Photoelectric conversion element and imaging device

Abstract

A photoelectric conversion element according to one embodiment of the present disclosure is provided with: a first electrode (11); a second electrode which is arranged so as to face the first electrode (11); a photoelectric conversion layer (13) which is arranged between the first electrode (11) and the second electrode, while containing a fullerene or a fullerene derivative; a first charge blocking layer (12A) which is arranged between the first electrode (11) and the photoelectric conversion layer (13), while containing an organic material that has a HOMO level which is deeper than the work function of the first electrode (11) by 1 eV or more and a LUMO level of 3.7 eV to 4.8 eV; and a second charge blocking layer (12B) which is arranged between the first charge blocking layer (12A) and the photoelectric conversion layer (13), while containing a fullerene or a fullerene derivative.

Description

Technical Field

[0001] The present disclosure relates to a photoelectric conversion device using an organic semiconductor and an imaging device including the same.

Background Art

[0002] For example, Patent Document 1 discloses a photoelectric conversion device provided with a hole blocking layer including a fullerene and / or a fullerene derivative and a transparent hole transport material having an ionization potential of 5.5 eV or more between a photoelectric conversion layer and an electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] By the way, in a photoelectric conversion device used in an imaging device, improvement of device characteristics such as reduction of dark current, improvement of external quantum efficiency, and improvement of optical responsiveness is required, for example.

[0005] The photoelectric conversion device according to an embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode and including a fullerene or a fullerene derivative, a first charge blocking layer provided between the first electrode and the photoelectric conversion layer and including an organic material having a HOMO level deeper than 1 eV with respect to the work function of the first electrode and a LUMO level of 3.7 eV or more and 4.8 eV or less, and a second charge blocking layer provided between the first charge blocking layer and the photoelectric conversion layer and including a fullerene or a fullerene derivative. The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges, and the second charge blocking layer includes a fullerene or fullerene derivative and a dye material. 。

[0006] A photoelectric conversion element in one embodiment of the present disclosure comprises a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode and containing a fullerene or fullerene derivative, a first charge blocking layer provided between the first electrode and the photoelectric conversion layer and containing an organic material having a HOMO level 1 eV or more deeper than the work function of the first electrode and a LUMO level 3.7 eV to 4.8 eV, and a second charge blocking layer provided between the first charge blocking layer and the photoelectric conversion layer and containing a fullerene or fullerene derivative.

[0007] An imaging device according to one embodiment of the present disclosure comprises a plurality of pixels, each of which is provided with an image sensor having one or more photoelectric conversion units, and the one or more photoelectric conversion units include the photoelectric conversion elements of the present disclosure described above.

[0008] In one embodiment of the photoelectric conversion element and one embodiment of the imaging device of the present disclosure, a first charge blocking layer containing an organic material having a HOMO level 1 eV or more deeper than the work function of the first electrode and a LUMO level between 3.7 eV and 4.8 eV, and a second charge blocking layer containing a fullerene or fullerene derivative are provided between the first electrode and the photoelectric conversion layer in this order from the first electrode side. This suppresses charge injection from the first electrode while reducing the electron barrier at the interface with the first electrode. It also suppresses the generation of dark current at the interface of the photoelectric conversion layer while reducing the occurrence of interface traps with the photoelectric conversion layer. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an example of the configuration of a photoelectric conversion element according to one embodiment of the present disclosure. [Figure 2] Figure 1 shows an example of the energy levels of the materials constituting each layer of the photoelectric conversion element. [Figure 3] Figure 1 is a schematic cross-sectional view showing an example of the configuration of an image sensor using a photoelectric conversion element. [Figure 4]Figure 3 is a schematic plan view illustrating an example of the pixel configuration of an imaging device having the image sensor shown. [Figure 5] Figure 3 shows the equivalent circuit diagram of the image sensor. [Figure 6] Figure 3 is a schematic diagram showing the arrangement of transistors that constitute the lower electrode and control unit of the image sensor. [Figure 7] Figure 3 is a cross-sectional view illustrating the manufacturing method of the image sensor shown. [Figure 8] This is a cross-sectional view showing the process that follows Figure 7. [Figure 9] This is a cross-sectional view showing the process following Figure 8. [Figure 10] This is a cross-sectional view showing the process that follows Figure 9. [Figure 11] This is a cross-sectional view showing the process following Figure 10. [Figure 12] This is a cross-sectional view showing the process following Figure 11. [Figure 13] Figure 3 is a timing diagram illustrating one example of the operation of the image sensor. [Figure 14] This is a schematic cross-sectional view showing an example of the configuration of an image sensor according to Modification 1 of this disclosure. [Figure 15] This is a schematic cross-sectional view showing an example of the configuration of an image sensor according to Modification 2 of this disclosure. [Figure 16A] This is a schematic cross-sectional view showing an example of the configuration of an image sensor according to Modification 3 of this disclosure. [Figure 16B] Figure 16A is a schematic diagram showing the planar configuration of the image sensor. [Figure 17A] This is a schematic cross-sectional view showing an example of the configuration of an image sensor according to Modification 4 of this disclosure. [Figure 17B] Figure 17A is a schematic diagram showing the planar configuration of the image sensor. [Figure 18] This is a schematic cross-sectional view showing another example of the image sensor configuration of Modification 2, which relates to other modifications of the present disclosure. [Figure 19A] This is a schematic cross-sectional view showing another example of the image sensor configuration of Modification 3, which relates to other modifications of the present disclosure. [Figure 19B]This is a schematic diagram showing the planar configuration of the image sensor shown in Figure 19A. [Figure 20A] This is a schematic cross-sectional view showing another example of the image sensor configuration of Modification 4, which relates to other modifications of the present disclosure. [Figure 20B] Figure 20A is a schematic diagram showing the planar configuration of the image sensor. [Figure 21] Figure 3 shows a block diagram illustrating the overall configuration of an imaging device equipped with an image sensor. [Figure 22] Figure 21 is a block diagram showing an example of the configuration of an electronic device using the imaging device shown. [Figure 23A] Figure 21 is a schematic diagram illustrating an example of the overall configuration of a photodetection system using the imaging device shown. [Figure 23B] Figure 23A shows an example of the circuit configuration of the photodetection system. [Figure 24] This figure shows an example of a schematic configuration of an endoscopic surgical system. [Figure 25] This block diagram shows an example of the functional configuration of a camera head and CCU. [Figure 26] This block diagram shows an example of a schematic configuration of a vehicle control system. [Figure 27] This is an explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit. [Modes for carrying out the invention]

[0010] The embodiments described below will be explained in detail with reference to the drawings. The following description is one specific example of the disclosure, and the disclosure is not limited to the following embodiments. Furthermore, the disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each drawing. The order of explanation is as follows. 1. Embodiment (Example of a photoelectric conversion element having a hole-blocking layer consisting of a layer having predetermined HOMO and LUMO levels and a layer containing fullerene or a derivative thereof) 1-1. Configuration of a photoelectric conversion element 1-2. Image sensor configuration 1-3. Method for manufacturing an image sensor 1-4. Signal acquisition operation of the image sensor 1-5. Action and Effects 2. Variations 2-1. Variation 1 (Another example of image sensor configuration) 2-2. Modification Example 2 (Another example of image sensor configuration) 2-3. Modification 3 (Another example of image sensor configuration) 2-4. Modification 4 (Another example of image sensor configuration) 2-5. Modification 5 (Other Modifications of Image Sensors) 3. Examples of application 4. Application Examples 5. Examples

[0011] <1. Embodiment> Figure 1 schematically shows an example of the cross-sectional configuration of a photoelectric conversion element (photoelectric conversion element 10) according to one embodiment of the present disclosure. The photoelectric conversion element 10 is used, for example, in an imaging device (imaging device 100, see Figure 21, for example) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. It is used as an image sensor (image sensor 1A, see, for example, Figure 3) that constitutes a pixel (unit pixel P). The photoelectric conversion element 10 has a configuration in which a lower electrode 11, a hole blocking layer 12, a photoelectric conversion layer 13, an electron blocking layer 14, a work function adjustment layer 15, and an upper electrode 16 are stacked in this order. The hole blocking layer 12 in this embodiment consists of a first layer 12A containing an organic material having a HOMO (Highest Occupied Molecular Orbital) level that is 1 eV or more deeper than the work function of the lower electrode 11 and a LUMO (Lowest Unoccupied Molecular Orbital) level that is 3.7 eV or more and 4.8 eV or less, and a fullerene or This is a laminated structure consisting of a second layer 12B containing a fullerene derivative.

[0012] (1-1. Configuration of the photoelectric conversion element) The photoelectric conversion element 10 absorbs light corresponding to some or all of the wavelengths in a selective wavelength range (for example, the visible light region and the near-infrared light region between 400 nm and less than 1300 nm) to generate excitons (electron-hole pairs). In the image sensor (for example, image sensor 1A) described later, among the electron-hole pairs generated by photoelectric conversion, for example, electrons are read out as signal charges from the lower electrode 11 side. The following describes the configuration and materials of each part using the case where electrons are read out as signal charges from the lower electrode 11 side as an example.

[0013] The lower electrode 11 (cathode) is composed of, for example, a conductive film having light transmittance. Preferably, the lower electrode 11 has a work function of 4.0 eV to 5.5 eV and a deeper LUMO level than the organic material constituting the first layer 12A, which will be described later. Examples of constituent materials for such a lower electrode 11 include indium tin oxide (ITO), which is In2O3 with tin (Sn) added as a dopant. The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, other constituent materials for the lower electrode 11 include tin oxide (SnO2)-based materials with added dopants, such as ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or zinc oxide-based materials with added dopants may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) dopant added, gallium zinc oxide (GZO) with gallium (Ga) dopant added, boron zinc oxide with boron (B) dopant added, and indium zinc oxide (IZO) with indium (In) dopant added. Furthermore, zinc oxide with indium and gallium dopant added (IGZO, In-GaZnO4) is also used. Alternatively, the constituent material of the lower electrode 11 may be CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, ZnSnO3, or TiO2, or it may be a spinel-type oxide or an oxide having a YbFe2O4 structure.

[0014] Furthermore, when light transmittance is not required for the lower electrode 11 (for example, when light is incident from the upper electrode 16 side), a single metal or alloy with a low work function (e.g., φ = 3.5 eV to 4.5 eV) can be used. Specifically, examples include alkali metals (e.g., lithium (Li), sodium (Na), and potassium (K), etc.) and their fluorides or oxides, and alkaline earth metals (e.g., magnesium (Mg), calcium (Ca), etc.) and their fluorides or oxides. Other examples include aluminum (Al), Al-Si-Cu alloys, zinc (Zn), tin (Sn), thallium (Tl), Na-K alloys, Al-Li alloys, Mg-Ag alloys, rare earth metals such as In and ytterbium (Yb), or alloys thereof.

[0015] Furthermore, the materials constituting the lower electrode 11 include metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum (Mo), or alloys containing these metal elements, or conductive particles made from these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, graphene, and other conductive materials. In addition, organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid [PEDOT / PSS] can be used as materials constituting the lower electrode 11. Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which can then be cured and used as an electrode.

[0016] The lower electrode 11 can be formed as a single layer or a multilayer film made of the above material. The thickness of the lower electrode 11 in the stacking direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0017] The hole blocking layer 12 selectively transports electrons from the charge generated in the photoelectric conversion layer 13 to the lower electrode 11, while also inhibiting the injection of holes from the lower electrode 11. In this embodiment, the hole blocking layer 12 is composed of two layers: a first layer 12A and a second layer 12B.

[0018] The first layer 12A selectively transports electrons to the lower electrode 11 and inhibits hole injection from the lower electrode 11. The first layer 12A can be formed using, for example, an organic material having a HOMO level that is 1 eV or more deeper than the work function of the lower electrode 11 and a LUMO level that is 3.7 eV to 4.8 eV. Furthermore, it is preferable that the organic material has a band gap of 2.6 eV or more. Moreover, it is preferable that the organic material has a HOMO level deeper than 6.3 eV. Examples of such organic materials include the compounds shown in the following formulas (1-1) to (1-27).

[0019] [ka]

[0020] [ka]

[0021] [ka]

[0022] The second layer 12B selectively extracts electrons from the electron-hole pairs generated in the photoelectric conversion layer 13 and transports them to the lower electrode 11. It is preferable that the sum of the densities of states within the gap levels at the interface with the photoelectric conversion layer 13 is smaller than the sum of the densities of states within the gap levels in the photoelectric conversion layer 13. Such a second layer 12B can be formed using, for example, an electron transport material that functions as an electron acceptor in the photoelectric conversion layer 13. Specifically, the second layer 12B may be made of fullerene C 60 , fullerene C70 , fullerene C 74 It is formed using fullerenes and their derivatives, such as those represented by the following formula (2), including higher-order fullerenes and encapsulated fullerenes.

[0023] [ka]

[0024] The second layer 12B may further contain other materials. Examples of other materials include the compounds shown in formulas (1-1) to (1-27) above that constitute the first layer 12A. Other materials include dye materials used in the photoelectric conversion layer 13. Examples of these dye materials include the subphthalocyanine derivatives shown in formulas (3-1) to (3-8) below. Other examples of pigment materials include subphthalocyanine, porphyrin, phthalocyanine, dipyromethane, azadipyromethane, dipyridyl, azadipyridyl, coumarin, perylene, perylenediimide, pyrene, naphthalenediimide, quinacridone, xanthene, xanthenoxanthene, phenoxazine, indigo, azo, oxazine, benzodithiophene, naphthodithiophene, anthradithiophene, rubicene, anthracene, tetracene, pentacene, anthraquinone, tetraquinone, pentaquinone, dinaphthothienothiophene, diketopyrrolopyrrole, oligothiophene, cyanine, merocyanine, squalium, croconium, and boron-dipyrromethene (BODIPY) or derivatives thereof.

[0025] [ka]

[0026] The first layer 12A and the second layer 12B each have a thickness of, for example, 1 nm to 30 nm.

[0027] The photoelectric conversion layer 13 absorbs, for example, 60% or more of predetermined wavelengths included in at least the visible light region to the near-infrared region to separate charges. For example, the photoelectric conversion layer 13 absorbs some or all wavelengths of light in the visible light region and the near-infrared light region from 400 nm to less than 1300 nm. The photoelectric conversion layer 13 is composed of, for example, two or more organic materials that function as p-type semiconductors or n-type semiconductors, and has a junction surface (p / n junction surface) between the p-type semiconductor and the n-type semiconductor within the layer. In addition, the photoelectric conversion layer 13 may be a stacked structure of a layer made of a p-type semiconductor (p-type semiconductor layer) and a layer made of an n-type semiconductor (n-type semiconductor layer) (p-type semiconductor layer / n-type semiconductor layer), a stacked structure of a p-type semiconductor layer and a mixed layer of p-type and n-type semiconductors (bulk heterolayer) (p-type semiconductor layer / bulk heterolayer), or a stacked structure of an n-type semiconductor layer and a bulk heterolayer (n-type semiconductor layer / bulk heterolayer). Alternatively, it may be formed solely from a mixed layer (bulk heterolayer) of p-type and n-type semiconductors.

[0028] p-type semiconductors are hole transport materials that function relatively as electron donors, while n-type semiconductors are electron transport materials that function relatively as electron acceptors. The photoelectric conversion layer 13 provides a field where excitons (electron-hole pairs) generated when light is absorbed are separated into electrons and holes. Specifically, the electron-hole pairs are separated into electrons and holes at the interface (p / n junction) between the electron donor and the electron acceptor.

[0029] Examples of p-type semiconductors include naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, pentacene derivatives, quinacridone derivatives, thiophene derivatives, thienothiophene derivatives, benzothiophene derivatives, benzothienobenzothiophene (BTBT) derivatives, dinaphthothienothiophene (DNTT) derivatives, dianthrasenothienothiophene (DATT) derivatives, benzobisbenzothiophene (BBBT) derivatives, and thienothiophene. Examples of thienoacene-based materials include nobisbenzothiophene (TBBT) derivatives, dibenzothienobisbenzothiophene (DBTBT) derivatives, dithienobenzodithiophene (DTBDT) derivatives, dibenzothienodithiophene (DBTDT) derivatives, benzodithiophene (BDT) derivatives, naphthodithiophene (NDT) derivatives, anthracenodithiophene (ADT) derivatives, tetrasenodithiophene (TDT) derivatives, and pentacenodithiophene (PDT) derivatives. Other examples of p-type semiconductors include triphenylamine derivatives, carbazole derivatives, picene derivatives, chrysene derivatives, for example, fluorantene derivatives, phthalocyanine derivatives, subphthalocyanine derivatives, subporphyrazine derivatives, metal complexes with heterocyclic compounds as ligands, polythiophene derivatives, polybenzothiadiazole derivatives, and polyfluorene derivatives.

[0030] Examples of n-type semiconductors include fullerene C 60 , fullerene C 70Examples of substituents in fullerene derivatives include higher-order fullerenes such as fullerene C74 and encapsulated fullerenes, as well as their derivatives. Examples of substituents in fullerene derivatives include halogen atoms, linear or branched or cyclic alkyl groups or phenyl groups, groups having linear or fused aromatic compounds, groups having halides, partial fluoroalkyl groups, perfluoroalkyl groups, silylalkyl groups, silylalkoxy groups, arylsilyl groups, arylsulfanyl groups, alkylsulfanyl groups, arylsulfonyl groups, alkylsulfonyl groups, arylsulfide groups, alkylsulfide groups, amino groups, alkylamino groups, arylamino groups, hydroxyl groups, alkoxy groups, acylamino groups, acyloxy groups, carbonyl groups, carboxyl groups, carboxoamide groups, carboalkoxy groups, acyl groups, sulfonyl groups, cyano groups, nitro groups, groups having chalcogenides, phosphine groups, phosphone groups, and derivatives thereof. Specific examples of fullerene derivatives include fullerene fluorides, PCBM fullerene compounds, and fullerene polymers. Other examples of n-type semiconductors include organic semiconductors with larger (deeper) HOMO and LUMO levels than p-type semiconductors, and inorganic metal oxides with light-transmitting properties.

[0031] Examples of n-type organic semiconductors include heterocyclic compounds containing nitrogen, oxygen, or sulfur atoms. Specifically, examples include organic molecules having pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, isoquinoline derivatives, acridine derivatives, phenazine derivatives, phenanthroline derivatives, tetrazole derivatives, pyrazole derivatives, imidazole derivatives, thiazole derivatives, oxazole derivatives, imidazole derivatives, benzimidazole derivatives, benzotriazole derivatives, benzoxazole derivatives, benzoxazole derivatives, carbazole derivatives, benzofuran derivatives, dibenzofuran derivatives, subporphyrazine derivatives, polyphenylenevinylene derivatives, polybenzothiadiazole derivatives, polyfluorene derivatives, etc., as part of their molecular skeleton, as well as organometallic complexes, subphthalocyanine derivatives, quinacridone derivatives, cyanine derivatives, and merocyanine derivatives.

[0032] The photoelectric conversion layer 13 may also be composed of an organic material, a so-called dye material, that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges, in addition to the p-type semiconductor and n-type semiconductor. When the photoelectric conversion layer 13 is formed using three types of organic materials—a p-type semiconductor, an n-type semiconductor, and a dye material—it is preferable that the p-type semiconductor and n-type semiconductor are materials that are light-transmitting in the visible light region. This allows the photoelectric conversion layer 13 to selectively convert light in the wavelength range absorbed by the dye material into photoelectric energy.

[0033] The photoelectric conversion layer 13 has a thickness of, for example, 10 nm to 500 nm, and preferably 100 nm to 400 nm.

[0034] The electron blocking layer 14 selectively transports holes to the upper electrode 16 among the charges generated in the photoelectric conversion layer 13 and inhibits the injection of electrons from the upper electrode 16 side. Examples of the material constituting the electron blocking layer 14 include thienoacene-based materials represented by naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, quinacridone derivatives, thiophene derivatives, thienothiophene derivatives, benzothiophene derivatives, benzothieno[3,2-b]benzothiophene (BTBT) derivatives, dinaphthothieno[3,2-b]thiophene (DNTT) derivatives, benzobisbenzothiophene (BBBT) derivatives, thienobisbenzothiophene (TBBT) derivatives, dibenzothieno[3,2-b]benzothiophene (DBTBT) derivatives, dithieno[3,2-b:2’,3’-d]benzodithiophene (DTBDT) derivatives, dibenzothieno[3,2-b]dithiophene (DBTDT) derivatives, benzodithiophene (BDT) derivatives, naphthodithiophene (NDT) derivatives, and anthracenodithiophene (ADT) derivatives. In addition, examples of the p-type semiconductor include fluorene derivatives, triphenylene derivatives, triphenylamine derivatives, carbazole derivatives, picene derivatives, chrysene derivatives, etc.

[0035] The electron blocking layer 14 has a thickness of, for example, 5 nm or more and 100 nm or less, preferably 5 nm or more and 50 nm or less. More preferably, the electron blocking layer 14 has a thickness of 5 nm or more and 20 nm or less.

[0036] The work function adjustment layer 15 has an electron affinity or work function greater than that of the upper electrode 16 and improves the electrical junction property between the electron blocking layer 14 and the upper electrode 16. Examples of the material constituting the work function adjustment layer 15 include dipyrazino[2,3-f:2’,3’-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN). In addition, examples of the material constituting the work function adjustment layer 15 include PEDOT / PSS and polyaniline, and MoO x , RuO x , VO x and WO xExamples of metal oxides include the following.

[0037] The upper electrode 16 (anode), like the lower electrode 11, is composed of, for example, a light-transmitting conductive film. Examples of materials for the upper electrode 16 include indium tin oxide (ITO), which is In2O3 with tin (Sn) added as a dopant. The crystallinity of the ITO thin film can be high or low (approaching amorphous). Other materials for the lower electrode 11 include tin oxide (SnO2)-based materials with added dopants, such as ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or zinc oxide-based materials with added dopants may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide (IGZO, In-GaZnO4) doped with indium and gallium may be used as a dopant. In addition, CuI and InS bO4, ZnMgO, CuInO2, MgIN2O4, CdO, ZnSnO3, or TiO2 may be used, or spinel-type oxides or oxides having a YbFe2O4 structure may be used.

[0038] Furthermore, if light transmittance is not required for the upper electrode 16, a single metal or alloy with a high work function (e.g., φ = 4.5 eV to 5.5 eV) can be used. Specifically, examples include Au, Ag, Cr, Ni, Pd, Pt, Fe, iridium (Ir), germanium (Ge), osmium (Os), rhenium (Re), tellurium (Te), and their alloys.

[0039] Furthermore, the materials constituting the upper electrode 16 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, or alloys containing these metal elements, or conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, graphene, and other conductive materials. In addition, organic materials (conductive polymers) such as PEDOT / PSS can be used as materials constituting the upper electrode 16. Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which can then be cured and used as an electrode.

[0040] The upper electrode 16 can be formed as a single layer or a multilayer film made of the above material. The thickness of the upper electrode 16 is, for example, 20 nm to 200 nm, preferably 30 nm to 150 nm.

[0041] In addition to the hole-blocking layer 12, photoelectric conversion layer 13, electron-blocking layer 14, and work function adjustment layer 15, other layers may be provided between the lower electrode 11 and the upper electrode 16. For example, in addition to the hole-blocking layer 12, a bottom layer may be provided between the lower electrode 11 and the photoelectric conversion layer 13.

[0042] Figure 2 shows an example of the energy levels of the materials constituting each layer (lower electrode 11, hole blocking layer 12, and photoelectric conversion layer 13) of the photoelectric conversion element 10 shown in Figure 1. Light incident on the photoelectric conversion element 10 is absorbed in the photoelectric conversion layer 13. The resulting excitons (electron-hole pairs) undergo exciton separation, i.e., dissociation into electrons and holes, at the interface (p / n junction) between the p-type semiconductor and n-type semiconductor constituting the photoelectric conversion layer 13. The carriers (electrons and holes) generated here are transported to different electrodes by diffusion due to the carrier concentration difference and by the internal electric field due to the difference in work functions between the anode and cathode, and are detected as a photocurrent. Specifically, electrons separated at the p / n junction are extracted from the lower electrode 11 via the hole blocking layer 12. Holes separated at the p / n junction are extracted from the upper electrode 16 via the electron blocking layer 14 and the work function adjustment layer 15. Furthermore, the transport direction of electrons and holes can also be controlled by applying a potential between the lower electrode 11 and the upper electrode 16.

[0043] (1-2. Image sensor configuration) Figure 3 schematically shows an example of the cross-sectional configuration of an image sensor (image sensor 1A) using the photoelectric conversion element 10 described above. Figure 4 schematically shows an example of the planar configuration of the image sensor 1A shown in Figure 3, and Figure 3 shows the cross-section along line II shown in Figure 4. The image sensor 1A constitutes, for example, one pixel (unit pixel P) that is repeatedly arranged in an array in the pixel section 100A of the imaging device 100 shown in Figure 21. In the pixel section 100A, as shown in Figure 4, a pixel unit 1a consisting of four pixels arranged in, for example, 2 rows x 2 columns becomes the repeating unit and is repeatedly arranged in an array consisting of row and column directions.

[0044] The image sensor 1A is a so-called vertical spectral type, in which one photoelectric conversion unit, formed using, for example, an organic material, and two photoelectric conversion units (photoelectric conversion regions 32B, 32R), made of, for example, an inorganic material, are stacked vertically to selectively detect light in different wavelength ranges and perform photoelectric conversion. The photoelectric conversion element 10 described above can be used as a photoelectric conversion unit constituting the image sensor 1A. Hereafter, the photoelectric conversion unit will be described using the same reference numeral 10 as the photoelectric conversion element 10 described above, assuming it has the same configuration.

[0045] In the image sensor 1A, the photoelectric conversion unit 10 is provided on the back side (first surface 30S1) of the semiconductor substrate 30. The photoelectric conversion regions 32B and 32R are embedded within the semiconductor substrate 30 and are stacked in the thickness direction of the semiconductor substrate 30.

[0046] The photoelectric conversion unit 10 and the photoelectric conversion regions 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 10 acquires a green (G) color signal. The photoelectric conversion regions 32B and 32R acquire blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. As a result, the image sensor 1A can acquire multiple types of color signals in a single pixel without using a color filter.

[0047] In the section on image sensor 1A, we will explain the case where electrons are read out as signal charges from the electron-hole pairs generated by photoelectric conversion. Also, in the diagram, the "+" (plus) signs attached to "p" and "n" indicate a high concentration of p-type or n-type impurities.

[0048] The semiconductor substrate 30 is made of, for example, an n-type silicon (Si) substrate and has p-wells 31 in a predetermined region. The second surface (the surface of the semiconductor substrate 30) 30S2 of the p-wells 31 is provided with, for example, various floating diffusion layers FD (e.g., FD1, FD2, FD3) and various transistors Tr (e.g., a vertical transistor (transfer transistor) Tr2, a transfer transistor Tr3, an amplifier transistor (modulation element) AMP, and a reset transistor RST). A multilayer wiring layer 40 is further provided on the second surface 30S2 of the semiconductor substrate 30 via a gate insulating layer 33. The multilayer wiring layer 40 has, for example, a configuration in which wiring layers 41, 42, and 43 are stacked within an insulating layer 44. Peripheral circuits (not shown), such as logic circuits, are provided around the periphery of the semiconductor substrate 30.

[0049] A protective layer 51 is provided above the photoelectric conversion unit 10. Within the protective layer 51, for example, a light-shielding film 53 and wiring that electrically connects the upper electrode 16 and the peripheral circuit section around the pixel section 100A are provided. Further above the protective layer 51, optical components such as a planarization layer (not shown) and an on-chip lens 52L are arranged.

[0050] In Figure 3, the first surface 30S1 of the semiconductor substrate 30 is represented as the light incident surface S1, and the second surface 30S2 is represented as the wiring layer side S2.

[0051] The following provides a detailed explanation of the composition and materials of each part.

[0052] In the photoelectric conversion unit 10, a hole blocking layer 12 (first layer 12A and second layer 12B), a photoelectric conversion layer 13, an electron blocking layer 14, and a work function adjustment layer 15 are stacked in this order between the opposing lower electrode 11 and upper electrode 16. In the image sensor 1A, the lower electrode 11 consists of multiple electrodes (for example, two electrodes, a readout electrode 11A and a storage electrode 11B), and between the lower electrode 11 and the hole blocking layer 12, for example, an insulating layer 17 and a semiconductor layer 18 are stacked in this order. Of the lower electrodes 11, the readout electrode 11A is electrically connected to the semiconductor layer 18 via an opening 17H provided in the insulating layer 17.

[0053] The read electrode 11A is for transferring charge generated in the photoelectric conversion layer 13 to the floating diffusion FD1, and is connected to the floating diffusion FD1 via, for example, the upper second contact 24B, pad portion 39B, upper first contact 29A, pad portion 39A, through electrode 34, connection portion 41A, and lower second contact 46. The storage electrode 11B is for storing electrons as signal charge in the semiconductor layer 18 from the charge generated in the photoelectric conversion layer 13. The storage electrode 11B is provided in a region that covers the light-receiving surfaces of the photoelectric conversion regions 32B and 32R formed in the semiconductor substrate 30, directly facing these light-receiving surfaces. The storage electrode 11B is preferably larger than the read electrode 11A, thereby enabling the storage of a larger amount of charge. As shown in Figure 6, the voltage application portion 54 is connected to the storage electrode 11B via wiring such as the upper third contact 24C and pad portion 39C.

[0054] The insulating layer 17 is for electrically isolating the storage electrode 11B and the semiconductor layer 18. The insulating layer 17 is provided, for example, on the interlayer insulating layer 23 so as to cover the lower electrode 11. The insulating layer 17 is made of, for example, silicon oxide (SiO x ), silicon nitride (SiN x ) and silicon oxynitride (SiO x N yIt is composed of a single layer film made of one of the following, or a multilayer film made of two or more of these. The thickness of the insulating layer 17 is, for example, 20 nm to 500 nm.

[0055] The semiconductor layer 18 is for accumulating signal charges generated in the photoelectric conversion layer 13. Preferably, the semiconductor layer 18 is formed using a material with higher charge mobility and a larger band gap than the photoelectric conversion layer 13. For example, the band gap of the constituent material of the semiconductor layer 18 is preferably 3.0 eV or greater. Examples of such materials include oxide semiconductors such as IGZO and organic semiconductors. Examples of organic semiconductors include transition metal dichalcogenides, silicon carbide, diamond, graphene, carbon nanotubes, condensed polycyclic hydrocarbon compounds, and condensed heterocyclic compounds. The thickness of the semiconductor layer 18 is, for example, 10 nm to 300 nm. By providing a semiconductor layer 18 made of the above material between the lower electrode 11 and the photoelectric conversion layer 13, it is possible to prevent charge recombination during charge accumulation and improve transfer efficiency.

[0056] In Figure 3, an example is shown in which the semiconductor layer 18, hole blocking layer 12 (first layer 12A and second layer 12B), photoelectric conversion layer 13, electron blocking layer 14, work function adjustment layer 15, and upper electrode 16 are provided as a continuous layer common to multiple pixels (unit pixels P, see Figure 21), but the invention is not limited to this. The semiconductor layer 18, hole blocking layer 12, photoelectric conversion layer 13, electron blocking layer 14, work function adjustment layer 15, and upper electrode 16 may be formed separately for each unit pixel P, for example.

[0057] Between the semiconductor substrate 30 and the lower electrode 11, for example, a layer having a fixed charge (fixed charge layer) 21, an insulating dielectric layer 22, and an interlayer insulating layer 23 are provided in this order from the first surface 30S1 side of the semiconductor substrate 30.

[0058] The fixed charge layer 21 may be a film having a positive fixed charge or a film having a negative fixed charge. It is preferable to form the fixed charge layer 21 using a semiconductor or conductive material with a band gap wider than that of the semiconductor substrate 30. This suppresses the generation of dark current at the interface of the semiconductor substrate 30. Examples of materials for the fixed charge layer 21 include hafnium oxide (HfO). x ), aluminum oxide (AlO x ), zirconium oxide (ZrO x ), tantalum oxide (TaO x ), titanium dioxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), Europium oxide (EuO x ), gadolinium oxide (GdO x ), terbium oxide (TbO x ), dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), hafnium nitride (HfN x ), aluminum nitride (AlN x ), hafnium oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y Examples include:

[0059] The dielectric layer 22 is intended to prevent light reflection caused by the refractive index difference between the semiconductor substrate 30 and the interlayer insulating layer 23. The constituent material of the dielectric layer 22 is preferably a material having a refractive index between that of the semiconductor substrate 30 and that of the interlayer insulating layer 23. For example, SiO2 is a suitable constituent material for the dielectric layer 22. x TEOS, SiN x and SiO x N y These are some examples.

[0060] The interlayer insulating layer 23 is, for example, SiO x SiN x and SiO x N y It is composed of a single layer film made of one of these materials, or a multilayer film made of two or more of these materials.

[0061] A shield electrode 28 is provided on the interlayer insulating layer 23, along with the lower electrode 11. The shield electrode 28 is intended to prevent capacitive coupling between adjacent pixel units 1a, and is provided around, for example, a pixel unit 1a consisting of four pixels arranged in a 2x2 grid, to which a fixed potential is applied. The shield electrode 28 further extends within the pixel unit 1a between adjacent pixels in the row and column directions.

[0062] The photoelectric conversion regions 32B and 32R are, for example, of the PIN (Positive Intrinsic Negative) type. Each photodiode is composed of a pn junction in a predetermined region of the semiconductor substrate 30. The photoelectric conversion regions 32B and 32R utilize the fact that different wavelength ranges are absorbed in the silicon substrate depending on the incident depth of light, enabling the spectral separation of light in the longitudinal direction.

[0063] Photoelectric conversion region 32B selectively detects blue light and accumulates a signal charge corresponding to blue light, and is formed to a depth that allows for efficient photoelectric conversion of blue light. Photoelectric conversion region 32R selectively detects red light and accumulates a signal charge corresponding to red light, and is formed to a depth that allows for efficient photoelectric conversion of red light. Blue (B) corresponds to a wavelength range of, for example, 400 nm to less than 495 nm, and red (R) corresponds to a wavelength range of, for example, 620 nm to less than 750 nm. Photoelectric conversion regions 32B and 32R only need to be capable of detecting light in some or all of the wavelength ranges within their respective wavelength ranges.

[0064] Specifically, as shown in Figure 3, the photoelectric conversion region 32B and the photoelectric conversion region 32R each have, for example, a p+ region that serves as a hole storage layer and an n region that serves as an electron storage layer (having a pnp stacked structure). The n region of the photoelectric conversion region 32B is connected to the vertical transistor Tr2. The p+ region of the photoelectric conversion region 32B bends along the vertical transistor Tr2 and connects to the p+ region of the photoelectric conversion region 32R.

[0065] The gate insulating layer 33 is, for example, SiO x SiN x and SiO x N y It is composed of a single layer film made of one of these materials, or a multilayer film made of two or more of these materials.

[0066] A through electrode 34 is provided between the first surface 30S1 and the second surface 30S2 of the semiconductor substrate 30. The through electrode 34 functions as a connector between the photoelectric conversion unit 10 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1, and also serves as a transmission path for the charge generated in the photoelectric conversion unit 10. The reset gate Grst of the reset transistor RST is located next to the floating diffusion FD1 (one source / drain region 36B of the reset transistor RST). This makes it possible to reset the charge accumulated in the floating diffusion FD1 by the reset transistor RST.

[0067] The upper end of the through electrode 34 is connected to the read electrode 11A via, for example, a pad portion 39A, an upper first contact 24A, a pad electrode 38B, and an upper second contact 24B provided within the interlayer insulating layer 23. The lower end of the through electrode 34 is connected to a connection portion 41A within the wiring layer 41, and the connection portion 41A is connected to the gate Gamp of the amplifier transistor AMP via a lower first contact 45. The connection portion 41A is connected to the floating diffusion FD1 (region 36B) via, for example, a lower second contact 46.

[0068] The upper first contact 24A, upper second contact 24B, upper third contact 24C, pad portions 39A, 39B, 39C, wiring layers 41, 42, 43, lower first contact 45, lower second contact 46, and gate wiring layer 47 can be formed using, for example, doped silicon material such as PDAS (Phosphorus Doped Amorphous Silicon), or metallic material such as Al, W, Ti, Co, Hf, and Ta.

[0069] The insulating layer 44 is, for example, SiO x SiN x and SiO x N y It is composed of a single layer film made of one of these materials, or a multilayer film made of two or more of these materials.

[0070] The protective layer 51 and the on-chip lens 52L are made of a light-transmitting material, for example, SiO x SiN x and SiO x N y It is composed of a single layer film made of one of these materials, or a multilayer film made of two or more of these materials. The thickness of the protective layer 51 is, for example, 100 nm to 30,000 nm.

[0071] The light-shielding film 53 is provided, for example, so as to cover the region of the readout electrode 21A that is in direct contact with the semiconductor layer 18, without covering the storage electrode 11B. The light-shielding film 53 can be formed using, for example, W, Al, and an alloy of Al and Cu.

[0072] Figure 5 is an equivalent circuit diagram of the image sensor 1A shown in Figure 3. Figure 6 schematically shows the arrangement of the transistors that constitute the lower electrode 11 and control unit of the image sensor 1A shown in Figure 3.

[0073] The reset transistor RST (reset transistor TR1rst) is used to reset the charge transferred from the photoelectric conversion unit 10 to the floating diffusion FD1, and is composed of, for example, a MOS transistor. Specifically, the reset transistor TR1rst consists of a reset gate Grst, a channel formation region 36A, and source / drain regions 36B and 36C. The reset gate Grst is connected to the reset line RST1, and one of the source / drain regions 36B of the reset transistor TR1rst also serves as the floating diffusion FD1. The other source / drain region 36C of the reset transistor TR1rst is connected to the power line VDD.

[0074] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the photoelectric conversion unit 10 into a voltage, and is composed of, for example, a MOS transistor. Specifically, the amplifier transistor AMP consists of a gate Gamp, a channel formation region 35A, and source / drain regions 35B and 35C. The gate Gamp is connected to the read electrode 11A and one of the source / drain regions 36B (floating diffusion FD1) of the reset transistor TR1rst via the lower first contact 45, connection portion 41A, lower second contact 46, and through electrode 34, etc. Furthermore, one of the source / drain regions 35B shares a region with the other source / drain region 36C that constitutes the reset transistor TR1rst and is connected to the power line VDD.

[0075] The selection transistor SEL (selection transistor TR1sel) consists of 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. One source / drain region 34B shares a region with the other source / drain region 35C that constitutes the amplifier transistor AMP, and the other source / drain region 34C is connected to the signal line (data output line) VSL1.

[0076] The transfer transistor TR2 (transfer transistor TR2trs) is for transferring the blue signal charge generated and accumulated in the photoelectric conversion region 32B to the floating diffusion FD2. Since the photoelectric conversion region 32B is formed deep from the second surface 30S2 of the semiconductor substrate 30, it is preferable that the transfer transistor TR2trs in the photoelectric conversion region 32B be a vertical transistor. The transfer transistor TR2trs is connected to the transfer gate line TG2. A floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2trs. The charge accumulated in the photoelectric conversion region 32B is read out to the floating diffusion FD2 via a transfer channel formed along the gate Gtrs2.

[0077] The transfer transistor TR3 (transfer transistor TR3trs) is used to transfer the signal charge corresponding to the red color, which is generated and accumulated in the photoelectric conversion region 32R, to the floating diffusion FD3, and is composed of, for example, a MOS transistor. The transfer transistor TR3trs is connected to the transfer gate line TG3. A floating diffusion FD3 is provided in the region 38C near the gate Gtrs3 of the transfer transistor TR3trs. The charge accumulated in the photoelectric conversion region 32R is read out to the floating diffusion FD3 via a transfer channel formed along the gate Gtrs3.

[0078] On the second surface 30S2 side of the semiconductor substrate 30, a reset transistor TR2rst, an amplifier transistor TR2amp, and a selection transistor TR2sel are provided, which constitute the control unit of the photoelectric conversion region 32B. Furthermore, a reset transistor TR3rst, an amplifier transistor TR3amp, and a selection transistor TR3sel are provided, which constitute the control unit of the photoelectric conversion region 32R.

[0079] The reset transistor TR2rst consists of a gate, a channel formation region, and a source / drain region. The gate of the reset transistor TR2rst is connected to the reset line RST2, and one of the source / drain regions of the reset transistor TR2rst is connected to the power line VDD. The other source / drain region of the reset transistor TR2rst also serves as the floating diffusion FD2.

[0080] The amplifier transistor TR2amp consists of a gate, a channel formation region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD2) of the reset transistor TR2rst. One source / drain region of the amplifier transistor TR2amp shares a region with the other source / drain region of the reset transistor TR2rst and is connected to the power line VDD.

[0081] The selection transistor TR2sel consists of a gate, a channel formation region, and a source / drain region. The gate is connected to the selection line SEL2. One source / drain region of the selection transistor TR2sel shares a region with the other source / drain region of the amplifier transistor TR2amp. The other source / drain region of the selection transistor TR2sel is connected to the signal line (data output line) VSL2.

[0082] The reset transistor TR3rst consists of a gate, a channel formation region, and a source / drain region. The gate of the reset transistor TR3rst is connected to the reset line RST3, and one of the source / drain regions constituting the reset transistor TR3rst is connected to the power line VDD. The other source / drain region constituting the reset transistor TR3rst also serves as the floating diffusion FD3.

[0083] The amplifier transistor TR3amp consists of a gate, a channel formation region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD3) that constitutes the reset transistor TR3rst. One source / drain region of the amplifier transistor TR3amp shares a region with the other source / drain region of the reset transistor TR3rst and is connected to the power line VDD.

[0084] The selection transistor TR3sel consists of a gate, a channel formation region, and a source / drain region. The gate is connected to the selection line SEL3. One source / drain region of the selection transistor TR3sel shares a region with the other source / drain region of the amplifier transistor TR3amp. The other source / drain region of the selection transistor TR3sel is connected to the signal line (data output line) VSL3.

[0085] The reset lines RST1, RST2, RST3, the selection lines SEL1, SEL2, SEL3, and the transfer gate lines TG2, TG3 are each connected to the vertical drive circuit that constitutes the drive circuit. The signal lines (data output lines) VSL1, VSL2, VSL3 are connected to the column signal processing circuit 112 that constitutes the drive circuit.

[0086] (1-3. Method for manufacturing an image sensor) The image sensor 1A of this embodiment can be manufactured, for example, as follows.

[0087] Figures 7 to 12 show the manufacturing method of the image sensor 1A in order of steps. First, as shown in Figure 8, for example, a p-well 31 is formed in the semiconductor substrate 30, and for example, n-type photoelectric conversion regions 32B and 32R are formed in this p-well 31. A p+ region is formed near the first surface 30S1 of the semiconductor substrate 30.

[0088] On the second surface 30S2 of the semiconductor substrate 30, as shown in Figure 7, an n+ region, for example, a floating diffusion FD1 to FD3, is formed, followed by the formation of a gate insulating layer 33 and a gate wiring layer 47 including the gates of the transfer transistor Tr2, transfer transistor Tr3, selection transistor SEL, amplifier transistor AMP, and reset transistor RST. This forms the transfer transistor Tr2, transfer transistor Tr3, selection transistor SEL, amplifier transistor AMP, and reset transistor RST. Furthermore, a multilayer wiring layer 40 consisting of wiring layers 41 to 43 including a lower first contact 45, a lower second contact 46, and a connection portion 41A, and an insulating layer 44 is formed on the second surface 30S2 of the semiconductor substrate 30.

[0089] As the substrate for the semiconductor substrate 30, for example, an SOI (Silicon on Insulator) substrate is used, which is formed by laminating the semiconductor substrate 30, an embedded oxide film (not shown), and a holding substrate (not shown). The embedded oxide film and the holding substrate are bonded to the first surface 30S1 of the semiconductor substrate 30, although they are not shown in Figure 7. After ion implantation, an annealing treatment is performed.

[0090] Next, a support substrate (not shown) or another semiconductor substrate is bonded to the multilayer wiring layer 40 provided on the second surface 30S2 side of the semiconductor substrate 30, and then the substrate is inverted. Subsequently, the semiconductor substrate 30 is separated from the embedded oxide film and holding substrate of the SOI substrate, exposing the first surface 30S1 of the semiconductor substrate 30. The above steps can be carried out using techniques commonly used in CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

[0091] Next, as shown in Figure 8, the semiconductor substrate 30 is processed from the first surface 30S1 side by, for example, dry etching to form, for example, an annular opening 34H. As shown in Figure 9, the depth of the opening 34H penetrates from the first surface 30S1 to the second surface 30S2 of the semiconductor substrate 30, and also reaches, for example, the connection portion 41A.

[0092] Subsequently, on the first surface 30S1 of the semiconductor substrate 30 and the side surface of the opening 34H, for example, a negative fixed charge layer 21 and a dielectric layer 22 are formed in this order. The fixed charge layer 21 can be formed, for example, by forming a HfO x film using an atomic layer deposition method (ALD method). The dielectric layer 22 can be formed, for example, by forming a SiO x film using a plasma CVD method. Next, at a predetermined position on the dielectric layer 22, for example, a pad portion 39A in which a barrier metal made of a laminated film of titanium and titanium nitride (Ti / TiN film) and a W film are laminated is formed. Thereafter, an interlayer insulating layer 23 is formed on the dielectric layer 22 and the pad portion 39A, and the surface of the interlayer insulating layer 23 is planarized using a chemical mechanical polishing (CMP) method.

[0093] Subsequently, as shown in FIG. 9, after forming an opening 23H1 on the pad portion 39A, a conductive material such as Al is embedded in this opening 23H1 to form an upper first contact 24A. Next, as shown in FIG. 9, in the same manner as the pad portion 39A, after forming pad portions 39B and 39C, an interlayer insulating layer 23, an upper second contact 24B, and an upper third contact 24C are formed in this order.

[0094] Subsequently, as shown in FIG. 10, after forming a conductive film 11X on the interlayer insulating layer 23 using, for example, a sputtering method, patterning is performed using photolithography technology. Specifically, after forming a photoresist PR at a predetermined position of the conductive film 11X, the conductive film 11X is processed using dry etching or wet etching. Thereafter, by removing the photoresist PR, a readout electrode 11A and a storage electrode 11B are formed as shown in FIG. 11.

[0095] Next, as shown in FIG. 12, an insulating layer 17, a semiconductor layer 18, a hole blocking layer 12 (first layer 12A and second layer 12B), a photoelectric conversion layer 13, an electron blocking layer 14, a work function adjustment layer 15, and an upper electrode 16 are formed in this order. The insulating layer 17 is, for example, SiO formed using the ALD method xAfter the film is fabricated, the surface of the insulating layer 17 is planarized using the CMP method. Then, an aperture 17H ​​is formed on the readout electrode 11A, for example, using wet etching. The semiconductor layer 18 can be formed, for example, using the sputtering method. The hole blocking layer 12 (first layer 12A and second layer 12B), the photoelectric conversion layer 13, the electron blocking layer 14, and the work function adjustment layer 15 are formed, for example, using the vacuum deposition method. The upper electrode 16 is formed, similar to the lower electrode 11, for example, using the sputtering method. Finally, a protective layer 51, a light-shielding film 53, and an on-chip lens 52L are placed on the upper electrode 16. With these steps, the image sensor 1A shown in Figure 3 is completed.

[0096] Furthermore, it is desirable that the hole-blocking layer 12 (first layer 12A and second layer 12B), the photoelectric conversion layer 13, the electron-blocking layer 14, and the work function adjustment layer 15 be formed continuously in a vacuum process (a single vacuum process). In addition, organic layers such as the hole-blocking layer 12 (first layer 12A and second layer 12B), the photoelectric conversion layer 13, the electron-blocking layer 14, and the work function adjustment layer 15, as well as conductive films such as the lower electrode 11 and the upper electrode 16, can be formed using a dry deposition method or a wet deposition method. Dry deposition methods include vacuum deposition using resistance heating or high-frequency heating, as well as electron beam (EB) deposition, various sputtering methods (magnetron sputtering, RF-DC coupled bias sputtering, ECR sputtering, opposing target sputtering, high-frequency sputtering), ion plating, laser aeration, molecular beam epitaxy, and laser transfer. Other dry film deposition methods include chemical vapor deposition methods such as plasma CVD, thermal CVD, MOCVD, and photoCVD. Wet film deposition methods include spin coating, inkjet printing, spray coating, stamping, microcontact printing, flexographic printing, offset printing, gravure printing, and dip printing.

[0097] For patterning, in addition to photolithography, chemical etching such as shadow masks and laser transfer, and physical etching using ultraviolet light or lasers can be used. For planarization, in addition to the CMP method, laser planarization and reflow methods can be used.

[0098] (1-4. Signal acquisition operation of the image sensor) In the image sensor 1A, when light enters the photoelectric conversion unit 10 via the on-chip lens 52L, the light passes through the photoelectric conversion unit 10, then the photoelectric conversion regions 32B and 32R in that order, and during this process, green, blue, and red light are photoelectrically converted. The signal acquisition operation for each color will be described below.

[0099] (Acquisition of green signal by photoelectric conversion unit 10) Of the light incident on the image sensor 1A, green light (G) is first selectively detected (absorbed) by the photoelectric conversion unit 10 and converted into photoelectric energy.

[0100] The photoelectric conversion unit 10 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1 via a through electrode 34. Therefore, electrons from the excitons generated in the photoelectric conversion unit 10 are extracted from the lower electrode 11 side, transferred to the second surface 30S2 side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD1. At the same time, the amount of charge generated in the photoelectric conversion unit 10 is modulated into a voltage by the amplifier transistor AMP.

[0101] Furthermore, the reset gate Grst of the reset transistor RST is located next to the floating diffusion transistor FD1. This ensures that the charge accumulated in the floating diffusion transistor FD1 is reset by the reset transistor RST.

[0102] Since the photoelectric conversion unit 10 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 via the through-electrode 34, the charge accumulated in the floating diffusion FD1 can be easily reset by the reset transistor RST.

[0103] In contrast, if the through electrode 34 and the floating diffusion FD1 are not connected, it becomes difficult to reset the charge accumulated in the floating diffusion FD1, requiring a large voltage to be applied to pull it out towards the upper electrode 16. This could potentially damage the photoelectric conversion layer 24. Furthermore, a structure that allows for quick resetting would lead to increased noise in the dark, creating a trade-off, making this structure impractical.

[0104] Figure 13 shows an example of the operation of the image sensor 1A. (A) shows the potential at the storage electrode 11B, (B) shows the potential at the floating diffusion FD1 (readout electrode 11A), and (C) shows the potential at the gate (Gsel) of the reset transistor TR1rst. In the image sensor 1A, the readout electrode 11A and the storage electrode 11B are each supplied with voltages individually.

[0105] In the image sensor 1A, during the storage period, a potential V1 is applied to the readout electrode 11A from the drive circuit, and a potential V2 is applied to the storage electrode 11B. Here, the potentials V1 and V2 are set such that V2 > V1. As a result, the charge (signal charge; electrons) generated by photoelectric conversion is attracted to the storage electrode 11B and stored in the region of the semiconductor layer 18 facing the storage electrode 11B (storage period). Incidentally, the potential of the region of the semiconductor layer 18 facing the storage electrode 11B becomes more negative as the photoelectric conversion progresses. Holes are sent from the upper electrode 16 to the drive circuit.

[0106] In the imaging element 1A, a reset operation is performed in the latter stage of the accumulation period. Specifically, at timing t1, the scanning unit changes the voltage of the reset signal RST from a low level to a high level. As a result, in the unit pixel P, the reset transistor TR1rst is turned on, and the voltage of the floating diffusion FD1 is set to the power supply voltage, and the voltage of the floating diffusion FD1 is reset (reset period).

[0107] After the completion of the reset operation, the charge is read out. Specifically, at timing t2, the potential V3 is applied to the readout electrode 11A from the drive circuit, and the potential V4 is applied to the storage electrode 11B. Here, the potentials V3 and V4 are set such that V3 < V4. As a result, the charge accumulated in the region corresponding to the storage electrode 11B is read out from the readout electrode 11A to the floating diffusion FD1. That is, the charge accumulated in the semiconductor layer 18 is read out to the control unit (transfer period).

[0108] After the completion of the readout operation, again, the potential V1 is applied to the readout electrode 11A from the drive circuit, and the potential V2 is applied to the storage electrode 11B. As a result, the charge generated by photoelectric conversion is attracted to the storage electrode 11B and accumulated in the region of the photoelectric conversion layer 24 facing the storage electrode 11B (accumulation period).

[0109] (Acquisition of blue and red signals by the photoelectric conversion regions 32B and 32R) Subsequently, among the light transmitted through the photoelectric conversion unit 10, blue light (B) is sequentially absorbed and photoelectrically converted in the photoelectric conversion region 32B, and red light (R) is sequentially absorbed and photoelectrically converted in the photoelectric conversion region 32R. In the photoelectric conversion region 32B, electrons corresponding to the incident blue light (B) are accumulated in the n-region of the photoelectric conversion region 32B, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2. Similarly, in the photoelectric conversion region 32R, electrons corresponding to the incident red light (R) are accumulated in the n-region of the photoelectric conversion region 32R, and the accumulated electrons are transferred to the floating diffusion FD3 by the transfer transistor Tr3.

[0110] (1-5. Actions and Effects) In the photoelectric conversion element 10 of this embodiment, a hole blocking layer 12 is provided between the lower electrode 11 and the photoelectric conversion layer 13. This layer includes a first layer 12A containing an organic material having a HOMO level 1 eV or more deeper than the work function of the lower electrode 11 and a LUMO level between 3.7 eV and 4.8 eV, and a second layer 12B containing a fullerene or a fullerene derivative. This suppresses the injection of holes from the lower electrode 11 while reducing the electron barrier at the interface with the lower electrode 11. It also suppresses the generation of dark current at the interface with the photoelectric conversion layer 13 while reducing the occurrence of interface traps with the photoelectric conversion layer 13. This will be explained below.

[0111] In CMOS image sensors used in electronic devices such as digital still cameras and video cameras, the photoelectric conversion elements used as image sensors constituting each pixel require a good signal-to-noise ratio (S / N ratio) between photocurrent and dark current, as well as a high response speed. For example, in the aforementioned photoelectric conversion elements, sensitivity, S / N ratio, and response speed are improved by providing a hole blocking layer between the photoelectric conversion layer and the electrode, which includes a fullerene and / or fullerene derivative and a transparent hole transport material with an ionization potential of 5.5 eV or higher.

[0112] However, the above-mentioned photoelectric conversion element cannot be said to have sufficient characteristics in terms of dark current, external quantum efficiency, and afterimage characteristics. This is presumably because, although the efficiency of electron extraction and the reduction of trapping at the interface between the photoelectric conversion layer and the hole blocking layer have been improved, the suppression of hole injection from the electrodes and the barrier at the interface between the electrodes and the hole blocking layer have not been considered.

[0113] In contrast, in this embodiment, the hole blocking layer 12 has a laminated structure of a first layer 12A and a second layer 12B. The first layer 12A, which contains an organic material having a HOMO level 1 eV or more deeper than the work function of the lower electrode 11 and a LUMO level between 3.7 eV and 4.8 eV, is placed on the lower electrode 11 side, while the second layer 12B, which contains a fullerene or fullerene derivative, is placed on the photoelectric conversion layer 13 side. This suppresses the injection of holes from the lower electrode 11 while reducing the electron barrier at the interface with the lower electrode 11. Furthermore, it suppresses the generation of dark current at the interface of the photoelectric conversion layer 13 while reducing the occurrence of interface traps with the photoelectric conversion layer.

[0114] As a result of the above, the photoelectric conversion element 10 of this embodiment makes it possible to improve the element characteristics.

[0115] For example, in the photoelectric conversion element 10 of this embodiment, the injection of holes from the lower electrode 11 is suppressed, and the outflow of charge at the interface between the hole block layer 12 and the photoelectric conversion layer is reduced, thereby reducing the dark current. Furthermore, in the photoelectric conversion element 10 of this embodiment, the electron barriers at the interface between the lower electrode 11 and the hole block layer 12 and the interface between the photoelectric conversion layer 13 and the hole block layer 12 are reduced, making it possible to improve the electron extraction efficiency, i.e., the external quantum efficiency. Moreover, in the photoelectric conversion element 10 of this embodiment, the occurrence of traps at the interface between the hole block layer 12 and the photoelectric conversion layer 13 is reduced, making it possible to improve the photoresponsiveness.

[0116] Next, modifications 1 to 5 of the present disclosure will be described. Note that the same reference numerals are used for the components corresponding to the photoelectric conversion element 10 and image sensor 1A in the above embodiments, and their descriptions are omitted.

[0117] <2. Variant> (2-1. Variation 1) Figure 14 schematically shows the cross-sectional configuration of the image sensor 1B according to Modification 1 of the present disclosure. The image sensor 1B is an image sensor such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, similar to the image sensor 1A in the above embodiment. The image sensor 1B of this modification differs from the above embodiment in that the lower electrode 11 consists of one electrode for each unit pixel P.

[0118] Similar to the image sensor 1A, the image sensor 1B has one photoelectric conversion unit 10 and two photoelectric conversion regions 32B and 32R stacked vertically for each unit pixel P. The photoelectric conversion unit 10 corresponds to the photoelectric conversion element 10 and is provided on the back side (first surface 30A) of the semiconductor substrate 30. The photoelectric conversion regions 32B and 32R are embedded within the semiconductor substrate 30 and are stacked in the thickness direction of the semiconductor substrate 30.

[0119] The modified image sensor 1B has the same configuration as the image sensor 1A, except that the lower electrode 11 of the photoelectric conversion unit 10 consists of a single electrode, and there is no insulating layer 17 and semiconductor layer 18 between the lower electrode 11 and the hole blocking layer 12.

[0120] Thus, the configuration of the photoelectric conversion unit 10 is not limited to the image sensor 1A of the above embodiment, and the same effects as in the above embodiment can be obtained even with the configuration of the photoelectric conversion unit 10 of the image sensor 1B of this modified example.

[0121] (2-2. Variation 2) Figure 15 schematically shows the cross-sectional configuration of the image sensor 1C according to Modification 2 of the present disclosure. Similar to the image sensor 1A in the above embodiment, the image sensor 1C is an image sensor such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. In this modified image sensor 1C, two photoelectric conversion units 10, 80 and one photoelectric conversion region 32 are stacked in the vertical direction.

[0122] The photoelectric conversion units 10 and 80 and the photoelectric conversion region 32 selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 10 acquires a green (G) color signal. For example, the photoelectric conversion unit 80 acquires a blue (B) color signal. For example, the photoelectric conversion region 32 acquires a red (R) color signal. As a result, the image sensor 1C can acquire multiple types of color signals in a single pixel without using a color filter.

[0123] The photoelectric conversion units 10 and 80 have the same configuration as the image sensor 1A in the above embodiment. Specifically, the photoelectric conversion unit 10, like the image sensor 1A, has a lower electrode 11, a hole blocking layer 12 (first layer 12A and second layer 12B), a photoelectric conversion layer 13, an electron blocking layer 14, a work function adjustment layer 15, and an upper electrode 16 stacked in this order. The lower electrode 11 consists of a plurality of electrodes (for example, a readout electrode 11A and a storage electrode 11B), and an insulating layer 17 and a semiconductor layer 18 are stacked between the lower electrode 11 and the hole blocking layer 12 in this order. Of the lower electrodes 11, the readout electrode 11A is electrically connected to the semiconductor layer 18 via an opening 17H provided in the insulating layer 17. Similar to the photoelectric conversion unit 10, the photoelectric conversion unit 80 has the lower electrode 81, hole blocking layer 82 (first layer 82A and second layer 82B), photoelectric conversion layer 83, electron blocking layer 84, work function adjustment layer 85, and upper electrode 86 stacked in this order. The lower electrode 81 consists of multiple electrodes (for example, a read electrode 81A and a storage electrode 81B), and an insulating layer 87 and a semiconductor layer 88 are stacked between the lower electrode 81 and the hole blocking layer 82 (first layer 82A and second layer 82B) in this order. Of the lower electrode 81, the read electrode 81A is electrically connected to the semiconductor layer 88 via an opening 87H provided in the insulating layer 87. Note that one or both of the semiconductor layer 18 and semiconductor layer 88 may be omitted.

[0124] The read electrode 81A is connected to a through electrode 91 that penetrates the interlayer insulating layer 89 and the photoelectric conversion unit 10 and is electrically connected to the read electrode 11A of the photoelectric conversion unit 10. Furthermore, the read electrode 81A is electrically connected to a floating diffusion FD provided on the semiconductor substrate 30 via through electrodes 34 and 91, and can temporarily store the charge generated in the photoelectric conversion layer 83. In addition, the read electrode 81A is electrically connected to an amplifier transistor AMP and the like provided on the semiconductor substrate 30 via through electrodes 34 and 91.

[0125] (2-3. Variation 3) Figure 16A schematically shows the cross-sectional configuration of the image sensor 1D according to Modification 3 of the present disclosure. Figure 16B schematically shows an example of the planar configuration of the image sensor 1D shown in Figure 16A, and Figure 16A shows the cross-section along line II-II shown in Figure 16B. The image sensor 1D is, for example, a stacked image sensor in which a photoelectric conversion region 32 and a photoelectric conversion unit 60 are stacked. In the pixel section 100A of an imaging device (for example, imaging device 100) equipped with this image sensor 1D, as shown in Figure 16B, for example, pixel units 1a consisting of four pixels arranged in a 2x2 grid are repeated units and are repeatedly arranged in an array consisting of row and column directions.

[0126] In this modified image sensor 1D, above the photoelectric conversion unit 60 (light incident side S1), a color filter 55 that selectively transmits red light (R), green light (G), and blue light (B) is provided for each unit pixel P. Specifically, in a pixel unit 1a consisting of four pixels arranged in a 2x2 grid, two color filters that selectively transmit green light (G) are arranged diagonally, and one color filter that selectively transmits red light (R) and one color filter that selectively transmits blue light (B) are arranged on orthogonal diagonals. In the unit pixels (Pr, Pg, Pb) provided with each color filter, for example, the photoelectric conversion unit 60 detects the corresponding color light. That is, in the pixel section 100A, pixels (Pr, Pg, Pb) that detect red light (R), green light (G), and blue light (B), respectively, are arranged in a Bayer pattern.

[0127] The photoelectric conversion unit 60 absorbs light corresponding to some or all of the wavelengths in the visible light region between 400 nm and 750 nm to generate excitons (electron-hole pairs), and consists of a lower electrode 61, an insulating layer (interlayer insulating layer 67), a semiconductor layer 68, a hole blocking layer 62 (first layer 62A and second layer 62B), a photoelectric conversion layer 63, an electron blocking layer 64, a work function adjustment layer 65, and an upper electrode 66, stacked in this order. The lower electrode 61, interlayer insulating layer 67, semiconductor layer 68, hole blocking layer 62 (first layer 62A and second layer 62B), photoelectric conversion layer 63, electron blocking layer 64, work function adjustment layer 65, and upper electrode 66 have the same configuration as the lower electrode 11, insulating layer 17, semiconductor layer 18, hole blocking layer 12, photoelectric conversion layer 13, electron blocking layer 14, work function adjustment layer 15, and upper electrode 16 of the image sensor 1A in the above embodiment. The lower electrode 61 has, for example, a read electrode 61A and a storage electrode 61B that are independent of each other, and the read electrode 61A is shared by, for example, four pixels. The semiconductor layer 68 may be omitted.

[0128] The photoelectric conversion region 32 detects, for example, infrared light in the range of 750 nm to 1300 nm.

[0129] In the image sensor 1D, of the light transmitted through the color filter 55, visible light (red light (R), green light (G), and blue light (B)) is absorbed by the photoelectric conversion units 60 of the unit pixels (Pr, Pg, Pb) where each color filter is provided, while other light, such as infrared light (IR) in the infrared light region (e.g., 750 nm to 1000 nm), is transmitted through the photoelectric conversion units 60. This infrared light (IR) transmitted through the photoelectric conversion units 60 is detected in the photoelectric conversion regions 32 of each unit pixel Pr, Pg, Pb, and a signal charge corresponding to the infrared light (IR) is generated in each unit pixel Pr, Pg, Pb. In other words, the imaging device 100 equipped with the image sensor 1D can simultaneously generate both visible light images and infrared light images.

[0130] Furthermore, the imaging device 100 equipped with the image sensor 1D can acquire visible light images and infrared light images at the same position in the XZ plane. Therefore, it becomes possible to achieve high integration in the XZ plane.

[0131] (2-4. Modification 4) Figure 17A schematically shows the cross-sectional configuration of the image sensor 1E according to Modification 4 of this disclosure. Figure 17B schematically shows an example of the planar configuration of the image sensor 1E shown in Figure 17A, and Figure 17A shows the cross-section along line III-III shown in Figure 17B. In Modification 3 described above, an example was shown in which the color filter 55 is provided above the photoelectric conversion unit 60 (on the light incident side S1), but the color filter 55 may be provided between the photoelectric conversion region 32 and the photoelectric conversion unit 60, for example, as shown in Figure 17A.

[0132] In the image sensor 1E, for example, the color filter 55 has a configuration in which a color filter (color filter 55R) that selectively transmits at least red light (R) and a color filter (color filter 55B) that selectively transmits at least blue light (B) are arranged diagonally to each other within the pixel unit 1a. The photoelectric conversion unit 60 (photoelectric conversion layer 63) is configured to selectively absorb light having a wavelength corresponding to, for example, green light (G). In the photoelectric conversion region 32R, light having a wavelength corresponding to red light (R) is selectively absorbed, and in the photoelectric conversion region 32B, light having a wavelength corresponding to blue light (B) is selectively absorbed. As a result, it is possible to acquire signals corresponding to red light (R), green light (G), or blue light (B) in the photoelectric conversion regions 32 (photoelectric conversion regions 32R, 32B) located below the photoelectric conversion unit 60 and the color filters 55R, 55B, respectively. In this modified image sensor 1E, the area of ​​each RGB photoelectric conversion section can be enlarged compared to a photoelectric conversion element with a typical Bayer array, making it possible to improve the signal-to-noise ratio.

[0133] (2-5. Modification 5) Figure 18 shows another example of the cross-sectional configuration of image sensor 1C (image sensor 1F) in Modification 2, which is another modification of the present disclosure. Figure 19A schematically shows another example of the cross-sectional configuration of image sensor 1D (image sensor 1G) in Modification 3, which is another modification of the present disclosure. Figure 19B schematically shows an example of the planar configuration of image sensor 1G shown in Figure 19A. Figure 20A schematically shows another example of the cross-sectional configuration of image sensor 1E (image sensor 1H) in Modification 4, which is another modification of the present disclosure. Figure 20B schematically shows an example of the planar configuration of image sensor 1H shown in Figure 20A.

[0134] In the above modifications 2 to 4, examples were shown in which the lower electrodes 11, 61, and 81 constituting the photoelectric conversion units 60 and 80 consist of multiple electrodes (readout electrodes 11A, 61A, 81A and storage electrodes 11B, 61B, 81B), but the method is not limited to this. The image sensors 1C, 1D, and 1E according to the above modifications 2 to 4 can also be applied when the lower electrodes consist of one electrode for each unit pixel P, similar to the above modification 1, and the same effects as the above modifications 2 to 4 can be obtained.

[0135] <3. Application Examples> (Application Example 1) Figure 21 shows an example of the overall configuration of an imaging device (imaging device 100) equipped with an image sensor (for example, image sensor 1A) as shown in Figure 3, etc.

[0136] The imaging device 100 is, for example, a CMOS image sensor that captures incident light (image light) from a subject via an optical lens system (not shown), converts the amount of light of the incident light formed on the imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs it as a pixel signal. The imaging device 100 has a pixel section 100A as an imaging area on a semiconductor substrate 30, and in the area surrounding this pixel section 100A, it has, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116.

[0137] The pixel section 100A has, for example, a plurality of unit pixels P arranged in a two-dimensional matrix. Each of these unit pixels P is wired with, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) for each pixel row, and a vertical signal line Lsig for each pixel column. The pixel drive line Lread transmits drive signals for reading signals from the pixels. One end of the pixel drive line Lread is connected to the output terminal corresponding to each row of the vertical drive circuit 111.

[0138] The vertical drive circuit 111 is a pixel drive unit composed of a shift register, an address decoder, etc., which drives each unit pixel P of the pixel unit 100A, for example, in row units. The signals output from each unit pixel P of the pixel row selected and scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 through each of the vertical signal lines Lsig. The column signal processing circuit 112 is composed of amplifiers, horizontal selection switches, etc., provided for each vertical signal line Lsig.

[0139] The horizontal drive circuit 113 is composed of a shift register, an address decoder, etc., and sequentially drives each horizontal selection switch of the column signal processing circuit 112 while scanning it. Through this selection scanning by the horizontal drive circuit 113, the signals of each pixel transmitted through each of the vertical signal lines Lsig are sequentially output to the horizontal signal line 121 and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal line 121.

[0140] The output circuit 114 processes the signals sequentially supplied from each of the column signal processing circuits 112 via the horizontal signal line 121 and outputs them. The output circuit 114 may, for example, only perform buffering, or it may perform black level adjustment, column variation correction, and various digital signal processing.

[0141] The circuit portion consisting of the vertical drive circuit 111, column signal processing circuit 112, horizontal drive circuit 113, horizontal signal line 121, and output circuit 114 may be formed directly on the semiconductor substrate 30, or it may be arranged on an external control IC. Alternatively, these circuit portions may be formed on other substrates connected by cables or the like.

[0142] The control circuit 115 receives a clock signal and data commanding the operating mode from outside the semiconductor substrate 30, and outputs data such as internal information of the imaging device 100. The control circuit 115 also has a timing generator that generates various timing signals, and controls the drive of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

[0143] The input / output terminal 116 is used for exchanging signals with the outside world.

[0144] (Application Example 2) Furthermore, the imaging device 100 described above can be applied to various electronic devices, such as imaging systems like digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions.

[0145] Figure 22 is a block diagram showing an example of the configuration of electronic device 1000.

[0146] As shown in Figure 22, the electronic device 1000 includes an optical system 1001, an imaging device 100, and a DSP (Digital Signal Processor) 1002. The DSP 1002, memory 1003, display device 1004, recording device 1005, operating system 1006, and power supply system 1007 are connected via a bus 1008, and it is capable of capturing still and moving images.

[0147] The optical system 1001 is composed of one or more lenses and captures incident light (image light) from the subject and forms an image on the imaging surface of the imaging device 100.

[0148] The imaging device 100 is the same as described above. The imaging device 100 converts the amount of incident light imaged onto the imaging surface by the optical system 1001 into an electrical signal on a pixel-by-pixel basis and supplies it to the DSP 1002 as a pixel signal.

[0149] The DSP 1002 performs various signal processing on the signal from the imaging device 100 to acquire an image, and temporarily stores the image data in the memory 1003. The image data stored in the memory 1003 is recorded in the recording device 1005 or supplied to the display device 1004 to display the image. The operation system 1006 accepts various operations from the user and supplies operation signals to each block of the electronic equipment 1000, and the power supply system 1007 supplies the power necessary to drive each block of the electronic equipment 1000.

[0150] (Application Example 3) Figure 23A schematically shows an example of the overall configuration of a photodetection system 2000 equipped with an imaging device 100. Figure 23B shows an example of the circuit configuration of the photodetection system 2000. The photodetection system 2000 includes a light-emitting device 2001 as a light source that emits infrared light L2, and a photodetection device 2002 as a light-receiving unit having a photoelectric conversion element. The imaging device 100 described above can be used as the photodetection device 2002. The photodetection system 2000 may further include a system control unit 2003, a light source drive unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0151] The photodetector 2002 can detect light L1 and light L2. Light L1 is light reflected from ambient light from the outside by the subject (object to be measured) 2100 (Figure 23A). Light L2 is light that has been emitted by the light-emitting device 2001 and then reflected by the subject 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 is detectable in the photoelectric conversion unit of the photodetector 2002, and light L2 is detectable in the photoelectric conversion region of the photodetector 2002. Image information of the subject 2100 can be obtained from light L1, and distance information between the subject 2100 and the photodetector system 2000 can be obtained from light L2. The photodetector system 2000 can be mounted on, for example, electronic devices such as smartphones or mobile devices such as cars. The light-emitting device 2001 can be, for example, a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The detection method for light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can, for example, be the iTOF method, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100 by, for example, the time-of-flight (TOF). The detection method for light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, the structured light method or the stereo vision method. For example, in the structured light method, the distance between the photodetector 2000 and the subject 2100 can be measured by projecting a predetermined pattern of light onto the subject 2100 and analyzing the degree of distortion of the pattern. In the stereo vision method, for example, the distance between the photodetector 2000 and the subject can be measured by using two or more cameras to acquire two or more images of the subject 2100 from two or more different viewpoints. The light-emitting device 2001 and the photodetector 2002 can be synchronized and controlled by the system control unit 2003.

[0152] <4. Application Examples> (Examples of application to endoscopic surgical systems) The technology described herein (the Technology) can be applied to a variety of products. For example, the Technology described herein may be applied to an endoscopic surgical system.

[0153] Figure 24 is a diagram showing an example of a schematic configuration of an endoscopic surgical system to which the technology described herein (the technology) may be applied.

[0154] Figure 24 illustrates a surgeon (physician) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgical system 11000. As shown in the figure, the endoscopic surgical system 11000 consists of an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment device 11112, a support arm device 11120 for supporting the endoscope 11100, and a cart 11200 equipped with various devices for endoscopic surgery.

[0155] The endoscope 11100 consists of a barrel 11101, the tip of which is inserted into the body cavity of the patient 11132 for a predetermined length, and a camera head 11102 connected to the base end of the barrel 11101. In the illustrated example, the endoscope 11100 is shown as a so-called rigid endoscope having a rigid barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible endoscope having a flexible barrel.

[0156] An opening into which an objective lens is fitted is provided at the tip of the endoscope tube 11101. A light source device 11203 is connected to the endoscope 11100, and the light generated by the light source device 11203 is guided to the tip of the endoscope tube by a light guide extending inside the endoscope tube 11101, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0157] The camera head 11102 contains an optical system and an image sensor. Reflected light from the object being observed (observation light) is focused onto the image sensor by the optical system. The image sensor converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. This image signal is transmitted as RAW data to the camera control unit (CCU) 11201.

[0158] The CCU11201 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and controls the operation of the endoscope 11100 and the display device 11202. It controls everything comprehensively. Furthermore, the CCU11201 receives an image signal from the camera head 11102 and performs various image processing operations on that image signal, such as development processing (demosaic processing), to display an image based on that image signal.

[0159] The display device 11202 displays an image based on an image signal that has been processed by the CCU 11201, under control from the CCU 11201.

[0160] The light source device 11203 consists of a light source such as an LED (light-emitting diode) and supplies illumination light to the endoscope 11100 when photographing the surgical area, etc.

[0161] The input device 11204 is an input interface for the endoscopic surgical system 11000. The user can input various information and instructions to the endoscopic surgical system 11000 via the input device 11204. For example, the user can input instructions to change the imaging conditions (type of light, magnification, focal length, etc.) of the endoscope 11100.

[0162] The treatment instrument control device 11205 controls the drive of the energy treatment instrument 11112 for purposes such as tissue cauterization, incision, or vascular sealing. The insufflation device 11206 delivers gas into the patient's body cavity via the insufflation tube 11111 to inflate the body cavity of the patient 11132 for the purpose of securing a field of view by the endoscope 11100 and securing the operator's working space. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, images, or graphs.

[0163] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical area, can be configured as a white light source consisting of, for example, an LED, a laser light source, or a combination thereof. When the white light source is configured as a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to time-divisionally capture images corresponding to each of the RGB light sources by irradiating the observation target with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter on the image sensor.

[0164] Furthermore, the light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the drive of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity, images can be acquired in time-division order, and these images can be combined to generate high dynamic range images without so-called black crushing and white clipping.

[0165] Furthermore, the light source device 11203 may be configured to supply light in a predetermined wavelength range corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissues and irradiating with narrow-band light compared to the irradiation light used during normal observation (i.e., white light), so-called narrow-band imaging is performed to capture images of predetermined tissues such as blood vessels on the surface of mucous membranes with high contrast. Alternatively, in special light observation, excitation light is irradiated. Fluorescence observation may be performed to obtain an image from the fluorescence generated by irradiation. In fluorescence observation, excitation light is irradiated onto body tissue and the fluorescence from the body tissue is observed (autofluorescence observation), or a reagent such as indocyanine green (ICG) is injected locally into body tissue and the body tissue is... By irradiating the reagent with excitation light corresponding to its fluorescence wavelength, a fluorescence image can be obtained. The light source device 11203 can be configured to supply narrowband light and / or excitation light suitable for such special light observations.

[0166] Figure 25 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Figure 24.

[0167] The camera head 11102 includes a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so that they can communicate with one another.

[0168] The lens unit 11401 is an optical system provided at the connection point with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and then incident on the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses, including a zoom lens and a focus lens.

[0169] The imaging unit 11402 may consist of one image sensor (a so-called single-chip type) or multiple image sensors (a so-called multi-chip type). If the imaging unit 11402 is configured as a multi-chip type, for example, each image sensor may generate an image signal corresponding to RGB, and these may be combined to obtain a color image. Alternatively, the imaging unit 11402 may acquire image signals for the right eye and left eye, respectively, to support 3D (dimensional) display. The system may be configured to have a pair of image sensors. 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue in the surgical area. If the imaging unit 11402 is configured as a multi-plate system, multiple lens units 11401 may be provided corresponding to each image sensor.

[0170] Furthermore, the imaging unit 11402 does not necessarily have to be located in the camera head 11102. For example, the imaging unit 11402 may be located inside the lens barrel 11101, directly behind the objective lens.

[0171] The drive unit 11403 is composed of actuators and, under control from the camera head control unit 11405, moves the zoom lens and focus lens of the lens unit 11401 along the optical axis by a predetermined distance. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted as appropriate.

[0172] The communication unit 11404 consists of communication devices for sending and receiving various types of information with the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400.

[0173] Furthermore, the communication unit 11404 receives control signals from the CCU 11201 to control the drive of the camera head 11102 and supplies them to the camera head control unit 11405. These control signals include information regarding imaging conditions, such as information to specify the frame rate of the captured image, information to specify the exposure value at the time of imaging, and / or information to specify the magnification and focus of the captured image.

[0174] The above imaging conditions, such as frame rate, exposure value, magnification, and focus, may be specified by the user as appropriate, or they may be automatically set by the control unit 11413 of the CCU11201 based on the acquired image signal. In the latter case, the so-called AE (Auto Exposure), AF (Auto Focus), and AWB (Auto White Balance) functions will be applied to the endoscope 11 This means it will be installed in the 100.

[0175] The camera head control unit 11405 controls the drive of the camera head 11102 based on the control signal received from the CCU 11201 via the communication unit 11404.

[0176] The communication unit 11411 consists of a communication device for sending and receiving various types of information with the camera head 11102. The communication unit 11411 receives image signals transmitted from the camera head 11102 via the transmission cable 11400.

[0177] Furthermore, the communication unit 11411 transmits control signals to the camera head 11102 to control the driving of the camera head 11102. Image signals and control signals can be transmitted via telecommunications, optical communications, etc.

[0178] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102.

[0179] The control unit 11413 performs various controls related to imaging the surgical area, etc., by the endoscope 11100, and the display of the images obtained from imaging the surgical area, etc. For example, the control unit 11413 generates control signals to control the driving of the camera head 11102.

[0180] Furthermore, the control unit 11413 displays the captured image showing the surgical area on the display device 11202 based on the image signal processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical instruments such as forceps, specific biological sites, bleeding, mist when using the energy treatment device 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information onto the image of the surgical area. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced, and the surgeon 11131 can proceed with the surgery with confidence.

[0181] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable compatible with electrical signal communication, an optical fiber compatible with optical communication, or a composite cable thereof.

[0182] In the illustrated example, communication was performed via a wired connection using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may be performed wirelessly.

[0183] The above describes an example of an endoscopic surgical system to which the technology described herein may be applied. The technology described herein can be applied to the imaging unit 11402 of the configuration described above. By applying the technology described herein to the imaging unit 11402, the detection accuracy is improved.

[0184] While an endoscopic surgical system has been described here as an example, the technology described herein may also be applied to other systems, such as microsurgical systems.

[0185] (Examples of applications to mobile devices) The technology disclosed herein can be applied to a variety of products. For example, the technology disclosed herein may be implemented as a device mounted on any type of mobile vehicle, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, robots, construction machinery, or agricultural machinery (tractors).

[0186] Figure 26 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0187] The vehicle control system 12000 comprises multiple electronic control units connected via a communication network 12001. In the example shown in Figure 26, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The integrated control unit 12050 also includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 120 Figure 53 is shown.

[0188] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0189] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0190] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0191] 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 as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0192] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0193] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking system based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform ADAS (Advanced Driver Assistance System) functions such as collision avoidance or impact mitigation, following based on distance between vehicles, maintaining vehicle speed, collision warning, or lane departure warning. Cooperative control can be performed for the purpose of achieving a specific function.

[0194] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0195] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0196] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 26, the output devices are exemplified as an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0197] Figure 27 shows an example of the installation position of the imaging unit 12031.

[0198] In Figure 27, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0199] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0200] Figure 27 shows an example of the imaging range of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0201] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0202] For example, the microcomputer 12051, based on distance information obtained from imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to vehicle 12100). In particular, it can extract the nearest object on the vehicle 12100's path that is traveling in approximately the same direction as vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0203] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, heavy vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0204] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0205] The above describes an example of a mobile object control system to which the technology described herein can be applied. The technology described herein can be applied to the imaging unit 12031 of the configuration described above. Specifically, the image sensor (for example, image sensor 1A) according to the above embodiment and its modified form can be applied to the imaging unit 12031. By applying the technology described herein to the imaging unit 12031, high-definition captured images with low noise can be obtained, so that high-precision control using captured images can be performed in the mobile object control system.

[0206] <5. Examples> Next, embodiments of the present disclosure will be described.

[0207] (Experiment 1) In Experiment 1, the second layer 12B of the hole-blocking layer 12 was made of fullerene (fullerene C 60 The dark current characteristics, external quantum efficiency, and afterimage characteristics were evaluated when the film was formed as a mixed film containing ).

[0208] (Experimental Example 1-1) First, a 100 nm thick ITO film was deposited on a silicon substrate using a sputtering apparatus. This was then processed by photolithography and etching to form the lower electrode 11. Next, an insulating film was deposited on the silicon substrate and the lower electrode 11, and a 1 mm square opening exposing the lower electrode 11 was formed by lithography and etching. Subsequently, the silicon substrate was cleaned with UV / ozone treatment, and then the silicon substrate was transferred to a vacuum deposition apparatus, and the deposition tank was set to 1 × 10⁻⁶ -5 While the substrate holder was rotated under reduced pressure below Pa, a hole blocking layer 12 (first layer 12A, second layer 12B), a photoelectric conversion layer 13, an electron blocking layer 14, and a work function adjustment layer 15 were sequentially deposited on the lower electrode 11. Specifically, the naphthalenediimide (NDI) derivative shown in formula (1-27) above was deposited to a thickness of 10 nm at a substrate temperature of 40°C, and this was designated as the first layer 12A. Next, the subphthalocyanine derivative shown in formula (3-5) above and the fullerene C shown in formula (2) were deposited. 60 These were deposited at a substrate temperature of 40°C at deposition rates of 1.0 Å / sec and 0.250 Å / sec, respectively, to a thickness of 10 nm, and this was designated as the second layer 12B. Subsequently, the subphthalocyanine derivative shown in formula (3-5) above, DPh-BTBT shown in formula (4) below, and fullerene C shown in formula (2) were deposited. 60 At a substrate temperature of 40°C, two films were deposited at deposition rates of 0.50 Å / sec, 0.50 Å / sec, and 0.25 Å / sec, respectively, to a thickness of 230 nm, and this was designated as the photoelectric conversion layer 13. Next, the PC-IC shown in equation (5) below was deposited at a substrate temperature of 0°C to a thickness of 10 nm, and this was designated as the electron block layer 14. Subsequently, the HAT-CN shown in equation (6) below was deposited to a thickness of 10 nm, and this was designated as the work function adjustment layer 15. Finally, the silicon substrate was transferred to a sputtering apparatus, and a 50 nm thick ITO film was deposited on the work function adjustment layer 15, and this was designated as the upper electrode 16. After that, the silicon substrate was annealed at 150°C for 210 minutes under a nitrogen atmosphere, and this was designated as the evaluation element.

[0209] [ka]

[0210] (Experimental Examples 1-2) An evaluation element was fabricated using the same method as in Experimental Example 1-1, except that the second layer 12B deposited in Experimental Example 1-1 was omitted.

[0211] (Experimental Examples 1-3) An evaluation element was fabricated using the same method as in Experimental Example 1-1, except that the first layer 12A deposited in Experimental Example 1-1 was omitted.

[0212] (Evaluation of dark current and external quantum efficiency) The wavelength of the light irradiated onto the evaluation element from a green LED light source via a bandpass filter is 560 nm, and the light intensity is 1.62 μW / cm². 2 The bias voltage applied between the electrodes of the evaluation element was controlled using a semiconductor parameter analyzer, and a current-voltage curve was obtained by sweeping the voltage applied to the lower electrode 11 relative to the upper electrode 16. The dark current value and bright current value were obtained in the reverse bias applied state (voltage applied at +2.6V), and the external quantum efficiency (EQE) was calculated by subtracting the dark current value from the bright current value and dividing the result by the number of incident photons.

[0213] (Evaluation of afterimage) The wavelength of light irradiated from a green LED light source through a bandpass filter onto the photoelectric conversion element is 560 nm, and the light intensity is 162 μW / cm². 2 The voltage applied to the LED driver was controlled by a function generator, and pulsed light with a pulse width of 100 ms was irradiated from the upper electrode 16 side. A bias voltage of +2.6V was applied to the lower electrode 11 relative to the upper electrode 16 when the pulsed light was irradiated, and the current decay waveform was observed using an oscilloscope. The amount of Coulombs during the current decay process from immediately after the light pulse irradiation stopped to 110 ms later was measured and used as an indicator of the afterimage amount. A lower afterimage amount indicates a faster photoresponse.

[0214] [Table 1]

[0215] Table 1 summarizes the configuration and device characteristics (dark current, EQE, and afterimage) of the hole block layer 12 for Experimental Examples 1-1 to 1-3. The values ​​for dark current, EQE, and afterimage summarized in Table 1 are relative values, with the characteristic value for Experimental Example 1-1 set as the reference value (1.0).

[0216] Experimental Example 1-1 showed lower dark current, equivalent EQE, and less afterimage compared to Experimental Example 1-2. In Experimental Example 1-2, the dark current was higher because the suppression of dark current generation at the interface between the hole blocking layer 1 (first layer 12A) and the photoelectric conversion layer 13 was insufficient compared to Experimental Example 1-1. Furthermore, in Experimental Example 1-2, the afterimage was increased because the suppression of interface trapping between the hole blocking layer 1 and the photoelectric conversion layer 13 was insufficient compared to Experimental Example 1-1.

[0217] Experimental Example 1-1 showed lower dark current, superior EQE, and comparable afterimage compared to Experimental Example 1-3. This is thought to be because, in Experimental Example 1-3, the HOMO of the hole block was 0.9 eV shallower with respect to the work function of the lower electrode 11 compared to Experimental Example 1-1, which was insufficient to suppress hole injection from the lower electrode 11, resulting in a higher dark current. Furthermore, in Experimental Example 1-3, the presence of an electron barrier at the interface between the lower electrode 11 and the hole block is thought to have resulted in a lower EQE compared to Experimental Example 1-1.

[0218] Furthermore, in Experimental Example 1-1, since the hole blocking layer 1 was placed on the side in contact with the lower electrode 11, the injection of holes from the lower electrode 11 was suppressed, and by placing the hole blocking layer 2 (second layer 12B) on the side in contact with the photoelectric conversion layer 13, the generation at the interface of the photoelectric conversion layer 13 was suppressed, and it is thought that these effects suppressed the dark current. In addition, since the hole blocking layer 1 was placed on the side in contact with the lower electrode 11, the electron barrier at the interface between the lower electrode 11 and the hole blocking layer 1 was reduced, resulting in a high EQE. Furthermore, since the hole blocking layer 2 was placed on the side of the photoelectric conversion layer 13, it is thought that interface trapping between the hole blocking layer 2 and the photoelectric conversion layer 13 was suppressed, resulting in a low afterimage amount.

[0219] Note that by disposing the hole-blocking layer 1 on the side contacting the lower electrode 11, the reason why the electron barrier at the interface between the lower electrode 11 and the hole-blocking layer 1 becomes small is that an interfacial dipole occurs due to the bonding of the hole-blocking layer 1 and the lower electrode 11, the Fermi level of the lower electrode 11 shifts in the direction of positive potential with respect to the vacuum level, and the potential gradient during voltage application becomes advantageous for electron extraction, so that the electron barrier from the LUMO of the apparent hole-blocking layer 1 to the Fermi level of the lower electrode 11 is considered to have become small.

[0220] (Experiment 2) In Experiment 2, the dark current characteristics, external quantum efficiency, and afterimage characteristics when the second layer 12B of the hole-blocking layer 12 was formed as a single-layer film of fullerene (fullerene C 60 ) were evaluated. Note that the applied voltage was changed from Experiment 1 to Experiment 2. Specifically, the dark current characteristics were obtained under a voltage application state of -2.6 V, the external quantum efficiency was obtained under a voltage application state of 0 V, and the afterimage characteristics were obtained under a voltage application state of -2.6 V.

[0221] (Experimental Example 2-1) First, an ITO film with a thickness of 100 nm was formed on a silicon substrate using a sputtering apparatus. This was processed by photolithography and etching to form the lower electrode 11. Next, an insulating film was formed on the silicon substrate and the lower electrode 11, and an opening with a size of 1 mm square where the lower electrode 11 was exposed was formed by lithography and etching. Subsequently, after the silicon substrate was cleaned by UV / ozone treatment, the silicon substrate was transferred to a vacuum evaporation apparatus, and while rotating the substrate holder under a reduced pressure of 1×10 -5 Pa or less, an electron-blocking layer 14, a photoelectric conversion layer 13, and a hole-blocking layer 12 (first layer 12A, second layer 12B) were sequentially formed on the lower electrode 11. Specifically, PC-IC shown in the above formula (5) was formed at a substrate temperature of 0 °C to a thickness of 10 nm, and this was used as the electron-blocking layer 14. Next, the subphthalocyanine derivative shown in the above formula (3-5), DPh-BTBT shown in the above formula (4), and fullerene C shown in the formula (2) 60And were each formed on a substrate at a temperature of 40°C at a film formation rate of 0.50 Å / second, 0.50 Å / second, and 0.25 Å / second to a thickness of 230 nm, which was used as the photoelectric conversion layer 13. Subsequently, fullerene C shown in formula (2) 60 was formed on a substrate at a temperature of 0°C to a thickness of 10 nm, which was used as the second layer 12B. Next, the naphthalenediimide (NDI) derivative shown in the above formula (1-23) was formed on a substrate at a temperature of 0°C to a thickness of 10 nm, which was used as the first layer 12A. Finally, the silicon substrate was transferred to a sputtering apparatus, and an ITO film with a thickness of 50 nm was formed on the first layer 12A, which was used as the upper electrode 16. Thereafter, in a nitrogen atmosphere, the silicon substrate was annealed at 150°C for 210 minutes to obtain an evaluation element.

[0222] (Experimental Example 2-2) An evaluation element was fabricated in the same manner as in Experimental Example 2-1, except that the second layer 12B formed in Experimental Example 2-1 was omitted.

[0223] (Experimental Example 2-3) An evaluation element was fabricated in the same manner as in Experimental Example 2-1, except that DPh-BTBT used in the photoelectric conversion layer 13 formed in Experimental Example 2-1 was changed to BP-rBDT shown in the following formula (7).

[0224]

Chemical formula

[0225] (Experimental Example 2-4) An evaluation element was fabricated in the same manner as in Experimental Example 2-3, except that the second layer 12B formed in Experimental Example 2-3 was omitted.

[0226]

Table 2

[0227] Table 2 summarizes the configuration and device characteristics (dark current, EQE, and afterimage) of the hole block layer 12 for Experimental Examples 2-1 to 2-4. Note that the values ​​for dark current, EQE, and afterimage summarized in Table 1 are relative values, with the characteristic values ​​for Experimental Examples 2-1 and 2-3 set as the baseline value (1.0).

[0228] Experimental Example 2-1 showed lower dark current, higher EQE, and less afterimage compared to Experimental Example 2-2. In Experimental Example 2-2, the dark current was higher because the suppression of dark current generation at the interface between the hole block layer 1 (first layer 12A) and the photoelectric conversion layer 13 was insufficient compared to Experimental Example 2-1. In addition, in Experimental Example 2-2, the EQE was lower because an electron barrier was present at the interface between the hole block layer 1 and the photoelectric conversion layer 13 compared to Experimental Example 2-1. Furthermore, in Experimental Example 2-2, the afterimage was higher because the suppression of interface trapping between the hole block layer 1 and the photoelectric conversion layer 13 was insufficient compared to Experimental Example 2-1.

[0229] Experimental Example 2-3 showed lower dark current, higher EQE, and less afterimage compared to Experimental Example 2-4. In Experimental Example 2-4, the dark current was higher than in Experimental Example 2-3 because the suppression of dark current generation at the interface between the hole blocking layer 1 and the photoelectric conversion layer 13 was insufficient. In addition, in Experimental Example 2-4, the EQE was lower than in Experimental Example 2-3 because an electron barrier was present at the interface between the hole blocking layer 1 and the photoelectric conversion layer 13. Furthermore, in Experimental Example 2-4, the afterimage was higher than in Experimental Example 2-3 because the suppression of interface trapping between the hole blocking layer 1 and the photoelectric conversion layer 13 was insufficient.

[0230] In Experimental Examples 2-1 and 2-3, the hole blocking layer 1 was placed on the side in contact with the upper electrode 16, which suppressed the injection of holes from the upper electrode 16. The hole blocking layer 2 (second layer 12B) was placed on the side in contact with the photoelectric conversion layer 13, which suppressed the generation of holes at the interface with the photoelectric conversion layer 13. It is thought that these effects suppressed the dark current. Furthermore, since the hole blocking layer 2 was placed on the side of the photoelectric conversion layer 13, it is thought that interface trapping between the hole blocking layer 2 and the photoelectric conversion layer 13 was suppressed, resulting in a high EQE and low afterimage at 0V.

[0231] The present technology has been described above with reference to embodiments, modifications 1 to 5, examples, application examples, and application examples. However, the contents of this disclosure are not limited to the above embodiments, and various modifications are possible. For example, in the above embodiments, an example was shown in which electrons are read out as signal charges from the lower electrode 11 side, but it is not limited to this, and holes may be read out as signal charges from the lower electrode 11 side. In that case, a work function adjustment layer 15 and an electron blocking layer 14 are stacked between the lower electrode 11 and the photoelectric conversion layer 13 in this order from the lower electrode 11 side, and a first layer 12A and a second layer 12B constituting a hole blocking layer 12 are formed between the upper electrode 16 and the photoelectric conversion layer 13 in this order from the upper electrode 16 side. In this configuration, the work function adjustment layer 15 may be omitted.

[0232] Furthermore, in the above embodiment, the image sensor 1A is configured by stacking a photoelectric conversion unit 10 made of an organic material that detects green light (G) with a photoelectric conversion region 32B and a photoelectric conversion region 32R that detect blue light (B) and red light (R), respectively. However, the contents of this disclosure are not limited to this structure. That is, the photoelectric conversion unit made of an organic material may be configured to detect red light (R) or blue light (B), or the photoelectric conversion region made of an inorganic material may be configured to detect green light (G).

[0233] Furthermore, the number and ratio of photoelectric conversion units made of organic materials and photoelectric conversion regions made of inorganic materials are not limited. Moreover, the structure is not limited to stacking the photoelectric conversion units made of organic materials and photoelectric conversion regions made of inorganic materials in the vertical direction; they may also be arranged in parallel along the substrate surface.

[0234] Furthermore, although the above embodiments illustrate the configuration of a back-illuminated image sensor, the contents of this disclosure are also applicable to front-illuminated image sensors.

[0235] Furthermore, the photoelectric conversion element 10, image sensor 1A, etc., and imaging device 100 of this disclosure do not need to have all of the components described in the above embodiments, and conversely, they may have other components. For example, the imaging device 100 may be equipped with a shutter for controlling the incidence of light to the image sensor 1A, or it may be equipped with an optical cut filter depending on the purpose of the imaging device 100. In addition, the arrangement of pixels (Pr, Pg, Pb) that detect red light (R), green light (G), and blue light (B) may be an interline arrangement, G-stripe RB checkerboard arrangement, G-stripe RB complete checkerboard arrangement, checkerboard complementary arrangement, stripe arrangement, diagonal stripe arrangement, primary color difference arrangement, field color difference sequential arrangement, frame color difference sequential arrangement, MOS type arrangement, improved MOS type arrangement, frame interleaved arrangement, or field interleaved arrangement, in addition to the Bayer arrangement.

[0236] Furthermore, although the above embodiments and other examples show the photoelectric conversion element 10 being used as an image sensor, the photoelectric conversion element 10 of this disclosure may also be applied to solar cells. When applied to solar cells, it is preferable that the photoelectric conversion layer be designed to broadly absorb wavelengths of, for example, 400 nm to 800 nm.

[0237] Note that the present technology can also adopt the following configuration. According to the present technology with the following configuration, a first charge blocking layer containing an organic material having a HOMO level deeper than the work function of the first electrode by 1 eV or more and a LUMO level of 3.7 eV or more and 4.8 eV or less, and a second charge blocking layer containing a fullerene or a fullerene derivative are provided in this order from the side of the first electrode between the first electrode and the photoelectric conversion layer. Thereby, while suppressing the injection of charges from the first electrode, the electron barrier at the interface with the first electrode is reduced. Also, while suppressing the generation of dark current at the interface of the photoelectric conversion layer, the generation of interface traps with the photoelectric conversion layer is reduced. Therefore, it becomes possible to improve the device characteristics. (1) A first electrode, A second electrode disposed opposite to the first electrode, A photoelectric conversion layer provided between the first electrode and the second electrode and containing a fullerene or a fullerene derivative, A first charge blocking layer provided between the first electrode and the photoelectric conversion layer and containing an organic material having a HOMO level deeper than the work function of the first electrode by 1 eV or more and a LUMO level of 3.7 eV or more and 4.8 eV or less, A second charge blocking layer provided between the first charge blocking layer and the photoelectric conversion layer and containing the fullerene or the fullerene derivative. 、 The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges. The second charge-blocking layer comprises the fullerene or fullerene derivative and the dye material. A photoelectric conversion device. [[ID=二十一]](2)[[ID=二十二]] [[ID=二十三]]The organic material has a band gap of 2.6 eV or more, and the photoelectric conversion device according to (1) above. [[ID=二十四]] [[ID=二十五]](3)[[ID=二十六]] [[ID=二十七]]The organic material has a HOMO level deeper than 6.3 eV, and the photoelectric conversion device according to (1) or (2) above. [[ID=二十八]] [[ID=二十九]](4)[[ID=三十]] [[ID=三十一]]The first charge blocking layer has a thickness of 1 nm or more and 30 nm or less, and the photoelectric conversion device according to any one of (1) to (3) above. [[ID=三十二]] [[ID=三十三]](5)[[ID=三十四]] The photoelectric conversion element according to any one of (1) to (4) above, wherein the second charge blocking layer has a thickness of 1 nm to 30 nm. (6) The photoelectric conversion element according to any one of (1) to (5), wherein the first electrode has a work function of 4.0 eV or more and 5.5 eV or less, and a work function deeper than the LUMO level of the organic material. (7 ) before The second charge-blocking layer comprises the fullerene or fullerene derivative and the material of the first charge-blocking layer. Any one of the above (1) through (6) The photoelectric conversion element described above. (8) The first charge-blocking layer and the second charge-blocking layer are hole-blocking layers. Any one of the above (1) through (7) The photoelectric conversion element described above. (9) The first electrode consists of a plurality of electrodes that are independent of each other. Any one of the above (1) through (8) The photoelectric conversion element described above. (10) A voltage is applied to each of the aforementioned multiple electrodes individually. (9) The photoelectric conversion element described above. (11) The semiconductor further comprises an oxide semiconductor between the first electrode and the first charge blocking layer. (9) or (10) above The photoelectric conversion element described above. (12) The first electrode and the semiconductor layer further have an insulating layer covering the first electrode, The insulating layer has an opening above one of the plurality of electrodes constituting the first electrode, and the one electrode is electrically connected to the semiconductor layer through the opening. (11) The photoelectric conversion element described above. (13) The image sensor comprises multiple pixels, each of which is provided with one or more photoelectric conversion units. The aforementioned photoelectric conversion unit is First electrode and, A second electrode positioned opposite the first electrode, A photoelectric conversion layer comprising a fullerene or fullerene derivative is provided between the first electrode and the second electrode, A first charge-blocking layer is provided between the first electrode and the photoelectric conversion layer and comprises an organic material having a HOMO level that is 1 eV or more deeper than the work function of the first electrode and a LUMO level that is 3.7 eV or more and 4.8 eV or less. A second charge-blocking layer is provided between the first charge-blocking layer and the photoelectric conversion layer, and the second charge-blocking layer includes the fullerene or fullerene derivative. It has, The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges. The second charge-blocking layer comprises the fullerene or fullerene derivative and the dye material. Imaging device. (14) The image sensor further has one or more photoelectric conversion regions that perform photoelectric conversion in a wavelength band different from that of the one or more photoelectric conversion units. (13) The imaging device described above. (15) The one or more photoelectric conversion regions are embedded and formed in a semiconductor substrate. The one or more photoelectric conversion units are arranged on the light incident surface side of the semiconductor substrate. (14) The imaging device described above. (16) A multilayer wiring layer is formed on the semiconductor substrate on the side opposite to the light incident surface. (15) The imaging device described above.

[0238] Furthermore, this technology can also be configured as follows. In this configuration, a first charge-blocking layer containing an organic material having a HOMO level at least 1 eV deeper than the work function of the first electrode and a LUMO level between 3.7 eV and 4.8 eV, and a second charge-blocking layer containing a fullerene or fullerene derivative are provided between the first electrode and the photoelectric conversion layer, in this order from the first electrode side. This suppresses charge injection from the first electrode while reducing the electron barrier at the interface with the first electrode. It also suppresses the generation of dark current at the interface with the photoelectric conversion layer while reducing the occurrence of interface traps with the photoelectric conversion layer. Thus, it is possible to improve the device characteristics. (1) First electrode and, A second electrode positioned opposite the first electrode, A photoelectric conversion layer comprising a fullerene or fullerene derivative is provided between the first electrode and the second electrode, A first charge-blocking layer is provided between the first electrode and the photoelectric conversion layer and comprises an organic material having a HOMO level that is 1 eV or more deeper than the work function of the first electrode and a LUMO level that is 3.7 eV or more and 4.8 eV or less. A second charge-blocking layer is provided between the first charge-blocking layer and the photoelectric conversion layer, and the second charge-blocking layer includes the fullerene or fullerene derivative. A photoelectric conversion element equipped with a photoelectric converter. (2) The organic material is the photoelectric conversion element according to (1) above, having a band gap of 2.6 eV or more. (3) The photoelectric conversion element according to (1) or (2), wherein the organic material has a HOMO level deeper than 6.3 eV. (4) The first charge blocking layer has a thickness of 1 nm to 30 nm, and is a photoelectric conversion element according to any one of (1) to (3) above. (5) The photoelectric conversion element according to any one of (1) to (4) above, wherein the second charge blocking layer has a thickness of 1 nm to 30 nm. (6) The photoelectric conversion element according to any one of (1) to (5), wherein the first electrode has a work function of 4.0 eV or more and 5.5 eV or less, and a work function deeper than the LUMO level of the organic material. (7) A photoelectric conversion element according to any one of (1) to (6), wherein the sum of the densities of states in the gap levels at the interface between the second charge block layer and the photoelectric conversion layer is less than the sum of the densities of states in the gap levels in the photoelectric conversion layer. (8) The photoelectric conversion element according to any one of (1) to (7), wherein the second charge blocking layer comprises the fullerene or fullerene derivative and the material of the first charge blocking layer. (9) The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges. The photoelectric conversion element according to any one of (1) to (8), wherein the second charge blocking layer comprises the fullerene or fullerene derivative and the dye material. (10) The photoelectric conversion element according to any one of (1) to (9), wherein the first charge-blocking layer and the second charge-blocking layer are hole-blocking layers. (11) The first electrode is a photoelectric conversion element according to any one of (1) to (10) above, comprising a plurality of electrodes that are independent of each other. (12) The photoelectric conversion element according to (11), wherein a voltage is individually applied to each of the plurality of electrodes. (13) The photoelectric conversion element according to (11) or (12), further comprising a semiconductor layer containing an oxide semiconductor between the first electrode and the first charge blocking layer. (14) The first electrode and the semiconductor layer further have an insulating layer covering the first electrode, The photoelectric conversion element according to (13), wherein the insulating layer has an opening above one of the plurality of electrodes constituting the first electrode, and the one electrode is electrically connected to the semiconductor layer through the opening. (15) The image sensor comprises multiple pixels, each of which is provided with one or more photoelectric conversion units. The aforementioned photoelectric conversion unit is First electrode and, A second electrode positioned opposite the first electrode, A photoelectric conversion layer comprising a fullerene or fullerene derivative is provided between the first electrode and the second electrode, A first charge-blocking layer is provided between the first electrode and the photoelectric conversion layer and comprises an organic material having a HOMO level that is 1 eV or more deeper than the work function of the first electrode and a LUMO level that is 3.7 eV or more and 4.8 eV or less. A second charge-blocking layer is provided between the first charge-blocking layer and the photoelectric conversion layer, and the second charge-blocking layer includes the fullerene or fullerene derivative. An imaging device having (16) The imaging apparatus according to (15), wherein the image sensor further has one or more photoelectric conversion regions that perform photoelectric conversion in a wavelength band different from that of the one or more photoelectric conversion units. (17) The one or more photoelectric conversion regions are embedded and formed in a semiconductor substrate. The imaging apparatus according to (16), wherein the one or more photoelectric conversion units are arranged on the light incident surface side of the semiconductor substrate. (18) The imaging apparatus according to (17), wherein a multilayer wiring layer is formed on the semiconductor substrate on the side opposite to the light incident surface.

[0239] This application claims priority based on Japanese Patent Application No. 2021-088808, filed with the Japan Patent Office on 26 May 2021, and all contents of that application are incorporated herein by reference.

[0240] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. First electrode and, A second electrode positioned opposite the first electrode, A photoelectric conversion layer comprising a fullerene or fullerene derivative is provided between the first electrode and the second electrode, A first charge-blocking layer is provided between the first electrode and the photoelectric conversion layer and comprises an organic material having a HOMO level that is 1 eV or more deeper than the work function of the first electrode and a LUMO level that is 3.7 eV or more and 4.8 eV or less. The device comprises a second charge-blocking layer provided between the first charge-blocking layer and the photoelectric conversion layer, and containing the fullerene or fullerene derivative, The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges. The second charge-blocking layer comprises the fullerene or fullerene derivative and the dye material. Photoelectric conversion element.

2. The photoelectric conversion element according to claim 1, wherein the organic material has a band gap of 2.6 eV or more.

3. The photoelectric conversion element according to claim 1, wherein the organic material has a HOMO level deeper than 6.3 eV.

4. The photoelectric conversion element according to claim 1, wherein the first charge blocking layer has a thickness of 1 nm to 30 nm.

5. The photoelectric conversion element according to claim 1, wherein the second charge blocking layer has a thickness of 1 nm to 30 nm.

6. The photoelectric conversion element according to claim 1, wherein the first electrode has a work function of 4.0 eV or more and 5.5 eV or less, and has a work function deeper than the LUMO level of the organic material.

7. The photoelectric element according to claim 1, wherein the second charge blocking layer comprises the fullerene or fullerene derivative and the material of the first charge blocking layer.

8. The photoelectric conversion element according to claim 1, wherein the first charge blocking layer and the second charge blocking layer are hole blocking layers.

9. The photoelectric conversion element according to claim 1, wherein the first electrode comprises a plurality of electrodes that are independent of each other.

10. The photoelectric conversion element according to claim 9, wherein a voltage is individually applied to each of the plurality of electrodes.

11. The photoelectric conversion element according to claim 10, further comprising a semiconductor layer containing an oxide semiconductor between the first electrode and the first charge blocking layer.

12. The first electrode and the semiconductor layer further have an insulating layer covering the first electrode, The photoelectric conversion element according to claim 11, wherein the insulating layer has an opening above one of the plurality of electrodes constituting the first electrode, and the one electrode is electrically connected to the semiconductor layer through the opening.

13. The image sensor comprises multiple pixels, each of which is provided with one or more photoelectric conversion units. The aforementioned photoelectric conversion unit is First electrode and, A second electrode positioned opposite the first electrode, A photoelectric conversion layer comprising a fullerene or fullerene derivative is provided between the first electrode and the second electrode, A first charge-blocking layer is provided between the first electrode and the photoelectric conversion layer and comprises an organic material having a HOMO level that is 1 eV or more deeper than the work function of the first electrode and a LUMO level that is 3.7 eV or more and 4.8 eV or less. The first charge-blocking layer and the photoelectric conversion layer are provided with a second charge-blocking layer which contains the fullerene or fullerene derivative, The photoelectric conversion layer further includes a dye material that absorbs light in a predetermined wavelength range while transmitting light in other wavelength ranges. The second charge-blocking layer comprises the fullerene or fullerene derivative and the dye material. Imaging device.

14. The imaging apparatus according to claim 13, wherein the image sensor further has one or more photoelectric conversion regions that perform photoelectric conversion in a wavelength band different from that of the one or more photoelectric conversion units.

15. The one or more photoelectric conversion regions are embedded and formed in a semiconductor substrate. The imaging apparatus according to claim 14, wherein the one or more photoelectric conversion units are arranged on the light incident surface side of the semiconductor substrate.

16. The imaging apparatus according to claim 15, wherein a multilayer wiring layer is formed on the semiconductor substrate on the side opposite to the light incident surface.

Images