Photoelectric conversion element and imaging device

Abstract

The photoelectric conversion element according to an embodiment of the present invention includes: a first electrode including a plurality of electrodes independent of each other; a second electrode opposite to the first electrode; a photoelectric conversion layer including quantum dots and arranged between the first electrode and the second electrode; and a semiconductor layer including an oxide semiconductor material and arranged between the first electrode and the photoelectric conversion layer. The energy level of the conduction band of the photoelectric conversion layer is equal to or lower than the energy level of the conduction band of the semiconductor layer.

Description

Technical Field

[0001] The present invention relates to, for example, a photoelectric conversion element having a photoelectric conversion layer including semiconductor nanoparticles and an imaging device including the photoelectric conversion element. Background Art

[0002] The pixel size of an imaging device such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor has been decreasing. Generally, an imaging device having a photoelectric conversion unit outside a semiconductor substrate accumulates charges generated by photoelectric conversion in a floating diffusion (FD) formed inside the semiconductor substrate.

[0003] Incidentally, an image pickup device having a photoelectric conversion unit disposed inside a semiconductor substrate temporarily accumulates the charge generated by photoelectric conversion in the photoelectric conversion unit inside the semiconductor substrate, and then transfers the charge to the FD. This makes it possible to completely deplete the photoelectric conversion unit. In contrast, as described above, the charge generated by the photoelectric conversion unit disposed outside the semiconductor substrate is directly accumulated in the FD, so it is difficult to completely deplete the photoelectric conversion unit. This increases kTC noise and causes more unfavorable random noise, resulting in a decrease in image pickup quality.

[0004] In order to solve this problem, for example, Patent Document 1 discloses an imaging element provided with an electrode for charge accumulation. The electrode for charge accumulation is arranged on the first electrode side of a first electrode and a second electrode spaced apart from the first electrode, and is opposite to a photoelectric conversion layer via an insulating layer. The first electrode and the second electrode are arranged opposite to each other via the photoelectric conversion layer. The first electrode is arranged on the opposite side of the light incident side. The imaging element can accumulate the charge generated by photoelectric conversion in the photoelectric conversion layer, and can completely deplete the charge accumulation portion when exposure is started. Therefore, the degradation of imaging quality can be reduced.

[0005] Reference List

[0006] Patent Literature

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-157816

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2010-177392 Summary of the invention

[0009] By the way, for example, as a recently developed photoelectric conversion element sensitive to near-infrared light, Patent Document 2 discloses a photoelectric conversion element using quantum dots (semiconductor nanoparticles) of a narrow-gap semiconductor for a photoelectric conversion layer. A photoelectric conversion element having a photoelectric conversion layer formed in a photoelectric conversion element by using semiconductor nanoparticles is required to reduce the occurrence of dark current.

[0010] It is desirable to provide a photoelectric conversion element and an imaging device that can reduce the occurrence of dark current.

[0011] The photoelectric conversion element according to an embodiment of the present invention includes: a first electrode including a plurality of electrodes independent of each other; a second electrode arranged opposite to the first electrode; a photoelectric conversion layer including quantum dots; and a semiconductor layer including an oxide semiconductor material. The photoelectric conversion layer is disposed between the first electrode and the second electrode. The semiconductor layer is disposed between the first electrode and the photoelectric conversion layer. The energy level of the conduction band of the photoelectric conversion layer is equal to or higher than the energy level of the conduction band of the semiconductor layer.

[0012] An image pickup device according to an embodiment of the present invention includes a plurality of pixels each provided with one or more photoelectric conversion elements, and includes the photoelectric conversion element according to the above-described embodiment as a photoelectric conversion element.

[0013] In the photoelectric conversion element and the camera device according to various embodiments of the present invention, the energy level of the photoelectric conversion layer is equal to or higher than the energy level of the conduction band of the semiconductor layer. The photoelectric conversion layer is stacked with the semiconductor layer between the first electrode and the second electrode. The photoelectric conversion layer includes semiconductor nanoparticles. The semiconductor layer includes an oxide semiconductor material. This improves the efficiency of transferring the charge generated in the photoelectric conversion layer to the semiconductor layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic cross-sectional view of an image pickup element according to an embodiment of the present invention.

[0015] Figure 2 yes Figure 1 Schematic cross-sectional view of a photoelectric conversion element shown in .

[0016] Figure 3 yes Figure 1 Equivalent circuit diagram of the imaging element shown in .

[0017] Figure 4 It is a diagram including Figure 1 Schematic diagram of the arrangement of lower electrodes and transistors in the control section of the imaging element shown in FIG.

[0018] Figure 5It is a characteristic diagram illustrating the relationship between the particle size of semiconductor nanoparticles and the conduction band and the valence band.

[0019] Figure 6 This is a characteristic diagram illustrating energy changes in the conduction band and valence band of ligand-type semiconductor nanoparticles.

[0020] Fig. 7A Is a description Figure 1 The operating principle of the photoelectric conversion element is shown in the diagram.

[0021] Figure 7B Is a description Figure 1 The operating principle of the photoelectric conversion element is shown in the diagram.

[0022] Figure 7C Is a description Figure 1 The operating principle of the photoelectric conversion element is shown in the diagram.

[0023] Fig. 8A Is used to describe Figure 1 A schematic cross-sectional view of a method for manufacturing an image pickup element shown in FIG.

[0024] Figure 8B It's a picture. Fig. 8A Schematic cross-sectional view of the following steps.

[0025] Figure 8C It's a picture. Figure 8B Schematic cross-sectional view of the following steps.

[0026] Fig.8D It's a picture. Figure 8C Schematic cross-sectional view of the following steps.

[0027] Fig. 8E It's a picture. Fig.8D Schematic cross-sectional view of the following steps.

[0028] Fig. 9 It's a picture. Figure 1 A timing chart of an operation example of the photoelectric conversion element shown in FIG.

[0029] Fig.10 It is a diagram including pixels Figure 1 0 is a block diagram of the configuration of an imaging device including an imaging element shown in FIG.

[0030] Fig.11 The diagram includes Fig.10 A functional block diagram of an example of an electronic device (camera) of an image pickup device shown in FIG.

[0031] Fig.12 is a block diagram showing an example of a schematic configuration of an in-vivo information acquisition system.

[0032] Fig.13 is a diagram showing an example of a schematic configuration of an endoscopic surgery system.

[0033] Fig.14 : is a block diagram showing an example of the functional configuration of a camera head and a camera control unit (CCU: camera control unit).

[0034] Fig.15 is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0035] Fig.16 This is a diagram for assisting in explaining an example of the installation position of the imaging unit.

[0036] Fig.17A is a graph illustrating the results of EQE in Experimental Examples 1 to 4.

[0037] Fig. 17B is a graph illustrating the results of dark current in Experimental Examples 1 to 4.

[0038] Fig.18A is a graph illustrating the results of EQE in Experimental Examples 5 to 7.

[0039] Fig.18B is a graph illustrating the results of dark current in Experimental Examples 5 to 7. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings. The following description is a specific example of the present invention, but the present invention is not limited to the following mode. In addition, the present invention is not limited to the arrangement, size, and size ratio of the corresponding parts illustrated in the corresponding drawings. It should be noted that the description is given in the following order.

[0041] 1. Implementation Method (with E CS ≥E CCQD An example of a photoelectric conversion element as a semiconductor layer (S) and a conduction band energy level of a photoelectric conversion layer (CQD)

[0042] 1-1. Structure of the imaging element

[0043] 1-2. Method for manufacturing imaging element

[0044] 1-3. Control method of imaging element

[0045] 1-4. Actions and Effects

[0046] 2. Application Examples

[0047] 3. Example

[0048] <1. Implementation Method>

[0049] Figure 1 The cross-sectional configuration of an image pickup element (image pickup element 1 ) according to an embodiment of the present invention is schematically illustrated. Figure 2 yes Figure 1 Schematic enlarged view of the cross-sectional structure of the main part (photoelectric conversion element 10) of the image pickup element 1 shown in FIG. Figure 3 yes Figure 1 An equivalent circuit diagram of the image pickup element 1 shown in FIG. Figure 4 Schematically illustrates the Figure 1 The arrangement of the lower electrode 11 and the transistor in the control section of the image pickup element 1 shown in FIG. In an image pickup device such as a CMOS image sensor (image pickup device 100; see FIG. Fig.10 ), for example, the imaging element 1 is included in one pixel (unit pixel P).

[0050] (1-1. Structure of Image Pickup Element)

[0051] The imaging element 1 is provided with a photoelectric conversion element 10, for example, on the first surface (back surface) 30A side of a semiconductor substrate 30. The photoelectric conversion element 10 includes a photoelectric conversion layer (photoelectric conversion layer 14) containing semiconductor nanoparticles between a lower electrode 11 (first electrode) and an upper electrode 15 (second electrode) arranged opposite to each other. A semiconductor layer 13 is provided between the lower electrode 11 and the photoelectric conversion layer 14 via an insulating layer 12. In the present embodiment, the photoelectric conversion layer 14 is configured to have an energy level equal to or higher than the energy level of the conduction band of the semiconductor layer 13. The lower electrode 11 includes a readout electrode 11A, an accumulation electrode 11B, and a transfer electrode 11C as a plurality of electrodes independent of each other. The transfer electrode 11C is, for example, arranged between the readout electrode 11A and the accumulation electrode 11B. The accumulation electrode 11B and the transfer electrode 11C are covered by the insulating layer 12. The readout electrode 11A is electrically connected to the semiconductor layer 13 via an opening 12H provided on the insulating layer 12.

[0052] Note that in this embodiment, the case where electrons in electron-hole pairs (electron-hole pairs) generated by photoelectric conversion are read out as signal charges is described. In addition, in the drawings, "+ (plus sign)" attached to "p" or "n" indicates that the concentration of p-type or n-type impurities is high, and "++" indicates that the concentration of p-type or n-type impurities is higher than "+".

[0053] The photoelectric conversion element 10 is a photoelectric conversion element that absorbs light corresponding to a part or all of a selected wavelength range (for example, 700 nm or more and 2500 nm or less) to generate electron-hole pairs. The photoelectric conversion element 10 has the following structure: Figure 2As shown, the lower electrode 11, the insulating layer 12, the semiconductor layer 13, the photoelectric conversion layer 14 and the upper electrode 15 are sequentially stacked on, for example, the first surface 30A side of the semiconductor substrate 30. Note that, Figure 2 The fixed charge layer 16A, dielectric layer 16B, interlayer insulating layer 17, etc. are omitted. The lower electrode 11 is formed, for example, for each unit pixel P. The lower electrode 11 also includes a readout electrode 11A, an accumulation electrode 11B, and a transfer electrode 11C separated from each other by an insulating layer 12 as described in detail below. Figure 1 The example in which the semiconductor layer 13, the photoelectric conversion layer 14 and the upper electrode 15 are formed separately for each imaging element 1 is illustrated. However, the semiconductor layer 13, the photoelectric conversion layer 14 and the upper electrode 15 may be provided as a continuous layer common to a plurality of imaging elements 1, for example.

[0054] As described above, the lower electrode 11 includes, for example, the readout electrode 11A, the accumulation electrode 11B, and the transfer electrode 11C, which are independent of each other. For example, the lower electrode 11 can be formed by using a conductive material having light transmittance (transparent conductive material). For example, the transparent conductive material preferably has a band gap energy of 2.5 eV or more, and desirably has a band gap energy of 3.1 eV or more. The transparent conductive material includes a metal oxide. Specific examples thereof include indium oxide, indium tin oxide (ITO (Indium Tin Oxide): including Sn-doped In2O3, crystalline ITO and amorphous ITO), indium zinc oxide (IZO: Indium Zinc Oxide) obtained by adding indium as a dopant to zinc oxide, indium gallium oxide (IGO: indium gallium oxide) obtained by adding indium as a dopant to gallium oxide, indium gallium zinc oxide (IGZO (indium gallium zinc oxide): In-GaZnO4) obtained by adding indium and gallium as dopants to zinc oxide, indium tin zinc oxide (ITZO: indium tin zinc oxide) obtained by adding indium and tin as dopants to zinc oxide, IFO (F-doped In2O3), tin oxide (SnO2), ATO (Sb-doped SnO2), FTO (F-doped SnO2), zinc oxide (including ZnO doped with another element), aluminum zinc oxide (AZO: aluminum zinc oxide) obtained by adding aluminum as a dopant to zinc oxide oxide), gallium zinc oxide (GZO: gallium zinc oxide) obtained by adding gallium as a dopant to zinc oxide, titanium oxide (TiO2), niobium titanium oxide (TNO: niobium titanium oxide) obtained by adding niobium as a dopant to titanium oxide, antimony oxide, spinel oxide, and oxide having a YbFe2O4 structure. In addition, a transparent electrode including gallium oxide, titanium oxide, niobium oxide, or nickel oxide as a base layer can be exemplified. The film thickness of the lower electrode 11 in the Y-axis direction (hereinafter referred to as thickness) is, for example, 2×10 -8 m or more and 2×10 -7 m or less, and preferably 3×10 -8 m or more and 1×10 -7 m or less.

[0055] It should be noted that, for example, the lower electrode 11 can be formed by using a metal material. For example, in the case of performing photoelectric conversion in the near-infrared region, it is preferable to use a metal material having a smaller work function than the upper electrode 15 and a higher reflectivity to light in the near-infrared region. Examples of such materials include titanium (Ti), silver (Ag), aluminum (Al), magnesium (Mg), chromium (Cr), nickel (Ni), tungsten (W), and copper (Cu). Table 1 lists the work functions of ITO used as the upper electrode 15 and the above-mentioned metal materials and their reflectivity in the near-infrared region. Preferably, the lower electrode 11 is formed by using any one of silver, aluminum, and copper among the above-mentioned metal materials.

[0056] [Table 1]

[0057]

[0058] The readout electrode 11A transfers the signal charge generated in the photoelectric conversion layer 14 to the floating diffusion FD1. The readout electrode 11A is connected to the floating diffusion FD1 provided on the second surface (front surface) 30B side of the semiconductor substrate 30 via, for example, the upper first contact 17A, the pad portion 39A, the through electrode 34, the connection portion 41A, and the lower second contact 46.

[0059] The accumulation electrode 11B accumulates signal charges (electrons) of the charges generated in the photoelectric conversion layer 14 in the semiconductor layer 13. It is desirable that the accumulation electrode 11B is larger than the readout electrode 11A, thereby allowing the accumulation electrode 11B to accumulate many charges.

[0060] The transfer electrode 11C improves the efficiency of transferring the charge accumulated on the accumulation electrode 11B to the readout electrode 11A, and is provided between the readout electrode 11A and the accumulation electrode 11B. The transfer electrode 11C is connected to the pixel drive circuit, for example, via the upper third contact 17C and the pad portion 39C. The pixel drive circuit is included in the drive circuit. Corresponding voltages can be applied independently to the readout electrode 11A, the accumulation electrode 11B, and the transfer electrode 11C.

[0061] The insulating layer 12 electrically isolates the semiconductor layer 13 from the accumulation electrode 11B and the transfer electrode 11C. The insulating layer 12 is provided on the interlayer insulating layer 17 to cover the lower electrode 11, for example. In addition, the insulating layer 12 is provided with an opening 12H, which is located on the readout electrode 11A of the lower electrode 11. The readout electrode 11A and the semiconductor layer 13 are electrically connected via the opening 12H. For example, Figure 2 As shown, it is preferable to make the side surface of the opening 12H inclined so as to expand the side surface of the opening 12H toward the light incident side S1. This facilitates the movement of charges from the semiconductor layer 13 to the readout electrode 11A.

[0062] The material of the insulating layer 12 includes an inorganic insulating material, such as a silicon oxide-based material, a silicon nitride (SiN x ) and metal oxide high dielectric constant insulating materials such as aluminum oxide (Al2O3). In addition, examples of the material of the insulating layer 12 may also include polymethyl methacrylate (PMMA), polyvinyl phenol (PVP), polyvinyl alcohol (PVA), polyimide, polycarbonate (PC), polyethylene terephthalate (PET), polystyrene, silanol derivatives (silane coupling agents) such as N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (AEAPTMS), 3-mercaptopropyltrimethoxysilane (MPTMS) or octadecyltrichlorosilane (OTS), novolac type phenolic resin, fluorine-based resin, and organic insulating materials (organic polymers), such as linear hydrocarbons such as octadecyl mercaptan or dodecyl isocyanate having a functional group capable of bonding to a control electrode at one end thereof, and combinations of the above materials may be used. Note that examples of silicon oxide-based materials include silicon oxide (SiO x ), BPSG, PSG, BSG, AsSG, PbSG, silicon oxynitride (SiON), spin-on-glass (SOG) and low dielectric constant materials (for example, polyarylether, cycloperfluorocarbon polymer and benzocyclobutene, cyclofluorine resin, polytetrafluoroethylene, arylether fluoride, polyimide fluoride, amorphous carbon and organic SOG).

[0063] The semiconductor layer 13 accumulates the signal charges generated in the photoelectric conversion layer 14 and transfers the signal charges to the readout electrode 11A. The carrier density of the semiconductor layer 13 is preferably 1e+16 / cm -3 Below, more preferably 1e+15 / cm -3 The semiconductor layer 13 is preferably formed by using a material having a higher charge mobility and a larger band gap than the photoelectric conversion layer 14. This makes it possible, for example, to transfer charges at a higher speed and to suppress hole injection from the readout electrode to the semiconductor layer.

[0064] The semiconductor layer 13 includes, for example, an oxide semiconductor material. Examples of oxide semiconductor materials include IGZO (In-Ga-Zn-O-based oxide semiconductor), ZTO (Zn-Sn-O-based oxide semiconductor; Zn2SnO4), IGZTO (In-Ga-Zn-Sn-O-based oxide semiconductor; InGaZnSnO), GTO (Ga-Sn-O-based oxide semiconductor; Ga2O3:SnO2), and IGO (In-Ga-O-based oxide semiconductor). It is preferred to use at least one of the above oxide semiconductor materials for the semiconductor layer 13, and IGZO is particularly advantageously used. The thickness of the semiconductor layer 13 is, for example, greater than 30 nm and less than 200 nm, preferably greater than 60 nm and less than 150 nm.

[0065] The photoelectric conversion layer 14 converts light energy into electrical energy. For example, the photoelectric conversion layer 14 provides a field for separating excitons generated when absorbing light in a wavelength range of more than 700nm and less than 2500nm into electrons and holes. The photoelectric conversion layer 14 includes semiconductor nanoparticles and has a structure in which, for example, a plurality of semiconductor nanoparticles are dispersed in a conductive polymer. Semiconductor nanoparticles are particles that generally have a particle size of several nm to tens of nm, and include, for example, a core, a shell disposed around the core, and a ligand bound to the shell surface. It should be noted that the shell is not required, and the semiconductor nanoparticles may have a ligand directly bound to the core surface. As described above, the photoelectric conversion layer 14 according to the present embodiment is constructed so that its energy level is equal to or higher than the energy level of the conduction band of the semiconductor layer 13, and the photoelectric conversion layer 14 is, for example, constructed to satisfy the following expression (1).

[0066] [Expression 1]

[0067] E CS ≥E CCQD ..... (1)

[0068] (E CS represents the energy level at the lowest end of the conduction band of the semiconductor layer, and E CCQD Indicates the energy level at the lowest end of the conduction band of the photoelectric conversion layer)

[0069] It should be noted that, in the case where expression (1) is satisfied, since the difference (effective band gap) between the energy level at the lowest end of the conduction band of the semiconductor layer 13 and the energy level at the highest end of the valence band of the photoelectric conversion layer 14 becomes smaller, more dark current may occur. Therefore, a larger effective band gap is desired. The band gap of the photoelectric conversion layer 14 is determined according to the wavelength required for spectral separation. As described above, preferably, E CS and E CCQDThey are equal to each other to reduce dark current while maintaining high external quantum efficiency (EQE). Note that the energy level at the highest end of the valence band and the energy level at the lowest end of the conduction band are referred to as the valence band and the conduction band below.

[0070] Examples of materials included in semiconductor nanoparticles include the following materials. Examples of materials included in the core include PbS, PbSe, PbTe, CuInSe2, ZnCuInSe, CuInS2, ZnCuInS, CuInTe2, ZnCuInTe, AgInSe2, ZnAgInSe, AgInTe2, ZnAgInTe, ZnCuSnSSe, HgTe, InAs, InSb, Ag2S, Ag2Se, and Ag2Te, etc., as compound semiconductors, and include semiconductor particles such as CH3NH3SnPbI3, CsSnPbI3, CH3NH3SnI3, and CsSnI3, etc., as perovskite compounds. Examples of materials included in the shell include PbO, PbO2, Pb3O4, ZnS, ZnSe, ZnTe, GaS, and GaSe, etc. Tables 2 and 3 list the particle size (nm), band gap (eV) and absorption end wavelength (nm) of the core material included in the above semiconductor nanoparticles, and the conduction band (E C ) and valence band (E V ) energy level.

[0071] [Table 2]

[0072]

[0073] [Table 3]

[0074]

[0075] In this embodiment, a structure for photoelectric conversion of light of 940 nm is described. The conduction band (E CCQD ) and the conduction band of the semiconductor layer 13 (E CS ) preferably has a difference of more than 0eV and less than 0.2eV, and more preferably has the same value. In addition, the semiconductor nanoparticles used for the photoelectric conversion layer 14 preferably have a band gap of more than 0.6eV and less than 1.3eV. The semiconductor nanoparticles change the semiconductor band gap according to the particle size. The band gap becomes larger as the particle size decreases. Here, it is assumed that the particle size of the semiconductor nanoparticle is the particle size of the core, or in the case where the core is covered by the shell, it is the particle size of the core including the shell. The size of the core and the size of the core including the shell can be adjusted according to the amount of raw materials to be supplied and the reaction conditions of their synthesis. Figure 5The diagram shows the relationship between the particle size of semiconductor nanoparticles and the energy levels of the conduction band and valence band of the photoelectric conversion layer. Figure 5 In the example, PbS is used as semiconductor nanoparticles. In addition, as an indicator, the energy level (E C =4.6eV).

[0076] The conduction band (E) of semiconductor nanoparticles can be controlled according to the type of ligands. CCQD ) and valence band (E VCQD ). The ligand includes, for example, an absorbing group that interacts with the surface of the shell covering the core and an alkyl chain bonded thereto. The alkyl chain includes, for example, 2 to 50 carbon atoms, and examples of the absorbing group include an amine group, a phosphono group, a phosphino group, a carboxyl group, a hydroxyl group, and a thiol group. In addition, halogen atoms such as chlorine (Cl), bromine (Br), and iodine (I) are included. In addition, a sulfur atom may be included. Figure 6 The diagram shows the energy changes of the conduction band and valence band of ligand-type semiconductor nanoparticles. Figure 6 The diagram shows an example including IGZO as a semiconductor layer. Table 4 lists the conduction band (E) when chlorine (Cl), bromine (Br), iodine (I), 3-mercaptopropionic acid (MPA), 1,2-ethanedithiol (EDT) and 1,4-butanedithiol (BDT) are used as ligands for PbS as semiconductor particles having an average particle size of 5.5 nm. C ) and valence band (E V ) and the band gap (Eg) therebetween. In the case where IGZO is used to form the semiconductor layer 13 and PbS is used as the semiconductor particles included in the semiconductor nanoparticles of the photoelectric conversion layer 14, a halogen atom such as chlorine (Cl) or iodine (I) is used as a ligand so that the conduction band (Eg) of the photoelectric conversion layer 14 is CCQD ) is roughly equal to the conduction band of the semiconductor layer 13.

[0077] [Table 4]

[0078] Br T Cl BDT EDT MPA Ec 4.7 4.6 4.6 4.5 4.1 4 Ev 5.8 5.7 5.7 5.6 5.2 5.1 Eg 1.1 1.1 1.1 1.1 1.1 1.1

[0079] As described above, the semiconductor nanoparticles used for the photoelectric conversion layer 14 preferably have an average particle diameter of 3 nm or more and 6 nm or less. The semiconductor nanoparticles preferably include, for example, PbS as semiconductor particles and include halogen atoms such as chlorine (Cl), bromine (Br) and iodine (I) as ligands.

[0080] The photoelectric conversion layer 14 has a thickness of, for example, 100 nm or more and 1000 nm or less, and preferably has a thickness of 300 nm or more and 800 nm or less.

[0081] The upper electrode 15 includes a conductive material having light transmittance. The upper electrode 15 may be separated for each unit pixel P, or may be formed as an electrode common to each unit pixel P. The upper electrode 15 preferably includes an electrode material having a work function higher than that of the lower electrode 11, and examples of the electrode material include Ti, Ag, and Al. In addition, the upper electrode 15 may be formed as a stacked film in which Ti and Al are stacked. The upper electrode 15 has a thickness of, for example, 10 nm to 200 nm.

[0082] It is to be noted that other layers may be provided between the semiconductor layer 13 and the photoelectric conversion layer 14 and between the photoelectric conversion layer 14 and the upper electrode 15. For example, in the case of reading out electrons as signal charges as in the present embodiment, a layer including a material having a large work function such as MoO3, WO3, or V2O5 may be added between the photoelectric conversion layer 14 and the upper electrode 15. Therefore, this makes it possible to enhance the internal electric field generated between the lower electrode 11 and the upper electrode 15.

[0083] In the photoelectric conversion element 10, the near infrared light L incident on the photoelectric conversion element 10 from the upper electrode 15 side is absorbed by the photoelectric conversion layer 14. For example, Fig. 7A As shown, the excitons thus generated are separated and dissociated into electrons and holes. Figure 7B As shown, the various charges (electrons and holes) generated here are transferred to different electrodes by diffusion due to the difference in carrier concentration, or by the internal electric field due to the difference in work function between the anode (here, the upper electrode 15) and the cathode (here, the lower electrode 11). The transfer direction of electrons and holes is controlled by applying a potential between the lower electrode 11 and the upper electrode 15. Here, electrons are transported to the lower electrode 11 side as signal charges. The electrons transported to the lower electrode 11 side are accumulated in the semiconductor layer 13 above the accumulation electrode 11B, and then as shown in FIG. Figure 7C As shown, the electrons are transferred to the readout electrode 11A. The transferred electrons are detected as photocurrent.

[0084] The second surface 30B of the semiconductor substrate 30 is provided with, for example, a floating diffusion portion (floating diffusion layer) FD1 (region 36B in the semiconductor substrate 30), an amplifier transistor (modulation element) AMP, a reset transistor RST, a selection transistor SEL, and a multilayer wiring 40. The multilayer wiring 40 has a configuration in which wiring layers 41, 42, and 43 are stacked in an insulating layer 44, for example.

[0085] Note that the figure illustrates the first surface 30A side of the semiconductor substrate 30 as the light incident side S1 , and the second surface 30B side thereof as the wiring layer side S2 .

[0086] For example, a layer 16A having a fixed charge (fixed charge layer), a dielectric layer 16B having an insulating property, and an interlayer insulating layer 17 are provided between the first surface 30A of the semiconductor substrate 30 and the lower electrode 11. A protective layer 18 is provided on the upper electrode 15. A light shielding film 21 is provided in the protective layer 18, and is provided, for example, above the readout electrode 11A. It is sufficient that the light shielding film 21A is provided to cover at least the region of the readout electrode 11A that is in direct contact with the photoelectric conversion layer 14 without at least overlapping with the accumulation electrode 11B. For example, the light shielding film 21 is preferably slightly larger than the readout electrode 11A formed in the same layer as the accumulation electrode 11B. In addition, for example, a color filter 22 is provided, for example, above the accumulation electrode 11B. The color filter 22 prevents, for example, visible light from being incident on the photoelectric conversion layer 14, and it is sufficient that the color filter 22 is provided to cover at least the region of the accumulation electrode 11B. It should be noted that although Figure 1 An example is shown in which the light shielding film 21 and the color filter 22 are arranged at different positions in the film thickness direction of the protective layer 18, but the light shielding film 21 and the color filter 22 may be arranged at the same position. Optical components such as a planarization layer (not shown) and an on-chip lens 23 are arranged above the protective layer 18.

[0087] The fixed charge layer 16A may be a film having a positive fixed charge or a film having a negative fixed charge. The material of the film having a negative fixed charge includes hafnium oxide, aluminum oxide, zirconium oxide, tantalum oxide, titanium oxide, and the like. In addition, as materials other than the above materials, lanthanum oxide, praseodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, thulium oxide, ytterbium oxide, lutetium oxide, yttrium oxide, aluminum nitride film, hafnium oxynitride film, or aluminum oxynitride film may be used.

[0088] The fixed charge layer 16A may also have a configuration in which two or more types of films are stacked. For example, in the case of a film having a negative fixed charge, this makes it possible to further improve the function of the hole accumulation layer.

[0089] Although the material of the dielectric layer 16B is not particularly limited, the dielectric layer 16B includes, for example, a silicon oxide film, TEOS, a silicon nitride film, a silicon nitride oxide film, or the like.

[0090] The interlayer insulating layer 17 includes, for example, a single-layer film containing one of silicon oxide, silicon nitride, silicon oxynitride (SiON), and the like, or a stacked film containing two or more of the foregoing materials.

[0091] The protective layer 18 includes a light-transmitting material and includes, for example, a single layer film containing any one of silicon oxide, silicon nitride, and silicon oxynitride, or a stacked film containing two or more of the above materials. The protective layer 18 has a thickness of, for example, 100 nm to 30,000 nm.

[0092] The through electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The photoelectric conversion element 10 is connected to the gate Gamp of the amplifier transistor AMP and one source / drain region 36B of the reset transistor RST (reset transistor Tr1rst) via the through electrode 34, and the source / drain region 36B also serves as the floating diffusion portion FD1. This makes it possible to advantageously transfer the signal charge generated in the photoelectric conversion element 10 on the first surface 30A side of the semiconductor substrate 30 to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34 in the imaging element 1, and to improve the characteristics.

[0093] The lower end of the through electrode 34 is connected to the 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 the lower first contact 45. The connection portion 41A and the floating diffusion portion FD1 (region 36B) are connected, for example, via the lower second contact 46. The upper end of the through electrode 34 is connected to the readout electrode 11A via the pad portion 39A and the upper first contact 17A, for example.

[0094] The through-electrode 34 has a function of a connector between the photoelectric conversion element 10 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1 , and serves as a transfer path for charges (here, electrons) generated in the photoelectric conversion element 10 .

[0095] The reset gate Grst of the reset transistor RST is arranged next to the floating diffusion FD1 (one source / drain region 36B of the reset transistor RST). This makes it possible for the reset transistor RST to reset the charge accumulated in the floating diffusion FD1.

[0096] The semiconductor substrate 30 includes, for example, an n-type silicon (Si) substrate, and has a p-well 31 in a predetermined region. The second surface 30B of the p-well 31 is provided with the above-mentioned amplifier transistor AMP, reset transistor RST, selection transistor SEL, etc. In addition, the peripheral portion of the semiconductor substrate 30 is provided with a peripheral circuit (not shown) including a logic circuit, etc.

[0097] The reset transistor RST (reset transistor Tr1rst) resets the charge transferred from the photoelectric conversion element 10 to the floating diffusion FD1, and includes, for example, a MOS transistor. Specifically, the reset transistor Tr1rst includes a reset gate Grst, a channel forming region 36A, and source / drain regions 36B and 36C. The reset gate Grst is connected to the reset line RST1. One source / drain region 36B of the reset transistor Tr1rst also serves as the floating diffusion FD1. Another source / drain region 36C included in the reset transistor Tr1rst is connected to the power supply VDD.

[0098] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the photoelectric conversion element 10 into a voltage, and includes, for example, a MOS transistor. Specifically, the amplifier transistor AMP includes a gate Gamp, a channel formation region 35A, and source / drain regions 35B and 35C. The gate Gamp is connected to the readout electrode 11A and one source / drain region 36B (floating diffusion FD1) of the reset transistor Tr1rst via the lower first contact 45, the connection portion 41A, the lower second contact 46, and the through electrode 34, etc. In addition, one source / drain region 35B shares an area with another source / drain region 36C included in the reset transistor Tr1rst, and one source / drain region 35B is connected to the power supply VDD.

[0099] The selection transistor SEL (selection transistor TR1sel) includes a gate Gsel, a channel formation region 34A, and source / drain regions 34B and 34C. The gate Gsel is connected to the selection line SEL1. In addition, one source / drain region 34B shares an area with another source / drain region 35C included in the amplifier transistor AMP, and the other source / drain region 34C is connected to the signal line (data output line) VSL1.

[0100] The reset line RST1 and the selection line SEL1 are each connected to a vertical driving circuit 112 included in the driving circuit. The signal line (data output line) VSL1 is connected to a column signal processing circuit 113 included in the driving circuit.

[0101] The lower first contact 45, the upper first contact 17A, the upper second contact 17B and the upper third contact 17C, for example, all include doped silicon materials such as phosphorus-doped amorphous silicon (PDAS: Phosphorus Doped Amorphous Silicon) or metal materials such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf) or tantalum (Ta).

[0102] (1-2. Method for manufacturing imaging element)

[0103] For example, the image pickup element 1 according to the present embodiment can be manufactured as follows.

[0104] FIG. 8A to FIG. 8E The method for manufacturing the imaging element 1 is illustrated in the order of steps. First, Fig. 8A As shown, for example, a p-well 31 is formed as a first conductive well in a semiconductor substrate 30. A p+ region is formed near a first surface 30A of the semiconductor substrate 30.

[0105] Likewise Fig. 8A As shown, an n+ region used as a floating diffusion portion FD1 is formed on the second surface 30B of the semiconductor substrate 30, and then a gate insulating layer 32 and a gate wiring layer 47 are formed. The gate wiring layer 47 includes the gates of the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST. This forms the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST. In addition, a multilayer wiring 40 is formed on the second surface 30B of the semiconductor substrate 30. The multilayer wiring 40 includes wiring layers 41 to 43 and an insulating layer 44. The wiring layers 41 to 43 include a lower first contact 45, a lower second contact 46, and a connection portion 41A.

[0106] As a base of the semiconductor substrate 30, for example, a silicon on insulator (SOI) substrate is used in which the semiconductor substrate 30, an embedded oxide film (not shown), and a holding substrate (not shown) are stacked. Fig. 8A The embedded oxide film and the holding substrate are not shown in the figure, but the embedded oxide film and the holding substrate are bonded to the first surface 30A of the semiconductor substrate 30. After the ion implantation, annealing treatment is performed.

[0107] Then, a support substrate (not shown) or another semiconductor base or the like is bonded to the second surface 30B side (multilayer wiring 40 side) of the semiconductor substrate 30 and vertically turned over. Subsequently, the semiconductor substrate 30 is separated from the embedded oxide film of the SOI substrate and the holding substrate to expose the first surface 30A of the semiconductor substrate 30. These steps can be performed using techniques such as ion implantation and chemical vapor deposition (CVD: Chemical Vapor Deposition) used in conventional CMOS processes.

[0108] For example, Figure 8B As shown, the semiconductor substrate 30 is then processed from the first surface 30A side by dry etching, for example, and a ring-shaped opening 34H is formed. Figure 8B As shown, the depth of the opening 34H extends from the first surface 30A to the second surface 30B of the semiconductor substrate 30 and reaches the connection portion 41A, for example.

[0109] Subsequently, for example, a negative fixed charge layer 16A is formed on the first surface 30A of the semiconductor substrate 30 and the side surface of the opening 34H. Two or more types of films may be stacked as the negative fixed charge layer 16A. This makes it possible to further improve the function of the hole accumulation layer. The dielectric layer 16B is formed after the negative fixed charge layer 16A is formed. Next, pad portions 39A, 39B, and 39C are formed at predetermined positions on the dielectric layer 16B, and then an interlayer insulating layer 17 is formed on the dielectric layer 16B and the pad portions 39A, 39B, and 39C. Subsequently, the interlayer insulating layer 17 is formed, and then the surface of the interlayer insulating layer 17 is flattened, for example, by using chemical mechanical polishing (CMP: Chemical Mechanical Polishing).

[0110] Then, if Figure 8C As shown, openings 17H1, 17H2 and 17H3 are respectively formed in the interlayer insulating layer 17 on the pad portions 39A, 39B and 39C, and then these openings 17H1, 17H2 and 17H3 are filled with a conductive material such as Al, for example, to form an upper first contact 17A, an upper second contact 17B and an upper third contact 17C.

[0111] Then, if Fig.8D As shown in FIG. 1 , a conductive film 11x is formed on the interlayer insulating layer 17, and then a photoresist PR is formed at a predetermined position on the conductive film 11x (for example, on the pad portion 39A, the pad portion 39B, and the pad portion 39C). Thereafter, the photoresist PR is etched and removed. Fig. 8E The readout electrode 11A, the accumulation electrode 11B, and the transfer electrode 11C shown in FIG. 1 are patterned.

[0112] Subsequently, the insulating layer 12 is then formed over the interlayer insulating layer 17 and the readout electrode 11A, the accumulation electrode 11B, and the upper third contact 17C. After that, the opening 12H is provided on the readout electrode 11A. After that, the semiconductor layer 13, the photoelectric conversion layer 14, the upper electrode 15, the protective layer 18, the light shielding film 21, and the color filter 22 are formed over the interlayer insulating layer 17. Finally, optical components such as a planarization layer and an on-chip lens 23 are arranged. As described above, the Figure 1 The image pickup element 1 shown in FIG.

[0113] (1-3. Method for controlling imaging element)

[0114] (Signal collection of the photoelectric conversion element 10)

[0115] In the image pickup element 1 according to the present embodiment, light in the near-infrared region of light incident on the image pickup element 1 is selectively detected (absorbed) by the photoelectric conversion element 10 and photoelectrically converted.

[0116] The photoelectric conversion element 10 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1 via the through electrode 34. Therefore, the electrons (signal charges) of the electron-hole pairs generated in the photoelectric conversion element 10 are extracted from the lower electrode 11 side, transferred to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD1. At the same time, the amplifier transistor AMP modulates the charge amount generated in the photoelectric conversion element 10 into a voltage.

[0117] Furthermore, the reset gate Grst of the reset transistor RST is arranged beside the floating diffusion FD1. This allows the reset transistor RST to reset the charge accumulated in the floating diffusion FD1.

[0118] In the present embodiment, the photoelectric conversion element 10 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 via the through-electrode 34 , thereby being able to help the reset transistor RST reset the charge accumulated in the floating diffusion FD1 .

[0119] In contrast, in the case where the through electrode 34 and the floating diffusion FD1 are not connected, it is difficult to reset the charge accumulated in the floating diffusion FD1, resulting in a large voltage being applied to the upper electrode 15 side to pull out the charge. The photoelectric conversion layer 14 may be damaged as a result. In addition, a structure capable of resetting in a short time may result in an increase in dark noise, and this structure may result in a compromise. Therefore, this structure is difficult.

[0120] Fig. 9 The diagram shows an operation example of the photoelectric conversion element 10. (A) represents the potential at the accumulation electrode 11B, (B) represents the potential at the floating diffusion FD1 (readout electrode 11A), and (C) represents the potential at the gate (Grst) of the reset transistor TR1rst. In the photoelectric conversion element 10, corresponding voltages are applied to the readout electrode 11A, the accumulation electrode 11B, and the transfer electrode 11C, respectively.

[0121] In the photoelectric conversion element 10, during the accumulation period, the potential V1 is applied from the drive circuit to the readout electrode 11A, and the potential V2 is applied to the accumulation electrode 11B. Here, it is assumed that the potentials V1 and V2 satisfy V1>V2. This causes the signal charge (electrons in this case) generated by the photoelectric conversion to be attracted to the accumulation electrode 11B and accumulated in the region of the semiconductor layer 13 opposite to the accumulation electrode 11B (accumulation period). Incidentally, the potential of the region of the semiconductor layer 13 opposite to the accumulation electrode 11B has a value that becomes more positive as the time of the photoelectric conversion passes. It should be noted that holes are sent from the upper electrode 15 to the drive circuit.

[0122] In the photoelectric conversion element 10, a reset operation is performed in the second half of the accumulation period. Specifically, at time t1, the scanning section changes the voltage of the reset signal RST from a low level to a high level. This turns on the reset transistor TR1rst in the unit pixel P. 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).

[0123] After the reset operation is completed, the charge is read out. Specifically, at time t2, the potential V3 is applied from the drive circuit to the readout electrode 11A, the potential V4 is applied to the accumulation electrode 11B, and the potential V5 is applied to the transfer electrode 11C. Here, it is assumed that the potentials V3, V4, and V5 satisfy V4>V5>V3. This causes the signal charge accumulated in the region corresponding to the accumulation electrode 11B to sequentially move from the accumulation electrode 11B to the transfer electrode 11C and the readout electrode 11A, and to be read out from the readout electrode 11A to the floating diffusion FD1. That is, the charge accumulated in the semiconductor layer 13 is read out to the control section (transfer period).

[0124] After the readout operation is completed, the potential V1 is applied from the drive circuit to the readout electrode 11A again, and the potential V2 is applied to the accumulation electrode 11B. This causes the signal charge generated by the photoelectric conversion to be attracted to the accumulation electrode 11B and accumulated in the region of the semiconductor layer 13 opposite to the accumulation electrode 11B (accumulation period).

[0125] (1-4. Actions and Effects)

[0126] As described above, a photoelectric conversion element in which quantum dots are used for a photoelectric conversion layer has recently been developed as a photoelectric conversion element sensitive to near-infrared light. From the perspective of reset noise, a photoelectric conversion element in which quantum dots are used for a photoelectric conversion layer has a semiconductor layer provided between a lower electrode and the photoelectric conversion layer, which is similar to Figure 1 The photoelectric conversion element 10 shown in FIG. The semiconductor layer accumulates the charge generated in the photoelectric conversion layer on the charge accumulation electrode included in the lower electrode, and transfers the accumulated charge to the charge collection electrode. For example, the semiconductor layer is formed by using an oxide semiconductor material such as IGZO having high charge mobility. However, the photoelectric conversion element in which the semiconductor layer and the photoelectric conversion layer including quantum dots are stacked has concerns about an increase in dark current and a decrease in quantum efficiency.

[0127] In order to solve this problem, in the photoelectric conversion element (photoelectric conversion element 10) according to the present embodiment, the energy level of the photoelectric conversion layer 14 provided above the lower electrode 11 via the insulating layer 12 and the semiconductor layer 13 is equal to or higher than the energy level of the conduction band of the semiconductor layer 13. This makes it possible to improve the efficiency of transferring signal charges (electrons) generated by photoelectric conversion performed by the photoelectric conversion layer 14 from the photoelectric conversion layer 14 to the semiconductor layer 13.

[0128] As described above, in the present embodiment, the photoelectric conversion layer 14 having an energy level equal to or higher than the energy level of the conduction band of the semiconductor layer 13 is stacked on the semiconductor layer 13 provided above the lower electrode 11, the lower electrode 11 including a plurality of electrodes independent of each other and with the insulating layer 12 interposed between the electrodes. This makes it possible to improve the efficiency of transferring the signal charges (electrons) generated by the photoelectric conversion performed by the photoelectric conversion layer 14 from the photoelectric conversion layer 14 to the semiconductor layer 13, and to improve the quantum efficiency.

[0129] It should be noted that, in the case where another layer is provided between the semiconductor layer 13 and the photoelectric conversion layer 14, the energy level of the conduction band of the photoelectric conversion layer 14 is preferably equal to or higher than the energy level of the conduction band of the other layer. That is, the energy level of the conduction band of the photoelectric conversion layer 14 is preferably equal to or higher than the energy level of the layer adjacent to the electrode (in this embodiment, the lower electrode 11) side including a plurality of electrodes independent of each other. This improves the efficiency of transferring the signal charge generated in the photoelectric conversion layer 14 to another adjacent layer, thereby improving the quantum efficiency.

[0130] <2. Application Examples>

[0131] (Application Example 1)

[0132] Fig.10 The overall configuration of an image pickup device (image pickup device 100) including the image pickup element 1 described in the above embodiment for each pixel is illustrated. The image pickup device 100 is a CMOS image sensor and includes a pixel section 1a as an image pickup area and a peripheral circuit section 130 in a peripheral area of ​​the pixel section 1a on a semiconductor substrate 30. The peripheral circuit section 130 includes, for example, a row scanner 131, a horizontal selector 133, a column scanner 134, and a system controller 132.

[0133] The pixel section 1a includes, for example, a plurality of unit pixels P arranged two-dimensionally in a matrix form. In these unit pixels P, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) is arranged in each pixel row, and a vertical signal line Lsig is arranged in each pixel column. The pixel drive line Lread is used to transmit a drive signal for reading a signal from a pixel. One end of each pixel drive line Lread is connected to an output end of a row scanner 131 corresponding to each row.

[0134] The row scanner 131 is a pixel driver including a shift register, an address decoder, and the like, and drives each unit pixel P of the pixel section 1a in a row unit, for example. A signal output from each unit pixel P of a pixel row selectively scanned by the row scanner 131 is supplied to the horizontal selector 133 through each vertical signal line Lsig. The horizontal selector 133 includes an amplifier and a horizontal selection switch, and the like, provided for each vertical signal line Lsig.

[0135] The column scanner 134 includes a shift register, an address decoder, and the like, and sequentially drives each horizontal selection switch of the horizontal selector 133 while scanning the horizontal selection switch. The selective scanning of the column scanner 134 causes the signals of the respective pixels transmitted through the respective vertical signal lines Lsig to be sequentially output to the horizontal signal lines 135, and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal lines 135.

[0136] Circuit components including the row scanner 131, the horizontal selector 133, the column scanner 134, and the horizontal signal line 135 may be directly formed on the semiconductor substrate 30 or arranged in an external control IC. In addition, these circuit components may be formed on another substrate connected by a cable or the like.

[0137] The system controller 132 receives data such as a clock and instructions on an operation mode supplied from the outside of the semiconductor substrate 30, and outputs data such as internal information of the image pickup device 100. The system controller 132 also includes a timing generator for generating various timing signals, and controls driving of peripheral circuits such as the row scanner 131, the horizontal selector 133, and the column scanner 134 based on the various timing signals generated by the timing generator.

[0138] (Application Example 2)

[0139] The above-described imaging device 100 and the like can be applied to, for example, any type of electronic equipment including a digital camera or a video camera and the like, each having an imaging function such as a camera system and the like, and a mobile phone having an imaging function. Fig.11The schematic structure of an electronic device 200 (camera) as an example is shown. The electronic device 200 is, for example, a video camera capable of taking still images or moving images. The electronic device 200 includes an image pickup device 100, an optical system (optical lens) 210, a shutter device 211, a driving unit 213 for driving the image pickup device 100 and the shutter device 211, and a signal processing unit 212.

[0140] The optical system 210 guides image light (incident light) from a subject to the pixel section 1a of the image pickup device 100. The optical system 210 may include a plurality of optical lenses. The shutter device 211 controls a period of irradiating light to the image pickup device 100 and shielding the image pickup device 100 from light. The driving section 213 controls a transmission operation of the image pickup device 100 and a shutter operation of the shutter device 211. The signal processing section 212 performs various signal processing on a signal output from the image pickup device 100. The image signal Dout after the signal processing is stored in a storage medium such as a memory, or is output to a monitor, etc.

[0141] (Application Example 3)

[0142] <Application examples of in vivo information acquisition systems>

[0143] In addition, the technology according to the present invention (the present technology) can be applied to various products. For example, the technology according to the present invention can be applied to an in vivo information acquisition system.

[0144] Fig.12 : is a block diagram showing an example of a schematic configuration of a patient in vivo information acquisition system using a capsule endoscope to which the technology according to an embodiment of the present invention (the present technology) can be applied.

[0145] The in vivo information acquisition system 10001 includes a capsule endoscope 10100 and an external control device 10200 .

[0146] During the examination, the patient swallows the capsule endoscope 10100. The capsule endoscope 10100 has an imaging function and a wireless communication function, and for a period of time before being naturally expelled by the patient, the capsule endoscope 10100 moves inside an organ such as the stomach and intestines by peristaltic motion, and sequentially captures internal images of the organ (hereinafter referred to as in-vivo images) at predetermined intervals. Then, the capsule endoscope 10100 sequentially transmits the information of the in-vivo images to the external control device 10200 outside the body by wireless transmission.

[0147] The external control device 10200 integrally controls the operation of the in-vivo information acquisition system 10001. In addition, the external control device 10200 also receives in-vivo image information 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 in-vivo image information.

[0148] In the in-vivo information acquisition system 10001, in-vivo images of the patient's internal body conditions can be acquired at any time in this manner during a period from swallowing the capsule endoscope 10100 until it is excreted.

[0149] Next, the configuration and function of the capsule endoscope 10100 and the external control device 10200 will be described in more detail.

[0150] The capsule endoscope 10100 includes a capsule-shaped shell 10101, and the shell 10101 accommodates a light source unit 10111, a camera unit 10112, an image processing unit 10113, a wireless communication unit 10114, a feeding unit 10115, a power supply unit 10116 and a control unit 10117.

[0151] The light source unit 10111 includes a light source such as a light emitting diode (LED), and irradiates light onto the imaging field of the imaging unit 10112 .

[0152] The imaging unit 10112 includes an imaging element and an optical system including a plurality of lenses arranged at the front stage of the imaging element. Reflected light (hereinafter referred to as observation light) of light irradiated on body tissue as an observation target is converged by the optical system and introduced into the imaging element. In the imaging unit 10112, the incident observation light is photoelectrically converted by the imaging element, thereby generating an image signal corresponding to the observation light. The image signal generated by the imaging unit 10112 is provided to the image processing unit 10113.

[0153] The image processing unit 10113 includes a processor such as a central processing unit (CPU) or a graphics processing unit (GPU), and performs various signal processing on the image signal generated by the camera unit 10112. Therefore, the image processing unit 10113 provides the image signal that has been subjected to the signal processing to the wireless communication unit 10114 as RAW data.

[0154] The wireless communication unit 10114 performs predetermined processing such as modulation processing on the image signal that has been signal-processed by the image processing unit 10113, and transmits the resulting image signal to the external control device 10200 through the antenna 10114A. In addition, the wireless communication unit 10114 also receives a control signal related to the drive control of the capsule endoscope 10100 from the external control device 10200 through the antenna 10114A. The wireless communication unit 10114 provides the control signal received from the external control device 10200 to the control unit 10117.

[0155] The feed unit 10115 includes an antenna coil for power reception, a power regeneration circuit for regenerating power according to a current generated in the antenna coil, a booster circuit, etc. The feed unit 10115 generates power using a non-contact charging principle.

[0156] The power supply unit 10116 includes a secondary battery, and stores the power generated by the feed unit 10115. Fig.12 In order to avoid complicated illustration, arrows indicating the power supply destination of the power supply unit 10116 are omitted. However, the power stored in the power supply unit 10116 is supplied to the light source unit 10111, the camera unit 10112, the image processing unit 10113, the wireless communication unit 10114 and the control unit 10117, and can be used to drive these components.

[0157] The control unit 10117 includes 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 feeding unit 10115 according to a control signal transmitted from the external control device 10200 .

[0158] The external control device 10200 includes 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 and incorporated. The external control device 10200 transmits a control signal to the control unit 10117 of the capsule endoscope 10100 through the antenna 10200A to control the operation of the capsule endoscope 10100. In the capsule endoscope 10100, for example, the condition under which the light source unit 10111 emits light to the observation target can be changed according to the control signal from the external control device 10200. In addition, the imaging condition (for example, the frame rate or exposure value of the imaging unit 10112) can also be changed according to the control signal from the external control device 10200. In addition, the content of the processing of the image processing unit 10113 and the condition for transmitting the image signal from the wireless communication unit 10114 (for example, the transmission interval or the number of images to be transmitted) can also be changed according to the control signal from the external control device 10200.

[0159] In addition, the external control device 10200 also performs various image processing on the image signal transmitted from the capsule endoscope 10100 to generate image data for displaying the captured in-vivo image on the display device. As image processing, various signal processing such as development processing (demosaic processing), image quality improvement processing (bandwidth enhancement processing, super-resolution processing, noise reduction (NR: Noise reduction) processing and / or image stabilization processing, etc.) and / or magnification processing (electronic zoom processing) can be performed. The external control device 10200 controls the driving of the display device so that the display device displays the captured in-vivo image based on the generated image data. Alternatively, the external control device 10200 may also control a recording device (not shown) to record the generated image data, or control a printing device (not shown) to output the generated image data by printing.

[0160] An example of an in-vivo information acquisition system to which the technology according to the present invention can be applied has been described above. The technology according to the present invention can be applied to, for example, the imaging unit 10112 among the above-mentioned components. This makes it possible to improve the detection accuracy.

[0161] (Application Example 4)

[0162] <Application examples of endoscopic surgery systems>

[0163] The technology according to the present invention (the present technology) can be applied to various products. For example, the technology according to the present invention can be applied to an endoscopic surgery system.

[0164] Fig.13 : is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present invention (the present technology) can be applied.

[0165] exist Fig.13 , a surgeon (physician) 11131 is shown performing surgery on a patient 11132 on a bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a support arm device 11120 for supporting the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are installed.

[0166] The endoscope 11100 includes: a barrel 11101 having a region of a predetermined length from a distal end to be inserted into a body cavity of a patient 11132; and a camera 11102 connected to the proximal end of the barrel 11101. In the example shown in the figure, the endoscope 11100 is shown as a rigid endoscope including a rigid barrel 11101. However, the endoscope 11100 may additionally include a flexible endoscope including a flexible barrel 11101.

[0167] The lens barrel 11101 has an opening at its distal end, in which an objective lens is installed. The light source device 11203 is connected to the endoscope 11100, so that the light generated by the light source device 11203 is introduced into the distal end of the lens barrel 11101 through the light guide extending inside the lens barrel 11101, and the light is irradiated toward the observation target in the body cavity of the patient 11132 through the objective lens. It should be noted that the endoscope 11100 may be a forward-looking endoscope, or may be an oblique-looking endoscope or a side-looking endoscope.

[0168] The optical system and the imaging element are arranged inside the camera head 11102 so that the reflected light (observation light) from the observation target is focused on the imaging element through the optical system. The observation light is photoelectrically converted by the imaging element to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. The image signal is transmitted to the CCU 11201 as RAW data.

[0169] The CCU 11201 includes a central processing unit (CPU) or a graphics processing unit (GPU) or the like, and integrally controls the operations of the endoscope 11100 and the display device 11202. In addition, the CCU 11201 receives an image signal from the camera 11102, and performs various image processing such as development processing (demosaic processing) on ​​the image signal to display an image based on the image signal.

[0170] Under the control of the CCU 11201 , the display device 11202 displays thereon an image based on an image signal that has been image-processed by the CCU 11201 .

[0171] The light source device 11203 includes a light source such as a light emitting diode (LED), and supplies irradiation light to the endoscope 11100 when imaging the surgical field.

[0172] The input device 11204 is an input interface of the endoscopic surgery system 11000. The user can input various information or instructions to the endoscopic surgery system 11000 through the input device 11204. For example, the user can input instructions to change the imaging conditions of the endoscope 11100 (such as the type of irradiation light, magnification or focal length).

[0173] The treatment tool control device 11205 controls the driving of the energy device 11112 for tissue cauterization, tissue cutting or blood vessel sealing, etc. The pneumoperitoneum device 11206 feeds gas into the body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to expand the body cavity so as to ensure the field of view of the endoscope 11100 and the working space of the surgeon. The recorder 11207 is a device capable of recording various information related to the operation. The printer 11208 is a device capable of printing various information related to the operation in various forms such as text, images or graphics.

[0174] It should be noted that the light source device 11203 that supplies irradiation light to the endoscope 11100 when imaging the surgical area may include a white light source, which includes, for example, an LED, a laser light source, or a combination of the two. In the case where the white light source includes a combination of red, green, and blue (RGB) laser light sources, the light source device 11203 can adjust the white balance of the captured image because the output intensity and output timing can be controlled with high precision for various colors (various wavelengths). In addition, in this case, if the laser beams from the respective RGB laser light sources are irradiated on the observation target in a time-division manner and the driving of the imaging element of the camera 11102 is controlled in a manner synchronized with the irradiation timing, images corresponding to the R, G, and B colors, respectively, can also be captured in a time-division manner. According to this method, a color image can be obtained even if a color filter is not provided for the imaging element.

[0175] In addition, the light source device 11203 can be controlled so that the intensity of the light to be output is changed for each predetermined time. By controlling the drive of the imaging element of the camera 11102 in synchronization with the timing of the change in light intensity so as to acquire images in a time-division manner and synthesize the images, a high dynamic range image without underexposed shadows and overexposed highlights can be created.

[0176] In addition, the light source device 11203 may be configured to supply light of a predetermined wavelength band prepared for special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissue to emit narrow-band light compared to the irradiation light (i.e., white light) during ordinary observation, it is possible to perform narrow-band observation (narrow-band imaging) of a predetermined tissue such as blood vessels in the surface portion of a mucosa with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image based on fluorescence generated by irradiation with excitation light. In fluorescence observation, observation of fluorescence from body tissue (autofluorescence observation) may be performed by irradiating excitation light on body tissue, or a fluorescence image may be obtained by locally injecting an agent such as indocyanine green (ICG) into body tissue and irradiating excitation light corresponding to the fluorescence wavelength of the agent onto the body tissue. The light source device 11203 may be configured to supply such narrow-band light and / or excitation light suitable for special light observation as described above.

[0177] Fig.14 It shows Fig.13 A block diagram of an example of the functional configuration of the camera 11102 and the CCU 11201 shown in FIG.

[0178] The camera 11102 includes a lens unit 11401, an imaging unit 11402, a driving unit 11403, a communication unit 11404, and a camera control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera 11102 and the CCU 11201 are connected via a transmission cable 11400 to communicate with each other.

[0179] The lens unit 11401 is an optical system, which is provided at a connection position with the lens barrel 11101. Observation light acquired from the distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focus lens.

[0180] The number of imaging elements included in the imaging unit 11402 can be one (so-called single-board type) or multiple (so-called multi-board type). In the case where the imaging unit 11402 is constructed as a multi-board type imaging unit, for example, the imaging element generates image signals corresponding to the corresponding R, G and B, and the image signals can be synthesized to obtain a color image. The imaging unit 11402 can also be configured to have a pair of imaging elements to respectively obtain an image signal for the right eye and an image signal for the left eye prepared for three-dimensional (3D) display. If a 3D display is performed, the surgeon 11131 can more accurately understand the depth of living tissue in the surgical area. It should be noted that in the case where the imaging unit 11402 is constructed as a stereoscopic imaging unit, a plurality of systems of lens units 11401 are arranged in a manner corresponding to the respective imaging elements.

[0181] In addition, the imaging unit 11402 does not have to be arranged on the camera head 11102. For example, the imaging unit 11402 can be arranged inside the lens barrel 11101 immediately behind the objective lens.

[0182] The driving unit 11403 includes an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera control unit 11405. Therefore, the magnification and focus of the captured image of the camera unit 11402 can be appropriately adjusted.

[0183] The communication unit 11404 includes a communication device to transmit and receive various information to and from the CCU 11201. The communication unit 11404 transmits an image signal obtained from the imaging unit 11402 to the CCU 11201 as RAW data via the transmission cable 11400.

[0184] In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and supplies the control signal to the camera control unit 11405. The control signal includes information related to imaging conditions, such as information specifying a frame rate for capturing an image, information specifying an exposure value when capturing an image, and / or information specifying a magnification and a focus for capturing an image.

[0185] It should be noted that imaging conditions such as frame rate, exposure value, magnification, or focus may be specified by the user, or may be automatically set based on the acquired image signal by the control unit 11413 of the CCU 11201. In the latter case, an automatic exposure (AE: Auto Exposure) function, an automatic focus (AF: Auto Focus) function, and an automatic white balance (AWB: Auto White Balance) function may be incorporated into the endoscope 11100.

[0186] The camera control unit 11405 controls the driving of the camera 11102 based on the control signal from the CCU 11201 received through the communication unit 11404 .

[0187] The communication unit 11411 includes a communication device to transmit various information to the camera 11102 and receive various information from the camera 11102. The communication unit 11411 receives an image signal transmitted from the camera 11102 through the transmission cable 11400.

[0188] Furthermore, the communication unit 11411 transmits a control signal for controlling the driving of the camera 11102 to the camera 11102. The image signal and the control signal can be transmitted through electrical communication, optical communication, or the like.

[0189] The image processing unit 11412 performs various image processing on the image signal in the form of RAW data transmitted from the camera 11102 .

[0190] The control unit 11413 performs various controls related to the imaging of the operation area, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the operation area, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102 .

[0191] In addition, the control unit 11413 controls the display device 11202 based on the image signal that has been image-processed by the image processing unit 11412 to display a captured image that photographs the surgical area, etc. Thus, the control unit 11413 can use various image recognition technologies to recognize various objects in the captured image. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body areas, bleeding, and mist when using the energy device 11112, etc. by detecting the shape and color of the edge of the object included in the captured image. When the display device 11202 is controlled to display the captured image, the control unit 11413 can use the recognition result to display various surgical support information in an overlapping manner with the image of the surgical area. In the case where the surgical support information is displayed in an overlapping manner and presented to the surgeon 11131, the burden of the surgeon 11131 can be reduced, and the surgeon 11131 can perform the operation with certainty.

[0192] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 to each other is an electrical signal cable prepared for electrical signal communication, an optical fiber prepared for optical communication, or a composite cable prepared for both electrical communication and optical communication.

[0193] Here, although in the example shown in the figure, communication is performed by wired communication using the transmission cable 11400, communication between the camera 11102 and the CCU 11201 may be performed by wireless communication.

[0194] An example of an endoscopic surgery system to which the technology according to the present invention can be applied has been described above. The technology according to the present invention can be applied to the imaging unit 11402 among the above components. Applying the technology according to the present invention to the imaging unit 11402 can improve detection accuracy.

[0195] It should be noted that although the endoscopic surgery system has been described herein as an example, the technology according to the present invention can also be applied to, for example, a microsurgery system.

[0196] (Application Example 5)

[0197] <Application examples for mobile objects>

[0198] The technology according to the present invention can be applied to various products. For example, the technology according to the present invention can be implemented as a device installed on any type of mobile body, such as a car, an electric car, a hybrid electric car, a motorcycle, a bicycle, a personal mobile device, an airplane, a drone, a ship, a robot, a construction machine, or an agricultural machine (tractor).

[0199] Fig.15 : is a block diagram showing an example of a schematic configuration of a vehicle control system as an example of a moving body control system to which the technology according to the embodiment of the present invention can be applied.

[0200] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig.15 In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an inside information detection unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are illustrated as a functional configuration of the integrated control unit 12050.

[0201] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 acts as a control device for the following devices: a drive force generating device for generating a vehicle drive force, such as an internal combustion engine or a drive motor, etc.; a drive force transmitting 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 vehicle braking force, etc.

[0202] The body system control unit 12020 controls the operation of various devices installed on the vehicle body according to various programs. For example, the body system control unit 12020 acts as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a taillight, a brake light, a turn signal light, or a fog light. In this case, a radio wave transmitted from a mobile device that replaces the key or a signal of various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls the door lock device, the power window device, or the light, etc. of the vehicle.

[0203] The vehicle exterior information detection unit 12030 detects information on the exterior of the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the camera unit 12031. The vehicle exterior information detection unit 12030 causes the camera unit 12031 to capture an image of the exterior of the vehicle and receive the captured image. Based on the received image, the vehicle exterior information detection unit 12030 may perform detection processing of objects such as people, vehicles, obstacles, signs, or text on the road surface, or may perform detection processing of the distance to the above-mentioned objects.

[0204] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or can output the electrical signal as information about distance measurement. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0205] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. For example, the in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 for detecting the state of the driver. The driver state detection unit 12041 includes, for example, a camera for photographing the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue level or the driver's concentration level, or can determine whether the driver is dozing off.

[0206] Based on the information about the exterior or interior of the vehicle obtained by the exterior information detection unit 12030 or the interior information detection unit 12040, the microcomputer 12051 can calculate the control target value of the driving force generating device, the steering mechanism or the braking device, and output the control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of the Advanced Driver Assistance System (ADAS), which includes collision avoidance or impact mitigation of the vehicle, following driving based on the vehicle-to-vehicle distance, vehicle speed maintenance driving, vehicle collision warning or vehicle lane departure warning, etc.

[0207] In addition, based on the information about the outside or inside of the vehicle obtained by the outside information detection unit 12030 or the inside information detection unit 12040, the microcomputer 12051 can perform collaborative control aimed at automatic driving by controlling the driving force generating device, steering mechanism or braking device, etc. Automatic driving enables the vehicle to drive autonomously without relying on the driver's operation.

[0208] Furthermore, based on the information about the outside of the vehicle obtained by the vehicle exterior information detection unit 12030, the microcomputer 12051 can output a control command to the body system control unit 12020. For example, by controlling the headlights to change from high beam to low beam, for example, according to the position of a preceding vehicle or an oncoming vehicle detected by the vehicle exterior information detection unit 12030, the microcomputer 12051 can perform cooperative control aimed at preventing glare.

[0209] The sound / image output unit 12052 transmits an output signal of at least one of sound and image to an output device, which can notify the occupants of the vehicle or the outside of the vehicle of the information in a visual or auditory manner. Fig.15 In the example of FIG. 1 , an audio speaker 12061, a display unit 12062, and a dashboard 12063 are illustrated as output devices. For example, the display unit 12062 may include at least one of an in-vehicle display and a head-up display.

[0210] Fig.16 12031 is a diagram showing an example of the installation position of the imaging unit 12031.

[0211] exist Fig.16 In the figure, the camera unit 12031 includes camera units 12101, 12102, 12103, 12104 and 12105.

[0212] The camera units 12101, 12102, 12103, 12104 and 12105 are arranged, for example, at positions on the front nose, side mirrors, rear bumper and rear door of the vehicle 12100 and at an upper position of the windshield in the vehicle. The camera unit 12101 arranged on the front nose and the camera unit 12105 arranged on the upper part of the windshield in the vehicle mainly obtain images in front of the vehicle 12100. The camera units 12102 and 12103 arranged on the side mirrors mainly obtain images on the sides of the vehicle 12100. The camera unit 12104 arranged on the rear bumper or rear door mainly obtains images behind the vehicle 12100. The camera unit 12105 arranged on the upper part of the windshield in the vehicle is mainly used to detect the preceding vehicle, pedestrians, obstacles, traffic lights, traffic signs or lanes, etc.

[0213] By the way, Fig.16 An example of the photographing range of the camera units 12101 to 12104 is shown. The photographing range 12111 indicates the photographing range of the camera unit 12101 provided on the front nose. The photographing ranges 12112 and 12113 respectively indicate the photographing ranges of the camera units 12102 and 12103 provided on the side mirrors. The photographing range 12114 indicates the photographing range of the camera unit 12104 provided on the rear bumper or the rear door. For example, by superimposing the image data photographed by the camera units 12101 to 12104, a bird's-eye view image of the vehicle 12100 observed from above is obtained.

[0214] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0215] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can determine the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the time change of the distance (relative speed to the vehicle 12100), thereby being able to particularly extract the nearest three-dimensional object as the preceding vehicle: the three-dimensional object is present on the driving path of the vehicle 12100 and the three-dimensional object is traveling at a predetermined speed (e.g., equal to or greater than 0 km / h) in the substantially same direction as the vehicle 12100. In addition, the microcomputer 12051 can pre-set the inter-vehicle distance to be maintained in front of the preceding vehicle, and can perform automatic braking control (including follow-up stop control) or automatic acceleration control (including follow-up start control), etc. Therefore, cooperative control such as automatic driving, which is intended to make the vehicle travel autonomously without relying on the operation of the driver, can be performed.

[0216] For example, based on the distance information obtained from the camera units 12101 to 12104, the microcomputer 12051 can classify the three-dimensional object data on the three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard-sized vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects, extract the classified three-dimensional object data, and use the extracted three-dimensional object data to automatically avoid obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that the driver of the vehicle 12100 can visually identify and obstacles that the driver of the vehicle 12100 is difficult to visually identify. Then, the microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle. In the case where the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or evasive steering via the drive system control unit 12010. Thus, the microcomputer 12051 can assist driving to avoid collision.

[0217] At least one of the camera units 12101 to 12104 may be an infrared camera for detecting infrared rays. For example, the microcomputer 12051 is capable of identifying pedestrians by determining whether there are pedestrians in the camera images of the camera units 12101 to 12104. For example, such pedestrian identification is performed by the following process: a process of extracting feature points in the camera images of the camera units 12101 to 12104 as infrared cameras; and a process of determining whether it is a pedestrian by performing pattern matching processing on a series of feature points representing the contour of the object. When the microcomputer 12051 determines that there are pedestrians in the camera images of the camera units 12101 to 12104 and thus identifies the pedestrians, the sound / image output unit 12052 controls the display unit 12062 so that a rectangular contour line for emphasis is displayed in a manner superimposed on the identified pedestrian. The sound / image output unit 12052 may also control the display unit 12062 so that an icon representing a pedestrian or the like is displayed at a desired position.

[0218] <3. Example>

[0219] Next, an embodiment of the present invention is described in detail. In each of Experimental Examples 1 to 4, a photoelectric conversion element in which PbS is used as a core included in semiconductor nanoparticles is manufactured, and its electrical characteristics are evaluated. In Experimental Examples 5 to 7, CuInSe2 (Experimental Example 5), CuInSe2 / ZnS (Experimental Example 6) and CH3NH3SnPbI3 (Experimental Example 7) are used instead of PbS as the core included in the semiconductor nanoparticles, thereby manufacturing each photoelectric conversion element, and evaluating its electrical characteristics. It should be noted that in a structure in which the insulating layer 12 of the above-mentioned photoelectric conversion element 10 is omitted, the electrical characteristics of the photoelectric conversion element according to this embodiment are evaluated. The valence band of the material used in the experiment is measured by ultraviolet spectroscopy, and its conduction band is obtained by using the optical band gap and valence band provided by the absorption spectrum characteristics of the material.

[0220] The samples for evaluating electrical characteristics were prepared by the following method, and their dark current characteristics and external quantum efficiency were evaluated. Note that the external quantum efficiency was calculated by averaging 1.0 × 10 -5 W cm -2 The intensity is measured by irradiating light with a wavelength of 940nm.

[0221] (Experimental Example 1)

[0222] First, as Experimental Example 1, a glass substrate having a film thickness of 100 nm was provided with an Al electrode, and a semiconductor layer including IGZO and having a thickness of 100 nm was formed on the Al electrode on the glass substrate by sputtering. Subsequently, the substrate was heat treated at 350°C for 1 hour in the atmosphere to exhaust the IGZO. Next, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2500 rpm. The ink was obtained by dispersing PbS nanoparticles in an octane solvent at a concentration of 50 mg / ml. Oleic acid coordinated with each PbS nanoparticle on the surface of the nanoparticles. Afterwards, a solution obtained by dispersing MPA (mercaptopropionic acid) in a methanol solvent at a concentration of 1% by volume was added dropwise, and a ligand exchange from oleic acid to MPA was performed. After the ligand exchange, methanol was added dropwise to wash away excess organic substances such as oleic acid. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Subsequently, heat treatment was performed at 120°C for 5 minutes in an inert gas environment to remove the residual solvent. Next, a MoO3 film with a thickness of 10 nm was formed on the photoelectric conversion layer by vacuum deposition, and then a 50 nm ITO film was stacked by sputtering to form an upper electrode. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1 mm×1 mm was manufactured.

[0223] (Experimental Example 2)

[0224] After forming the semiconductor layer as in Experimental Example 1, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2500 rpm. The ink was obtained by dispersing PbS nanoparticles in an octane solvent at a concentration of 50 mg / ml. Oleic acid coordinated with each PbS nanoparticle on the surface of the nanoparticles. Thereafter, a solution obtained by dispersing BDT (1,4-benzenedithiol) in a methanol solvent at a concentration of 0.02 mol / L was added dropwise, and a ligand exchange from oleic acid to BDT was performed. After the ligand exchange, methanol was added dropwise to wash away excess organic substances such as oleic acid. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Thereafter, a MoO3 film and an ITO film were stacked in sequence as in Experimental Example 1. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1 mm×1 mm was produced.

[0225] (Experimental Example 3)

[0226] After forming the semiconductor layer as in Experimental Example 1, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2500 rpm. The ink was obtained by dispersing PbS nanoparticles in an octane solvent at a concentration of 50 mg / ml. Oleic acid coordinated with each PbS nanoparticle on the surface of the nanoparticles. Thereafter, a solution obtained by dispersing TBAI (tetrabutylammonium iodide) in a methanol solvent at a concentration of 0.03 mol / L was added dropwise, and ligand exchange from oleic acid to iodine atoms was performed. After the ligand exchange, methanol was added dropwise to wash away excess organic substances such as oleic acid. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Thereafter, a MoO3 film and an ITO film were stacked in sequence as in Experimental Example 1. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1 mm×1 mm was produced.

[0227] (Experimental Example 4)

[0228] After forming the semiconductor layer as in Experimental Example 1, the ink is applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2500rpm. The ink is obtained by dispersing PbS nanoparticles in an octane solvent at a concentration of 50mg / ml. Oleic acid coordinates with each PbS nanoparticle on the surface of the nanoparticle. After that, a solution obtained by dispersing TBABr (tetrabutylammonium bromide) in a methanol solvent at a concentration of 0.03mol / L is added dropwise, and a ligand exchange from oleic acid to bromine atoms is performed. After the ligand exchange, methanol is added dropwise to wash away excess organic substances such as oleic acid. This operation is repeated ten times to form a photoelectric conversion layer having a thickness of about 300nm. After that, as in Experimental Example 1, a MoO3 film and an ITO film are stacked in sequence. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1mm×1mm is produced.

[0229] Fig.17A The results of EQE in Experimental Examples 1 to 4 are shown. Fig. 17B The dark current results in Experimental Examples 1 to 4 are shown in the figure. The two figures respectively show the relative values ​​using MPA as a ligand as an indicator. The EQE results show that when E CS ≥E CCQD In the case of E CS and E CCQD It has been shown that when E CS <E CCQD When Br is used as a ligand, the EQE decreases relative to MPA. The dark current results show that the dark current increases with E CS -E VCQD The above results prove that it is preferred to satisfy E CS ≥E CCQD , and more preferably, E CS and E CCQD are substantially equal to each other to manufacture a photoelectric conversion element having excellent EQE and reduced occurrence of dark current.

[0230] (Experimental Example 5)

[0231] As in Experimental Example 1, a glass substrate having a film thickness of 100 nm was provided with an Al electrode, and a semiconductor layer including IGZO and having a thickness of 100 nm was formed on the Al electrode on the glass substrate by sputtering. Subsequently, the substrate was heat treated at 350°C for 1 hour in the atmosphere to deplete the IGZO. Next, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2000 rpm. The ink was obtained by dispersing CuInSe2 nanoparticles in an octane solvent at a concentration of 40 mg / ml. Oleylamine coordinated with each CuInSe2 nanoparticle on the surface of the nanoparticles. Thereafter, a solution obtained by dispersing BDT (1,4-benzenedithiol) in an acetonitrile solvent at a concentration of 0.2% by volume was added dropwise, and a ligand exchange from oleylamine to BDT was performed. After the ligand exchange, acetonitrile was added dropwise to wash away excess organic substances such as oleylamine. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Subsequently, heat treatment was performed at 120°C for 5 minutes in an inert gas environment to remove the residual solvent. Next, a MoO3 film with a thickness of 10 nm was formed on the photoelectric conversion layer by vacuum deposition, and then a 50 nm ITO film was stacked by sputtering to form an upper electrode. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1 mm×1 mm was manufactured.

[0232] (Experimental Example 6)

[0233] After forming the semiconductor layer as in Experimental Example 1, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2000 rpm. The ink was obtained by dispersing CuInSe2 / ZnS nanoparticles in an octane solvent at a concentration of 40 mg / ml. Oleylamine coordinated with each CuInSe2 / ZnS nanoparticle on the surface of the nanoparticles. After that, a solution obtained by dispersing BDT (1,4-benzenedithiol) in an acetonitrile solvent at a concentration of 0.2 volume % was added dropwise, and a ligand exchange from oleylamine to BDT was performed. After the ligand exchange, acetonitrile was added dropwise to wash away excess organic substances such as oleylamine. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Subsequently, a heat treatment was performed at 120°C for 5 minutes in an inert gas environment to remove the residual solvent. Next, a MoO3 film with a thickness of 10 nm was formed on the photoelectric conversion layer by vacuum deposition, and then a 50 nm ITO film was stacked by sputtering to form an upper electrode. As described above, a photoelectric conversion element including a photoelectric conversion region of 1 mm×1 mm was manufactured.

[0234] (Experimental Example 7)

[0235] After forming the semiconductor layer as in Experimental Example 1, the ink was applied to the semiconductor layer as a photoelectric conversion layer by spin coating at a rotation speed of 2000 rpm. The ink was obtained by dispersing CH3NH3SnPbI3 nanoparticles in an octane solvent at a concentration of 40 mg / ml. Oleic acid and oleylamine coordinated with each CH3NH3SnPbI3 nanoparticle on the surface of the nanoparticles. The ratio of Sn to Pb was 1:1. Thereafter, a solution obtained by dispersing Pb(NO3)2 (lead nitrate) in methyl acetate at a concentration of 1 mg / ml was added dropwise, and oleic acid and oleylamine were removed. This operation was repeated ten times to form a photoelectric conversion layer having a thickness of about 300 nm. Subsequently, a solution obtained by dispersing CsI (cesium iodide) in ethyl acetate at a concentration of 1 mg / ml was added dropwise, and the defects on the surface of the nanoparticles were terminally treated. After methyl acetate was added dropwise to remove the excess material, heat treatment was performed at 120°C for 5 minutes in an inert gas environment to remove the residual solvent. Next, a MoO3 film with a thickness of 10 nm was formed on the photoelectric conversion layer by vacuum deposition, and then a 50 nm ITO film was stacked by sputtering to form an upper electrode. As described above, a photoelectric conversion element including a photoelectric conversion area of ​​1 mm×1 mm was manufactured.

[0236] Fig.18A The results of EQE in Experimental Examples 5 to 7 are shown. Fig.18B The results of dark current in Experimental Examples 5 to 7 are shown in the graphs. Fig.18A and Fig.18BThe results are respectively shown as relative values ​​of the results of Experimental Example 1 in which the MPA ligand was used for PbS nanoparticles. Fig.18A and Fig.18B It is respectively illustrated that the semiconductor nanoparticles included in the photoelectric conversion layer are not limited to PbS, but even when CuInSe2, CuInSe2 / ZnS, or CH3NH3SnPbI3, etc. are used, EQE characteristics and dark current characteristics substantially the same as those of PbS can be obtained.

[0237] The description has been given above with reference to the embodiment, the application example, and the embodiment, but the content of the present invention is not limited to the above-mentioned embodiment and the like, and various modifications are possible. For example, in the above-mentioned embodiment, an example has been described in which the photoelectric conversion element 10 is used alone in the imaging element 1. The photoelectric conversion element 10 performs photoelectric conversion on light having a wavelength in the near-infrared region. However, for example, another photoelectric conversion element that performs photoelectric conversion on light having a wavelength in a region other than the near-infrared region such as visible light may be combined and used. Examples of other photoelectric conversion elements include: a so-called inorganic photoelectric conversion element that is buried and formed in the semiconductor substrate 30; and a so-called organic photoelectric conversion element that has a photoelectric conversion layer formed by using an organic semiconductor material.

[0238] In addition, in the above-mentioned embodiments and the like, the configuration of the back-illuminated imaging element 1 is described as an example. However, the embodiments and the like can also be applied to a front-illuminated imaging element. In addition, in the case where another photoelectric conversion element is combined and used as described above, the imaging element 1 can be configured as a so-called vertical spectrum type imaging element, or can be an imaging element including a semiconductor substrate in which photoelectric conversion elements that perform photoelectric conversion on light in another wavelength range are two-dimensionally arranged (for example, Bayer arrangement). In addition, for example, a substrate provided with another functional device such as a storage element can be stacked on the multilayer wiring side.

[0239] Furthermore, each of the photoelectric conversion element 10 , the image pickup element 1 , and the image pickup device 100 according to the present invention does not necessarily include all of the corresponding components described in the above-mentioned embodiments and the like, but instead may include other layers.

[0240] Furthermore, in addition to the camera device, for example, the technology according to the present invention can also be applied to a photovoltaic cell.

[0241] It should be noted that the effects described in this article are merely examples and are not restrictive. In addition, there may be other effects.

[0242] It should be noted that the present invention may have the following configuration. According to the present technology having the following configuration, a photoelectric conversion layer having a conduction band energy level equal to or higher than the conduction band energy level of the semiconductor layer is provided on the semiconductor layer, thereby improving the efficiency of transferring charges generated in the photoelectric conversion layer to the semiconductor layer. This makes it possible to suppress the occurrence of dark current at the interface of the photoelectric conversion layer without reducing the external quantum efficiency (EQE: External Quantum Efficiency).

[0243] (1) A photoelectric conversion element comprising:

[0244] a first electrode, the first electrode comprising a plurality of electrodes independent of each other;

[0245] a second electrode, the second electrode being arranged opposite to the first electrode;

[0246] a photoelectric conversion layer, the photoelectric conversion layer including semiconductor nanoparticles, and the photoelectric conversion layer is disposed between the first electrode and the second electrode; and

[0247] a semiconductor layer, the semiconductor layer comprising an oxide semiconductor material, and the semiconductor layer is disposed between the first electrode and the photoelectric conversion layer, wherein

[0248] An energy level of a conduction band of the photoelectric conversion layer is equal to or higher than an energy level of a conduction band of the semiconductor layer.

[0249] (2) The photoelectric conversion element according to (1), wherein the energy level of the conduction band of the photoelectric conversion layer and the energy level of the conduction band of the semiconductor layer have a difference of 0 eV or more and 0.2 eV or less.

[0250] (3) The photoelectric conversion element according to (1) or (2), wherein the energy level of the conduction band of the photoelectric conversion layer is equal to the energy level of the conduction band of the semiconductor layer.

[0251] (4) The photoelectric conversion element according to any one of (1) to (3), wherein the semiconductor nanoparticles have a band gap of 0.6 eV or more and 1.3 eV or less.

[0252] (5) The photoelectric conversion element according to any one of (1) to (4), wherein

[0253] The semiconductor nanoparticle includes a core and a ligand, the ligand is bound to the surface of the core, and

[0254] The core is constituted as a semiconductor particle including any one of PbS, PbSe, PbTe, CuInSe2, ZnCuInSe, CuInS2, ZnCuInS, CuInTe2, ZnCuInTe, AgInSe2, ZnAgInSe, AgInTe2, ZnAgInTe, ZnCuSnSSe, HgTe, InAs, InSb, Ag2S, Ag2Se, Ag2Te, CH3NH3SnI3, CH3NH3SnPbI3, CsSnI3 and CsSnPbI3.

[0255] (6) The photoelectric conversion element according to any one of (1) to (5), wherein

[0256] The semiconductor nanoparticle includes a core and a ligand, the ligand is bound to the surface of the core, and

[0257] The ligand includes any one of a chlorine atom, a bromine atom, an iodine atom, and a sulfur atom.

[0258] (7) The photoelectric conversion element according to (5) or (6), wherein

[0259] The semiconductor nanoparticle further includes a shell disposed around the core, and

[0260] The shell is configured to include at least one of PbO, PbO2, Pb3O4, ZnS, ZnSe, ZnTe, GaS, and GaSe.

[0261] (8) The photoelectric conversion element according to any one of (1) to (7), wherein the semiconductor layer is configured to include at least one of IGZO, ZTO, Zn2SnO4, InGaZnSnO, GTO, Ga2O3:SnO2 and IGO.

[0262] (9) The photoelectric conversion element according to any one of (1) to (8), wherein the first electrode includes an electrode material having a work function smaller than a work function of the second electrode.

[0263] (10) The photoelectric conversion element according to any one of (1) to (9), wherein

[0264] The first electrode is formed by using any one of titanium (Ti), silver (Ag), aluminum (Al), magnesium (Mg), chromium (Cr), nickel (Ni), tungsten (W), and copper (Cu), and

[0265] The second electrode is formed by using indium tin oxide (ITO).

[0266] (11) The photoelectric conversion element according to any one of (1) to (10), comprising:

[0267] an insulating layer, the insulating layer being located between the first electrode and the semiconductor layer, wherein

[0268] The first electrode includes a charge readout electrode electrically connected to the photoelectric conversion layer via an opening provided to the insulating layer, and a charge accumulation electrode arranged to be opposed to the photoelectric conversion layer via the insulating layer.

[0269] (12) The photoelectric conversion element according to (11), wherein the first electrode includes a charge transfer electrode located between the charge readout electrode and the charge accumulation electrode.

[0270] (13) The photoelectric conversion element according to any one of (1) to (12), wherein corresponding voltages are applied to the plurality of electrodes included in the first electrode, respectively.

[0271] (14) The photoelectric conversion element according to any one of (1) to (13), further comprising:

[0272] Semiconductor substrate, wherein

[0273] The first electrode, the semiconductor layer, the photoelectric conversion layer, and the second electrode are provided in this order on the first surface side of the semiconductor substrate.

[0274] (15) The photoelectric conversion element according to (14), wherein the semiconductor substrate includes a drive circuit, and the plurality of electrodes included in the first electrode are respectively connected to the drive circuit.

[0275] (16) The photoelectric conversion element according to (14) or (15), wherein a multilayer wiring layer is formed on a second surface side of the semiconductor substrate opposite to the first surface.

[0276] (17) An imaging device comprising a plurality of pixels, each of the plurality of pixels being provided with one or more photoelectric conversion elements,

[0277] The one or more photoelectric conversion elements respectively include:

[0278] a first electrode, the first electrode comprising a plurality of electrodes independent of each other,

[0279] a second electrode, the second electrode being arranged opposite to the first electrode,

[0280] a photoelectric conversion layer, the photoelectric conversion layer including semiconductor nanoparticles, and the photoelectric conversion layer is provided between the first electrode and the second electrode, and

[0281] a semiconductor layer, the semiconductor layer comprising an oxide semiconductor material, and the semiconductor layer is disposed between the first electrode and the photoelectric conversion layer, wherein

[0282] An energy level of a conduction band of the photoelectric conversion layer is equal to or higher than an energy level of a conduction band of the semiconductor layer.

[0283] This application claims priority based on Japanese Patent Application No. 2018-015390 filed in the Japan Patent Office on January 31, 2018, and Japanese Patent Application No. 2018-198410 filed in the Japan Patent Office on October 22, 2018, and the entire contents of these two patent applications are incorporated into this application by reference.

[0284] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. A photoelectric conversion element, comprising: a first electrode, the first electrode comprising a plurality of electrodes independent of each other; a second electrode, the second electrode being arranged opposite to the first electrode; a photoelectric conversion layer, the photoelectric conversion layer comprising semiconductor nanoparticles, and the photoelectric conversion layer is disposed between the first electrode and the second electrode; as well as a semiconductor layer, the semiconductor layer comprising an oxide semiconductor material, and the semiconductor layer is disposed between the first electrode and the photoelectric conversion layer, wherein The energy level of the conduction band of the photoelectric conversion layer is equal to or higher than the energy level of the conduction band of the semiconductor layer, The semiconductor layer is formed using a material having higher charge mobility than that of the photoelectric conversion layer.

2. The photoelectric conversion element according to claim 1, wherein The energy level of the conduction band of the photoelectric conversion layer and the energy level of the conduction band of the semiconductor layer have a difference of 0 eV or more and 0.2 eV or less.

3. The photoelectric conversion element according to claim 1, wherein The energy level of the conduction band of the photoelectric conversion layer is equal to the energy level of the conduction band of the semiconductor layer.

4. The photoelectric conversion element according to claim 1, wherein The semiconductor nanoparticles have a band gap of 0.6 eV or more and 1.3 eV or less.

5. The photoelectric conversion element according to claim 1, wherein The semiconductor nanoparticle includes a core and a ligand, the ligand is bound to the surface of the core, and The core is constituted as a semiconductor particle including any one of PbS, PbSe, PbTe, CuInSe2, ZnCuInSe, CuInS2, ZnCuInS, CuInTe2, ZnCuInTe, AgInSe2, ZnAgInSe, AgInTe2, ZnAgInTe, ZnCuSnSSe, HgTe, InAs, InSb, Ag2S, Ag2Se, Ag2Te, CH3NH3SnI3, CH3NH3SnPbI3, CsSnI3 and CsSnPbI3.

6. The photoelectric conversion element according to claim 1, wherein The semiconductor nanoparticle includes a core and a ligand, the ligand is bound to the surface of the core, and The ligand includes any one of a chlorine atom, a bromine atom, an iodine atom, and a sulfur atom.

7. The photoelectric conversion element according to claim 5, wherein The semiconductor nanoparticle further includes a shell disposed around the core, and The shell is configured to include at least one of PbO, PbO2, Pb3O4, ZnS, ZnSe, ZnTe, GaS, and GaSe.

8. The photoelectric conversion element according to claim 1, wherein The semiconductor layer is configured to include at least one of IGZO, ZTO, Zn2SnO4, InGaZnSnO, GTO, Ga2O3:SnO2, and IGO.

9. The photoelectric conversion element according to claim 1, wherein The first electrode includes an electrode material having a work function smaller than a work function of the second electrode.

10. The photoelectric conversion element according to claim 1, wherein The first electrode is formed by using any one of titanium, silver, aluminum, magnesium, chromium, nickel, tungsten, and copper, and The second electrode is formed by using indium tin oxide.

11. The photoelectric conversion element according to claim 1, comprising: an insulating layer, the insulating layer being located between the first electrode and the semiconductor layer, wherein The first electrode includes a charge readout electrode electrically connected to the photoelectric conversion layer via an opening provided to the insulating layer, and a charge accumulation electrode arranged to be opposed to the photoelectric conversion layer via the insulating layer.

12. The photoelectric conversion element according to claim 11, wherein The first electrode includes a charge transfer electrode located between the charge readout electrode and the charge accumulation electrode.

13. The photoelectric conversion element according to claim 1, wherein The plurality of electrodes included in the first electrode are respectively applied with corresponding voltages.

14. The photoelectric conversion element according to any one of claims 1 to 13, further comprising: Semiconductor substrate, wherein The first electrode, the semiconductor layer, the photoelectric conversion layer, and the second electrode are provided in this order on the first surface side of the semiconductor substrate.

15. The photoelectric conversion element according to claim 14, wherein The semiconductor substrate includes a driving circuit, and the plurality of electrodes included in the first electrode are respectively connected to the driving circuit.

16. The photoelectric conversion element according to claim 14, wherein A multi-layer wiring layer is formed on a second surface side of the semiconductor substrate opposite to the first surface. 17 . An imaging device comprising a plurality of pixels, each of which is provided with one or more photoelectric conversion elements according to claim 1 .

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