Photoelectric conversion element and imaging device

Abstract

The photoelectric conversion element according to one embodiment comprises a first electrode, a second electrode that is arranged opposite the first electrode, and an organic photoelectric conversion layer that is provided between the first electrode and the second electrode and includes, as a first organic semiconductor material, a benzothienobenzothiophene compound that is represented by general formula (1).

Description

[Technical field]

[0001] The present disclosure relates to a photoelectric conversion element using, for example, an organic material, and an imaging device including the same. [Background technology]

[0002] For example, Patent Document 1 and Non-Patent Document 1 report the use of a combination of a coumarin dye and fullerene as a material for a photoelectric conversion layer that absorbs blue light and performs photoelectric conversion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-129276 A [Non-patent literature]

[0004] [Non-Patent Document 1] Jpn. J. Appl. Phys., Vol. 49, No. 11, pp. 111601.1-11601.4 (2010) Summary of the Invention

[0005] Meanwhile, there is a demand for the development of photoelectric conversion elements having high external quantum efficiency and photoresponsiveness.

[0006] It is desirable to provide a photoelectric conversion element and an imaging device that can improve the external quantum efficiency and the photoresponsiveness.

[0007] A photoelectric conversion element according to an embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite to the first electrode, and a benzothienobenzothiophene-based compound represented by any one of the following formulae (1-1) to (1-10) as a first organic semiconductor material provided between the first electrode and the second electrode. At least one species and an organic photoelectric conversion layer including the organic layer. [ka]

[0008] An imaging device according to an embodiment of the present disclosure includes a plurality of pixels each having one or a plurality of organic photoelectric conversion units, and includes the photoelectric conversion element according to the embodiment described above as the organic photoelectric conversion unit.

[0009] In the photoelectric conversion element according to an embodiment of the present disclosure and the imaging device according to an embodiment of the present disclosure, a benzothienobenzothiophene-based compound represented by any one of the above formulas (1-1) to (1-10) is At least one species The organic photoelectric conversion layer is formed using the organic compound semiconductor layer 10. This improves the mobility of carriers to the first electrode and the second electrode that are disposed opposite each other with the organic photoelectric conversion layer therebetween. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a configuration of an imaging element according to a first embodiment of the present disclosure. [Diagram 2] 2 is a diagram illustrating an overall configuration of the image sensor illustrated in FIG. [Diagram 3] 2 is an equivalent circuit diagram of the image sensor shown in FIG. 1. [Figure 4] 2 is a schematic diagram showing the arrangement of transistors constituting a lower electrode and a control unit of the image sensor shown in FIG. 1. [Diagram 5] 4 is a schematic cross-sectional view illustrating another example of the configuration of the imaging element according to the first embodiment of the present disclosure. FIG. [Figure 6] 2A to 2C are cross-sectional views for explaining a method of manufacturing the image sensor shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view showing a step following FIG. [Figure 8] FIG. 8 is a cross-sectional view showing a step following FIG. 7. [Figure 9] 9 is a cross-sectional view showing a step following FIG. 8. [Figure 10] FIG. 10 is a cross-sectional view showing a step following FIG. [Figure 11]2 is a timing chart illustrating an example of an operation of the image sensor illustrated in FIG. [Figure 12] 11 is a schematic cross-sectional view illustrating an example of a configuration of an imaging element according to a second embodiment of the present disclosure. FIG. [Figure 13] 13 is a schematic cross-sectional view illustrating an example of a configuration of an imaging element according to a third embodiment of the present disclosure. FIG. [Figure 14] FIG. 13 is a schematic cross-sectional view illustrating an example of a configuration of an imaging element according to a fourth embodiment of the present disclosure. [Figure 15] 2 is a block diagram showing a configuration of an imaging device using the imaging element shown in FIG. 1 etc. as a pixel. [Figure 16] 16 is a functional block diagram illustrating an example of an electronic device (camera) using the imaging device illustrated in FIG. 15. [Figure 17] 1 is a block diagram showing an example of a schematic configuration of an in-vivo information acquiring system. [Figure 18] 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. [Figure 19] 2 is a block diagram showing an example of a functional configuration of a camera head and a CCU. FIG. [Figure 20] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 21] 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspect. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of description is as follows. 1. First embodiment (Example of a photoelectric conversion element having a photoelectric conversion layer containing a benzothienobenzothiophene-based compound) 1-1.Image sensor configuration 1-2. Manufacturing method of image sensor 1-3. Actions and Effects 2. Second embodiment (example in which two organic photoelectric conversion units are stacked on a semiconductor substrate) 3. Third embodiment (example in which the lower electrode has an organic photoelectric conversion unit formed of a solid film) 4. Fourth embodiment (example in which three organic photoelectric conversion units are stacked on a semiconductor substrate) 5. Application Examples 6. Application Examples 7. Working Example

[0012] <1. First embodiment> FIG. 1 shows an example of a cross-sectional configuration of an imaging element (imaging element 10A) according to the first embodiment of the present disclosure. FIG. 2 shows a planar configuration of the imaging element 10A shown in FIG. 1. FIG. 3 is an equivalent circuit diagram of the imaging element 10A shown in FIG. 1, which corresponds to the region 100 shown in FIG. 2. FIG. 4 shows a schematic arrangement of a lower electrode 21 and transistors constituting a control unit of the imaging element 10A shown in FIG. 1. The imaging element 10A constitutes one pixel (unit pixel P) in an imaging device (imaging device 1; see FIG. 17) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. The imaging element 10A of this embodiment has an organic photoelectric conversion section 20 in which a lower electrode 21, a photoelectric conversion layer 24, and an upper electrode 25 are laminated in this order. The photoelectric conversion layer 24 is formed using a benzothienobenzothiophene-based compound represented by general formula (1) described later. The organic photoelectric conversion section 20 corresponds to a specific example of a "photoelectric conversion element" of the present disclosure.

[0013] (1-1. Configuration of the image sensor) The imaging element 10A is a so-called vertical spectroscopic type in which, for example, one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32G and 32R are stacked in the vertical direction. The organic photoelectric conversion unit 20 is provided on the first surface (back surface; surface 30S1) side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32G and 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30. As described above, the organic photoelectric conversion unit 20 has a photoelectric conversion layer 24 formed of an organic material between the lower electrode 21 and the upper electrode 25 arranged opposite to each other. This photoelectric conversion layer 24 is configured to include a p-type semiconductor and an n-type semiconductor, and has a bulk heterojunction structure in the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing a p-type semiconductor and an n-type semiconductor.

[0014] The organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32G and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the organic photoelectric conversion unit 20 acquires a blue (G) color signal. The inorganic photoelectric conversion units 32G and 32R acquire green (G) and red (R) color signals, respectively, due to differences in absorption coefficients. This makes it possible for the image sensor 10A to acquire multiple types of color signals in one pixel without using a color filter.

[0015] In this embodiment, a case where electrons among pairs of electrons and holes (electron-hole pairs) generated by photoelectric conversion are read out as signal charges (when an n-type semiconductor region is used as a photoelectric conversion layer) will be described. In addition, in the figure, the "+ (plus)" attached to "p" and "n" indicates that the p-type or n-type impurity concentration is high.

[0016] On the second surface (front surface; 30S2) of the semiconductor substrate 30, for example, floating diffusions FD1 (region 36B in the semiconductor substrate 30), FD2 (region 37C in the semiconductor substrate 30), and FD3 (region 38C in the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplifier transistor (modulation element) AMP, a reset transistor RST, a selection transistor SEL, and a multilayer wiring 40 are provided. The multilayer wiring 40 has a configuration in which wiring layers 41, 42, and 43 are stacked in an insulating layer 44, for example.

[0017] In the drawings, the first surface (surface 30S1) of the semiconductor substrate 30 is represented as the light incident side S1, and the second surface (surface 30S2) is represented as the wiring layer side S2.

[0018] In the organic photoelectric conversion section 20, a lower electrode 21, a semiconductor layer 23, a photoelectric conversion layer 24, and an upper electrode 25 are laminated in this order from the first surface (surface 30S1) side of the semiconductor substrate 30. 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 imaging element 10A, and is composed of a readout electrode 21A and a storage electrode 21B separated from each other by the insulating layer 22, as will be described in detail later. Of the lower electrode 21, the readout electrode 21A is electrically connected to the semiconductor layer 23 through an opening 22H provided in the insulating layer 22. In FIG. 1, the semiconductor layer 23, the photoelectric conversion layer 24, and the upper electrode 25 are provided as a continuous layer common to the multiple imaging elements 10A, but may be formed separately for each imaging element 10A, for example. Between the first surface (surface 30S1) of the semiconductor substrate 30 and the lower electrode 21, for example, a dielectric film 26, an insulating film 27, and an interlayer insulating layer 28 are provided. A protective layer 51 is provided on the upper electrode 25. A light-shielding film 52 is provided in the protective layer 51 at a position corresponding to the read electrode 21A, for example. This light-shielding film 52A only needs to be provided so as not to overlap at least the storage electrode 21B, and to cover at least the region of the read electrode 21A that is in direct contact with the semiconductor layer 23. Optical members such as a planarization layer (not shown) and an on-chip lens 53 are provided above the protective layer 51.

[0019] A through electrode 34 is provided between the first surface (surface 30S1) and the second surface (surface 30S2) of the semiconductor substrate 30. This through electrode 34 is electrically connected to the readout electrode 21A of the organic photoelectric conversion unit 20, and the organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and one of the source / drain regions 36B of the reset transistor RST (reset transistor Tr1rst) that also serves as the floating diffusion FD1 via the through electrode 34. This makes it possible for the image sensor 10A to satisfactorily transfer the charge generated in the organic photoelectric conversion unit 20 on the first surface (surface 30S21) side of the semiconductor substrate 30 to the second surface (surface 30S2) side of the semiconductor substrate 30, thereby improving the characteristics.

[0020] The lower end of the through electrode 34 is connected to a connection portion 41A in the wiring layer 41, and the connection portion 41A and the gate Gamp of the amplifier transistor AMP are connected via a lower first contact 45. The connection portion 41A and the floating diffusion FD1 (region 36B) are connected, for example, via a lower second contact 46. The upper end of the through electrode 34 is connected to the readout electrode 21A, for example, via an upper first contact 29A, a pad portion 39A, and an upper second contact 29B.

[0021] The through electrode 34 is provided, for example, for each organic photoelectric conversion unit 20 in each of the imaging elements 10A. The through electrode 34 functions as a connector between the organic photoelectric conversion unit 20 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1, and also serves as a transmission path for charges generated in the organic photoelectric conversion unit 20.

[0022] A reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD1 (one of the source / drain regions 36B of the reset transistor RST). This makes it possible to reset the charge stored in the floating diffusion FD1 by the reset transistor RST.

[0023] In the imaging device 10A of the present embodiment, light incident on the organic photoelectric conversion section 20 from the upper electrode 25 side is absorbed by the photoelectric conversion layer 24. The excitons generated by this move to the interface between the electron donor and electron acceptor constituting the photoelectric conversion layer 24, and are dissociated into excitons, that is, into electrons and holes. The charges (electrons and holes) generated here are carried to different electrodes by diffusion due to the difference in carrier concentration and by an internal electric field due to the difference in work function between the anode (e.g., the upper electrode 25) and the cathode (e.g., the lower electrode 21), and are detected as a photocurrent. In addition, the transport direction of the electrons and holes can be controlled by applying a potential between the lower electrode 21 and the upper electrode 25.

[0024] The structure and materials of each part will be described below.

[0025] The organic photoelectric conversion section 20 is an organic photoelectric conversion element that absorbs light corresponding to a part or the entire wavelength range of a selective wavelength range (for example, 400 nm or more and 700 nm or less) and generates electron-hole pairs.

[0026] As described above, the lower electrode 21 is composed of the read electrode 21A and the storage electrode 21B which are formed separately. The read electrode 21A is for transferring the charge generated in the photoelectric conversion layer 24 to the floating diffusion FD1, and is connected to the floating diffusion FD1 via, for example, the upper second contact 29B, the pad portion 39A, the upper first contact 29A, the through electrode 34, the connection portion 41A, and the lower second contact 46. The storage electrode 21B is for storing electrons as signal charges in the semiconductor layer 23 among the charges generated in the photoelectric conversion layer 24. The storage electrode 21B is provided in a region covering the light receiving surfaces of the inorganic photoelectric conversion units 32G and 32R formed in the semiconductor substrate 30, facing directly against these light receiving surfaces. The storage electrode 21B is preferably larger than the read electrode 21A, and thus can store a large amount of charge. As shown in FIG. 4, the voltage application circuit 60 is connected to the storage electrode 21B via wiring.

[0027] The lower electrode 21 is made of a conductive film having optical transparency. Examples of the material of the lower electrode 21 include ITO, In2O3 with tin (Sn) added as a dopant, and indium tin oxide including crystalline ITO and amorphous ITO. In addition to the above, the material of the lower electrode 21 may be a tin oxide (SnO2)-based material with a dopant added, or a zinc oxide-based material with a dopant added. Examples of the zinc oxide-based material include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Examples of the material of the lower electrode 21 may include CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, ZnSnO3, TiO2, or the like. Furthermore, a spinel oxide or an oxide having a YbFe2O4 structure may be used. The lower electrode 21 formed using the above-mentioned materials generally has a high work function and functions as an anode electrode.

[0028] 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 is for accumulating signal charges generated in the photoelectric conversion layer 24. The semiconductor layer 23 is preferably formed using a material having a higher charge mobility and a larger band gap than the photoelectric conversion layer 24. For example, the band gap of the material constituting the semiconductor layer 23 is preferably 3.0 eV or more. Examples of such materials include oxide semiconductor materials such as IGZO and organic semiconductor materials. Examples of organic semiconductor materials include transition metal dichalcogenides, silicon carbide, diamond, graphene, carbon nanotubes, condensed polycyclic hydrocarbon compounds, and condensed heterocyclic compounds. The thickness of the semiconductor layer 23 is, for example, 10 nm or more and 300 nm or less. By providing the semiconductor layer 23 made of the above material below the photoelectric conversion layer 24, it is possible to prevent recombination of charges during charge accumulation and improve transfer efficiency.

[0029] The photoelectric conversion layer 24 converts light energy into electrical energy. The photoelectric conversion layer 24 of this embodiment absorbs, for example, a part or all of the wavelengths of light in the range of 400 nm to 700 nm. The photoelectric conversion layer 24 is configured to include, for example, two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type semiconductors or n-type semiconductors, respectively. The photoelectric conversion layer 24 has a junction surface (p / n junction surface) between the p-type semiconductor material and the n-type semiconductor material within the 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 place where excitons generated when light is absorbed are separated into electrons and holes. Specifically, the excitons are separated into electrons and holes at the interface (p / n junction surface) between the electron donor and the electron acceptor.

[0030] The photoelectric conversion layer 24 may be configured to include an organic material, so-called dye material, that converts light in a predetermined wavelength range into electric current while transmitting light in other wavelength ranges, in addition to the p-type semiconductor material and the n-type semiconductor material. When the photoelectric conversion layer 24 is formed using three types of organic materials, the p-type semiconductor material, the n-type semiconductor material, and the dye material, it is preferable that the p-type semiconductor material and the n-type semiconductor material are materials that have optical transparency in the visible range (for example, 400 nm to 700 nm). The thickness of the photoelectric conversion layer 24 is, for example, 25 nm or more and 400 nm or less, preferably 50 nm or more and 350 nm or less. More preferably, it is 150 nm or more and 300 nm or less.

[0031] In the present embodiment, the photoelectric conversion layer 24 is formed, for example, by including a benzothienobenzothiophene-based compound represented by the following general formula (1) that absorbs light having a wavelength of 400 nm or more and 500 nm or less. This benzothienobenzothiophene-based compound corresponds to a specific example of the "first organic semiconductor material" of the present disclosure.

[0032] [ka] (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 binaphthalene group, a thiophene group, a bithiophene group, a terthiophene group, a benzothiophene group, a phenylbenzothiophene group, a biphenylbenzothiophene group, a benzofuran group, a phenylbenzofuran group, a biphenylbenzothiophene group, an alkane group, a cycloalkane group, a fluorene group, a phenylfluorene group, or a derivative thereof.)

[0033] Examples of other organic materials constituting the photoelectric conversion layer 24 include fullerene or fullerene derivatives. Fullerene or fullerene derivatives correspond to a specific example of a "second organic semiconductor material" in the present disclosure.

[0034] Furthermore, the photoelectric conversion layer 24 may contain an organic semiconductor material that absorbs light having a wavelength of, for example, 400 nm or more and 700 nm or less. Examples of such materials include coumarin derivatives, perylene derivatives, porphyrin derivatives, merocyanine derivatives, and anthraquinone derivatives. The above organic semiconductor material corresponds to a specific example of the "third organic semiconductor material" of the present disclosure.

[0035] The above organic semiconductor materials function as p-type or n-type semiconductors depending on the combination.

[0036] The photoelectric conversion layer 24 may contain an organic material other than the organic semiconductor material. As the organic material other than the organic semiconductor material, for example, any one of quinacridone, chlorinated boron subphthalocyanine, pentacene, benzothienobenzothiophene, naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene, and fluoranthene or derivatives thereof is preferably used. Alternatively, a polymer such as phenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene or a derivative thereof may be used. In addition, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaannulene dyes, azulene dyes, naphthoquinone, anthraquinone dyes, condensed polycyclic aromatics such as anthracene and pyrene, and chain compounds in which aromatic rings or heterocyclic compounds are condensed, or two nitrogen-containing heterocycles such as quinoline, benzothiazole, and benzoxazole having a squarylium group and a croconite methine group as a binding chain, or cyanine-like dyes bonded by a squarylium group and a croconite methine group, etc. can be preferably used. Note that, as the above-mentioned metal complex dyes, dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, or ruthenium complex dyes are preferred, but are not limited thereto.

[0037] The upper electrode 25 is made of a conductive film having optical transparency, similar to the lower electrode 21. In an imaging device 1 using the imaging element 10A as one pixel, the upper electrode 25 may be separated for each pixel, or may be formed as an electrode common to each pixel. The thickness of the upper electrode 25 is, for example, 10 nm to 200 nm.

[0038] Other layers 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. For example, as in the image sensor 10B shown in Fig. 5, the semiconductor layer 23, the electron block layer 24A (first charge block layer), the photoelectric conversion layer 24, and the hole block layer 24B (second charge block layer) may be laminated in this order from the lower electrode 21 side. Furthermore, an undercoat layer and a hole transport layer may be provided between the lower electrode 21 and the photoelectric conversion layer 24, and a work tube adjustment layer, a buffer layer, or an electron transport layer may be provided between the photoelectric conversion layer 24 and the upper electrode 25.

[0039] The insulating layer 22 serves to electrically separate the storage electrode 21B from the semiconductor layer 23. The insulating layer 22 is provided, for example, on the interlayer insulating layer 28 so as to cover the lower electrode 21. The insulating layer 22 has an opening 22H provided on the read electrode 21A of the lower electrode 21, and the read electrode 21A and the semiconductor layer 23 are electrically connected through this opening 22H. The insulating layer 22 is made of, for example, silicon oxide (SiO x ), silicon nitride (SiN x The insulating layer 22 is formed of a single layer film made of one of silicon oxynitride (SiON) and the like, or a laminate film made of two or more of these materials. The thickness of the insulating layer 22 is, for example, 20 nm to 500 nm.

[0040] The dielectric film 26 is intended to prevent light reflection caused by the difference in refractive index between the semiconductor substrate 30 and the insulating film 27. The material of the dielectric film 26 is preferably a material having a refractive index between the refractive index of the semiconductor substrate 30 and the refractive index of the insulating film 27. Furthermore, the material of the dielectric film 26 is preferably a material capable of forming a film having a negative fixed charge. Alternatively, the material of the dielectric film 26 is preferably a semiconductor material or a conductive material having a wider band gap than the semiconductor substrate 30. This makes it possible to suppress the generation of dark current at the interface of the semiconductor substrate 30. Examples of such materials include hafnium oxide (HfO x ), aluminum oxide (AlO x ), zirconium oxide (ZrOx ), tantalum oxide (TaO x ), titanium dioxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), 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 (AlN x ), hafnium oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ) etc.

[0041] The insulating film 27 is provided on the first surface (surface 30S1) of the semiconductor substrate 30 and the dielectric film 26 formed on the side surface of the through hole 30H, and serves to electrically insulate the through electrode 34 from the semiconductor substrate 30. Examples of the material for the insulating film 27 include silicon oxide (SiO x ), TEOS, silicon nitride (SiN x ) and silicon oxynitride (SiON).

[0042] The interlayer insulating layer 28 is, for example, silicon oxide (SiO x ), TEOS, silicon nitride (SiN x It is composed of a single layer film made of one of silicon oxynitride (SiON) and silicon oxide nitride (SiON), or a laminate film made of two or more of these.

[0043] The protective layer 51 is made of a light-transmitting material, such as silicon oxide (SiO x ), silicon nitride (SiN x The protective layer 51 is made of a single layer film made of any one of silicon oxynitride (SiON) and silicon oxide nitride (SiON), or a laminated film made of two or more of these. The thickness of the protective layer 51 is, for example, 100 nm to 30,000 nm.

[0044] The semiconductor substrate 30 is, for example, made of an n-type silicon (Si) substrate, and has a p-well 31 in a predetermined region (for example, pixel section 1a). The above-mentioned transfer transistors Tr2 and Tr3, amplifier transistor AMP, reset transistor RST, and selection transistor SEL are provided on a second surface (surface 30S2) of the p-well 31. In addition, the peripheral portion (peripheral portion 1b) of the semiconductor substrate 30 is provided with, for example, a pixel readout circuit 110 and a pixel drive circuit 120, which are made up of logic circuits, as shown in FIG. 2.

[0045] The reset transistor RST (reset transistor Tr1rst) resets the charge transferred from the organic photoelectric conversion unit 20 to the floating diffusion FD1, and is composed of, for example, a MOS transistor. Specifically, the reset transistor Tr1rst is composed of a reset gate Grst, a channel formation region 36A, and source / drain regions 36B, 36C. The reset gate Grst is connected to a reset line RST1, and one source / drain region 36B of the reset transistor Tr1rst also serves as the floating diffusion FD1. The other source / drain region 36C constituting the reset transistor Tr1rst is connected to a power supply VDD.

[0046] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the organic photoelectric conversion unit 20 into a voltage, and is composed of, for example, a MOS transistor. Specifically, the amplifier transistor AMP is composed of a gate Gamp, a channel formation region 35A, and source / drain regions 35B, 35C. The gate Gamp is connected to the readout electrode 21A and one of the source / drain regions 36B (floating diffusion FD1) of the reset transistor Tr1rst via the lower first contact 45, the connection portion 41A, the lower second contact 46, the through electrode 34, etc. In addition, one of the source / drain regions 35B shares an area with the other of the source / drain regions 36C constituting the reset transistor Tr1rst, and is connected to a power supply VDD.

[0047] The selection transistor SEL (selection transistor TR1sel) is composed of a gate Gsel, a channel formation region 34A, and source / drain regions 34B and 34C. The gate Gsel is connected to a selection line SEL1. One source / drain region 34B shares an area with the other source / drain region 35C constituting the amplifier transistor AMP, and the other source / drain region 34C is connected to a signal line (data output line) VSL1.

[0048] The inorganic photoelectric conversion units 32G and 32R each have a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion units 32G and 32R are capable of splitting light in the vertical direction by utilizing the fact that the wavelength of light absorbed varies depending on the depth of incidence of light in a silicon substrate. The inorganic photoelectric conversion unit 32G selectively detects green light and accumulates a signal charge corresponding to green, and is disposed at a depth capable of efficiently photoelectrically converting the green light. The inorganic photoelectric conversion unit 32R selectively detects red light and accumulates a signal charge corresponding to red, and is disposed at a depth capable of efficiently photoelectrically converting the red light. Note that green (G) is a color corresponding to, for example, a wavelength range of 495 nm to 620 nm, and red (R) is a color corresponding to, for example, a wavelength range of 620 nm to 750 nm. Each of the inorganic photoelectric conversion units 32G and 32R may be capable of detecting light in a part or all of the wavelength ranges.

[0049] The inorganic photoelectric conversion unit 32G includes, for example, a p+ region that serves as a hole accumulation layer and an n region that serves as an electron accumulation layer. The inorganic photoelectric conversion unit 32R has, for example, a p+ region that serves as a hole accumulation layer and an n region that serves as an electron accumulation layer (having a pnp stacked structure). The n region of the inorganic photoelectric conversion unit 32G is connected to a vertical transfer transistor Tr2. The p+ region of the inorganic photoelectric conversion unit 32G is bent along the transfer transistor Tr2 and connected to the p+ region of the inorganic photoelectric conversion unit 32R.

[0050] The transfer transistor Tr2 (transfer transistor TR2trs) is for transferring the signal charge corresponding to green, which is generated and accumulated in the inorganic photoelectric conversion unit 32G, to the floating diffusion FD2. Since the inorganic photoelectric conversion unit 32G is formed at a deep position from the second surface (surface 30S2) of the semiconductor substrate 30, it is preferable that the transfer transistor TR2trs of the inorganic photoelectric conversion unit 32G is composed of a vertical transistor. In addition, the transfer transistor TR2trs is connected to a transfer gate line TG2. Furthermore, a floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2trs. The charge accumulated in the inorganic photoelectric conversion unit 32G is read out to the floating diffusion FD2 via a transfer channel formed along the gate Gtrs2.

[0051] The transfer transistor Tr3 (transfer transistor TR3trs) transfers the signal charge corresponding to red generated and accumulated in the inorganic photoelectric conversion unit 32R to the floating diffusion FD3, and is composed of, for example, a MOS transistor. The transfer transistor TR3trs is connected to a transfer gate line TG3. Furthermore, a floating diffusion FD3 is provided in the region 38C near the gate Gtrs3 of the transfer transistor TR3trs. The charge accumulated in the inorganic photoelectric conversion unit 32R is read out to the floating diffusion FD3 via a transfer channel formed along the gate Gtrs3.

[0052] A reset transistor TR2rst, an amplifier transistor TR2amp, and a selection transistor TR2sel constituting a control unit of the inorganic photoelectric conversion unit 32G are further provided on the second surface (surface 30S2) side of the semiconductor substrate 30. A reset transistor TR3rst, an amplifier transistor TR3amp, and a selection transistor TR3sel constituting a control unit of the inorganic photoelectric conversion unit 32R are further provided.

[0053] The reset transistor TR2rst is composed of a gate, a channel forming region, and a source / drain region. The gate of the reset transistor TR2rst is connected to a reset line RST2, and one of the source / drain regions of the reset transistor TR2rst is connected to a power supply VDD. The other source / drain region of the reset transistor TR2rst also serves as a floating diffusion FD2.

[0054] The amplifier transistor TR2amp is composed of a gate, a channel forming region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD2) of the reset transistor TR2rst. In addition, one of the source / drain regions constituting the amplifier transistor TR2amp shares an area with one of the source / drain regions constituting the reset transistor TR2rst, and is connected to the power supply VDD.

[0055] The selection transistor TR2sel is composed of a gate, a channel formation region, and a source / drain region. The gate is connected to a selection line SEL2. One of the source / drain regions constituting the selection transistor TR2sel shares the region with the other of the source / drain regions constituting the amplifier transistor TR2amp. The other of the source / drain regions constituting the selection transistor TR2sel is connected to a signal line (data output line) VSL2.

[0056] The reset transistor TR3rst is composed of a gate, a channel forming region, and a source / drain region. The gate of the reset transistor TR3rst is connected to a reset line RST3, and one of the source / drain regions constituting the reset transistor TR3rst is connected to a power supply VDD. The other source / drain region constituting the reset transistor TR3rst also serves as a floating diffusion FD3.

[0057] The amplifier transistor TR3amp is composed of a gate, a channel forming region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD3) constituting the reset transistor TR3rst. In addition, one of the source / drain regions constituting the amplifier transistor TR3amp shares an area with one of the source / drain regions constituting the reset transistor TR3rst, and is connected to the power supply VDD.

[0058] The selection transistor TR3sel is composed of a gate, a channel formation region, and a source / drain region. The gate is connected to a selection line SEL3. One of the source / drain regions constituting the selection transistor TR3sel shares the same region with the other of the source / drain regions constituting the amplifier transistor TR3amp. The other of the source / drain regions constituting the selection transistor TR3sel is connected to a signal line (data output line) VSL3.

[0059] The reset lines RST1, RST2, and RST3, the selection lines SEL1, SEL2, and SEL3, and the transfer gate lines TG2 and TG3 are each connected to a vertical drive circuit 112 that constitutes a drive circuit. The signal lines (data output lines) VSL1, VSL2, and VSL3 are connected to a column signal processing circuit 113 that constitutes a drive circuit.

[0060] The lower first contact 45, the lower second contact 46, the upper first contact 29A, the upper second contact 29B and the upper third contact 29C are made of, 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), tantalum (Ta), etc.

[0061] (1-2. Manufacturing method of image sensor) The imaging element 10A of the present embodiment can be manufactured, for example, as follows.

[0062] 6 to 10 show the manufacturing method of the image sensor 10A in the order of steps. First, as shown in Fig. 6, a first conductivity type well, for example, a p-well 31, is formed in a semiconductor substrate 30, and inorganic photoelectric conversion units 32G, 32R of a second conductivity type (for example, n-type) are formed in this p-well 31. A p+ region is formed in the vicinity of the first surface (surface 30S1) of the semiconductor substrate 30.

[0063] 6, n+ regions that become floating diffusions FD1 to FD3 are formed on the second surface (surface 30S2) of the semiconductor substrate 30, and then a gate insulating layer 33 and a gate wiring layer 47 including the gates of the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST are formed. This forms the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST. Furthermore, a multilayer wiring 40 consisting of wiring layers 41 to 43 including a lower first contact 45, a lower second contact 46, and a connection portion 41A and an insulating layer 44 is formed on the second surface (surface 30S2) of the semiconductor substrate 30.

[0064] The base of the semiconductor substrate 30 is, for example, an SOI (Silicon on Insulator) substrate in which the semiconductor substrate 30, a buried oxide film (not shown), and a holding substrate (not shown) are laminated. Although not shown in Fig. 6, the buried oxide film and the holding substrate are bonded to a first surface (surface 30S1) of the semiconductor substrate 30. After the ion implantation, an annealing process is performed.

[0065] Next, a support substrate (not shown) or another semiconductor base is bonded to the second surface (surface 30S2) side (multilayer wiring 40 side) of the semiconductor substrate 30, and the substrate is turned upside down. Next, the semiconductor substrate 30 is separated from the buried oxide film of the SOI substrate and the holding substrate, and the first surface (surface 30S1) of the semiconductor substrate 30 is exposed. The above steps can be performed by techniques used in normal CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

[0066] 7, the semiconductor substrate 30 is processed from the first surface (surface 30S1) side by, for example, dry etching to form, for example, an annular through hole 30H. As shown in FIG. 7, the depth of the through hole 30H penetrates from the first surface (surface 30S1) to the second surface (surface 30S2) of the semiconductor substrate 30 and reaches, for example, the connection portion 41A.

[0067] 8, a dielectric film 26 is formed on the first surface (surface 30S1) of the semiconductor substrate 30 and the side surface of the through hole 30H by, for example, atomic layer deposition (ALD). As a result, the dielectric film 26 is formed continuously on the first surface (surface 30S1) of the semiconductor substrate 30 and the side surface and bottom surface of the through hole 30H. Next, an insulating film 27 is formed on the first surface (surface 30S1) of the semiconductor substrate 30 and in the through hole 30H, and then the insulating film 27 and the dielectric film 26 formed on the bottom of the through hole 30H are removed by, for example, dry etching to expose the connection portion 41A. 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, by etching and removing the photoresist PR, the through electrode 34 having a protruding portion is formed on the first surface (surface 30S1) of the semiconductor substrate 30.

[0068] 9, an insulating film constituting the interlayer insulating layer 28 is formed on the insulating film 27 and the through electrode 34, and then the upper first contact 29A, pad portions 39A and 39B, the upper second contact 29B, and the upper third contact 29C are formed on the through electrode 34, and then the surface of the interlayer insulating layer 28 is planarized using a chemical mechanical polishing (CMP) 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 21x.

[0069] Subsequently, as shown in FIG. 10, the read electrode 21A and the storage electrode 21B are formed by etching and removing the photoresist.

[0070] Thereafter, an insulating layer 22 is formed on the interlayer insulating layer 28 and the readout electrode 21A and storage electrode 21B, and an opening 22H is provided on the readout electrode 21A. Next, a semiconductor layer 23, a photoelectric conversion layer 24, and an upper electrode 25 are formed in this order on the insulating layer 22. Finally, a protective layer 51, a light-shielding film 52, and an on-chip lens 53 are disposed on the upper electrode 25. With the above steps, the image sensor 10A shown in FIG. 1 is completed.

[0071] In addition, when the semiconductor layer 23 or other organic layers are formed using organic materials, it is desirable to form them continuously in a vacuum process (in a vacuum integrated process). In addition, the method of forming the photoelectric conversion layer 24 is not necessarily limited to a method using a vacuum deposition method, and other methods, such as a spin coat technique or a print technique, may be used. Furthermore, the method of forming the transparent electrodes (lower electrode 21 and upper electrode 25) depends on the material constituting the transparent electrodes, but may include physical vapor deposition methods (PVD methods) such as vacuum deposition methods, reactive deposition methods, various sputtering methods, electron beam deposition methods, and ion plating methods, pyrosol methods, methods of thermally decomposing organometallic compounds, various chemical vapor deposition methods (CVD methods) including spray methods, dipping methods, and MOCVD methods, electroless plating methods, and electrolytic plating methods.

[0072] In the imaging element 10A, when light is incident on the organic photoelectric conversion unit 20 through the on-chip lens 53, the light passes through the organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32G and 32R in this order, and is photoelectrically converted into green, blue, and red light during the passage. The operation of acquiring signals of each color will be described below.

[0073] (Obtaining a Blue Signal by Organic Photoelectric Conversion Unit 20) Of the light incident on the imaging element 10A, blue light is first selectively detected (absorbed) by the organic photoelectric conversion section 20 and undergoes photoelectric conversion.

[0074] The organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1 via the through electrode 34. Thus, the electrons of the electron-hole pairs generated in the organic photoelectric conversion unit 20 are extracted from the lower electrode 21 side, transferred to the second surface (surface 30S2) side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD1. At the same time, the amount of charge generated in the organic photoelectric conversion unit 20 is modulated into a voltage by the amplifier transistor AMP.

[0075] In addition, a reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD1, so that the charge accumulated in the floating diffusion FD1 is reset by the reset transistor RST.

[0076] Here, the organic photoelectric conversion unit 20 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 via the through electrode 34, so that the charge accumulated in the floating diffusion FD1 can be easily reset by the reset transistor RST.

[0077] On the other hand, if the through electrode 34 and the floating diffusion FD1 are not connected, it becomes difficult to reset the charge accumulated in the floating diffusion FD1, and a large voltage is applied to pull it out to the upper electrode 25 side. This may damage the photoelectric conversion layer 24. In addition, a structure that allows resetting in a short time leads to an increase in dark noise, which is a trade-off, making this structure difficult to implement.

[0078] 11 shows an example of the operation of the image sensor 10A. (A) shows the potential at the storage 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 TR1rst. In the image sensor 10A, voltages are applied to the readout electrode 21A and the storage electrode 21B individually.

[0079] In the image sensor 10A, during the accumulation period, a potential V1 is applied from the drive circuit to the readout electrode 21A, and a potential V2 is applied to the storage electrode 21B. Here, the potentials V1 and V2 are set to V2>V1. As a result, the charge (signal charge; electrons) generated by photoelectric conversion is attracted to the storage electrode 21B and accumulated in the region of the semiconductor layer 23 facing the storage electrode 21B (accumulation period). Incidentally, the potential of the region of the semiconductor layer 23 facing the storage electrode 21B becomes a more negative value as the photoelectric conversion time passes. Incidentally, the holes are sent from the upper electrode 25 to the drive circuit.

[0080] In the image sensor 10A, a reset operation is performed in the latter half of the accumulation period. Specifically, at timing t1, the scanning unit changes the voltage of the reset signal RST from low level to high level. As a result, in the unit pixel P, the reset transistor TR1rst is turned on, and as a result, 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).

[0081] After the reset operation is completed, the charge is read out. Specifically, at timing t2, a potential V3 is applied to the readout electrode 21A from the drive circuit, and a potential V4 is applied to the storage electrode 21B. Here, the potentials V3 and V4 are set such that V3 < V4. As a result, the charge accumulated in the region corresponding to the storage electrode 21B is read out from the readout electrode 21A to the floating diffusion FD1. That is, the charge accumulated in the semiconductor layer 23 is read out to the control unit (transfer period).

[0082] After the readout operation is completed, again, a potential V1 is applied to the readout electrode 21A from the drive circuit, and a potential V2 is applied to the storage electrode 21B. As a result, the charge generated by the photoelectric conversion is attracted to the storage electrode 21B and accumulated in the region of the photoelectric conversion layer 24 facing the storage electrode 21B (accumulation period).

[0083] (Acquisition of green and red signals by inorganic photoelectric conversion units 32G and 32R) Subsequently, among the light transmitted through the organic photoelectric conversion unit 20, the green light is absorbed and photoelectrically converted in the inorganic photoelectric conversion unit 32G, and the red light is absorbed and photoelectrically converted in the inorganic photoelectric conversion unit 32R in this order. In the inorganic photoelectric conversion unit 32G, electrons corresponding to the incident green light are accumulated in the n-region of the inorganic photoelectric conversion unit 32G, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2. Similarly, in the inorganic photoelectric conversion unit 32R, electrons corresponding to the incident red light are accumulated in the n-region of the inorganic photoelectric conversion unit 32R, and the accumulated electrons are transferred to the floating diffusion FD3 by the transfer transistor Tr3.

[0084] (1 - 3. Actions and effects) As described above, the development of a photoelectric conversion element for blue light having a high external quantum efficiency is required. For example, a blue organic photoelectric conversion element using a porphyrin dye has been reported, but its external quantum efficiency is about 20% at 80V. Also, a photoelectric conversion element using a combination of fullerene and coumarin dye as the material of the blue organic photoelectric conversion film has been reported, but its external quantum efficiency is about 23% at 5V.

[0085] In contrast to this, in the present embodiment, the benzothienobenzothiophene-based compound represented by the above general formula (1) is used as the material for the photoelectric conversion layer 24.

[0086] The benzothienobenzothiophene compound represented by the general formula (1) has a face-on orientation in which the long axis of the molecule is horizontal to the substrate surface. The benzothienobenzothiophene compound represented by the general formula (1) can form a herringbone crystal, which is advantageous for carrier transport, due to the strong intermolecular interaction caused by the benzothienobenzothiophene skeleton. Therefore, the benzothienobenzothiophene compound represented by the general formula (1) in the photoelectric conversion layer 24 exhibits high carrier mobility in the direction perpendicular to the electrode surfaces of the lower electrode 21 and the upper electrode 25. The benzothienobenzothiophene compound represented by the general formula (1) also exhibits excellent photoresponse current at low voltage.

[0087] As a result, a photoelectric conversion layer 24 is formed that absorbs light having a wavelength of 400 nm or more and 500 nm or less, and has high carrier mobility to the lower electrode 21 and the upper electrode 25. This makes it possible to provide an imaging element 10A for blue light having high external quantum efficiency.

[0088] In addition, the benzothienobenzothiophene compound represented by the general formula (1) exhibits high carrier mobility in the direction perpendicular to the electrode surfaces of the lower electrode 21 and the upper electrode 25 that are opposed to each other with the photoelectric conversion layer 24 interposed therebetween, as described above. This makes it possible to improve the on / off response characteristics of the photocurrent depending on the presence or absence of light irradiation.

[0089] In addition, the benzothienobenzothiophene compound represented by the general formula (1) has a transition dipole moment parallel to the light incidence direction, and therefore can strongly absorb light of 400 nm or more and 500 nm or less. This eliminates the need for an on-chip color filter, and makes it possible to configure a so-called vertical spectroscopic imaging element in which photoelectric conversion units that absorb light of different wavelengths are stacked vertically, as in the imaging element 10A of the present embodiment.

[0090] Next, second to fifth embodiments of the present disclosure will be described. In the following, the same components as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0091] <2. Second embodiment>

[0092] 12 illustrates a cross-sectional configuration of an imaging element (imaging element 10C) according to a second embodiment of the present disclosure. The imaging element 10C constitutes one pixel (unit pixel P) in an imaging device (imaging device 1) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. The imaging element 10C of this embodiment has two organic photoelectric conversion units 20 and 70, and one inorganic photoelectric conversion unit 32 stacked in the vertical direction.

[0093] The organic photoelectric conversion units 20, 70 and the inorganic photoelectric conversion unit 32 selectively detect light in their respective wavelength ranges and perform photoelectric conversion. Specifically, for example, the organic photoelectric conversion unit 20 acquires a blue (B) color signal, as in the first embodiment. The organic photoelectric conversion unit 70 acquires, for example, a green (G) color signal. The inorganic photoelectric conversion unit 32 acquires, for example, a red (R) color signal. This makes it possible for the image sensor 10C to acquire multiple types of color signals in one pixel without using a color filter.

[0094] The organic photoelectric conversion section 70 is, for example, stacked above the organic photoelectric conversion section 20, and has a configuration in which a lower electrode 71, a semiconductor layer 73, a photoelectric conversion layer 74, and an upper electrode 75 are stacked in this order from the first surface (surface 30S1) side of the semiconductor substrate 30, similar to the organic photoelectric conversion section 20. In addition, an insulating layer 72 is provided between the lower electrode 71 and the semiconductor layer 73. The lower electrode 71 is, for example, formed separately for each imaging element 10C, and is composed of a readout electrode 71A and a storage electrode 71B separated from each other by the insulating layer 72, as will be described in detail later. Of the lower electrode 71, the readout electrode 71A is electrically connected to the photoelectric conversion layer 74 through an opening 72H provided in the insulating layer 72. In FIG. 12, an example in which the semiconductor layer 73, the photoelectric conversion layer 74, and the upper electrode 75 are formed separately for each imaging element 10C is shown, but for example, they may be provided as a continuous layer common to a plurality of imaging elements 10C.

[0095] The photoelectric conversion layer 74 converts light energy into electrical energy, and like the photoelectric conversion layer 24, is composed of two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type or n-type semiconductors, respectively. The photoelectric conversion layer 74 may be composed of an organic material that converts light in a predetermined wavelength range into electricity while transmitting light in other wavelength ranges, that is, a so-called dye material, in addition to the p-type semiconductor material and the n-type semiconductor material. When the photoelectric conversion layer 74 is formed using three types of 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 that have optical transparency in the visible range (for example, 400 nm to 700 nm). The thickness of the photoelectric conversion layer 74 is, for example, 25 nm or more and 400 nm or less, and preferably 50 nm or more and 350 nm or less. More preferably, it is 150 nm or more and 300 nm or less. Examples of the dye material used in the photoelectric conversion layer 74 include subphthalocyanine, phthalocyanine, coumarin, and porphyrin, or derivatives thereof.

[0096] Between the first surface (surface 30S1) and the second surface (surface 30S2) of the semiconductor substrate 30, two through electrodes 34X and 34Y are provided.

[0097] The through electrode 34X is electrically connected to the readout electrode 21A of the organic photoelectric conversion unit 20, as in the first embodiment, and the organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and one of the source / drain regions 36B1 of the reset transistor RST (reset transistor Tr1rst) which also serves as the floating diffusion FD1 via the through electrode 34X. The upper end of the through electrode 34X is connected to the readout electrode 21A via, for example, the upper first contact 29A, the pad portion 39A, and the upper second contact 29B.

[0098] The through electrode 34Y is electrically connected to the readout electrode 71A of the organic photoelectric conversion unit 70, and the organic photoelectric conversion unit 70 is connected to the gate Gamp of the amplifier transistor AMP and one of the source / drain regions 36B2 of the reset transistor RST (reset transistor Tr2rst) that also serves as the floating diffusion FD2 through the through electrode 34Y. The upper end of the through electrode 34Y is connected to the readout electrode 71A through, for example, the upper fourth contact 79A, the pad portion 69A, the upper fifth contact 79B, the pad portion 69B, and the upper sixth contact 79C. In addition, the pad 69C is connected to the storage electrode 71B of the lower electrode 71 that constitutes the organic photoelectric conversion unit 70 through the upper seventh contact 79D.

[0099] As described above, the imaging element 10B of this embodiment has a structure in which two organic photoelectric conversion units 20, 70 and one inorganic photoelectric conversion unit 32 are laminated, and similarly to the above-mentioned first embodiment, for example, the photoelectric conversion layer 24 constituting the organic photoelectric conversion unit 20 that acquires a blue (B) color signal is formed using the benzothienobenzothiophene-based compound represented by the above-mentioned general formula (1). This makes it possible to obtain the same effects as those of the above-mentioned first embodiment.

[0100] <3. Third embodiment> 13 is a schematic diagram showing a cross-sectional configuration of an imaging element (imaging element 10D) according to a third embodiment of the present disclosure. The imaging element 10D constitutes one pixel (unit pixel P) in an imaging device (imaging device 1) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. The organic photoelectric conversion section 80 of this embodiment has a configuration in which a lower electrode 81, a photoelectric conversion layer 24, and an upper electrode 25 are laminated in this order, and differs from the first and second embodiments in that the lower electrode 81 is formed as a solid film within the pixel.

[0101] The imaging element 10D is configured such that one organic photoelectric conversion section 80 and two inorganic photoelectric conversion sections 32G, 32R are stacked in the vertical direction for each unit pixel P. The organic photoelectric conversion section 80 and the inorganic photoelectric conversion sections 32G, 32R selectively detect light in different wavelength bands and perform photoelectric conversion. Specifically, the organic photoelectric conversion section 80 acquires, for example, a blue (B) color signal, as in the first embodiment. 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.

[0102] The organic photoelectric conversion section 80 is an organic photoelectric conversion element that absorbs light corresponding to a part or the entirety of a selective wavelength band (for example, 400 nm or more and 700 nm or less) and generates electron-hole pairs. As described above, the organic photoelectric conversion unit 80 is composed of, for example, a lower electrode 81 and an upper electrode 25 arranged opposite each other, and a photoelectric conversion layer 24 provided between the lower electrode 81 and the upper electrode 25. As shown in Fig. 13, the organic photoelectric conversion unit 80 of this embodiment has the same configuration as the organic photoelectric conversion unit 20 in the first embodiment described above, in that the lower electrode 81, the photoelectric conversion layer 24, and the upper electrode 25 have the same configuration as the organic photoelectric conversion unit 20 in the first embodiment described above, except that the lower electrode 81 is formed of a solid film in each pixel.

[0103] On the second surface (surface 30S2) of the semiconductor substrate 30, for example, floating diffusions (floating diffusion layers) FD1, FD2, and FD3, a vertical transistor (transfer transistor) Tr1, a transfer transistor Tr2, an amplifier transistor (modulation element) AMP, and a reset transistor RST are provided.

[0104] The vertical transistor Tr1 is a transfer transistor that transfers the signal charge corresponding to green, which is generated and accumulated in the inorganic photoelectric conversion unit 32G, to the floating diffusion FD1. Since the inorganic photoelectric conversion unit 32G is formed at a deep position from the second surface (surface 30S2) of the semiconductor substrate 30, it is preferable that the transfer transistor of the inorganic photoelectric conversion unit 32G is composed of the vertical transistor Tr1. The transfer transistor Tr2 transfers the signal charge corresponding to red, which is generated and accumulated in the inorganic photoelectric conversion unit 32R, to the floating diffusion FD2, and is composed of, for example, a MOS transistor. The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the organic photoelectric conversion unit 80 into a voltage, and is composed of, for example, a MOS transistor. The reset transistor RST resets the charge transferred from the organic photoelectric conversion unit 80 to the floating diffusion FD3, and is composed of, for example, a MOS transistor.

[0105] The lower first contact 45 and the lower second contact 46 are made of, 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), or tantalum (Ta).

[0106] In the image sensor 10D, signals of each color are obtained as follows.

[0107] (Obtaining a Blue Signal by Organic Photoelectric Conversion Unit 80) Of the light incident on the imaging element 10D, blue light is first selectively detected (absorbed) by the organic photoelectric conversion section 80 and undergoes photoelectric conversion.

[0108] The organic photoelectric conversion unit 80 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD3 via the through electrode 34. Thus, the electrons of the electron-electron pairs generated in the organic photoelectric conversion unit 80 are extracted from the lower electrode 81 side, transferred to the second surface (surface 30S2) side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD3. At the same time, the amount of charge generated in the organic photoelectric conversion unit 80 is modulated into a voltage by the amplifier transistor AMP.

[0109] In addition, a reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD3, so that the charge accumulated in the floating diffusion FD3 is reset by the reset transistor RST.

[0110] Here, the organic photoelectric conversion unit 80 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD3 via the through electrode 34, so that the charge accumulated in the floating diffusion FD3 can be easily reset by the reset transistor RST.

[0111] On the other hand, if the through electrode 34 and the floating diffusion FD3 are not connected, it becomes difficult to reset the charge accumulated in the floating diffusion FD3, and a large voltage is applied to pull it out to the upper electrode 25 side. This may damage the photoelectric conversion layer 24. In addition, a structure that allows resetting in a short time leads to an increase in dark noise, which is a trade-off, making this structure difficult to implement.

[0112] (Acquisition of green and red signals by inorganic photoelectric conversion units 32G and 32R) Next, of the light transmitted through the organic photoelectric conversion unit 80, the green light is absorbed in the inorganic photoelectric conversion unit 32G, and the red light is absorbed in the inorganic photoelectric conversion unit 32R, respectively, and photoelectrically converted. In the inorganic photoelectric conversion unit 32G, electrons corresponding to the incident green light are accumulated in the n-region of the inorganic photoelectric conversion unit 32G, and the accumulated electrons are transferred to the floating diffusion FD1 by the vertical transistor Tr1. Similarly, in the inorganic photoelectric conversion unit 32R, electrons corresponding to the incident red light are accumulated in the n-region of the inorganic photoelectric conversion unit 32R, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2.

[0113] As described above, in the imaging element 10D of the present embodiment, the lower electrode 81 constituting the organic photoelectric conversion unit 80 is formed as a solid film, and similarly to the above-mentioned first embodiment, the photoelectric conversion layer 24 constituting the organic photoelectric conversion unit 80 that acquires, for example, a blue (B) color signal is formed using the benzothienobenzothiophene-based compound represented by the above-mentioned general formula (1). This makes it possible to obtain the same effects as those of the above-mentioned first embodiment.

[0114] <4. Fourth embodiment> 14 illustrates a cross-sectional configuration of an imaging element (imaging element 10E) according to a fourth embodiment of the present disclosure. The imaging element 10E constitutes one pixel (unit pixel P) in an imaging device 1 such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. The imaging element 10E of this embodiment has a configuration in which a red photoelectric conversion unit 90R, a green photoelectric conversion unit 90G, and a blue photoelectric conversion unit 90B are stacked in this order on a semiconductor substrate 30 via an insulating layer 96.

[0115] The red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B each have an organic photoelectric conversion layer 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. The organic photoelectric conversion layer 92B is formed using a benzothienobenzothiophene-based compound represented by the above general formula (1) in the same manner as in the first embodiment.

[0116] An on-chip lens 98L is provided on the blue photoelectric conversion unit 90B via a protective layer 97 and an on-chip lens layer 98. A red storage layer 310R, a green storage layer 310G, and a blue storage layer 310B are provided in the semiconductor substrate 30. Light incident on the on-chip lens 98L is photoelectrically converted by the red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B, and signal charges are sent from the red photoelectric conversion unit 90R to the red storage layer 310R, from the green photoelectric conversion unit 90G to the green storage layer 310G, and from the blue photoelectric conversion unit 90B to the blue storage layer 310B, respectively. The signal charges may be either electrons or holes generated by photoelectric conversion, but the following description will be given of an example in which electrons are read out as signal charges.

[0117] The semiconductor substrate 30 is made of, for example, a p-type silicon substrate. The red storage layer 310R, the green storage layer 310G, and the blue storage layer 310B provided on the semiconductor substrate 30 each include an n-type semiconductor region, and the signal charge (electrons) supplied from the red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B is stored in the n-type semiconductor region. The n-type semiconductor regions of the red storage layer 310R, the green storage layer 310G, and the blue storage layer 310B are formed by doping the semiconductor substrate 30 with an n-type impurity such as phosphorus (P) or arsenic (As). The semiconductor substrate 30 may be provided on a support substrate (not shown) made of glass or the like.

[0118] The semiconductor substrate 30 is provided with pixel transistors for reading out electrons from the red storage layer 310R, the green storage layer 310G, and the blue storage layer 310B, and transferring them to, for example, a vertical signal line (for example, a vertical signal line Lsig in FIG. 15, which will be described later). A floating diffusion of the pixel transistor is provided in the semiconductor substrate 30, and this floating diffusion is connected to the red storage layer 310R, the green storage layer 310G, and the blue storage layer 310B. The floating diffusion is composed of an n-type semiconductor region.

[0119] The insulating layer 96 is, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiON) and hafnium oxide (HfO x ) or a laminated film made of two or more of these. In addition, the insulating layer 96 may be formed using an organic insulating material. Although not shown, the insulating layer 96 is provided with plugs and electrodes for connecting the red storage layer 310R and the red photoelectric conversion unit 90R, the green storage layer 310G and the green photoelectric conversion unit 90G, and the blue storage layer 310B and the blue photoelectric conversion unit 90B, respectively.

[0120] The red photoelectric conversion unit 90R has a first electrode 91R, an organic photoelectric conversion layer 92R, and a second electrode 93R in this order from the position closest to the semiconductor substrate 30. The green photoelectric conversion unit 90G has a first electrode 91G, an organic photoelectric conversion layer 92G, and a second electrode 93G in this order from the position closest to the red photoelectric conversion unit 90R. The blue photoelectric conversion unit 90B has a first electrode 91B, an organic photoelectric conversion layer 92B, and a second electrode 93B in this order from the position closest to the green photoelectric conversion unit 90G. An insulating layer 94 is further provided between the red photoelectric conversion unit 90R and the green photoelectric conversion unit 90G, and an insulating layer 95 is further provided between the green photoelectric conversion unit 90G and the blue photoelectric conversion unit 90B. The red photoelectric conversion section 90R selectively absorbs red light (e.g., wavelength of 600 nm or more and less than 700 nm), the green photoelectric conversion section 90G selectively absorbs green light (e.g., wavelength of 500 nm or more and less than 600 nm), and the blue photoelectric conversion section 90B selectively absorbs blue light (e.g., wavelength of 400 nm or more and less than 500 nm), generating electron-hole pairs.

[0121] The first electrode 91R extracts the signal charge generated in the organic photoelectric conversion layer 92R, the first electrode 91G extracts the signal charge generated in the organic photoelectric conversion layer 92G, and the first electrode 91B extracts the signal charge generated in the organic photoelectric conversion layer 92B. The first electrodes 91R, 91G, and 91B are provided, for example, for each pixel. The first electrodes 91R, 91G, and 91B are made of, for example, a light-transmitting conductive material, specifically, ITO. The first electrodes 91R, 91G, and 91B may be made of, for example, a tin oxide-based material or a zinc oxide-based material. The tin oxide-based material is tin oxide to which a dopant is added, and the zinc oxide-based material is, for example, aluminum zinc oxide in which aluminum is added as a dopant to zinc oxide, gallium zinc oxide in which gallium is added as a dopant to zinc oxide, and indium zinc oxide in which indium is added as a dopant to zinc oxide. Other than these, it is also possible to use IGZO, CuI, InSbO4, ZnMgO, CuInO2, MgIn2O4, CdO, ZnSnO3, etc. The thickness of the first electrodes 91R, 91G, 91B is, for example, 50 nm to 500 nm.

[0122] For example, an electron transport layer may be provided 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 is for accelerating the supply of electrons generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the first electrodes 91R, 91G, and 91B, and is made of, for example, titanium oxide or zinc oxide. The electron transport layer may be formed by laminating a titanium oxide film and a zinc oxide film. The thickness of the electron transport layer is, for example, 0.1 nm to 1000 nm, and preferably 0.5 nm to 300 nm.

[0123] The organic photoelectric conversion layers 92R, 92G, and 92B each absorb light in a selective wavelength range and perform photoelectric conversion, and transmit light in other wavelength ranges. Here, the light in the selective wavelength range is, for example, light in a wavelength range of 600 nm or more and less than 700 nm in the organic photoelectric conversion layer 92R. For example, the light in the selective wavelength range is light in a wavelength range of 500 nm or more and less than 600 nm in the organic photoelectric conversion layer 92G. For example, the light in the selective wavelength range is light in a wavelength range of 400 nm or more and less than 500 nm in the organic photoelectric conversion layer 92B. The thickness of the organic photoelectric conversion layers 92R, 92G, and 92B is, for example, 25 nm or more and 400 nm or less, preferably 50 nm or more and 350 nm or less. More preferably, it is 150 nm or more and 300 nm or less.

[0124] The organic photoelectric conversion layers 92R, 92G, and 92B convert light energy into electrical energy, and are configured to contain two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type or n-type semiconductors, respectively, in the same manner as the photoelectric conversion layer 24. The organic photoelectric conversion layers 92R, 92G, and 92B may be configured to contain, in addition to the p-type semiconductor material and the n-type semiconductor material, an organic material that photoelectrically converts light in the above-mentioned predetermined wavelength range while transmitting light in other wavelength ranges, that is, a so-called dye material. Examples of such materials include, for example, rhodamine and merocyanine or derivatives thereof in the organic photoelectric conversion layer 92R. Examples of materials that can be used in the organic photoelectric conversion layer 92G include, for example, subphthalocyanine, phthalocyanine, coumarin, and porphyrin or derivatives thereof. Examples of materials that can be used in the organic photoelectric conversion layer 92B include benzothienobenzothiophene-based compounds represented by the above general formula (1).

[0125] Examples of the organic material constituting 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 those mentioned above.

[0126] 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, for example, a hole transport layer may be provided. The hole transport layer is for accelerating the supply of holes generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the second electrodes 93R, 93G, and 93B, and is made of, for example, molybdenum oxide, nickel oxide, or vanadium oxide. The hole transport layer may be made of an organic material such as PEDOT (Poly(3,4-ethylenedioxythiophene)) and TPD (N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine). The thickness of the hole transport layer is, for example, 0.5 nm or more and 100 nm or less.

[0127] The second electrode 93R is for extracting holes generated in the organic photoelectric conversion layer 92R, the second electrode 93G is for extracting holes generated in the organic photoelectric conversion layer 92G, and the second electrode 93B is for extracting holes generated in the organic photoelectric conversion layer 92G. The holes extracted from the second electrodes 93R, 93G, and 93B are discharged to, for example, a p-type semiconductor region (not shown) in the semiconductor substrate 30 via each transmission path (not shown). The second electrodes 93R, 93G, and 93B are made of a conductive material such as gold (Au), silver (Ag), copper (Cu), and aluminum (Al). As with the first electrodes 91R, 91G, and 91B, the second electrodes 93R, 93G, and 93B may be made of a transparent conductive material. In the imaging element 10E, the holes extracted from the second electrodes 93R, 93G, and 93B are discharged, so that, for example, when a plurality of imaging elements 10E are arranged in an imaging device 1 described later, the second electrodes 93R, 93G, and 93B may be provided in common to each of the imaging elements 10E (unit pixels P). The thickness of the second electrodes 93R, 93G, and 93B is, for example, 0.5 nm or more and 100 nm or less.

[0128] The insulating layer 94 is for insulating the second electrode 93R from the first electrode 91G, and the insulating layer 95 is for insulating the second electrode 93G from the first electrode 91B. The insulating layers 94 and 95 are made of, for example, a metal oxide, a metal sulfide, or an organic material. The metal oxide may be, for example, silicon oxide (SiO x ), aluminum oxide (AlO x ), zirconium oxide (ZrO x ), titanium dioxide (TiO x ), zinc oxide (ZnO x ), tungsten oxide (WO x ), Magnesium oxide (MgO x ), niobium oxide (NbO x ), tin oxide (SnO x ) and gallium oxide (GaO x) and the like. Examples of metal sulfides include zinc sulfide (ZnS) and magnesium sulfide (MgS). The band gap of the material constituting the insulating layers 94 and 95 is preferably 3.0 eV or more. The thickness of the insulating layers 94 and 95 is, for example, 2 nm or more and 100 nm or less.

[0129] As described above, by forming the organic photoelectric conversion layer 92B using the benzothienobenzothiophene compound represented by the general formula (1) above, it is possible to obtain the same effects as those of the first embodiment.

[0130] <5. Application Examples> (Application example 1) 15 shows the overall configuration of an imaging device (imaging device 1) in which the imaging element 10A (or imaging elements 10B to 10E) described in the first to fourth embodiments is used for each pixel. The imaging device 1 is a CMOS image sensor, and has a pixel section 1a as an imaging area on a semiconductor substrate 30, and also has a peripheral circuit section 130 in the peripheral region of the pixel section 1a, which includes, for example, a row scanning section 131, a horizontal selection section 133, a column scanning section 134, and a system control section 132.

[0131] The pixel section 1a has, for example, a plurality of unit pixels P (corresponding to the image sensor 10) arranged two-dimensionally in a matrix. In the unit pixels P, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) is wired for each pixel row, and a vertical signal line Lsig is wired for each pixel column. The pixel drive line Lread transmits a drive signal for reading out a signal from the pixel. One end of the pixel drive line Lread is connected to an output terminal of the row scanning section 131 corresponding to each row.

[0132] The row scanning unit 131 is a pixel driving unit that is configured with a shift register, an address decoder, etc., and drives each unit pixel P of the pixel unit 1a, for example, row by row. A signal output from each unit pixel P of a pixel row selected and scanned by the row scanning unit 131 is supplied to the horizontal selection unit 133 through each vertical signal line Lsig. The horizontal selection unit 133 is configured with an amplifier, a horizontal selection switch, etc., provided for each vertical signal line Lsig.

[0133] The column scanning unit 134 is composed of a shift register, an address decoder, etc., and sequentially drives while scanning each horizontal selection switch of the horizontal selection unit 133. By the selective scanning by this column scanning unit 134, the signals of each pixel transmitted through each vertical signal line Lsig are output in sequence to the horizontal signal line 135, and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal line 135.

[0134] A circuit portion consisting of row scanning section 131, horizontal selection section 133, column scanning section 134, and horizontal signal line 135 may be formed directly on semiconductor substrate 30, or may be disposed in an external control IC. Moreover, these circuit portions may be formed on another substrate connected by a cable or the like.

[0135] The system control unit 132 receives a clock and data instructing an operation mode provided from outside the semiconductor substrate 30, and also outputs data such as internal information of the imaging device 1. The system control unit 132 further has a timing generator that generates various timing signals, and performs drive control of peripheral circuits such as the row scanning unit 131, horizontal selection unit 133, and column scanning unit 134 based on the various timing signals generated by the timing generator.

[0136] (Application example 2) The imaging device 1 can be applied to any type of electronic device with an imaging function, such as a camera system such as a digital still camera or video camera, or a mobile phone with an imaging function. Fig. 16 shows a schematic configuration of an electronic device 2 (camera) as an example. The electronic device 2 is, for example, a video camera capable of taking still or moving images, and includes the imaging device 1, an optical system (optical lens) 310, a shutter device 311, a drive unit 313 that drives the imaging device 1 and the shutter device 311, and a signal processing unit 312.

[0137] The optical system 310 guides image light (incident light) from a subject to the pixel section 1a of the imaging device 1. This optical system 310 may be composed of a plurality of optical lenses. The shutter device 311 controls the light irradiation period and the light blocking period of the imaging device 1. The drive section 313 controls the transfer operation of the imaging device 1 and the shutter operation of the shutter device 311. The signal processing section 312 performs various signal processing on the signal output from the imaging device 1. The video signal Dout after the signal processing is stored in a storage medium such as a memory, or is output to a monitor, etc.

[0138] Furthermore, the imaging device 1 can be applied to the following electronic devices (a capsule endoscope 10100 and a moving object such as a vehicle).

[0139] <6. Application Examples> (Application example to an in-body information acquisition system) Furthermore, the technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0140] FIG. 17 is a block diagram showing an example of a schematic configuration of a patient's in-vivo information acquisition system using a capsule endoscope to which the technology according to the present disclosure (the present technology) can be applied.

[0141] The in-vivo information acquisition system 10001 includes a capsule endoscope 10100 and an external control device 10200 .

[0142] The capsule endoscope 10100 is swallowed by a patient during an examination. The capsule endoscope 10100 has an imaging function and a wireless communication function, and while moving inside an organ such as the stomach or intestines by peristalsis or the like until it is naturally discharged from the patient, sequentially captures images of the inside of the organ (hereinafter also referred to as in-vivo images) at predetermined intervals, and sequentially wirelessly transmits information about the in-vivo images to an external control device 10200 outside the body.

[0143] The external control device 10200 comprehensively controls the operation of the in-vivo information acquisition system 10001. In addition, the external control device 10200 receives information about the in-vivo image transmitted 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 about the in-vivo image.

[0144] In this manner, the in-vivo information acquiring system 10001 can obtain in-vivo images capturing images of the state inside the patient's body at any time from when the capsule endoscope 10100 is swallowed to when it is expelled.

[0145] The configurations and functions of the capsule endoscope 10100 and the external control device 10200 will be described in more detail.

[0146] The capsule endoscope 10100 has a capsule-shaped housing 10101, which houses a light source unit 10111, an imaging 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.

[0147] The light source unit 10111 is composed of a light source such as an LED (light emitting diode), and irradiates the imaging field of the imaging unit 10112 with light.

[0148] The imaging unit 10112 is composed of an imaging element and an optical system consisting of multiple lenses provided in front of the imaging element. Reflected light (hereinafter referred to as observation light) of light irradiated onto the body tissue to be observed is collected by the optical system and enters the imaging element. In the imaging unit 10112, the imaging element photoelectrically converts the observation light incident thereon, and generates an image signal corresponding to the observation light. The image signal generated by the imaging unit 10112 is provided to an image processing unit 10113.

[0149] The image processing unit 10113 is configured with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and performs various signal processing on the image signal generated by the imaging unit 10112. The image processing unit 10113 provides the image signal after the signal processing to the wireless communication unit 10114 as RAW data.

[0150] The wireless communication unit 10114 performs predetermined processing such as modulation processing on the image signal that has been subjected to signal processing by the image processing unit 10113, and transmits the image signal to the external control device 10200 via the antenna 10114A. The wireless communication unit 10114 also 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 provides the control signal received from the external control device 10200 to the control unit 10117.

[0151] The power supply unit 10115 is composed of an antenna coil for receiving power, a power regeneration circuit for regenerating power from a current generated in the antenna coil, a boost circuit, etc. In the power supply unit 10115, power is generated using the principle of so-called non-contact charging.

[0152] The power supply unit 10116 is composed of a secondary battery, and stores the power generated by the power supply unit 10115. In order to avoid cluttering the drawing, arrows and other symbols indicating the destination of the power supply from the power supply unit 10116 are omitted in Fig. 17, but the power stored in the power supply unit 10116 is supplied to the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the control unit 10117 and can be used to drive these units.

[0153] The control unit 10117 is composed of a processor such as a CPU, and appropriately controls the driving of the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the power supply unit 10115 in accordance with control signals transmitted from the external control device 10200.

[0154] The external control device 10200 is composed of a processor such as a CPU or a GPU, or a microcomputer or a control board in which a processor and a storage element such as a memory are mixed. The external control device 10200 controls the operation of the capsule endoscope 10100 by transmitting a control signal to the control unit 10117 of the capsule endoscope 10100 via the antenna 10200A. In the capsule endoscope 10100, for example, the light irradiation conditions for the observation target in the light source unit 10111 can be changed by the control signal from the external control device 10200. Furthermore, the imaging conditions (for example, the frame rate and exposure value in the imaging unit 10112) can be changed by the control signal from the external control device 10200. Furthermore, the content of the processing in the image processing unit 10113 and the conditions for the wireless communication unit 10114 to transmit an image signal (for example, the transmission interval, the number of transmitted images, etc.) may be changed by the control signal from the external control device 10200.

[0155] The external control device 10200 also applies various image processing to the image signal transmitted from the capsule endoscope 10100 to generate image data for displaying the captured in-vivo image on a display device. As the image processing, various signal processing such as development processing (demosaic processing), image quality improvement processing (band enhancement processing, super-resolution processing, NR (Noise reduction) processing, and / or image stabilization processing, etc.) and / or enlargement processing (electronic zoom processing) can be performed. The external control device 10200 controls the driving of the display device to display the captured in-vivo image based on the generated image data. Alternatively, the external control device 10200 may record the generated image data in a recording device (not shown) or print out the image data on a printing device (not shown).

[0156] An example of an in-vivo information acquisition system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the imaging unit 10112 of the above-described configuration. This improves detection accuracy.

[0157] (Application example to endoscopic surgery system) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0158] FIG. 18 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0159] 18 shows a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0160] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the illustrated example, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may be configured as a so-called flexible scope having a flexible lens barrel.

[0161] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an observation target in the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0162] An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from an observation target is collected on the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The image signal is transmitted to a camera control unit (CCU) 11201 as RAW data.

[0163] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

[0164] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0165] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies the endoscope 11100 with irradiation light when photographing an operation site or the like.

[0166] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiated light, magnification, focal length, etc.) of the endoscope 11100.

[0167] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 sends gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity for the purpose of securing the field of view of the endoscope 11100 and securing the working space of the surgeon. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, image, or graph.

[0168] The light source device 11203 that supplies irradiation light to the endoscope 11100 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation object with laser light from each of the RGB laser light sources in a time-division manner and controlling the driving of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0169] The light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. The driving of the image sensor of the camera head 11102 may be controlled in synchronization with the timing of the change in the light intensity to obtain images in a time-division manner, and the images may be synthesized to generate an image with a high dynamic range that is free of so-called blackout and whiteout.

[0170] The light source device 11203 may be configured to supply light of a predetermined wavelength band corresponding to the special light observation. In the special light observation, for example, by utilizing the wavelength dependency of light absorption in body tissue, a narrow band light is irradiated compared to the irradiated light (i.e., white light) during normal observation, and a predetermined tissue such as blood vessels on the mucous membrane surface is photographed with high contrast, so-called narrow band imaging is performed. Alternatively, in the special light observation, a fluorescent observation may be performed in which an image is obtained by fluorescence generated by irradiating an excitation light. In the fluorescent observation, it is possible to irradiate an excitation light to a body tissue and observe the fluorescence from the body tissue (autofluorescence observation), or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0171] FIG. 19 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0172] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so as to be able to communicate with each other.

[0173] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

[0174] The imaging unit 11402 may include one imaging element (so-called single-plate type) or multiple imaging elements (so-called multiple-plate type). When the imaging unit 11402 is configured as a multiple-plate type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining the image signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to a 3D (dimensional) display. By performing a 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. Note that when the imaging unit 11402 is configured as a multiple-plate type, the lens unit 11401 may also be provided in multiple systems corresponding to each imaging element.

[0175] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately behind the objective lens.

[0176] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be appropriately adjusted.

[0177] The communication unit 11404 is configured by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0178] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201, and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of capturing the image, and / or information specifying the magnification and focus of the captured image.

[0179] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by a user, or may be automatically set by the control unit 11413 of the CCU 11201 based on an acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0180] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404.

[0181] The communication unit 11411 is configured with a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0182] Furthermore, the communication unit 11411 transmits, to the camera head 11102, a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0183] The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data sent from the camera head 11102 .

[0184] The control unit 11413 performs various controls related to imaging of the surgical site etc. by the endoscope 11100 and display of the captured image obtained by imaging the surgical site etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0185] Further, the control unit 11413 causes the display device 11202 to display the captured image showing the surgical site, etc., based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body parts, bleeding, mist when the energy treatment tool 11112 is used, etc., by detecting the shape and color of the edge of an object included in the captured image. When the control unit 11413 causes the display device 11202 to display the captured image, it may use the recognition result to superimpose various types of surgery support information on the image of the surgical site. By superimposing and presenting the surgery support information to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0186] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0187] Here, in the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0188] An example of an endoscopic surgery system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 11402 among the configurations described above. By applying the technology according to the present disclosure to the imaging unit 11402, detection accuracy is improved.

[0189] Although an endoscopic surgery system has been described here as an example, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0190] (Example of application to moving objects) The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, a construction machine, an agricultural machine (tractor), etc.

[0191] FIG. 20 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied.

[0192] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 20, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[0193] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0194] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0195] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0196] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0197] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.

[0198] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0199] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0200] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0201] The audio / video output unit 12052 transmits at least one output signal of audio and image to an output device capable of visually or audibly notifying information to passengers in the vehicle or the outside of the vehicle. In the example of Fig. 20, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as the output device. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

[0202] FIG. 21 is a diagram showing an example of the installation position of the imaging unit 12031.

[0203] In FIG. 21, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0204] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin is mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0205] 21 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0206] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of a plurality of imaging elements, or may be an imaging element having pixels for detecting a phase difference.

[0207] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0208] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0209] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0210] <7. Examples> Next, an embodiment of the present disclosure will be described in detail.

[0211] (Experimental Example 1) A 100 nm thick ITO film was formed on a quartz substrate using a sputtering device. This ITO film was patterned by photolithography and etching to form an ITO electrode (lower electrode). The quartz substrate with the ITO electrode was then cleaned by UV / ozone treatment, after which the quartz substrate was transferred to a vacuum deposition machine and 1×10 -5 While rotating the substrate holder under reduced pressure of 0 Pa or less, an organic material film was formed on a quartz substrate by using a resistance heating method. First, an electron blocking material shown in the following formula (3) was formed into a film with a thickness of 10 nm at a substrate temperature of 0°C to form an electron blocking layer. Next, a benzothienobenzothiophene derivative shown in the following formula (1-1) and C 60Fullerene and (the following formula (2)) were deposited at a substrate temperature of 40° C. at deposition rates of 0.50 Å / sec and 0.25 Å / sec, respectively, so that the mixed layer had a thickness of 230 nm, forming a photoelectric conversion layer. Next, a hole blocking material shown in the following formula (4) was deposited at a substrate temperature of 0° C. to a thickness of 10 nm to form a hole blocking layer. Finally, the quartz substrate was transferred to a sputtering device, and ITO was deposited at a thickness of 50 nm on the hole blocking layer to form an upper electrode. By the above-mentioned fabrication method, a photoelectric conversion element (Experimental Example 1) having a photoelectric conversion region of 1 mm×1 mm was fabricated. The fabricated photoelectric conversion element was annealed at 150° C. for 210 minutes in a nitrogen (N2) atmosphere.

[0212] [ka]

[0213] [ka]

[0214] (Experimental Example 2) A photoelectric conversion element (Experimental Example 2) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-2) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0215] [ka]

[0216] (Experimental Example 3) A photoelectric conversion element (Experimental Example 3) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-3) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0217] [ka]

[0218] (Experimental Example 4) A photoelectric conversion element (Experimental Example 4) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-4) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0219] [ka]

[0220] (Experimental Example 5) A photoelectric conversion element (Experimental Example 5) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-5) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0221] [ka]

[0222] (Experimental Example 6) A photoelectric conversion element (Experimental Example 6) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-6) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0223] [ka]

[0224] (Experimental Example 7) A photoelectric conversion element (Experimental Example 7) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-7) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0225] [ka]

[0226] (Experimental Example 8) A photoelectric conversion element (Experimental Example 8) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-8) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0227] [ka]

[0228] (Experimental Example 9) A photoelectric conversion element (Experimental Example 9) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-9) below was used instead of the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1.

[0229] [ka]

[0230] (Experimental Example 10) A photoelectric conversion element (Experimental Example 10) was prepared in the same manner as in Experimental Example 1, except that the benzothienobenzothiophene derivative shown in the formula (1-1) used in Experimental Example 1 was replaced with the benzothienobenzothiophene derivative shown in the formula (1-10) below.

[0231] [ka]

[0232] (Experimental Example 11) Two types of benzothienobenzothiophene derivatives shown in formula (1-1) and formula (1-7) and C 60A photoelectric conversion element (Experimental Example 11) was produced in the same manner as in Experimental Example 1, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0233] (Experimental Example 12) Two types of benzothienobenzothiophene derivatives shown in formula (1-2) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 12) was produced in the same manner as in Experimental Example 2, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0234] (Experimental Example 13) Two types of benzothienobenzothiophene derivatives shown in formula (1-3) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 13) was produced in the same manner as in Experimental Example 3, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0235] (Experimental Example 14) Two types of benzothienobenzothiophene derivatives shown in formula (1-4) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 14) was produced in the same manner as in Experimental Example 4, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0236] (Experimental Example 15) Two types of benzothienobenzothiophene derivatives shown in formula (1-5) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 15) was produced in the same manner as in Experimental Example 5, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0237] (Experimental Example 16) Two types of benzothienobenzothiophene derivatives shown in formula (1-6) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 16) was produced in the same manner as in Experimental Example 6, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0238] (Experimental Example 17) Two types of benzothienobenzothiophene derivatives shown in formula (1-8) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 17) was produced in the same manner as in Experimental Example 8, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0239] (Experimental Example 18) Two types of benzothienobenzothiophene derivatives shown in formula (1-9) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 18) was produced in the same manner as in Experimental Example 9, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0240] (Experimental Example 19) Two types of benzothienobenzothiophene derivatives shown in formula (1-10) and formula (1-7), and C 60 A photoelectric conversion element (Experimental Example 19) was produced in the same manner as in Experimental Example 10, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0241] (Experimental Example 20) DNTT shown in the following formula (5) and C 60 A photoelectric conversion element (Experimental Example 20) was produced in the same manner as in Experimental Example 1, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0242] [ka]

[0243] (Experimental Example 21) DPh-BTBT and C 60 A photoelectric conversion element (Experimental Example 20) was produced in the same manner as in Experimental Example 1, except that a photoelectric conversion layer was formed using fullerene and (the above formula (2)).

[0244] [ka]

[0245] The external quantum efficiency (EQE) and response time of the photoelectric conversion elements prepared in Experimental Examples 1 to 21 were evaluated by the following methods. The results are summarized in Table 1 together with the benzothienobenzothiophene derivatives used in each Experimental Example.

[0246] The wavelength of light emitted from a blue LED light source through a bandpass filter to the photoelectric conversion element is 450 nm, and the light intensity is 1.62 μW / cm 2 A semiconductor parameter analyzer was used to control the bias voltage applied between the electrodes of the photoelectric conversion element, and the voltage applied to the lower electrode relative to the upper electrode was swept to obtain a current-voltage curve. The light current and dark current values ​​in the short-circuited state were measured to calculate the EQE. Furthermore, the bias voltage applied between the electrodes of the photoelectric conversion element was controlled, and a voltage of -2.6 V was applied to the lower electrode relative to the upper electrode, and a wavelength of 450 nm and a light intensity of 1.62 μW / cm were obtained. 2 The photoelectric conversion element was irradiated with a rectangular light pulse, and the decay waveform of the current was observed using an oscilloscope. The response time, which is an index of the response speed, is the time it takes for the current to decay to 3% from the current at the time of light pulse irradiation immediately after the light pulse irradiation.

[0247] [Table 1]

[0248] From Table 1, it was found that in Experimental Examples 1 to 19 in which a photoelectric conversion layer was formed using a benzothienobenzothiophene-based compound represented by the above general formula (1), the same level of EQE was obtained as in Experimental Examples 20 and 21 in which a photoelectric conversion layer was formed using a general material. In addition, it was found that in Experimental Examples 1 to 19 in which a photoelectric conversion layer was formed using a benzothienobenzothiophene-based compound represented by the above general formula (1), the response time was significantly improved compared to Experimental Examples 20 and 21 in which a photoelectric conversion layer was formed using a general material. Therefore, it was found that by forming a photoelectric conversion layer using a benzothienobenzothiophene-based compound represented by the above general formula (1), it is possible to improve the photoresponsiveness while maintaining a high EQE.

[0249] Although the first to fourth embodiments, examples, and application examples have been described above, the present disclosure is not limited to the above-mentioned embodiments, etc., and various modifications are possible. In addition, the number and ratio of these organic photoelectric conversion units and inorganic photoelectric conversion units are not limited, and color signals of multiple colors may be obtained by the organic photoelectric conversion unit alone.

[0250] Furthermore, in the above-mentioned embodiments, an example has been shown in which the multiple electrodes constituting the lower electrode 21 are composed of two electrodes, the read electrode 21A and the storage electrode 21B, but in addition to this, three or four or more electrodes such as a transfer electrode or an exhaust electrode may be provided.

[0251] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0252] The present disclosure may be configured as follows. According to the present disclosure having the following configuration, a benzothienobenzothiophene-based compound represented by any one of the above formulas (1-1) to (1-10) is At least one species Since the organic photoelectric conversion layer is formed using the organic compound semiconductor, the mobility of carriers to the first electrode and the second electrode arranged opposite each other with the organic photoelectric conversion layer therebetween is improved, and thus it is possible to improve the external quantum efficiency and the photoresponse. [1] A first electrode; a second electrode disposed opposite the first electrode; The organic semiconductor layer is provided between the first electrode and the second electrode, and contains, as a first organic semiconductor material, a benzothienobenzothiophene compound represented by any one of the following formulas (1-1) to (1-10): At least one species An organic photoelectric conversion layer comprising A photoelectric conversion element comprising: [ka] [2] The photoelectric conversion element according to [1] above, 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] above, 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 having a wavelength of 400 nm or more and 700 nm or less. [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 the range of 400 nm or more and 700 nm or less. [6] The photoelectric conversion element according to any one of [1] to [5], wherein the first electrode is made of a plurality of electrodes. [7] The photoelectric conversion element according to any one of [1] to [6], further comprising a first charge blocking layer between the first electrode and the organic photoelectric conversion layer. [8] The photoelectric conversion element according to any one of [1] to [7], further comprising a second charge blocking layer between the organic photoelectric conversion layer and the second electrode. [9] A plurality of pixels each having one or more organic photoelectric conversion units provided therein; The organic photoelectric conversion unit is A first electrode; a second electrode disposed opposite the first electrode; The organic semiconductor layer is provided between the first electrode and the second electrode, and contains, as a first organic semiconductor material, a benzothienobenzothiophene compound represented by any one of the following formulas (1-1) to (1-10): At least one species An organic photoelectric conversion layer comprising An imaging device having the above configuration. [ka]

[10] The imaging device described in [9], wherein each pixel has one or more of the organic photoelectric conversion units and one or more inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion units stacked therein.

[11] The inorganic photoelectric conversion unit is formed by embedding the inorganic photoelectric conversion unit in a semiconductor substrate, The imaging device according to

[10] , wherein the organic photoelectric conversion section is formed on a first surface side of the semiconductor substrate.

[12] The imaging device 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 organic photoelectric conversion unit performs photoelectric conversion of blue light, The imaging device according to

[11] or

[12] , wherein an inorganic photoelectric conversion unit that performs photoelectric conversion of green light and an inorganic photoelectric conversion unit that performs photoelectric conversion of red light are stacked within the semiconductor substrate.

[14] The imaging device according to any one of [9] to

[13] , wherein in each pixel, a plurality of the organic photoelectric conversion units that perform photoelectric conversion in different wavelength ranges are stacked.

[0253] This application claims priority based on Japanese Patent Application No. 2019-062367, filed on March 28, 2019 in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0254] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur to those skilled in the art depending on design requirements and other factors, and that such modifications are within the scope of the appended claims and their equivalents.

Claims

1. A first electrode; a second electrode disposed opposite the first electrode; an organic photoelectric conversion layer provided between the first electrode and the second electrode and containing at least one benzothienobenzothiophene-based compound represented by any one of the following formulas (1-1) to (1-10) as a first organic semiconductor material; A photoelectric conversion element comprising: 【Chemistry 1】

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

4. The photoelectric conversion element according to claim 3 , wherein the third organic semiconductor material absorbs light having a wavelength of 400 nm or more and 700 nm or less.

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

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

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

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

9. A plurality of pixels each having one or a plurality of organic photoelectric conversion units provided therein; The organic photoelectric conversion unit is A first electrode; a second electrode disposed opposite the first electrode; an organic photoelectric conversion layer provided between the first electrode and the second electrode and containing at least one benzothienobenzothiophene-based compound represented by any one of the following formulas (1-1) to (1-10) as a first organic semiconductor material; An imaging device having the above configuration. 【Chemistry 2】

10. The imaging device according to claim 9 , wherein each pixel includes one or more of the organic photoelectric conversion units and one or more inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion units.

11. The inorganic photoelectric conversion unit is formed by embedding the inorganic photoelectric conversion unit in a semiconductor substrate, The imaging device according to claim 10 , wherein the organic photoelectric conversion section is formed on a first surface side of the semiconductor substrate.

12. The imaging device 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 organic photoelectric conversion unit performs photoelectric conversion of blue light, The imaging device according to claim 11 , wherein an inorganic photoelectric conversion section that performs photoelectric conversion of green light and an inorganic photoelectric conversion section that performs photoelectric conversion of red light are stacked within the semiconductor substrate.

14. The imaging device according to claim 9 , wherein each pixel includes a plurality of the organic photoelectric conversion units that perform photoelectric conversion in mutually different wavelength ranges.

Images