversion layer 24 between the lower electrode 21 and the upper electrode 25 which are opposed to each other. The photoelectric conversion layer 24 is formed by using an organic material. The photoelectric conversion layer 24 includes a p-type semiconductor and an n-type semiconductor, and has a bulk heterojunction structure in the layers. The bulk heterojunction structure is a p/n junction surface formed by mixing a p-type semiconductor and an n-type semiconductor.

The organic photoelectric conversion portion 20 and the inorganic photoelectric conversion portions 32G and 32R selectively detect light of a corresponding one of wavelength bands different from each other, respectively, and photoelectrically convert the light thus detected. For example, the organic photoelectric conversion portion 20 acquires a blue (B) color signal. The inorganic photoelectric conversion portions 32G and 32R obtain a green (G) color signal and a red (R) color signal, respectively, by the difference in absorption coefficient. This allows the image pickup element 10A to acquire a plurality of color signals in one pixel without using a color filter.

In this embodiment, a case where electrons in electron-hole pairs (electron-hole pairs) generated by photoelectric conversion are read as signal charges (a case where an n-type semiconductor region is used as a photoelectric conversion layer) will be described. In addition, "+ (plus)" following "p" or "n" in the drawings indicates that the p-type or n-type impurity concentration is high.

For example, a floating diffusion region (floating diffusion layer) FDl (region 36B of the semiconductor substrate 30), FD2 (region 37C of the semiconductor substrate 30) and FD3 (region 38C of the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplification transistor (modulation element) AMP, a reset transistor RST, a selection transistor SEL and a multilayer wiring 40 are provided on the second surface (front surface; 30S2) of the semiconductor substrate 30. The multilayer wiring 40 has, for example, a configuration in which wiring layers 41, 42, and 43 are stacked in an insulating layer 44.

Note that, in the drawing, the first surface (surface 30S1) side of the semiconductor substrate 30 is indicated as a light incident side Sl, and the second surface (surface 30S2) side of the semiconductor substrate 30 is indicated as a wiring layer side S2.

The organic photoelectric conversion portion 20 includes a lower electrode 21, a semiconductor layer 23, a photoelectric conversion layer 24, and an upper electrode 25 stacked in this order from the first surface (surface 30S1) side of the semiconductor substrate 30. Further, an insulating layer 22 is provided between the lower electrode 21 and the semiconductor layer 23. The lower electrode 21 is formed separately for each image pickup element 10A, for example, and includes a readout electrode 21A and an accumulation electrode 21B, the readout electrode 21A and the accumulation electrode 21B being separated from each other with an insulating layer 22 interposed therebetween as will be described in detail later. The readout electrode 21A of the lower electrode 21 is electrically connected to the semiconductor layer 23 via an opening 22H provided in the insulating layer 22. For example, fig. 1 shows an example in which the semiconductor layer 23, the photoelectric conversion layer 24, and the upper electrode 25 are provided as a common continuous layer for a plurality of image pickup elements 10A, but the semiconductor layer 23, the photoelectric conversion layer 24, and the upper electrode 25 may be formed separately for each image pickup element 10A, for example. For example, the dielectric film 26, the insulating film 27, and the interlayer insulating layer 28 are provided between the first surface (surface 30S1) of the semiconductor substrate 30 and the lower electrode 21. A protective layer 51 is provided on the upper electrode 21. For example, a light shielding film 52 is provided in the protective layer 51 at a position corresponding to the readout electrode 21A. It is sufficient that the light shielding film 52A is provided so as to cover at least the region of the readout electrode 21A which is in direct contact with the semiconductor layer 23 without covering at least the accumulation electrode 21B. Optical elements such as a planarization layer (not shown) and an on-chip lens 53 are provided over the protective layer 51.

The through electrode 34 is provided between the first surface (surface 30S1) and the second surface (surface 30S2) of the semiconductor substrate 30. The through electrode 34 is electrically connected to the readout electrode 21 of the organic photoelectric conversion portion 20, and the organic photoelectric conversion portion 20 is connected to the gate electrode Gamp of the amplification transistor AMP and one source/drain region 36B of the reset transistor RST (reset transistor Tr1RST) which also serves as the floating diffusion FD1 via the through electrode 34. This makes it possible to well transfer the electric charges generated in the organic photoelectric conversion portion 20 on the first surface (surface 30S21) side of the semiconductor substrate 30 to the second surface (surface 30S2) of the semiconductor substrate 30 and enhance the characteristics of the image pickup element 10A.

The lower end of the penetration electrode 34 is connected to the connection portion 41A in the wiring layer 41, and the connection portion 41A and the gate electrode Gamp of the amplification transistor AMP are connected to each other via the first lower contact portion 45. For example, the connection portion 41A and the floating diffusion FD1 (region 36B) are connected to each other via the second lower contact portion 46. For example, the upper end of the through electrode 34 is connected to the readout electrode 21A via the first upper contact portion 29A, the pad portion 39A, and the second upper contact portion 29B.

For example, the through electrode 34 is provided for each organic photoelectric conversion portion 20 of each image pickup element 10A. The through electrode 34 has a function as a connector between the organic photoelectric conversion portion 20 and both the gate Gamp of the amplification transistor AMP and the floating diffusion FD1, and functions as a transfer path of charges generated in the organic photoelectric conversion portion 20.

The reset gate Grst of the reset transistor RST is arranged adjacent to the floating diffusion region FDl (one source/drain region 36B of the reset transistor RST). This enables the charge accumulated in the floating diffusion FD1 to be reset by the reset transistor RST.

In the image pickup element 10A according to the present embodiment, the photoelectric conversion layer 24 absorbs light entering the organic photoelectric conversion portion 20 from the upper electrode 25 side. The excitons thus generated move to an interface between an electron donor (donor) and an electron acceptor (acceptor) contained in the photoelectric conversion layer 24, and the excitons are decomposed, that is, the excitons are decomposed into electrons and holes. The electric charges (electrons and holes) generated here are carried to different electrodes respectively by diffusion caused by a concentration difference between carriers or an internal electric field caused by a work function difference between an anode (e.g., the upper electrode 25) and a cathode (e.g., the lower electrode 21), and are detected as a photocurrent. Further, the transport direction of electrons and holes can also be controlled by applying an electric potential between the lower electrode 21 and the upper electrode 25.

The structure, material, and the like of each member will be described below.

The organic photoelectric conversion portion 20 is an organic photoelectric conversion element that absorbs light of a part or all of a wavelength band corresponding to a selected wavelength band (for example, from 400nm to 700nm) to generate electron-hole pairs.

The lower electrode 21 includes the readout electrode 21A and the accumulation electrode 21B which are formed separately as described above. For example, the readout electrode 21A transfers the electric charges generated in the photoelectric conversion layer 24 to the floating diffusion FD1, and is connected to the floating diffusion FD1 via the second upper contact portion 29B, the pad portion 39A, the first upper contact portion 29A, the through electrode 34, the connection portion 41A, and the second lower contact portion 46. The accumulation electrode 21B accumulates electrons as signal charges among the charges generated in the photoelectric conversion layer 24 in the semiconductor layer 23. The accumulation electrode 21B is directly opposed to the light receiving surfaces of the inorganic photoelectric conversion portions 32G and 32R formed in the semiconductor substrate 30, and is disposed in a region covering these light receiving surfaces. The accumulation electrode 21B is preferably larger than the readout electrode 21A, which enables accumulation of much electric charge. As shown in fig. 4, the voltage application circuit 60 is connected to the accumulation electrode 21B via a wiring.

The lower electrode 21 includes a conductive film having light-transmitting properties. Examples of the constituent material of the lower electrode 21 include ITO to which tin (Sn) is added as an impurity, In2O₃And indium tin oxide including crystalline ITO and amorphous ITO. In addition to the above materials, tin oxide (SnO) based on impurities may be added₂) Or a zinc oxide-based material prepared by adding impurities is used as a constituent material of the lower electrode 21. The zinc oxide-based material includes Aluminum Zinc Oxide (AZO) to which aluminum (Al) is added as an impurity, Gallium Zinc Oxide (GZO) to which gallium (Ga) is added, boron zinc oxide to which boron (B) is added, and Indium Zinc Oxide (IZO) to which indium (In) is added. In addition, CuI, InSbO may be used₄、ZnMgO、CuInO₂、MgIN₂O₄、CdO、ZnSnO₃、TiO₂Etc. are used as the constituent material of the lower electrode 21. In addition, spinel oxides or with YbFe can be used₂O₄An oxide of structure. Note that the lower electrode 21 formed using the above-described material generally has a high work function and functions as an anode electrode.

The semiconductor layer 23 is provided below the photoelectric conversion layer 24, specifically between the insulating layer 22 and the photoelectric conversion layer 24, and accumulates signal charges generated in the photoelectric conversion layer 24. The semiconductor layer 23 is preferably formed by using a material having higher charge mobility than that of the photoelectric conversion layer 24 and a large band gap. For example, the band gap of the constituent material of the semiconductor layer 23 is preferably 3.0eV or more. Examples of such materials include oxide semiconductor materials such as IGZO, organic semiconductor materials, and the like. Examples of organic semiconductor materials include transition metal disulfides, silicon carbide, diamond, graphene, carbon nanotubes, condensed polycyclic hydrocarbon compounds, condensed heterocyclic compounds, and the like. The semiconductor layer 23 has a thickness of, for example, 10nm to 300nm (inclusive). Providing the semiconductor layer 23 containing the above-described material below the photoelectric conversion layer 24 makes it possible to prevent charge recombination during charge accumulation and to improve transfer efficiency.

The photoelectric conversion layer 24 converts light energy into electric energy. The photoelectric conversion layer 24 according to the present embodiment absorbs, for example, a part or all of light of a wavelength in a range from 400nm to 700nm (inclusive). The photoelectric conversion layer 24 includes, for example, two or more organic materials (p-type semiconductor material or n-type semiconductor material) each serving as a p-type semiconductor or an n-type semiconductor. The photoelectric conversion layer 24 has a junction surface (p/n junction surface) of a p-type semiconductor material and an n-type semiconductor material in a layer. The p-type semiconductor functions relatively as an electron donor (donor), and the n-type semiconductor functions relatively as an electron acceptor (acceptor). The photoelectric conversion layer 24 provides a field where excitons generated upon absorption of light are decomposed into electrons and holes. Specifically, excitons are decomposed into electrons and holes at an interface (p/n junction surface) between an electron donor and an electron acceptor.

In addition to the p-type semiconductor material and the n-type semiconductor material, the photoelectric conversion layer 24 may include an organic material that photoelectrically converts light in a predetermined wavelength band and allows light in other wavelength bands to pass therethrough, so-called dye material (dye material). In the case where the photoelectric conversion layer 24 is formed by using three organic materials, that is, a p-type semiconductor material, an n-type semiconductor material, and a dye material, the p-type semiconductor material and the n-type semiconductor material are preferably materials having light transmittance in a visible light region (for example, 400nm to 700 nm). The thickness of the photoelectric conversion layer 24 is, for example, from 25nm to 400nm (inclusive), preferably from 50nm to 350nm (inclusive), and more preferably from 150nm to 300nm (inclusive).

In the present embodiment, the photoelectric conversion layer 24 is formed by including, for example, a benzothienobenzothiophene-based compound represented by the following general formula (1) that absorbs light of 400nm to 500nm (inclusive). The benzothienobenzothiophene-based compound corresponds to a specific example of the "first organic semiconductor material" of the present invention.

[ chemical formula 2]

(R1 to R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

Examples of the other organic material contained in the photoelectric conversion layer 24 include fullerene or a fullerene derivative. The fullerene or fullerene derivative corresponds to a specific example of the "second organic semiconductor material" of the present invention.

Further, the photoelectric conversion layer 24 may include, for example, an organic semiconductor material that absorbs any wavelength from 400nm to 700nm (inclusive). Examples of such materials include coumarin derivatives, perylene derivatives, porphyrin derivatives, cyanine derivatives, anthraquinone derivatives, and the like. The above-described organic semiconductor material corresponds to a specific example of the "third organic semiconductor material" of the present invention.

Depending on the combination, a combination of the above organic materials is used as a p-type semiconductor or an n-type semiconductor.

It is to be noted that the photoelectric conversion layer 24 may include an organic material other than the above-described organic semiconductor material. As the organic material other than the above-described organic semiconductor material, for example, one of quinacridone, boron chloride subphthalocyanine, pentacene, benzothiophenobenzothiophene, naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene, fluoranthene, and a derivative thereof is preferably used. Alternatively, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, or derivatives thereof may be used. Further, a metal complex dye, a cyanine-based dye, a merocyanine-based dye, a phenylxanthene-based dye, a triphenylmethane-based dye, a rhodanine-based (rhodacyanine) -based dye, a xanthene-based dye, a macrocyclic azacycloalkene-based dye, an azulene-based dye, naphthoquinone, an anthraquinone-based dye, a chain compound in which a condensed polycyclic aromatic group such as anthracene, pyrene, or the like is condensed with an aromatic ring or a heterocyclic compound, a cyanine-like dye bonded with two nitrogen-containing rings having a squarylium cyanine group and a crocoppressinemethyl group as a connecting chain, such as quinoline, benzothiazole, and benzoxazole, or a cyanine-like dye bonded with a squarylium cyanine group and a crocyanic deuteromethyl group, or the like can be preferably used. It is to be noted that, as the above-mentioned metal complex dye, a dye based on a dithiol metal complex, a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye is preferable, but the metal complex dye is not limited thereto.

The upper electrode 25 includes a conductive film having light transmittance, similarly to the lower electrode 21. In the image pickup device 1 using the image pickup element 10A as one pixel, the upper electrode 25 may be provided individually for each pixel, or may be formed as a common electrode for each pixel. For example, the upper electrode 25 has a thickness of 10nm to 200 nm.

Any other layer may be provided between the semiconductor layer 23 and the photoelectric conversion layer 24 and between the photoelectric conversion layer 24 and the upper electrode 25, respectively. For example, as in the image pickup element 10B shown in fig. 5, for example, a semiconductor layer 23, an electron blocking layer 24A (first charge blocking layer), a photoelectric conversion layer 24, and a hole blocking layer 24B (second charge blocking layer) are stacked in this order from the lower electrode 21 side. Further, a primer layer and a hole transport layer may be provided between the lower electrode 21 and the photoelectric conversion layer 24, or a work function adjusting layer, a buffer layer, or an electron transport layer may be provided between the photoelectric conversion layer 24 and the upper electrode 25.

The insulating layer 22 electrically isolates the accumulation electrode 21B and the semiconductor layer 23 from each other. The insulating layer 22 is provided on the interlayer insulating layer 28, for example, to cover the lower electrode 21. Further, the insulating layer 22 has an opening 2 above the readout electrode 21A of the lower electrode 212H, and the readout electrode 21A and the semiconductor layer 23 are electrically connected to each other via the opening 22H. The insulating layer 22 includes, for example, silicon oxide (SiO)_x) Silicon nitride (SiN)_x) A single layer film of one of silicon oxynitride (SiON), or a laminated film including two or more of them. For example, the insulating layer 22 has a thickness of 20nm to 500 nm.

The dielectric film 26 prevents reflection of light generated by a difference in refractive index between the semiconductor substrate 30 and the insulating film 27. As the material of the dielectric film 26, a material having a refractive index falling between the refractive index of the semiconductor substrate 30 and the refractive index of the insulating film 27 is preferable. Further, as the material of the dielectric film 26, for example, a material capable of forming a film having negative fixed charges is preferably used. Alternatively, as the material of the dielectric film 26, a semiconductor material or a conductive material having a wider band gap than that of the semiconductor substrate 30 is preferably used. This makes it possible to suppress generation of dark current at the interface of the semiconductor substrate 30. Such materials include hafnium oxide (HfO)_x) Aluminum oxide (AlO)_x) Zirconium oxide (ZrO)_x) Tantalum oxide (TaO)_x) Titanium oxide (TiO)_x) Lanthanum oxide (LaO)_x) Praseodymium oxide (PrO)_x) Cerium oxide (CeO)_x) Neodymium oxide (NdO)_x) Promethium oxide (Pm)_Ox) Samarium oxide (SmO)_x) Europium oxide (EuO)_x) Gadolinium oxide (GdO)_x) Terbium oxide (TbO)_x) Dysprosium oxide (DyO)_x) Holmium oxide (HoO)_x) Thulium oxide (TmO)_x) Ytterbium oxide (YbO)_x) Lutetium oxide (LuO)_x) Yttrium Oxide (YO)_x) Hafnium nitride (HfN)_x) Aluminum nitride (AlNx), hafnium oxynitride (HfO)_xN_y) Aluminum oxynitride (AlO)_xN_y) And the like.

The insulating film 27 is provided on the dielectric film 26, the dielectric film 26 is formed on the first surface (surface 30Sl) of the semiconductor substrate 30 and the side face of the through hole 30H, and the insulating film 27 electrically insulates the through electrode 34 and the semiconductor substrate 30 from each other. Examples of the material of the insulating film 27 include silicon oxide (SiO)_x) TEOS, silicon nitride (SiN)_x) Silicon oxynitride (SiON), and the like.

Interlayer insulating layer 28 comprises, for example, a silicon oxide (SiO)_x) TEOS, silicon nitride (SiN)_x) A single-layer film of one of silicon oxynitride (SiON), or a laminated film having two or more of these films.

The protective layer 51 includes a material having light transmittance, and includes, for example, a material having silicon oxide (SiO)_x) Silicon nitride (SiN)_x) A single-layer film of one of silicon oxynitride (SiON), or a laminated film having two or more of these films. For example, the protective layer 51 has a thickness of 100nm to 30000 nm.

The semiconductor substrate 30 includes, for example, an n-type silicon (Si) substrate, and has a p-well 31 in a predetermined region (for example, the pixel section 1 a). The above-described transfer transistors Tr2 and Tr3, the amplification transistor AMP, the reset transistor RST, the selection transistor SEL, and the like are provided on the second surface (surface 30S2) of the p-well 31. Further, as shown in fig. 2, for example, a pixel readout circuit 110 and a pixel drive circuit 120 including a logic circuit and the like are provided in the peripheral portion (peripheral portion 1b) of the semiconductor substrate 30.

The reset transistor RST (reset transistor Tr1RST) resets the electric charges transferred from the organic photoelectric conversion portion 20 to the floating diffusion FD1, and includes, for example, a MOS transistor. Specifically, the reset transistor Tr1rst includes a reset gate Grst, a channel formation region 36A, and source/drain regions 36B and 36C. The reset gate Grst is connected to a reset line RST1, and one source/drain region 36B of the reset transistor Tr1RST also functions as a floating diffusion FD 1. The other source/drain region 36C included in the reset transistor Tr1rst is connected to the power supply VDD.

The amplification transistor AMP is a modulation element that modulates the amount of charge generated in the organic photoelectric conversion portion 20 to a voltage, and includes, for example, a MOS transistor. Specifically, the amplifying transistor AMP includes a gate electrode Gamp, a channel forming region 35A, and source/drain regions 35B and 35C. The gate electrode Gamp is connected to the readout electrode 21A and the one source/drain region 36B (floating diffusion FD1) of the reset transistor Tr1rst via the first lower contact 45, the connection portion 41A, the second lower contact 46, the through electrode 34, and the like. Further, one source/drain region 35B shares one region with the other source/drain region 36C included in the reset transistor Tr1rst, and is connected to the power supply VDD.

The selection transistor SEL (selection transistor TR1SEL) includes a gate Gsel, a channel formation region 34A, and source/drain regions 34B and 34C. The gate Gsel is connected to the select line SEL 1. Further, one source/drain region 34B shares one region with the other source/drain region 35C included in the amplifying transistor AMP, and the other source/drain region 34C is connected to a signal line (data output line) VSL 1.

The inorganic photoelectric conversion portions 32G and 32R each have a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion portions 32G and 32R can split light in the longitudinal direction with a wavelength difference of absorbed light depending on the light incidence depth in the silicon substrate. The inorganic photoelectric conversion portion 32G selectively detects green light to accumulate signal charges corresponding to green, and is arranged at a depth such that the green light can be efficiently photoelectrically converted. The inorganic photoelectric conversion portion 32R selectively detects red light to accumulate signal charges corresponding to red, and is arranged at a depth such that red light can be efficiently photoelectrically converted. Note that green (G) and red (R) are colors corresponding to a wavelength band of, for example, 495nm to 620nm and a wavelength band of, for example, 620nm to 750nm, respectively. It is sufficient that each of the inorganic photoelectric conversion portions 32G and 32R can detect a part or all of the light of the corresponding one of the wavelength bands.

The inorganic photoelectric conversion portion 32G includes, for example, a p + region serving as a hole accumulation layer and an n region serving as an electron accumulation layer. The inorganic photoelectric conversion portion 32R includes, for example, a p + region serving as a hole accumulation layer and an n region (having a p-n-p stacked structure) serving as an electron accumulation layer. The n region of the inorganic photoelectric conversion portion 32G is connected to the vertical transfer transistor Tr 2. The p + region of the inorganic photoelectric conversion portion 32G is bent along the transfer transistor Tr2 and is connected to the p + region of the inorganic photoelectric conversion portion 32R.

The transfer transistor Tr2 (transfer transistor Tr2TRs) transfers the signal charge corresponding to the green color generated and accumulated in the inorganic photoelectric conversion section 32G to the floating diffusion FD 2. The inorganic photoelectric conversion portion 32G is formed at a position deeper from the second surface (surface 30S2) of the semiconductor substrate 30; therefore, the transfer transistor TR2TRs of the inorganic photoelectric conversion portion 32G preferably includes a vertical transistor. Further, the transfer transistor TR2TRs is connected to the transfer gate line TG 2. Further, the floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2 TRs. The electric charges accumulated in the inorganic photoelectric conversion portion 32G are read by the floating diffusion FD2 via a transfer channel formed along the gate Gtrs 2.

The transfer transistor Tr3 (transfer transistor Tr3TRs) transfers signal charges corresponding to red color generated and accumulated in the inorganic photoelectric conversion section 32R to the floating diffusion FD3, and includes, for example, a MOS transistor. Further, the transfer transistor TR3TRs is connected to the transfer gate line TG 3. Further, the floating diffusion FD3 is provided in the region 38C near the gate Gtrs3 of the transfer transistor TR3 TRs. The electric charges accumulated in the inorganic photoelectric conversion portion 32R are read by the floating diffusion FD3 via a transfer channel formed along the gate Gtrs 3.

A reset transistor TR2rst, an amplification transistor TR2amp, and a selection transistor TR2sel included in the control portion of the inorganic photoelectric conversion portion 32G are also provided on the second surface (surface 30S2) side of the semiconductor substrate 30. Further, a reset transistor TR3rst, an amplification transistor TR3amp, and a selection transistor TR3sel included in the control portion of the inorganic photoelectric conversion portion 32R are provided.

The reset transistor TR2rst includes a gate, a channel formation region, and source/drain regions. The gate of the reset transistor TR2RST is connected to the reset line RST2, and one source-drain region of the reset transistor TR2RST is connected to the power supply VDD. The other source/drain region of the reset transistor TR2rst also serves as the floating diffusion FD 2.

The amplification transistor TR2amp includes a gate, a channel formation region, and source/drain regions. The gate is connected to the other source/drain region (floating diffusion FD2) of the reset transistor TR2 rst. Further, one source/drain region included in the amplification transistor TR2amp shares a region with one source/drain region included in the reset transistor TR2rst, and is connected to the power supply VDD.

The selection transistor TR2sel includes a gate, a channel formation region, and source/drain regions. The gate is connected to a select line SEL 2. Further, one source/drain region included in the selection transistor TR2sel shares a region with the other source/drain region included in the amplification transistor TR2 amp. The other source/drain region included in the selection transistor TR2sel is connected to a signal line (data output line) VSL 2.

The reset transistor TR3rst includes a gate, a channel formation region, and source/drain regions. The gate of the reset transistor TR3RST is connected to the reset line RST3, and one source/drain region included in the reset transistor TR3RST is connected to the power supply VDD. The other source/drain region included in the reset transistor TR3rst also serves as the floating diffusion FD 3.

The amplification transistor TR3amp includes a gate, a channel formation region, and source/drain regions. The gate is connected to the other source/drain region (floating diffusion FD3) included in the reset transistor TR3 rst. Further, one source/drain region included in the amplification transistor TR3amp shares a region with one source/drain region included in the reset transistor TR3rst, and is connected to the power supply VDD.

The selection transistor TR3sel includes a gate, a channel formation region, and source/drain regions. The gate is connected to a select line SEL 3. One source/drain region included in the selection transistor TR3sel shares a region with the other source/drain region included in the amplification transistor TR3 amp. The other source/drain region included in the selection transistor TR3sel is connected to a signal line (data output line) VSL 3.

The reset lines RSTl, RST2, and RST3, the select lines SELl, SEL2, and SEL3, and the transmission gate lines TG2 and TG3 are all connected to the vertical drive circuit 112 included in the drive circuit. The signal lines (data output lines) VSL1, VSL2, and VSL3 are connected to the column signal processing circuit 113 included in the drive circuit.

The first lower contact 45, the second lower contact 46, the first upper contact 29A, the second upper contact 29B, and the third upper contact 29C each contain, for example, a doped silicon material such as PDAS (phosphorus-doped amorphous silicon), or a metal material such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), and tantalum (Ta).

(1-2. method for manufacturing image pickup device)

The image pickup element 10A according to the present embodiment can be manufactured, for example, as follows.

Fig. 6 to 10 illustrate a method of manufacturing the image pickup element 10A in order of process. First, as shown in fig. 6, for example, a p-well 31 as a well of a first conductivity type is formed in a semiconductor substrate 30, and inorganic photoelectric conversion portions 32G and 32R of a second conductivity type (for example, n-type) are formed in the p-well 31. A p + region is formed in the vicinity of the first surface (surface 30S1) of the semiconductor substrate 30.

Similarly, as shown in fig. 6, on the second surface (surface 30S2) of the semiconductor substrate 30, for example, n + regions serving as floating diffusion regions FD1 to FD3 are formed, and then, a gate insulating layer 33 and a gate wiring layer 47 including respective gates of the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplification transistor AMP, and the reset transistor RST are formed. Thus, the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplification transistor AMP, and the reset transistor RST are formed. Further, the multilayer wiring 40 including the wiring layers 41 to 43 and the insulating layer 44 is formed on the second surface (surface 30S2) of the semiconductor substrate 30. The wiring layers 41 to 43 include first lower contacts 45, second lower contacts 46, and connection portions 41A.

As a base substrate of the semiconductor substrate 30, an SOI (silicon on insulator) substrate in which the semiconductor substrate 30, an embedded oxide film (not shown), and a holding substrate (not shown) are stacked is used. The embedded oxide film and the holding substrate are not shown in fig. 6, but they are bonded to the first surface (surface 30S1) of the semiconductor substrate 30. Annealing treatment is performed after ion implantation.

Next, a supporting substrate (not shown), another semiconductor substrate, and the like are bonded to the second surface (surface 30S2) side (multilayer wiring 40 side) of the semiconductor substrate 30, and turned upside down. Next, the semiconductor substrate 30 is separated from the embedded oxide film of the SOI substrate and the holding substrate to expose the first surface of the semiconductor substrate 30 (surface 30S 1). The above-described process may be performed using a technique used in a general CMOS process such as ion implantation and CVD (chemical vapor deposition).

Next, as shown in fig. 7, the semiconductor substrate 30 is processed from the first surface (surface 30S1) side by, for example, dry etching to form, for example, a ring-shaped through hole 30H. As shown in fig. 7, for example, the depth of the through-hole 30H preferably penetrates from the first surface (surface 30S1) to the second surface (surface 30S2) of the semiconductor substrate 30 and reaches the connection portion 41A.

Next, as shown in fig. 8, the dielectric film 26 is formed on the first surface (surface 30S1) of the semiconductor substrate 30 and the side surfaces of the through-holes 30H, for example, by using an Atomic Layer Deposition (ALD) method. Thus, the dielectric film 26 is continuously formed on the first surface (surface 30S1) of the semiconductor substrate 30 and the side and bottom surfaces of the through-hole 30H. Next, insulating film 27 is formed in the first surface (surface 30S1) of semiconductor substrate 30 and through-hole 30H, and then, insulating film 27 and dielectric film 26 formed on the bottom surface of through-hole 30H are removed by, for example, dry etching to expose connection portion 41A. Note that, at this time, the insulating film 27 on the first surface (surface 30S1) is also thinned. Next, a conductive film is formed on the insulating film 27 and in the through hole 30H, and then a photoresist PR is formed at a predetermined position on the conductive film. Next, etching and removal of the photo-etchant PR are performed to form the through-electrode 34, the through-electrode 34 having a protruding portion on the first surface (surface 30S1) of the semiconductor substrate 30.

Next, as shown in fig. 9, an insulating film for forming the interlayer insulating layer 28 is formed on the insulating film 27 and the through electrode 34, and then the first upper contact portion 29A, the pad portions 39A and 39B, the second upper contact portion 29B, and the third upper contact portion 29C are formed on the through electrode 34 and the like. Then, the surface of the interlayer insulating layer 28 is planarized by using a CMP (chemical mechanical polishing) method. Next, a conductive film 21x is formed on the interlayer insulating layer 28, and then a photoresist is formed at a predetermined position of the conductive film 21 x.

Next, as shown in fig. 10, etching and removal of the photo-etchant are performed to form the readout electrode 21A and the accumulation electrode 21B.

Then, the insulating layer 22 is formed on the interlayer insulating layer 28, the readout electrode 21A, and the accumulation electrode 21B, and then the opening 22H is provided on the readout electrode 21A. Next, the semiconductor layer 23, the photoelectric conversion layer 24, and the upper electrode 25 are sequentially formed on the insulating layer 22. Finally, a protective layer 51, a light-shielding film 52, and an on-chip lens 53 are provided on the upper electrode 25. Thereby, the image pickup element 10A shown in fig. 1 is completed.

Note that in the case where the semiconductor layer 23 and other organic layers are formed using an organic material, it is desirable to form the semiconductor layer 23 and the organic layers continuously in a vacuum process (by an in-situ vacuum process). Further, the formation method of the organic photoelectric conversion layer 16 is not necessarily limited to a method using a vacuum evaporation method, and other methods such as a spin coating technique, a printing technique, and the like may be used. Further, depending on the material contained in the transparent electrode, the formation method of the transparent electrode (the lower electrode 21 and the upper electrode 25) may include a physical vapor deposition method (PVD method) such as a vacuum evaporation method, a reactive evaporation method, various sputtering methods, an electron beam evaporation method, and an ion plating method, a thermosol method, a thermal decomposition method of an organic metal component, a spray method, a dipping method, various chemical vapor deposition methods (CVD methods) including an MOCVD method, an electroless plating method, and an electroplating method.

In the image pickup element 10A, in the case where light enters the organic photoelectric conversion portion 20 via the on-chip lens 53, the light passes through the organic photoelectric conversion portion 20 and the inorganic photoelectric conversion portions 32G and 32R in this order, and each of green light, blue light, and red light is photoelectrically converted in the process of passing through. The signal acquisition operation for each color will be described below.

(acquisition of blue Signal by organic photoelectric conversion portion 20)

Of the light entering the image pickup element 10A, blue light is first selectively detected (absorbed) in the organic photoelectric conversion portion 20 and photoelectrically converted.

The organic photoelectric conversion portion 20 is connected to the gate Gamp of the amplification transistor AMP and the floating diffusion FD1 via the through electrode 34. Therefore, the electrons of the electron-hole pairs generated in the organic photoelectric conversion portion 20 are taken out from the lower electrode 21 side, transported to the second surface (surface 30S2) side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD 1. At the same time, the amount of electric charge generated in the organic photoelectric conversion portion 20 is modulated into a voltage by the amplifying transistor AMP.

Further, a reset gate Grst of the reset transistor RST is arranged adjacent to the floating diffusion region FDl. Accordingly, the charge accumulated in the floating diffusion FD1 is reset by the reset transistor RST.

Here, the organic photoelectric conversion portion 20 is connected not only to the amplification transistor AMP but also to the floating diffusion region FDl through the penetration electrode 34, thereby enabling the reset transistor RST to easily reset the electric charges accumulated in the floating diffusion region FD 1.

In contrast to this, in the case where the through electrode 34 is not connected to the floating diffusion region FDl, the electric charges accumulated in the floating diffusion region FDl are difficult to be reset, resulting in the electric charges being attracted to the upper electrode 25 side by the applied large voltage. This may damage the photoelectric conversion layer 24. Further, the configuration capable of resetting in a short time leads to an increase in dark-time noise, resulting in trade-offs; therefore, such a configuration is difficult.

Fig. 11 shows an operation example of the image pickup element 10A, in which (a) shows the potential at the accumulation electrode 21B, (B) shows the potential at the floating diffusion FD1 (readout electrode 21A), and (C) shows the potential at the gate (Gsel) of the reset transistor TR1 rst. In the image pickup element 10A, a voltage is individually applied to each of the readout electrode 21A and the accumulation electrode 21B.

In the image pickup element 10A, in the accumulation period, the drive circuit applies a potential Vl to the readout electrode 21A, and applies a potential V2 to the accumulation electrode 21B. Here, it is assumed that the potentials V1 and V2 satisfy V2 > V1. This causes the charges (signal charges; electrons) generated by the photoelectric conversion to be attracted to the accumulation electrode 21B and accumulated in a region of the semiconductor layer 23 opposite to the accumulation electrode 21B (accumulation period). Further, the potential value of the region of the semiconductor layer 23 opposed to the accumulation electrode 21B becomes more negative with the passage of time of photoelectric conversion. Note that holes are transferred from the upper electrode 25 to the driver circuit.

In the image pickup element 10A, the reset operation is performed in the latter stage of the accumulation period. Specifically, at time t1, the scanning unit changes the voltage of the reset signal RST from low level to high level. This turns on the reset transistor TR1rst in the unit pixel P, and therefore, the voltage of the floating diffusion FD1 is set to the power supply voltage VDD, and the voltage of the floating diffusion FD1 is reset (reset period).

After the reset operation is completed, the charges are read out. Specifically, at time t2, the drive circuit applies a potential V3 to the readout electrode 21A, and a potential V4 to the accumulation electrode 21B. Here, it is assumed that the potentials V3 and V4 satisfy V3 < V4. This causes the electric charges accumulated in the region corresponding to the accumulation electrode 21B to be read out from the readout electrode 21A to the floating diffusion FD 1. That is, the electric charges accumulated in the semiconductor layer 23 are read out by the control section (transfer period).

After the readout operation is completed, the drive circuit applies the potential Vl to the readout electrode 21A again, and applies the potential V2 to the accumulation electrode 21B again. This causes the electric charges generated by photoelectric conversion to be attracted to the accumulation electrode 21B and accumulated in the region of the photoelectric conversion layer 24 opposite to the accumulation electrode 21B (accumulation period).

(acquisition of Green and Red signals by the inorganic photoelectric conversion portions 32G and 32R)

Next, of the light that has passed through the organic photoelectric conversion portion 20, green light and red light are sequentially absorbed and photoelectrically converted in the inorganic photoelectric conversion portion 32G and the inorganic photoelectric conversion portion 32R, respectively. In the inorganic photoelectric conversion section 32G, electrons corresponding to incident green light are accumulated in the n region of the inorganic photoelectric conversion section 32G, and the accumulated electrons are transferred to the floating diffusion FD2 through the transfer transistor Tr 2. Similarly, in the inorganic photoelectric conversion section 32R, electrons corresponding to incident red light are accumulated in the n region of the inorganic photoelectric conversion section 32R, and the accumulated electrons are transferred to the floating diffusion FD3 through the transfer transistor Tr 3.

(1-3. action and Effect)

As described above, it is desired to develop a photoelectric conversion element for blue light having high external quantum efficiency. For example, blue organic photoelectric conversion elements using porphyrin dyes have been reported; however, its external quantum efficiency at 80V is about 20%. Further, a photoelectric conversion element using a combination of a fullerene and a coumarin dye as a material of a blue organic photoelectric conversion film has been reported. However, its external quantum efficiency at 5V is about 23%.

In contrast, in the present embodiment, as the material of the photoelectric conversion layer 24, a benzothiophene-based compound represented by the above general formula (1) is used.

In the benzothienobenzothiophene-based compound represented by the above general formula (1), the long axis of the molecule adopts a face-on orientation (surface-on orientation) horizontally with respect to the surface of the substrate. Further, the benzothiophene-based compound represented by the above general formula (1) can be a herringbone-type crystal which is favorable for carrier transport by a strong intermolecular interaction by the benzothiophene skeleton. Therefore, the benzothiophene-based compound represented by general formula (1) of the photoelectric conversion layer 24 exhibits high carrier mobility with respect to the vertical direction of the respective electrode surfaces of the lower electrode 21 and the upper electrode 25. In addition, the benzothienobenzothiophene-based compound represented by general formula (1) exhibits excellent photoresponse current at low voltage.

As described above, the photoelectric conversion layer 24 is formed to absorb light of 400nm to 500nm (inclusive) and has high carrier mobility toward the lower electrode 21 and the upper electrode 25. This enables provision of the image pickup element 10A for blue light with high external quantum efficiency.

Further, the benzothienobenzothiophene-based compound represented by general formula (1) exhibits high carrier mobility with respect to the vertical direction of the respective electrode surfaces of the lower electrode 21 and the upper electrode 25 which are opposed to each other with the photoelectric conversion layer 24 interposed therebetween. This makes it possible to improve the photocurrent switching response characteristic depending on the presence or absence of light irradiation.

Further, the benzothienobenzothiophene-based compound represented by the general formula (1) has a transition dipole moment horizontal to the light incidence direction, which enables strong absorption of light of 400nm to 500nm (inclusive). Therefore, no on-chip color filter is required, and a so-called longitudinal spectral type image pickup element in which photoelectric conversion portions absorbing light of wavelengths different from each other are stacked in the longitudinal direction like the imaging element 10A according to the present embodiment can be configured.

Next, the second to fifth embodiments of the present invention will be explained. Hereinafter, the components similar to those in the above-described first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

<2 > second embodiment

Fig. 12 shows a cross-sectional configuration of an image pickup element (image pickup element 10C) according to a second embodiment of the present invention. The image pickup element 10C is included in one pixel (unit pixel P) in an image pickup apparatus (image pickup apparatus 1) such as a CMOS image sensor used for electronic equipment such as a digital still camera and a video camera, for example. The image pickup element 10C according to the present embodiment includes two organic photoelectric conversion portions 20 and 70 and one inorganic photoelectric conversion portion 32 stacked in the longitudinal direction.

The organic photoelectric conversion portions 20 and 70 and the inorganic photoelectric conversion portion 32 selectively detect light in a corresponding one of wavelength bands different from each other, respectively, and photoelectrically convert the light thus detected. Specifically, for example, the organic photoelectric conversion portion 20 acquires a blue (B) color signal, similarly to the first embodiment described above. The organic photoelectric conversion portion 70 acquires, for example, a green (G) color signal. The inorganic photoelectric conversion portion 32 acquires, for example, a red (R) color signal. This allows the image pickup element 10C to acquire a plurality of color signals in one pixel without using a color filter.

The organic photoelectric conversion portion 70 is stacked over the organic photoelectric conversion portion 20, for example, and has a configuration in which the lower electrode 71, the semiconductor layer 73, the photoelectric conversion layer 74, and the upper electrode 75 are stacked in this order from the first surface (surface 30S1) of the semiconductor substrate 30, similarly to the organic photoelectric conversion portion 20. Further, an insulating layer 72 is provided between the lower electrode 71 and the semiconductor layer 73. The lower electrodes 71 are formed separately for each image pickup element 10C, for example, and include a readout electrode 71A and an accumulation electrode 71B separated from each other with an insulating layer 72 interposed therebetween as will be described later. The readout electrode 71A of the lower electrode 71 is electrically connected to the photoelectric conversion layer 74 via an opening 72H provided in the insulating layer 72. Fig. 12 shows an example in which the semiconductor layer 73, the photoelectric conversion layer 74, and the upper electrode 75 are formed separately for each image pickup element 10C. However, the semiconductor layer 73, the photoelectric conversion layer 74, and the upper electrode 75 may be formed as a common continuous layer for the plurality of image pickup elements 10C, for example.

The photoelectric conversion layer 74 converts light energy into electric energy, and includes, for example, two or more organic materials (p-type semiconductor material or n-type semiconductor material) serving as a p-type semiconductor or an n-type semiconductor, respectively, similarly to the photoelectric conversion layer 24. The photoelectric conversion layer 74 may include, in addition to the p-type semiconductor material and the n-type semiconductor material, an organic material that photoelectrically converts light in a predetermined wavelength band and allows light in other wavelength bands to pass therethrough, so-called a dye material. In the case where the photoelectric conversion layer 74 is formed by using three organic materials of a p-type semiconductor material, an n-type semiconductor material, and a dye material, the p-type semiconductor material and the n-type semiconductor material are preferably materials having light transmittance in a visible light region (for example, 400nm to 700 nm). The thickness of the photoelectric conversion layer 74 is, for example, from 25nm to 400nm (inclusive), preferably from 50nm to 350nm (inclusive), and more preferably from 150nm to 300nm (inclusive). Examples of the dye material for the photoelectric conversion layer 74 include subphthalocyanine, phthalocyanine, coumarin, porphyrin, derivatives thereof, and the like.

Two through electrodes 34X and 34Y are provided between the first surface (surface 30S1) and the second surface (surface 30S2) of the semiconductor substrate 30.

Similarly to the above-described first embodiment, the through electrode 34X is electrically connected to the readout electrode 21A of the organic photoelectric conversion portion 20, and the organic photoelectric conversion portion 20 is connected to the gate electrode Gamp of the amplification transistor AMP and one source/drain region 36B1 of the reset transistor RST (reset transistor Tr1RST) also serving as the floating diffusion FD1 via the through electrode 34X. For example, the upper end of the through electrode 34X is connected to the readout electrode 21A via the first upper contact portion 29A, the pad portion 39A, and the second upper contact portion 29B.

The through electrode 34Y is electrically connected to the readout electrode 71A of the organic photoelectric conversion portion 70, and the organic photoelectric conversion portion 70 is connected to the gate electrode Gamp of the amplification transistor AMP and one source/drain region 36B2 of the reset transistor (reset transistor Tr2rst) that also serves as the floating diffusion FD2 via the through electrode 34Y. The upper end of the through electrode 34Y is connected to the readout electrode 71A via, for example, a fourth upper contact portion 79A, a pad portion 69A, a fifth upper contact portion 79B, a pad portion 69B, and a sixth upper contact portion 79C. Further, the pad 69C is connected to the accumulation electrode 71B of the lower electrode 71 included in the organic photoelectric conversion portion 70 via the seventh upper contact portion 79D.

As described above, the image pickup element 10B according to the present embodiment has a configuration in which two organic photoelectric conversion portions 20 and 70 and one inorganic photoelectric conversion portion 32 are stacked, and similarly to the above-described first embodiment, the photoelectric conversion layer 24 included in the organic photoelectric conversion portion 20 that obtains a blue (B) color signal is formed, for example, by using a benzothienobenzothiophene-based compound represented by the above-described general formula (1). This enables effects similar to those in the first embodiment described above to be achieved.

<3. third embodiment >

Fig. 13 schematically shows a cross-sectional configuration of an image pickup element (image pickup element 10D) according to a third embodiment of the present invention. The image pickup element 10D is included in one pixel (unit pixel P) in an image pickup device (image pickup device 1) such as a CMOS image sensor used for an electronic apparatus such as a digital still camera and a video camera, for example. The organic photoelectric conversion portion 80 according to the present embodiment is different from the first and second embodiments described above in that: the organic photoelectric conversion portion 80 has the following structure: in which the lower electrode 81, the photoelectric conversion layer 24, and the upper electrode 25 are stacked in this order, and the lower electrode 81 is formed as a solid film in the pixel.

The image pickup element 10D includes one organic photoelectric conversion portion 80 and two inorganic photoelectric conversion portions 32G and 32R stacked in the longitudinal direction for each unit pixel P. The organic photoelectric conversion portion 80 and the inorganic photoelectric conversion portions 32G and 32R selectively detect light in a corresponding one of wavelength bands different from each other, respectively, and photoelectrically convert the light thus detected. Specifically, for example, the organic photoelectric conversion portion 80 acquires a blue (B) color signal, similarly to the first embodiment described above. A multilayer wiring layer 40 is provided on the second surface (surface 30S2) of the semiconductor substrate 30. The multilayer wiring layer 40 has, for example, a configuration in which wiring layers 41, 42, and 43 are stacked in an insulating layer 44.

The organic photoelectric conversion portion 80 is an organic photoelectric conversion element that absorbs light corresponding to a part or all of a wavelength band of a selected wavelength band (for example, from 400nm to 700nm, inclusive) to generate electron-hole pairs. As described above, the organic photoelectric conversion portion 80 includes, for example, the lower electrode 81 and the upper electrode 25 which face each other, and the photoelectric conversion layer 24 provided between the lower electrode 81 and the upper electrode 25. As shown in fig. 13, in the organic photoelectric conversion portion 80 according to the present embodiment, the lower electrode 81, the photoelectric conversion layer 24, and the upper electrode 25 each have a configuration similar to that of the organic photoelectric conversion portion 20 according to the above-described first embodiment except that the lower electrode 81 is formed as a solid film in each pixel.

For example, floating diffusion regions (floating diffusion layers) FDl, FD2, and FD3, a vertical transistor (transfer transistor) Trl, a transfer transistor Tr2, an amplification transistor (modulation element) AMP, and a reset transistor RST are provided on the second surface (surface 30S2) of the semiconductor substrate 30.

The vertical transistor Trl is a transfer transistor that transfers signal charges corresponding to green color generated and accumulated in the inorganic photoelectric conversion portion 32G to the floating diffusion region FDl. The inorganic photoelectric conversion portion 32G is formed at a position deeper from the second surface (surface 30S2) of the semiconductor substrate 30; therefore, the transfer transistor of the inorganic photoelectric conversion portion 32G preferably includes the vertical transistor Tr 1. The transfer transistor Tr2 transfers signal charges corresponding to red color generated and accumulated in the inorganic photoelectric conversion section 32R to the floating diffusion FD2, and includes, for example, a MOS transistor. The amplification transistor AMP is a modulation element that modulates the amount of electric charge generated in the organic photoelectric conversion portion 80 into a voltage, and includes, for example, a MOS transistor. The reset transistor RST resets the electric charges transferred from the organic photoelectric conversion portion 80 to the floating diffusion FD3, and includes, for example, a MOS transistor.

The first and second lower contacts 45 and 46 each include, for example, a doped silicon material such as PDAS (phosphorus-doped amorphous silicon), or a metal material such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), and tantalum (Ta).

In the image pickup element 10D, each color signal is acquired as follows.

(acquisition of blue Signal by organic photoelectric conversion portion 80)

Of the light that has entered the image pickup element 10D, blue light is first selectively detected (absorbed) in the organic photoelectric conversion portion 80 and photoelectrically converted.

The organic photoelectric conversion portion 80 is connected to the gate Gamp of the amplification transistor AMP and the floating diffusion FD3 via the through electrode 34. Therefore, electrons of the electron-hole pairs generated in the organic photoelectric conversion portion 80 are extracted from the lower electrode 81 side, transported to the second surface (surface 30S2) side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD 3. At the same time, the amount of electric charge generated in the organic photoelectric conversion portion 80 is modulated into a voltage by the amplifying transistor AMP.

Further, a reset gate Grst of a reset transistor RST is arranged adjacent to the floating diffusion FD 3. Accordingly, the charge accumulated in the floating diffusion FD3 is reset by the reset transistor RST.

Here, the organic photoelectric conversion portion 80 is connected not only to the amplification transistor AMP but also to the floating diffusion FD3 through the penetration electrode 34, thereby enabling the reset transistor RST to easily reset the electric charges accumulated in the floating diffusion FD 3.

In contrast to this, in the case where the through electrode 34 is not connected to the floating diffusion FD3, the electric charges accumulated in the floating diffusion FD3 are difficult to be reset, resulting in the electric charges being attracted to the upper electrode 25 side by the large voltage applied. This may damage the photoelectric conversion layer 24. Furthermore, a configuration capable of resetting in a short time leads to an increase in dark-time noise, resulting in a trade-off; therefore, such a configuration is difficult.

(acquisition of Green and Red signals by the inorganic photoelectric conversion portions 32G and 32R)

Next, of the light that has passed through the organic photoelectric conversion portion 80, green light and red light are sequentially absorbed and photoelectrically converted in the inorganic photoelectric conversion portion 32G and the inorganic photoelectric conversion portion 32R, respectively. In the inorganic photoelectric conversion section 32G, electrons corresponding to incident green light are accumulated in the n region of the inorganic photoelectric conversion section 32G, and the accumulated electrons are transferred to the floating diffusion FD1 through the vertical transistor Tr 1. Similarly, in the inorganic photoelectric conversion section 32R, electrons corresponding to incident red light are accumulated in the n region of the inorganic photoelectric conversion section 32R, and the accumulated electrons are transferred to the floating diffusion FD2 through the transfer transistor Tr 2.

As described above, in the image pickup element 10D according to the present embodiment, the lower electrode 81 included in the organic photoelectric conversion portion 80 is formed as a solid film, and the photoelectric conversion layer 24 including the acquisition of the blue (B) color signal in the photoelectric conversion portion is formed by using the benzothiophenobenzothiophene-based compound represented by the above general formula (1), for example, similarly to the above-described first embodiment. This enables effects similar to those in the first embodiment described above to be achieved.

<4. fourth embodiment >

Fig. 14 schematically shows a cross-sectional configuration of an image pickup element (image pickup element 10E) according to a fourth embodiment of the present invention. The image pickup element 10E is included in one pixel (unit pixel P) in an image pickup device (image pickup device 1) such as a CMOS image sensor used for electronic apparatuses such as a digital still camera and a video camera, for example. The image pickup element 10E according to the present embodiment has the following configuration: here, the red photoelectric conversion portion 90R, the green photoelectric conversion portion 90G, and the blue photoelectric conversion portion 90B are stacked in this order on the semiconductor substrate 30 with the insulating layer 96 interposed therebetween and the semiconductor substrate 30.

The red photoelectric conversion section 90R, the green photoelectric conversion section 90G, and the blue photoelectric conversion section 90B include organic photoelectric conversion layers 92R, 92G, and 92B between a pair of electrodes (specifically, between the first electrode 91R and the second electrode 93R, between the first electrode 91G and the second electrode 93G, and between the first electrode 91B and the second electrode 93B), respectively. Similarly to the above-described first embodiment, the organic photoelectric conversion layer 92B is formed, for example, by using a benzothienobenzothiophene-based compound represented by the above-described general formula (1).

The on-chip lens 98L is provided on the blue photoelectric conversion section 90B with the protective layer 97 and the on-chip lens layer 98 interposed therebetween. The red accumulation layer 310R, the green accumulation layer 310G, and the blue accumulation layer 310B are provided in the semiconductor substrate 30. The red photoelectric conversion section 90R, the green photoelectric conversion section 90G, and the blue photoelectric conversion section 90B photoelectrically convert light that has entered the on-chip lens 98L, and transfer signal charges from the red photoelectric conversion section 90R to the red accumulation layer 310R, from the green photoelectric conversion section 90G to the green accumulation layer 310G, and from the blue photoelectric conversion section 90B to the blue accumulation layer 310B. The signal charge may be an electron or a hole generated by photoelectric conversion, but a case where an electron is read out as a signal charge is explained below as an example.

The semiconductor substrate 30 includes, for example, a p-type silicon substrate. The red, green, and blue accumulation layers 310R, 310G, and 310B provided in the semiconductor substrate 30 each include an n-type semiconductor region, and the signal charges (electrons) supplied from the red, green, and blue photoelectric conversion portions 90R, 90G, and 90B are accumulated in the n-type semiconductor region. The n-type semiconductor regions of the red accumulation layer 310R, the green accumulation layer 310G, and the blue accumulation layer 310B are formed by doping n-type impurities such As phosphorus (P) or arsenic (As) in the semiconductor substrate 30, for example. Note that the semiconductor substrate 30 may be provided on a support substrate (not shown) including glass or the like.

In the semiconductor substrate 30, a pixel transistor is provided. For example, the pixel transistor is used to read electrons from each of the red accumulation layer 310R, the green accumulation layer 310G, and the blue accumulation layer 310B and transfer the electrons to a vertical signal line (for example, a vertical signal line Lsig of fig. 15 to be described later). A floating diffusion region of the pixel transistor is provided in the semiconductor substrate 30, and the floating diffusion region is connected to the red accumulation layer 310R, the green accumulation layer 310G, and the blue accumulation layer 310B. The floating diffusion region includes an n-type semiconductor region.

The insulating layer 96 includes, for example, silicon oxide (SiO)_x) Silicon nitride (SiN)_x) Silicon oxynitride (SiON), hafnium oxide (HfO)_x) Etc., or a monolayer film comprising two of themThe above laminated film. In addition, the insulating layer 96 may be formed by using an organic insulating material. Although not shown, the insulating layer 96 includes respective plugs (plugs) and electrodes for connection between the red accumulation layer 310R and the red photoelectric conversion section 90R, between the green accumulation layer 310G and the green photoelectric conversion section 90G, and between the blue accumulation layer 310B and the blue photoelectric conversion section 90R.

The red photoelectric conversion portion 90R includes a first electrode 91R, an organic photoelectric conversion layer 92R, and a second electrode 93R in this order from a position close to the semiconductor substrate 30. The green photoelectric conversion portion 90G includes a first electrode 91G, an organic photoelectric conversion layer 92G, and a second electrode 93G in this order from a position close to the red photoelectric conversion portion 90R. The blue photoelectric conversion portion 90B includes a first electrode 91B, an organic photoelectric conversion layer 92B, and a second electrode 93B in this order from a position close to the green photoelectric conversion portion 90G. An insulating layer 94 is provided between the red photoelectric conversion portion 90R and the green photoelectric conversion portion 90G, and an insulating layer 95 is provided between the green photoelectric conversion portion 90G and the blue photoelectric conversion portion 90B. The red photoelectric conversion portion 90R, the green photoelectric conversion portion 90G, and the blue photoelectric conversion portion 90B selectively absorb red (e.g., having a wavelength of 600nm or more and less than 700nm), green (e.g., having a wavelength of 500nm or more and less than 600nm), and blue (e.g., having a wavelength of 400nm or more and less than 500nm) light, respectively, to generate electron-hole pairs.

The first electrode 91R, the first electrode 91G, and the first electrode 91B extract the signal charge generated in the organic photoelectric conversion layer 92R, the signal charge generated in the organic photoelectric conversion layer 92G, and the signal charge generated in the organic photoelectric conversion layer 92B, respectively. For example, the first electrodes 91R, 91G, and 91B are provided for each pixel. The first electrodes 91R, 91G, and 91B include, for example, a conductive material having light transmissivity, particularly ITO. For example, the first electrodes 91R, 91G, and 91B may include a tin oxide-based material or a zinc oxide-based material. The tin oxide-based material is tin oxide to which impurities are added, and examples of the zinc oxide-based material include aluminum zinc oxide prepared by adding aluminum as an impurity to zinc oxide, zinc gallium oxide prepared by adding gallium as an impurity to zinc oxide, and indiumZinc indium oxide prepared by adding zinc oxide as an impurity, and the like. In addition to these materials, IGZO, CuI, InSbO can be used₄、ZnMgO、CuInO₂、MgIn₂O₄、CdO、ZnSnO₃And the like. Each of the first electrodes 91R, 91G, and 91B has a thickness of 50nm to 500nm, for example.

For example, electron transport layers may be respectively disposed between the first electrode 91R and the organic photoelectric conversion layer 92R, between the first electrode 91G and the organic photoelectric conversion layer 92G, and between the first electrode 91B and the organic photoelectric conversion layer 92B. The electron transport layer facilitates supply of electrons generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the first electrodes 91R, 91G, and 91B, and includes, for example, titanium oxide, zinc oxide, or the like. The electron transport layer may be constituted by stacking a titanium oxide film and a zinc oxide film. The thickness of the electron transport layer is, for example, 0.1nm to 1000nm, preferably from 0.5nm to 300 nm.

The organic photoelectric conversion layers 92R, 92G, and 92B absorb light in selected wavelength bands to perform photoelectric conversion, respectively, and allow light in other wavelength bands to pass therethrough. Here, the light in the wavelength band selected is, for example, light in a wavelength band having a wavelength of 600nm or more and less than 700nm for the organic photoelectric conversion layer 92R, light in a wavelength band having a wavelength of 500nm or more and less than 600nm for the organic photoelectric conversion layer 92G, and light in a wavelength band having a wavelength of 400nm or more and less than 500nm for the organic photoelectric conversion layer 92B. The thickness of each of the organic photoelectric conversion layers 92R, 92G, and 92B is, for example, from 25nm to 400nm (inclusive), preferably from 50nm to 350nm (inclusive), and more preferably from 150nm to 300nm (inclusive).

The organic photoelectric conversion layers 92R, 92G, and 92B each convert light energy into electric energy, and each include two or more organic materials (p-type semiconductor material or n-type semiconductor material) serving as a p-type semiconductor or an n-type semiconductor, respectively, similarly to the photoelectric conversion layer 24. The organic photoelectric conversion layers 92R, 92G, and 92B may include, in addition to the p-type semiconductor material and the n-type semiconductor material, an organic material that photoelectrically converts light in the above-described predetermined wavelength band and allows light in other wavelength bands to pass, so-called dye material. Examples of such a material for the organic photoelectric conversion layer 92R include rhodamine, merocyanine, and derivatives thereof. Examples for the organic photoelectric conversion layer 92G include subphthalocyanine, phthalocyanine, coumarin, porphyrin, and derivatives thereof. Examples for the organic photoelectric conversion layer 92B include benzothiophene-based compounds represented by general formula (1).

Examples of the organic material included in the organic photoelectric conversion layers 92R, 92G, and 92B include fullerene or a fullerene derivative. The organic photoelectric conversion layers 92R, 92G, and 92B may further include organic materials other than the above-described organic materials.

For example, a hole transport layer may be respectively disposed between the organic photoelectric conversion layer 92R and the second electrode 93R, between the organic photoelectric conversion layer 92G and the second electrode 93G, and between the organic photoelectric conversion layer 92B and the second electrode 93B. The hole transport layer facilitates supply of holes generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the second electrodes 93R, 93G, and 93B, and includes, for example, molybdenum oxide, nickel oxide, vanadium oxide, or the like. The hole transport layer may include organic materials such as PEDOT (poly (3, 4-ethylenedioxythiophene)) and TPD (N, N '-bis (3-methylphenyl) -N, N' -diphenylbenzidine). The hole transport layer has, for example, a thickness of 0.5nm to 100nm (inclusive).

The second electrode 93R, the second electrode 93G, and the second electrode 93B extract holes generated in the organic photoelectric conversion layer 92R, holes generated in the organic photoelectric conversion layer 92G, and holes generated in the organic photoelectric conversion layer 92B, respectively. The holes extracted from each of the second electrodes 93R, 93G, and 93B are discharged to a p-type semiconductor region (not shown) in the semiconductor substrate 30, for example, via each transfer path (not shown). The second electrodes 93R, 93G, and 93B include, for example, a conductive material such as gold (Au), silver (Ag), copper (Cu), and aluminum (Al). The second electrodes 93R, 93G, and 93B may include a transparent conductive material, similar to the first electrodes 91R, 91G, and 91B. In the image pickup element 10E, holes extracted from the second electrodes 93R, 93G, and 93B are discharged; therefore, for example, in the case where a plurality of image pickup elements 10E are arranged in the image pickup apparatus 1, which will be described later, the common second electrodes 93R, 93G, and 93B may be provided for the respective image pickup elements 10E (unit pixels P). Each of the second electrodes 93R, 93G, and 93B has a thickness of, for example, 0.5nm to 100nm (inclusive).

The insulating layer 94 insulates the second electrode 93R and the first electrode 91G from each other. The insulating layer 95 insulates the second electrode 93G and the first electrode 91B from each other. The insulating layers 94 and 95 include, for example, metal oxide, metal sulfide, or organic substance. Examples of the metal oxide include silicon oxide (SiO)_x) Aluminum oxide (AlO)_x) Zirconium oxide (ZrO)_x) Titanium oxide (TiO)_x) Zinc oxide (ZnO)_x) Tungsten oxide (WO)_x) Magnesium oxide (MgO)_x) Niobium oxide (NbO)_x) Tin oxide (SnO)_x) Gallium oxide (GaO)_x) And the like. Examples of the metal sulfide include zinc sulfide (ZnS), magnesium sulfide (MgS), and the like. The band gap of the constituent material of each of the insulating layers 94 and 95 is preferably 3.0eV or more. Each of the insulating layers 94 and 95 has a thickness of, for example, 2nm to 100nm (inclusive).

As described above, forming the organic photoelectric conversion layer 92B by using the benzothiophenobenzothiophene-based compound represented by the above general formula (1) enables effects similar to those of the above first embodiment to be achieved.

<5. application example >

(application example 1)

Fig. 15 shows the overall configuration of an image pickup apparatus (image pickup apparatus 1) using the image pickup element 10A (or any one of the image pickup elements 10B to 10E) described in the above-described first to fourth embodiments for each pixel. The image pickup apparatus 1 is a CMOS image sensor, and includes, on a semiconductor substrate 30, a pixel section 1a as an image pickup region, and a peripheral circuit section 130 including a row scanning section 131, a horizontal selection section 133, a column scanning section 134, and a system control section 132, for example, in a peripheral region of the pixel section 1 a.

For example, the pixel section 1a has a plurality of unit pixels P (corresponding to each of the image pickup elements 10) arranged in a two-dimensional matrix. For example, the unit pixel P is arranged with a pixel driving line Lread (specifically, a row selection line and a reset control line) for each pixel row and a vertical signal line Lsig for each pixel column. The pixel driving line Lread transmits a driving signal for reading a signal from a pixel. The pixel driving lines Lread have one ends connected to respective ones of the output terminals corresponding to the respective rows of the row scanning section 131, respectively.

The line scanning section 131 includes a shift register, an address decoder, and the like, and is, for example, a pixel driving section that drives each unit pixel P in the pixel section 1a row by row. The signals output from the respective unit pixels P in the pixel row selectively scanned by the row scanning section 131 are supplied to the horizontal selection section 133 through the respective vertical signal lines Lsig. The horizontal selection unit 133 includes amplifiers, horizontal selection switches, and the like provided for the respective vertical signal lines Lsig.

The column scanning section 134 includes a shift register, an address decoder, and the like, and sequentially drives each horizontal selection switch of the horizontal selection section 133 while scanning the horizontal selection switch. Such selective scanning by the column scanning section 134 causes signals of the respective pixels transmitted through the respective vertical signal lines Lsig to be sequentially output to the horizontal signal lines 135 and then transmitted to the outside of the semiconductor substrate 30 through the horizontal signal lines 135.

The circuit components including the row scanning section 131, the horizontal selection section 133, the column scanning section 134, and the horizontal signal line 135 may be directly formed on the semiconductor substrate 30 or arranged in an external control IC. Alternatively, these circuit components may be formed in any other substrate connected by a cable or the like.

The system control section 132 receives a clock given from the outside of the semiconductor substrate 30 or data of an instruction on an operation mode, and the like, and also outputs data such as internal information of the image pickup apparatus 1. The system control section 132 also has a timing generator that generates various timing signals, and performs drive control of peripheral circuits (such as the row scanning section 131, the horizontal selection section 133, and the column scanning section 134) based on the various timing signals generated by the timing generator.

(application example 2)

For example, the above-described image pickup apparatus 1 is applicable to various types of electronic devices having an image pickup function. Examples of the electronic apparatus include a camera system such as a digital still camera and a video camera, and a mobile phone having a camera function. For the purpose of example, fig. 16 shows a schematic configuration of the electronic device 2 (camera). The electronic apparatus 2 is, for example, a video camera capable of shooting still images or moving images, and includes an image pickup device 1, an optical system (optical lens) 310, a shutter device 311, a driver 313 that drives the image pickup device 1 and the shutter device 311, and a signal processor 312.

The optical system 310 guides image light (incident light) from an object to the pixel portion 1a of the image pickup device 1. The optical system 310 may include a plurality of optical lenses. The shutter device 311 controls a period during which the image pickup device 1 is irradiated with light and a period during which light is blocked. The driver 313 controls the transfer operation of the image pickup apparatus 1 and the shutter operation of the shutter device 311. The signal processor 312 performs various signal processes on the signal output from the image pickup apparatus 1. The image signal Dout after the signal processing is stored in a storage medium such as a memory or output to a monitor or the like.

(application example 3)

Further, the above-described image pickup apparatus 1 is applied to the following electronic devices (the capsule endoscope 10100 and a moving body such as a vehicle).

<6 practical application example >

< practical application example of in-vivo information collecting System >

Further, the technique according to the present invention (present technique) is applicable to various products. For example, the technique according to the present invention can be applied to an endoscopic surgical system.

Fig. 17 is a block diagram showing a schematic configuration of an in-vivo information acquisition system using a patient using a capsule endoscope to which the technology according to the embodiment of the present invention (present technology) can be applied.

The in-vivo information collection system 10001 includes a capsule endoscope 10100 and an external control device 10200.

At the time of examination, the patient swallows the capsule endoscope 10100. The capsule type endoscope 10100 has an image pickup function and a wireless communication function, and when it moves inside an organ by peristalsis for a certain time, it continuously takes images of the inside of the organ such as the stomach or the intestine (hereinafter referred to as in-vivo images) at predetermined time intervals until it is naturally excreted by the patient. Then, the capsule endoscope 10100 transmits the information of the in-vivo image to the external control device 10200 outside the body by wireless transmission.

The external control device 10200 integrally controls the operation of the in-vivo information acquisition system 10001. In addition, the external control device 10200 receives information of the in-vivo image transferred thereto from the capsule endoscope 10100 and generates image data for displaying the in-vivo image on a display device (not shown) based on the received information of the in-vivo image.

In the in-vivo information acquisition system 10001, an in-vivo image for imaging the state in the patient's body can be acquired at any time in this manner during the period from when the capsule endoscope 10100 is swallowed to when it is excreted.

The configuration and function of the capsule endoscope 10100 and the external control device 10200 will be described in detail below.

The capsule endoscope 10100 includes a capsule casing 10101, and the capsule casing 10101 accommodates therein a light source unit 10111, an image pickup unit 10112, an image processing unit 10113, a wireless communication unit 10114, a power supply unit 10115, a power supply unit 10116, and a control unit 10117.

The light source unit 10111 includes, for example, a light source such as a Light Emitting Diode (LED), and irradiates light on the imaging field of view of the imaging unit 10112.

The image pickup unit 10112 includes an image pickup element and an optical system. The optical system includes a plurality of lenses disposed in a front stage of the image pickup element. Reflected light of light irradiated on body tissue as an observation target (hereinafter referred to as observation light) is collected by an optical system and introduced to an image pickup element. In the imaging unit 10112, incident observation light is photoelectrically converted by the imaging element, thereby generating an image signal corresponding to the observation light. The image signal generated by the image pickup unit 10112 is supplied to the image processing unit 10113.

The image processing unit 10113 includes a processor such as a Central Processing Unit (CPU) or a Graphics Processing Unit (GPU), and performs various image processing on the image signal generated by the image capturing unit 10112. The image processing unit 10113 supplies the image signal, which has been subjected to the signal processing, to the wireless communication unit 10114 as RAW data.

The wireless communication unit 10114 performs predetermined processing such as modulation processing on the image signal that has been subjected to the signal processing by the image processing unit 10113, and transmits the processed image signal to the external control device 10200 through the antenna 10114A. In addition, the wireless communication unit 10114 receives a control signal related to drive control of the capsule endoscope 10100 from the external control device 10200 via the antenna 10114A. The wireless communication unit 10114 supplies the control signal received from the external control device 10200 to the control unit 10117.

The power supply unit 10115 includes an antenna coil for receiving power, a power source regeneration circuit for regenerating power from a current generated by the antenna coil, a booster circuit, and the like. The power supply unit 10115 generates power using a non-contact charging principle.

The power supply unit 10116 includes a storage battery, and stores the power generated by the power supply unit 10115. In fig. 17, in order to avoid complicated illustration, an arrow or the like indicating a power supply destination from the power supply unit 10116 is omitted. However, the power stored in the power supply unit 10116 is supplied to and can be used to drive the light source unit 10111, the image capturing unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the control unit 10117.

The control unit 10117 includes a processor such as a CPU, and appropriately controls driving of the light source unit 10111, the image capturing unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the power supply unit 10115 according to a control signal transmitted thereto from the external control device 10200.

The external control device 10200 includes a processor such as a CPU or a GPU, a microcomputer, a control board in which the processor and a storage element such as a memory are mixedly integrated, and the like. The external control device 10200 sends a control signal to the control unit 10117 of the capsule endoscope 10100 through the antenna 10200A to control the operation of the capsule endoscope 10100. In the capsule endoscope 10100, for example, the irradiation conditions of light on the observation target of the light source unit 10111 can be changed in accordance with a control signal from the external control device 10200. In addition, the image capturing conditions (for example, the frame rate, the exposure value, and the like of the image capturing unit 10112) may be changed according to a control signal from the external control device 10200. In addition, the content processed by the image processing unit 10113 or the condition (e.g., transmission interval, number of transmission images, etc.) of transmitting the image signal from the wireless communication unit 10114 may be changed according to a control signal from the external control device 10200.

In addition, the external control device 10200 performs various image processes on the image signal transmitted thereto from the capsule endoscope 10100 to generate image data for displaying the captured in-vivo image on the display device. As the image processing, for example, various signal processing such as development processing (demosaicing processing), image quality improvement processing (bandwidth enhancement processing, super-resolution processing, Noise Reduction (NR) processing, and/or image stabilization processing), and/or enlargement processing (electronic zoom processing) may be performed. The external control device 10200 controls the driving of the display device to cause the display device to display the captured in-vivo image based on the generated image data. Alternatively, the external control device 10200 may also control a recording device (not shown) to record the generated image data or control a printing device (not shown) to output the generated image data by printing.

One example of an in-vivo information collection system to which the technique according to the present invention can be applied has been described above. The technique according to the present invention can be applied to, for example, the image pickup unit 10112 configured as described above. This enables the accuracy of the inspection to be improved.

< practical application example of endoscopic surgery System >

The technique according to the present invention (present technique) is applicable to various products. For example, the technique according to the present invention may be applied to an endoscopic surgical system.

Fig. 18 is a view showing an example of a schematic configuration of an endoscopic surgery system to which the technique according to the embodiment of the present invention (present technique) can be applied.

In fig. 18, a state in which a surgeon (doctor) 11131 is performing an operation for a patient 11132 on a bed 11133 using an endoscopic surgery system 11000 is shown. As shown, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 (e.g., a pneumoperitoneum tube 11111 and an energy device 11112), a support arm device 11120 (on which the endoscope 11100 is supported), and a cart 11200 on which various devices for endoscopic surgery are loaded.

The endoscope 11100 includes a lens barrel 11101 and a camera 11102 connected to a proximal end of the lens barrel 11101, and the lens barrel 11101 has a region of a predetermined length from a distal end thereof for insertion into a body cavity of a patient 11132. In the illustrated example, the endoscope 11100 is illustrated as including a rigid endoscope as the lens barrel 11101 having a hard type. However, the endoscope 11100 may be a flexible endoscope including the lens barrel 11101 having flexibility.

The lens barrel 11101 has an opening portion at its distal end to which an objective lens is attached. The light source device 11203 is connected to the endoscope 11100 so that light generated by the light source device 11203 is guided to the distal end of the lens barrel through a light guide extending inside the lens barrel 11101 and irradiated toward an observation target in a body cavity of the patient 11132 through the objective lens. It is noted that endoscope 11100 can be a forward-looking endoscope, or can be a strabismus endoscope or a side-looking endoscope.

An optical system and an image pickup element are provided inside the camera 11102 so that reflected light (observation light) from an observation target is condensed on the image pickup element by the optical system. The image pickup element photoelectrically converts observation light to generate an electric signal corresponding to the observation light, that is, an image signal corresponding to an observation image. The image signal is transmitted as RAW data to a Camera Control Unit (CCU) 11201.

The CCU 11201 includes a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), and the like, and centrally controls the operations of the endoscope 11100 and the display device 11202. In addition, the CCU 11201 receives an image signal from the camera 11102, and performs various image processing for displaying an image based on the image signal, such as development processing (demosaicing processing), on the image signal.

The display device 11202 displays an image based on the image signal on which the image processing has been performed by the CCU 11201, under the control of the CCU 11201.

The light source device 11203 includes a light source such as, for example, a Light Emitting Diode (LED), and supplies irradiation light to the endoscope 11100 when imaging a surgical field or the like.

The input device 11204 is an input interface for the endoscopic surgical system 11000. The user can perform input of various types of information or instructions input to the endoscopic surgical system 11000 through the input device 11204. For example, the user will input an instruction or the like through the endoscope 11100 to change the image capturing conditions (the type, magnification, focal length, or the like of the illumination light).

The treatment tool control device 11205 controls the actuation of the energy device 11112 for cauterizing or incising tissue, sealing blood vessels, etc. Pneumoperitoneum device 11206 delivers gas through pneumoperitoneum tube 11111 into the body cavity of patient 11132 to inflate the body cavity to ensure the field of view of endoscope 11100 and to ensure the surgeon's working space. The recorder 11207 is a device capable of recording various types of information relating to the procedure. The printer 11208 is a device capable of printing various types of information relating to the operation in various forms (e.g., text, images, or graphics).

It is to be noted that the light source device 11203 that supplies irradiation light when the operation region is to be imaged to the endoscope 11100 may include, for example, a white light source including an LED, a laser light source, or a combination thereof. In the case where the white light source includes a combination of red, green, and blue (RGB) laser light sources, since the output intensity and the output timing of each color (each wavelength) can be controlled with high accuracy, white balance adjustment of a captured image can be performed by the light source device 11203. In this case, if the laser beams from the respective RGB laser light sources are time-divisionally irradiated onto the observation target and the driving of the image pickup element of the camera 11102 is controlled in synchronization with the irradiation timing, images corresponding to R, G and B can be time-divisionally picked up. According to this method, a color image can be obtained even if a color filter is not provided for the image pickup element.

In addition, the light source device 11203 may be controlled such that the intensity of light to be output is changed every predetermined time. By controlling the driving of the image pickup device of the camera 11102 in synchronization with the timing of the change in light intensity so as to time-divisionally acquire images and synthesize the images, an image of a high dynamic range free from underexposed shadows and overexposed light can be created.

In addition, the light source device 11203 may be configured to provide light of a predetermined wavelength band that can be used for special light observation. In the special light observation, for example, by irradiating light of a narrower wavelength band than that of the irradiation light (i.e., white light) for ordinary observation with wavelength dependence of light absorption in human tissue, narrow-band light observation for imaging a predetermined tissue (e.g., blood vessels of the surface of a mucous membrane, etc.) with high contrast is performed. Alternatively, in the special light observation, fluorescence observation for obtaining an image from fluorescence generated by irradiation of excitation light may be performed. In fluorescence observation, a fluorescence image can be obtained by irradiating excitation light onto body tissue to observe fluorescence from the body tissue (autofluorescence observation) or by locally injecting a reagent such as indocyanine green (ICG) and irradiating excitation light corresponding to the fluorescence wavelength of the reagent onto the body tissue. The light source device 11203 may be configured to provide narrow-band light and/or excitation light suitable for the special light observation described above.

Fig. 19 is a block diagram showing an example of the functional configuration of the camera 11102 and the CCU 11201 illustrated in fig. 18.

The camera 11102 includes a lens unit 11401, an image pickup unit 11402, a drive unit 11403, a communication unit 11404, and a camera control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 to communicate.

The lens unit 11401 is an optical system provided at a connection position with the lens barrel 11101. Observation light taken from the distal end of the lens barrel 11101 is guided to the camera 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focus lens.

The number of image pickup elements included in the image pickup unit 11402 may be one (single-plate type) or a plurality (multi-plate type). For example, in the case where the image pickup unit 11402 is configured as a multi-panel type image pickup unit, image signals corresponding to each of R, G and B are generated by the image pickup element, and the image signals may be synthesized to obtain a color image. The image pickup unit 11402 may also be configured to have a pair of image pickup elements for respectively acquiring an image signal for a right eye and an image signal for a left eye, thereby being used for three-dimensional (3D) display. If a 3D visualization is performed, the surgeon 11131 can more accurately understand the depth of the living tissue in the surgical field. It should be noted that in the case where the image pickup unit 11402 is configured as a stereoscopic type image pickup unit, a plurality of systems of the lens unit 11401 are provided corresponding to the respective image pickup elements.

Further, the image pickup unit 11402 is not necessarily provided on the camera 11102. For example, the image pickup unit 11402 may be provided immediately behind the objective lens inside the lens barrel 11101.

The driving unit 11403 includes an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera control unit 11405. Therefore, the magnification and focus of the image captured by the image capturing unit 11402 can be appropriately adjusted.

Communication unit 11404 includes communication devices to send and receive various types of information to and from CCU 11201. The communication unit 11404 transmits the image signal acquired from the image pickup unit 11402 to the CCU 11201 as RAW data via the transmission cable 11400.

In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and supplies the control signal to the camera control unit 11405. The control information includes information such as information related to image capturing conditions, for example, information specifying the frame rate of a captured image, information specifying the exposure value at the time of capturing an image, and/or information specifying the magnification and focus of a captured image.

It should be noted that image capturing conditions such as a frame rate, an exposure value, a magnification, a focus, or the like may be designated by a user or may be automatically set by the control unit 11413 of the CCU 11201 based on the obtained image signal. In the latter case, the endoscope 11100 includes an Auto Exposure (AE) function, an Auto Focus (AF) function, and an Auto White Balance (AWB) function.

The camera control unit 11405 controls driving of the camera 11102 based on a control signal from the CCU 11201 received through the communication unit 11404.

The communication unit 11411 includes a communication device for transmitting and receiving various types of information to and from the camera 11102. The communication unit 11411 receives an image signal transmitted thereto from the camera 11102 through the transmission cable 11400.

Further, the communication unit 11411 transmits a control signal for controlling driving of the camera 11102 to the camera 11102. The image signal and the control signal may be transmitted by electrical communication or optical communication or the like.

The image processing unit 11412 performs various image processes on the image signal in the form of RAW data transmitted thereto from the camera 11102.

The control unit 11413 performs various types of control related to image capturing of an operation area or the like by the endoscope 11100 and display of a captured image obtained by image capturing of the operation area or the like. For example, the control unit 11413 creates a control signal for controlling driving of the camera 11102.

Further, the control unit 11413 controls the display device 11202 to display a subject image imaged on the surgical region or the like based on the image signal on which the image processing unit 11412 has performed the image processing. Accordingly, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 may recognize a surgical tool such as forceps, a specific living body region, bleeding, fog when the energy device 11112 is used, and the like by detecting the shape, color, and the like of the edge of the object included in the captured image. When the control unit 11413 controls the display device 11202 to display the photographed image, the control unit 11413 may cause various types of operation support information to be displayed in an overlapping manner with the image of the operation region using the result of the recognition. When the operation support information is displayed in an overlapping manner and presented to the surgeon 11131, the burden on the surgeon 11131 can be reduced, and the surgeon 11131 can surely perform the operation.

The transmission cable 11400 connecting the camera 11102 and the CCU 11201 to each other is an electrical signal cable capable of electrical signal communication, an optical fiber capable of optical communication, or a composite cable capable of electrical communication and optical communication.

Here, although in the illustrated example, the communication is performed by wired communication using the transmission cable 11400, the communication between the camera 11102 and the CCU 11201 may also be performed by wireless communication.

One example of an endoscopic surgical system to which the techniques according to the present invention are applicable has been described above. The technique according to the present invention is applicable to the image pickup unit 11402 configured as described above, for example. Applying the technique according to the present invention to the image pickup unit 11402 enables the accuracy of inspection to be improved.

It is to be noted that the endoscopic surgical system is described here as an example, but the technique according to the present invention can be additionally applied to, for example, a microsurgical system or the like.

< practical application example of moving body >

The technique according to the present invention can be applied to various products. For example, the technology according to the present invention may be implemented in the form of an apparatus mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid vehicle, a motorcycle, a bicycle, a personal mobile device, an airplane, an unmanned aerial vehicle, a ship, a robot, a construction machine, and an agricultural machine (tractor).

Fig. 20 is a block diagram showing an example of a schematic configuration of a vehicle control system as an example of a mobile body control system to which the technique according to the embodiment of the present invention can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected to each other through a communication network 12001. In the example illustrated in fig. 20, the vehicle control system 12000 includes a drive system control unit 12010, a vehicle body system control unit 12020, a vehicle exterior information detection unit 12030, a vehicle interior information detection unit 12040, and an integrated control unit 12050. Further, a microcomputer 12051, a sound image output section 12052, and an in-vehicle network interface (I/F)12053 configured as functions of the integrated control unit 12050 are shown.

The drive system control unit 12010 controls the operations of devices related to the drive system of the vehicle according to various types of programs. For example, the drive system control unit 12010 functions as a control device of: a driving force generating device such as an internal combustion engine, a drive motor, or the like for generating a driving force of the vehicle, a driving force transmitting mechanism that transmits the driving force to wheels, a steering mechanism that adjusts a steering angle of the vehicle, a braking device that generates a braking force of the vehicle, or the like.

The vehicle body system control unit 12020 controls the operations of various types of devices provided on the vehicle body according to various types of programs. For example, the vehicle body system control unit 12020 functions as a control device of a keyless entry system, a smart key system, a power window device, or various lamps such as a headlamp, a backup lamp, a brake lamp, a turn lamp, a fog lamp, and the like. In this case, a radio wave transmitted from a mobile device that replaces a key or a signal of various switches may be input to the vehicle body system control unit 12020. The vehicle body system control unit 12020 receives input of these radio waves or signals, and controls a door lock device, a power window device, a lamp, or the like of the vehicle.

The vehicle exterior information detection unit 12030 detects information on the exterior of the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging section 12031 to image an image outside the vehicle, and receives the imaged image. Based on the received image, the vehicle exterior information detection unit 12030 may perform processing of detecting an object such as a person, a vehicle, an obstacle, a sign, a character on a road surface, or the like, or processing of detecting a distance from the above object.

The image pickup section 12031 is an optical sensor that receives light and outputs an electric signal corresponding to the amount of received light. The image pickup section 12031 may output the electric signal as an image, or may output the electric signal as information on the measured distance. Further, the light received by the image pickup portion 12031 may be visible light, or may be invisible light such as infrared light.

The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. The in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 that detects the state of the driver, for example. The driver state detection unit 12041 includes, for example, a camera that photographs the driver. Based on the detection information input from the driver state detection section 12041, the in-vehicle information detection unit 12040 may calculate the degree of fatigue of the driver or the degree of concentration of the driver, or may determine whether the driver is dozing.

The microcomputer 12051 can calculate a control target value of the driving force generation device, the steering mechanism, or the brake device based on information about the interior or exterior of the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and output a control command to the driving system control unit 12010. For example, the microcomputer 12051 may execute cooperative control intended to realize functions of an Advanced Driver Assistance System (ADAS) including collision avoidance or impact mitigation for the vehicle, follow-up driving based on a following distance, vehicle speed hold driving, vehicle collision warning, vehicle lane departure warning, and the like.

Further, by controlling the driving force generation device, the steering mechanism, the brake device, and the like based on the information on the outside or inside of the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, the microcomputer 12051 can perform cooperative control aimed at realizing automated driving and the like that enables the vehicle to travel autonomously without depending on the operation of the driver.

Further, based on the information on the outside of the vehicle acquired by the vehicle exterior information detection unit 12030, the microcomputer 12051 may output a control command to the vehicle body system control unit 12020. For example, the microcomputer 12051 may perform cooperative control intended to prevent glare by controlling the headlamps to change from high beam to low beam, for example, according to the position of a preceding vehicle or an oncoming vehicle detected by the vehicle exterior information detecting unit 12030.

The audio/video output unit 12052 transmits an output signal of at least one of audio and video to an output device that can visually or audibly notify a passenger of the vehicle or the outside of the vehicle. In the example of fig. 20, an audio speaker 12061, a display portion 12062, and a dashboard 12063 are shown as output devices. The display portion 12062 may include at least one of an in-vehicle display and a flat display, for example.

Fig. 21 is a schematic diagram illustrating an example of the mounting position of the imaging section 12031.

In fig. 21, the imaging unit 12031 includes an imaging unit 12101, an imaging unit 12102, an imaging unit 12103, an imaging unit 12104, and an imaging unit 12105.

The image pickup portion 12101, the image pickup portion 12102, the image pickup portion 12103, the image pickup portion 12104, and the image pickup portion 12105 are provided at positions on, for example, a front nose, side mirrors, a rear bumper, and a rear door of the vehicle 12100, and a position of an upper portion of a windshield in the vehicle. The imaging unit 12101 provided at the nose and the imaging unit 12105 provided at the upper portion of the windshield in the vehicle mainly acquire images in front of the vehicle 12100. The image pickup portions 12102 and 12103 provided on the side mirrors mainly acquire images of both sides of the vehicle 12100. An image pickup unit 12104 provided on a rear bumper or a rear door mainly acquires an image of the rear of the vehicle 12100. The imaging unit 12105 provided on the upper portion of the windshield in the vehicle is mainly used for detecting a preceding vehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, and the like.

Incidentally, fig. 21 shows an example of the imaging range of the imaging sections 12101 to 12104. The imaging range 12111 represents the imaging range of the imaging section 12101 provided at the nose. Imaging ranges 12112 and 12113 represent imaging ranges of the imaging section 12102 and the imaging section 12103 provided in the side view mirror, respectively. The imaging range 12114 represents an imaging range of an imaging section 12104 provided on a rear bumper or a rear cover. For example, a bird's eye view image of the vehicle 12100 viewed from above is obtained by superimposing image data imaged by the imaging sections 12101 to 12104.

At least one of the image pickup portions 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image pickup sections 12101 to 12104 may be a stereo camera composed of a plurality of image pickup elements, or may be an image pickup element having pixels for phase difference detection.

For example, based on the distance information acquired from the image pickup portions 12101 to 12104, the microcomputer 12051 may determine the distances of the respective three-dimensional objects within the imaging ranges 12111 to 12114 and the temporal changes of the distances (relative speed to the vehicle 12100), and thereby extract, as the preceding vehicle, the closest three-dimensional object that is particularly on the traveling path of the vehicle 12100 and that travels in the substantially same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km/h). Further, the microcomputer 12051 may set in advance the following distance to be kept in front of the preceding vehicle, and perform automatic braking control (including following stop control), automatic acceleration control (including following start control), and the like. Therefore, it is possible to execute cooperative control such as automatic driving in order to cause the vehicle to automatically travel without depending on the operation of the driver.

For example, based on the distance information acquired from the image pickup portion 12101 to the image pickup portion 12104, the microcomputer 12501 may classify three-dimensional object data on a three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard vehicles, large-sized vehicles, pedestrians, utility poles, and other three-dimensional objects, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic avoidance of an obstacle. For example, the microcomputer 12051 classifies the obstacles around the vehicle 12100 into obstacles that can be visually recognized by the driver of the vehicle 12100 and obstacles that are difficult for the driver of the vehicle 12100 to visually recognize. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle. In the case where the collision risk is equal to or higher than the set value and thus there is a possibility of collision, the microcomputer 12051 issues a warning to the driver via the audio speaker 12061 or the display portion 12062, and performs forced deceleration or evasive steering by the drive system control unit 12010. The microcomputer 12051 can thus assist driving to avoid a collision.

At least one of the image pickup portions 12101 to 12104 may be an infrared camera that detects infrared rays. The microcomputer 12051 can recognize a pedestrian, for example, by determining whether or not a pedestrian is present in images captured by the image capturing sections 12101 to 12104. For example, such identification of a pedestrian is performed by: a step of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras; and a step of performing pattern matching processing on a series of feature points representing the contour of the object to determine whether the feature points are pedestrians. If the microcomputer 12051 determines that a pedestrian is present in the captured images of the image capturing sections 12101 to 12104, and thus recognizes the pedestrian, the sound image output section 12052 controls the display section 12062 so that a square contour line for emphasis is displayed so as to be superimposed on the recognized pedestrian. Further, the audio-visual output portion 12052 may control the display portion 12062 so as to display an icon or the like representing a pedestrian at a desired position.

<7. example >

Next, embodiments of the present invention will be described in detail.

(Experimental example 1)

An ITO film having a thickness of 100nm was formed on the quartz substrate 111 using a sputtering apparatus. The ITO film is patterned by photolithography and etching to form an ITO electrode (lower electrode). Next, the quartz substrate provided with the ITO electrode was cleaned by UV/ozone treatment, and then the quartz substrate was moved into a vacuum evaporation apparatus, and an organic material was deposited on the quartz substrate using a resistance heating method while rotating the substrate holder under a reduced pressure of 1 × 10-5Pa or less. First, an electron blocking material represented by the following formula (3) was deposited at a substrate temperature of 0 ℃ at a thickness of 10nm to form an electron blocking layer. Then, the temperature of the substrate is controlled at 40 ℃ respectivelyPer second anddeposition Rate per second Benzothienobenzothiophene derivative represented by the following formula (1-1) and C₆₀Fullerene (the following formula (2)) to form a mixed layer having a thickness of 230nm, thereby forming a photoelectric conversion layer. Next, a hole blocking material represented by the following formula (4) was deposited at a thickness of 10nm at a substrate temperature of 0 ℃ to form a hole blocking layer. Finally, the quartz base is putThe plate was moved into a sputtering apparatus and ITO was deposited to a thickness of 50nm on the hole blocking layer to form an upper electrode. A photoelectric conversion element having a 1mm × 1mm photoelectric conversion region was manufactured by the above manufacturing method (experimental example 1). Under nitrogen (N)₂) The fabricated photoelectric conversion element was annealed at 150 ℃ for 120 minutes in an atmosphere.

[ chemical formula 3]

[ chemical formula 4]

(Experimental example 2)

A photoelectric conversion element (experimental example 2) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-2) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 5]

(Experimental example 3)

A photoelectric conversion element (experimental example 3) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-3) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 6]

(Experimental example 4)

A photoelectric conversion element (experimental example 4) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-4) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 7]

(Experimental example 5)

A photoelectric conversion element (experimental example 5) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-5) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 8]

(Experimental example 6)

A photoelectric conversion element (experimental example 6) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-6) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 9]

(Experimental example 7)

A photoelectric conversion element (experimental example 7) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-7) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 10]

(Experimental example 8)

A photoelectric conversion element (experimental example 8) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-8) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 11]

(Experimental example 9)

A photoelectric conversion element (experimental example 9) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-9) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 12]

(Experimental example 10)

A photoelectric conversion element (experimental example 10) was produced by a method similar to experimental example 1, except that a benzothienobenzothiophene derivative represented by the following formula (1-10) was used instead of the benzothienobenzothiophene derivative represented by the formula (1-1) used in experimental example 1.

[ chemical formula 13]

(Experimental example 11)

Except that two benzothienobenzothiophene derivatives represented by the formula (1-1) and the formula (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 11) was produced in a manner similar to that of experimental example 1.

(Experimental example 12)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-2) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 12) was produced in a manner similar to that of experimental example 2.

(Experimental example 13)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-3) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 13) was produced in a manner similar to that of experimental example 3.

(Experimental example 14)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-4) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 14) was produced in a manner similar to that of experimental example 4.

(Experimental example 15)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-5) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 15) was produced in a manner similar to that of experimental example 5.

(Experimental example 16)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-6) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 16) was produced in a manner similar to that of experimental example 6.

(Experimental example 17)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-8) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 17) was produced in a manner similar to that of experimental example 7.

(Experimental example 18)

Except that two benzothienobenzothienobenzothiophenes represented by the general formulae (1-9) and (1-7) are usedDerivatives and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 18) was produced in a manner similar to that of experimental example 8.

(Experimental example 19)

Except that two benzothienobenzothiophene derivatives represented by the formulae (1-10) and (1-7) and C₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 19) was produced in a manner similar to that of experimental example 9.

(Experimental example 20)

Except that DNTT and C represented by the following formula (5) are used₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 20) was produced in a manner similar to that of experimental example 1.

[ chemical formula 14]

(Experimental example 21)

Except that DPh-BTBT and C represented by the following formula (6) are used₆₀A fullerene (formula (2) above) was formed outside the photoelectric conversion layer, and a photoelectric conversion element (experimental example 21) was produced in a manner similar to that of experimental example 1.

[ chemical formula 15]

Evaluation of External Quantum Efficiency (EQE) and response time of each of the photoelectric conversion elements manufactured in experimental examples 1 to 21 was performed by the following method. Table 1 is a summary of the evaluation results of benzothiophenobenzothiophene derivatives used in the respective experimental examples.

The wavelength of light applied from the blue LED light source to each photoelectric conversion element via the band-pass filter was set to 450nm, and the light amount was set to 1.62. mu.W/cm²And controlling bias current to be applied between electrodes of the respective photoelectric conversion elements using a semiconductor parameter analyzerAnd a voltage to scan a voltage applied to the lower electrode with respect to the upper electrode, thereby obtaining a current-voltage curve. The light current value and the dark current value in the short-circuit state were measured to calculate EQE. Further, in a state where a bias voltage to be applied between the electrodes of the respective photoelectric conversion elements was controlled and a voltage of-2.6V was applied to the lower electrode with respect to the upper electrode, a wavelength of 450nm and a light amount of 1.62. mu.W/cm were used²The photoelectric conversion element is irradiated with the rectangular light pulse of (a), and the attenuation waveform of the current is observed by using an oscilloscope. The period of time from the current at the time of light pulse irradiation to the current decaying to 3% immediately after the light pulse irradiation was used as an index of the response speed.

[ Table 1]

As can be seen from table 1, in experimental examples 1 to 19 in which the photoelectric conversion layer was formed by using the benzothienobenzothiophene based compound represented by the above general formula (1), the obtained EQE was substantially equal to the EQE in experimental examples 20 and 21 in which the photoelectric conversion layer was formed by using typical materials. Furthermore, it can be found that, in experimental examples 1 to 19 in which the photoelectric conversion layer was formed using the benzothiophene-based benzothiophene compound represented by the above general formula (1), the response time was significantly improved as compared with experimental examples 20 and 21 in which the photoelectric conversion layer was formed using typical materials. Therefore, it can be found that the optical sensitivity can be improved while maintaining high EQE by forming the photoelectric conversion layer using the benzothienobenzothiophene based compound represented by general formula (1).

Although the description has been made by referring to the first to fourth embodiments, examples, application examples, and the like, the contents of the present invention are not limited to the above-described embodiments and the like, and may be modified in various ways. Further, the number of organic photoelectric conversion portions, the number of inorganic photoelectric conversion portions, and the ratio of the organic photoelectric conversion portions to the inorganic photoelectric conversion portions are not limited, and color signals of a plurality of colors can be acquired only by the organic photoelectric conversion portions.

Further, in the above-described embodiment and the like, an example has been described in which two electrodes, i.e., the reading electrode 21A and the accumulation electrode 21B, are provided as a plurality of electrodes included in the lower electrode 21; however, three or four or more electrodes such as a transfer electrode or a discharge electrode may be provided.

It should be noted that the effects described herein are merely illustrative and not restrictive, and that other effects may be included.

It should be noted that the present invention may have the following constitution. According to the present technology having the following configuration, the carrier mobility to the first electrode and the second electrode, which are opposed to each other and between which the organic photoelectric conversion layer is disposed, is improved by forming the organic photoelectric conversion layer using the benzothiophene-based compound represented by the above general formula (1). This enables to improve the external quantum efficiency and the optical sensitivity.

[1]

A photoelectric conversion element comprising:

a first electrode;

a second electrode opposite to the first electrode; and

an organic photoelectric conversion layer disposed between the first electrode and the second electrode, and containing a benzothiophene-based compound represented by the following general formula (1) as a first organic semiconductor material.

[ chemical formula 1]

(R1 to R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

[2]

The photoelectric conversion element according to [1], wherein the organic photoelectric conversion layer further contains a fullerene or a fullerene derivative as a second organic semiconductor material.

[3]

The photoelectric conversion element according to [1] or [2], wherein the organic photoelectric conversion layer further contains a third organic semiconductor material.

[4]

The photoelectric conversion element according to [3], wherein the third organic semiconductor material absorbs light of any wavelength from 400nm to 700nm (inclusive).

[5]

The photoelectric conversion element according to any one of [1] to [4], wherein the organic photoelectric conversion layer absorbs light of all wavelengths in a range from 400nm to 700nm (inclusive).

[6]

The photoelectric conversion element according to any one of [1] to [5], wherein the first electrode includes a plurality of electrodes.

[7]

The photoelectric conversion element according to any one of [1] to [6], wherein a first charge blocking layer is further provided between the first electrode and the organic photoelectric conversion layer.

[8]

The photoelectric conversion element according to any one of [1] to [7], wherein a second charge blocking layer is further provided between the organic photoelectric conversion layer and the second electrode.

[9]

An image pickup apparatus having a plurality of pixels each including one or more organic photoelectric conversion portions, the organic photoelectric conversion portions each including:

a first electrode;

a second electrode opposed to the first electrode; and

an organic photoelectric conversion layer disposed between the first electrode and the second electrode, and containing a benzothiophene-based compound represented by the following general formula (1) as a first organic semiconductor material.

[ chemical formula 2]

(R1 to R4 are each independently a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a phenylnaphthalene group, a biphenylnaphthalene group, a binaphthyl group, a thiophene group, a bithiophene group, a trithiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophenylbenzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkyl group, a fluorene group, a phenylfluorene group, or any derivative thereof.)

[10]

The image pickup apparatus according to [9], wherein one or more organic photoelectric conversion portions and one or more inorganic photoelectric conversion portions that perform photoelectric conversion in a wavelength band different from that of the organic photoelectric conversion portions are stacked in each of the pixels.

[11]

The image pickup apparatus according to [10], wherein,

the inorganic photoelectric conversion part is formed to be embedded in a semiconductor substrate, and

the organic photoelectric conversion portion is formed on a first surface side of the semiconductor substrate.

[12]

The image pickup apparatus according to [11], wherein the semiconductor substrate has a second surface opposite to the first surface, and a multilayer wiring layer is formed on the second surface side.

[13]

The image pickup apparatus according to [11] or [12], wherein,

the organic photoelectric conversion portion photoelectrically converts blue light, and

an inorganic photoelectric conversion portion that photoelectrically converts green light and an inorganic photoelectric conversion portion that photoelectrically converts red light are stacked in the semiconductor substrate.

[14]

The image pickup apparatus according to any one of [9] to [13], wherein a plurality of the organic photoelectric conversion portions that perform photoelectric conversion in wavelength bands different from each other are stacked in each of the pixels.

This application claims priority to japanese patent application JP2019-062367, filed on day 28 of 3.2019 with the sun to the office, and is incorporated herein by reference in its entirety.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made within the scope of the appended claims or their equivalents, depending on design requirements and other factors.