Image sensor and imaging device

Abstract

An imaging element according to one embodiment of the present disclosure is provided with: a first electrode; a second electrode which is arranged so as to face the first electrode; an organic layer which is arranged between the first electrode and the second electrode, while comprising at least a photoelectric conversion layer; and a first semiconductor layer which is arranged between the second electrode and the organic layer and has an electron affinity of 4.5 eV to 6.0 eV, while containing a first carbon-containing compound which has an electron affinity more than 4.8 eV or an electron affinity that is greater than the work function of the second electrode, and a second carbon-containing compound which has an ionization potential that is greater than 5.5 eV.

Description

[Technical Field]

[0001] This disclosure relates to an image sensor using, for example, an organic material and an imaging device equipped therewith. [Background technology]

[0002] In recent years, so-called vertical spectroscopic image sensors have been proposed, which have a vertical multilayer structure in which an organic photoelectric conversion unit is positioned above a semiconductor substrate. In a vertical spectroscopic image sensor, light in the red and blue wavelength ranges is photoelectrically converted by photoelectric conversion units (photodiodes PD1 and PD2) formed within the semiconductor substrate, respectively, while light in the green wavelength range is photoelectrically converted by an organic photoelectric conversion film provided on the organic photoelectric conversion unit.

[0003] In such image sensors, the charge generated by photoelectric conversion in photodiodes PD1 and PD2 is first stored in photodiodes PD1 and PD2 before being transferred to their respective floating diffusion layers. This allows for complete depletion of photodiodes PD1 and PD2. On the other hand, the charge generated in the organic photoelectric conversion section is directly stored in the floating diffusion layer, making it difficult to completely deplete the organic photoelectric conversion section. This results in increased kTC noise, worsening random noise, and a decrease in image quality.

[0004] In contrast, for example, Patent Document 1 discloses an image sensor in which a decrease in imaging quality is suppressed by providing a charge storage electrode that is spaced apart from the first electrode and faces the photoelectric conversion layer via an insulating layer, in a photoelectric conversion section provided on a semiconductor substrate and comprising a first electrode, a photoelectric conversion layer, and a second electrode stacked on top of each other. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-157816 [Overview of the Initiative]

[0006] By the way, improvements in manufacturing yield and element characteristics are required for image sensors.

[0007] It is desirable to provide an image sensor and imaging device that can improve manufacturing yield and element characteristics.

[0008] An image sensor according to one embodiment of the present disclosure comprises a first electrode, a second electrode positioned opposite the first electrode, an organic layer provided between the first electrode and the second electrode and including at least a photoelectric conversion layer, and a first semiconductor layer provided between the second electrode and the organic layer and including a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV.

[0009] An imaging device according to one embodiment of the present disclosure comprises one or more image sensors according to the present embodiment for each of a plurality of pixels.

[0010] In an image sensor and an imaging apparatus according to one embodiment of the present disclosure, a first semiconductor layer is provided between an organic layer including at least a photoelectric conversion layer and a second electrode, the first semiconductor layer comprising a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV and an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. This improves the adhesion between the organic layer and the second electrode and increases the electric field substantially applied to the photoelectric conversion layer. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an example of the schematic configuration of an image sensor according to the first embodiment of this disclosure. [Figure 2] Figure 1 is a schematic plan view illustrating an example of the pixel configuration of the image sensor shown. [Figure 3] Figure 1 shows the equivalent circuit diagram of the image sensor. [Figure 4] It is a schematic diagram showing the arrangement of the lower electrode of the organic optoelectronic conversion unit shown in FIG. 1 and the transistors constituting the control unit. [Figure 5A] It is a diagram showing the energy levels of a single layer film of a candidate material for the work function adjustment layer. [Figure 5B] It is a diagram showing the change in the energy level of the work function adjustment layer when it is a mixed film with the candidate material shown in FIG. 5B. [Figure 6] It is a cross-sectional view for explaining the manufacturing method of the image sensor shown in FIG. 1. [Figure 7] It is a cross-sectional view showing the process following FIG. 6. [Figure 8] It is a cross-sectional view showing the process following FIG. 7. [Figure 9] It is a cross-sectional view showing the process following FIG. 8. [Figure 10] It is a cross-sectional view showing the process following FIG. 9. [Figure 11] It is a cross-sectional view showing the process following FIG. 10. [Figure 12] It is a cross-sectional view showing the process following FIG. 11. [Figure 13] It is a timing diagram showing an example of an operation of the image sensor shown in FIG. 1. [Figure 14] It is a cross-sectional schematic diagram showing an example of the schematic configuration of the image sensor according to the second embodiment of the present disclosure. [Figure 15] It is a cross-sectional schematic diagram showing an example of the configuration of the image sensor according to Modification 1 of the present disclosure. [Figure 16A] It is a cross-sectional schematic diagram showing an example of the configuration of the image sensor according to Modification 2 of the present disclosure. [Figure 16B] It is a schematic diagram showing the planar configuration of the image sensor shown in FIG. 16A. [Figure 17A] It is a cross-sectional schematic diagram showing an example of the configuration of the image sensor according to Modification 3 of the present disclosure. [Figure 17B] It is a schematic diagram showing the planar configuration of the image sensor shown in FIG. 17A. [Figure 18] It is a cross-sectional schematic showing an example of the configuration of the image sensor according to Modification 4 of the present disclosure. [Figure 19] This is a schematic cross-sectional view showing another example of the configuration of the image sensor according to Modification 4 of this disclosure. [Figure 20A] This is a schematic cross-sectional view showing another example of the configuration of the image sensor according to Modification 4 of this disclosure. [Figure 20B] Figure 20A is a schematic diagram showing the planar configuration of the image sensor. [Figure 21A] This is a schematic cross-sectional view showing another example of the configuration of the image sensor according to Modification 4 of this disclosure. [Figure 21B] Figure 21A is a schematic diagram showing the planar configuration of the image sensor. [Figure 22] This is a block diagram showing the configuration of an imaging device using the image sensor shown in Figure 1 as pixels. [Figure 23] Figure 22 is a functional block diagram showing an example of an electronic device (camera) using the imaging device shown. [Figure 24A] Figure 22 is a schematic diagram illustrating an example of the overall configuration of a photodetection system using the imaging device shown. [Figure 24B] Figure 24A shows an example of the circuit configuration of the photodetection system. [Figure 25] This figure shows an example of a schematic configuration of an endoscopic surgical system. [Figure 26] This block diagram shows an example of the functional configuration of a camera head and CCU. [Figure 27] This block diagram shows an example of a schematic configuration of a vehicle control system. [Figure 28] This is an explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit. [Figure 29] This is a schematic cross-sectional view showing the device structure as evaluation sample 1. [Figure 30] This is a schematic cross-sectional diagram showing the device structure as evaluation sample 2. [Modes for carrying out the invention]

[0012] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following embodiment. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each figure. The order of description is as follows. 1. First Embodiment (An example in which a work function adjustment layer containing two types of materials is provided between the photoelectric conversion layer and the upper electrode) 1-1. Image sensor configuration 1-2. Method for manufacturing an image sensor 1-3. Action and Effects 2. Second Embodiment (An example in which an electron injection promoting layer having a predetermined energy level is provided between the work function adjustment layer and the upper electrode) 3. Variant 3-1. Modification Example 1 (Another example of image sensor configuration) 3-2. Modification Example 2 (Another example of image sensor configuration) 3-3. Modification 3 (Another example of image sensor configuration) 3-4. Modification 4 (Another example of image sensor configuration) 4. Examples of application 5. Application Examples 6. Examples

[0013] <1. First Embodiment> Figure 1 shows a cross-sectional configuration of an image sensor (image sensor 10) according to the first embodiment of this disclosure. Figure 2 schematically shows an example of the planar configuration of the image sensor 10 shown in Figure 1, and Figure 1 shows a cross-section along line II shown in Figure 2. Figure 3 is an equivalent circuit diagram of the image sensor 10 shown in Figure 1. Figure 4 schematically shows the arrangement of the lower electrode 21 and the transistors constituting the control unit of the image sensor 10 shown in Figure 1. The image sensor 10 constitutes one pixel (unit pixel P) in an imaging device (imaging device 1; see Figure 22), such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. In this embodiment, the image sensor 10 has an organic photoelectric conversion unit 20 provided on a semiconductor substrate 30, in which a work function adjustment layer 25 having an electron affinity of 4.5 eV to 6.0 eV is provided between the photoelectric conversion layer 24 and the upper electrode 26. This work function adjustment layer 25 is constructed using two types of materials having predetermined electron affinity and ionization potential.

[0014] (1-1. Image sensor configuration) The image sensor 10 is a so-called vertical spectral type image sensor, in which, for example, one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32B and 32R are stacked vertically. The organic photoelectric conversion unit 20 is provided on the first surface (back surface) 30A side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are embedded within the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30. The organic photoelectric conversion unit 20 has a photoelectric conversion layer 24 formed using an organic material between the opposing lower electrode 21 and upper electrode 26. The photoelectric conversion layer 24 is composed of a p-type semiconductor and an n-type semiconductor and has a bulk heterojunction structure within the layer. The bulk heterojunction structure is a p / n junction surface formed by the mixing of p-type semiconductors and n-type semiconductors.

[0015] The organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. Specifically, the organic photoelectric conversion unit 20 acquires, for example, a green (G) color signal. The inorganic photoelectric conversion units 32B and 32R acquire, for example, blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. As a result, the image sensor 10 can acquire multiple types of color signals in a single pixel without using a color filter.

[0016] In this embodiment, we will describe the case where electrons are read out as signal charges from the excitons (electron-hole pairs) generated by photoelectric conversion, that is, the case where the n-type semiconductor region is used as the photoelectric conversion layer. In the figure, the "+" (plus) sign attached to "p" and "n" indicates a high concentration of p-type or n-type impurities.

[0017] The second surface (front) 30B of the semiconductor substrate 30 is provided with, for example, floating diffusion FD1 (region 36B within the semiconductor substrate 30), FD2 (region 37C within the semiconductor substrate 30), FD3 (region 38C within the semiconductor substrate 30), transfer transistors Tr2 and Tr3, amplifier transistor (modulation element) AMP, reset transistor RST, selection transistor SEL, and a multilayer wiring layer 40. The multilayer wiring layer 40 has a configuration in which wiring layers 41, 42, and 43 are stacked within an insulating layer 44.

[0018] In the drawing, the first surface 30A of the semiconductor substrate 30 is referred to as the light incident side S1, and the second surface 30B is referred to as the wiring layer side S2.

[0019] The organic photoelectric conversion unit 20 has a configuration in which the lower electrode 21, charge storage layer 23, photoelectric conversion layer 24, work function adjustment layer 25, and upper electrode 26 are stacked in this order from the first surface 30A side of the semiconductor substrate 30. An insulating layer 22 is provided between the lower electrode 21 and the charge storage layer 23. The lower electrode 21 is formed separately for each image sensor 10, and, as will be described in detail later, is composed of a readout electrode 21A and a storage electrode 21B separated from each other by the insulating layer 22. Of the lower electrode 21, the readout electrode 21A is electrically connected to the charge storage layer 23 via an opening 22H provided in the insulating layer 22. In Figure 1, the charge storage layer 23, photoelectric conversion layer 24, work function adjustment layer 25, and upper electrode 26 are shown as being formed separately for each image sensor 10, but they may be provided as a continuous layer common to multiple image sensors 10, for example.

[0020] Between the first surface 30A of the semiconductor substrate 30 and the lower electrode 21, for example, an insulating layer 28 and an interlayer insulating layer 29 are provided. The insulating layer 28 is composed of a layer having a fixed charge (fixed charge layer) 28A and an insulating dielectric layer 28B. A protective layer 51 is provided on the upper electrode 26. Within the protective layer 51, for example, a light-shielding film 52 is provided above the readout electrode 21A. This light-shielding film 52 does not extend over the storage electrode 21B and only needs to be provided to cover the region of the readout electrode 21A that is in direct contact with the photoelectric conversion layer 24. An optical component such as a planarization layer (not shown) or an on-chip lens 53 is disposed above the protective layer 51.

[0021] A through-electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The organic photoelectric conversion unit 20 is connected via this through-electrode 34 to the gate Gamp of the amplifier transistor AMP located on the second surface 30B side of the semiconductor substrate 30, and to one of the source / drain regions 36B of the reset transistor RST (reset transistor Tr1rst), which also serves as a floating diffusion FD1. As a result, the image sensor 10 can efficiently transfer the charge (in this case, electrons) generated in the organic photoelectric conversion unit 20 on the first surface 30A side of the semiconductor substrate 30 to the second surface 30B side of the semiconductor substrate 30 via the through-electrode 34, thereby improving its characteristics.

[0022] The lower end of the through electrode 34 is connected to a connection portion 41A in the wiring layer 41, and the connection portion 41A 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. The upper end of the through electrode 34 is connected to the read electrode 21A via, for example, a pad portion 39A and an upper first contact 39C.

[0023] The through-electrode 34 is provided, for example, in each image sensor 10, for each organic photoelectric conversion unit 20. The through-electrode 34 functions as a connector between the organic photoelectric conversion unit 20 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1, and also serves as a transmission path for the charge generated in the organic photoelectric conversion unit 20.

[0024] The reset gate Grst of the reset transistor RST is located next to the floating diffusion FD1 (one of the source / drain regions 36B of the reset transistor RST). This allows the charge accumulated in the floating diffusion FD1 to be reset by the reset transistor RST.

[0025] In the image sensor 10 of this embodiment, light incident on the organic photoelectric conversion unit 20 from the upper electrode 26 side is absorbed by the photoelectric conversion layer 24. The excitons generated by this process move to the interface between the electron donor and electron acceptor constituting the photoelectric conversion layer 24, where they undergo exciton separation, i.e., dissociation into electrons and holes. The charges (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 (in this case, the upper electrode 26) and the cathode (in this case, the lower electrode 21), and are detected as photocurrents. Furthermore, the transport direction of electrons and holes can be controlled by applying a potential between the lower electrode 21 and the upper electrode 26.

[0026] The following describes the composition and materials of each part.

[0027] The image sensor 10 constitutes, for example, a single pixel (unit pixel P) that is repeatedly arranged in an array in the pixel section 100A of the imaging device 1 shown in Figure 22. In the pixel section 100A, as shown in Figure 2, a pixel unit 1a consisting of four pixels arranged in, for example, two rows and two columns, serves as the repeating unit and is repeatedly arranged in an array in the row direction and column direction.

[0028] The organic photoelectric conversion unit 20 is an organic photoelectric conversion element that absorbs green light corresponding to a selective wavelength range, for example, some or all of the wavelength range from 450 nm to 650 nm, to generate excitons.

[0029] The lower electrode 21 corresponds to a specific example of the "first electrode" of this disclosure. As described above, the lower electrode 21 is composed of a separately formed read electrode 21A and a storage electrode 21B. The read electrode 21A is for transferring charge (in this case, electrons) generated in the photoelectric conversion layer 24 to the floating diffusion FD1, and is connected to the floating diffusion FD1, for example, via the upper first contact 39C, pad portion 39A, through electrode 34, connection portion 41A and lower second contact 46. The storage electrode 21B is for storing electrons as signal charge from the charge generated in the photoelectric conversion layer 24 in the charge storage layer 23. The storage electrode 21B is provided in a region that covers the light-receiving surfaces of the inorganic photoelectric conversion portions 32B and 32R formed in the semiconductor substrate 30, directly facing these light-receiving surfaces. The storage electrode 21B is preferably larger than the read electrode 21A, thereby enabling the storage of a larger amount of charge.

[0030] The lower electrode 21 is composed of a light-transmitting conductive film, for example, ITO (indium tin oxide). However, in addition to ITO, other materials that may be used to construct the lower electrode 21 include tin oxide (SnO2)-based materials with added dopants, or zinc oxide-based materials obtained by adding dopants to zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, and indium zinc oxide (IZO) with indium (In) added. Other materials that may be used include CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, or ZnSnO3.

[0031] The charge storage layer 23 corresponds to a specific example of the "third semiconductor layer" of this disclosure. The charge storage layer 23 is provided below the photoelectric conversion layer 24, specifically between the insulating layer 22 and the photoelectric conversion layer 24, and is for storing signal charges generated in the photoelectric conversion layer 24. In this embodiment, since electrons are used as signal charges, it is preferable to form the charge storage layer 23 using an n-type semiconductor material, for example, a material in which the lowest end of the conduction band has an energy level shallower than the work function of the lower electrode 21. Examples of such n-type semiconductor materials include IGZO (In-Ga-Zn-O oxide semiconductor), ZTO (Zn-Sn-O oxide semiconductor), IGZTO (In-Ga-Zn-Sn-O oxide semiconductor), GTO (Ga-Sn-O oxide semiconductor), and IGO (In-Ga-O oxide semiconductor). It is preferable to use at least one of the above oxide semiconductor materials for the charge storage layer 23, and among them, IGZO is preferably used. The thickness of the charge storage layer 23 is, for example, 30 nm to 200 nm, preferably 60 nm to 150 nm. By providing the charge storage layer 23 made of the above material as a layer below the photoelectric conversion layer 24, it is possible to prevent charge recombination during charge storage and improve transfer efficiency.

[0032] The photoelectric conversion layer 24 is for converting light energy into electrical energy. The photoelectric conversion layer 24 is composed of two or more organic materials (p-type semiconductor material or n-type semiconductor material) that function as either p-type or n-type semiconductors, respectively. The photoelectric conversion layer 24 has a junction surface (p / n junction surface) between the p-type semiconductor material and the n-type semiconductor material within the layer. The p-type semiconductor functions relatively as an electron donor, and the n-type semiconductor functions relatively as an electron acceptor. The photoelectric conversion layer 24 provides a field where excitons generated when light is absorbed are separated into electrons and holes. Specifically, the excitons are separated into electrons and holes at the interface (p / n junction surface) between the electron donor and the electron acceptor.

[0033] The photoelectric conversion layer 24 may include, in addition to the p-type semiconductor material and the n-type semiconductor material, an organic material, so-called dye material, that photoelectrically converts light in a predetermined wavelength range while transmitting light in other wavelength ranges. When the photoelectric conversion layer 24 is formed using three types of organic materials—a p-type semiconductor material, an n-type semiconductor material, and a dye material—it is preferable that the p-type semiconductor material and the n-type semiconductor material are light-transmitting materials in the visible region (for example, 450 nm to 800 nm). The thickness of the photoelectric conversion layer 24 is, for example, 50 nm to 500 nm.

[0034] The photoelectric conversion layer 24 of this embodiment preferably contains an organic material and has absorption between visible light and near-infrared light. Examples of organic materials constituting the photoelectric conversion layer 24 include quinacridone, boron chloride subphthalocyanine, pentacene, benzothienobenzothiophene, fullerene, and their derivatives. The photoelectric conversion layer 24 is composed of a combination of two or more of the above organic materials. Depending on the combination, the above organic materials function as a p-type semiconductor or an n-type semiconductor.

[0035] The organic material constituting the photoelectric conversion layer 24 is not particularly limited. Other organic materials that can be suitably used include, for example, naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene, and fluorantene or their derivatives. Alternatively, polymers such as phenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, or their derivatives, may be used. In addition, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaanurene dyes, azulene dyes, naphthoquinone, anthraquinone dyes, chain compounds formed by the condensation of fused polycyclic aromatic and aromatic rings or heterocyclic compounds such as anthracene and pyrene, or two nitrogen-containing heterocyclic rings such as quinoline, benzothiazole, and benzoxazole having a squarylium group and a croconicmethine group as a linking chain, or cyanine-like dyes linked by a squarylium group and a croconicmethine group can be preferably used. As the above metal complex dyes, dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, or ruthenium complex dyes are preferred, but are not limited thereto.

[0036] The work function adjustment layer 25 corresponds to a specific example of the "first semiconductor layer" of this disclosure. The work function adjustment layer 25 is provided on top of the photoelectric conversion layer 24 and changes the internal electric field within the photoelectric conversion layer 24 to quickly transfer and store the signal charge generated in the photoelectric conversion layer 24 to the charge storage layer 23. The work function adjustment layer 25 is light-transmitting, and preferably has a light absorption rate of 10% or less for visible light. As described above, the work function adjustment layer 25 has an electron affinity of 4.5 eV to 6.0 eV. The work function adjustment layer 25 is composed of two types of materials having predetermined electron affinity and ionization potential. These two types of materials are carbon-containing compounds (a first carbon-containing compound and a second carbon-containing compound).

[0037] The first carbon-containing compound has, for example, an electron affinity greater than 4.8 eV or an electron affinity greater than the work function of the upper electrode 26. The second carbon-containing compound has, for example, an ionization potential greater than 5.5 eV. Note that electron affinity corresponds to the energy difference between the LUMO level and the vacuum level.

[0038] Examples of the first carbon-containing compound include hexaazatriphenylene derivatives such as dipyradino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonnitrile (HATCN). Examples of the second carbon-containing compound include fullerene C 60 and fullerene C 70 Examples include fullerene derivatives such as 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (NBphen), naphthalenediimide derivatives (e.g., NDI-35), carbazole derivatives (CzBDF), aromatic amine materials (IT-102), indrocarbazole derivatives (e.g., PC-IC), acene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, chrysene derivatives, fluorantene derivatives, phthalocyanine derivatives, subphthalocyanine derivatives, hexaazatriphenylene derivatives, metal complexes with heterocyclic compounds as ligands, thiophene derivatives, thienothiophene derivatives, and thienoacene derivatives. Alternatively, examples include organic molecules and organometallic complexes that incorporate a nitrogen (N)-containing heterocycle as part of their molecular skeleton, such as pyridine, pyrazine, pyrimidine, triazine, quinoline, quinoxaline, isoquinoline, acridine, phenazine, indole, imidazole, benzimidazole, phenanthroline, tetrazole, naphthalenetetracarboxylic acid diimide, naphthalenedicarboxylic acid monoimide, hexazatriphenylene, and hexazatrinaphthylene.

[0039] Figure 5A shows the energy levels of the monolayer films of the first carbon-containing compound and the second carbon-containing compound. Figure 5B shows the energy levels of the monolayer film of the first carbon-containing compound (HATCN) and the mixed film of the first carbon-containing compound (HATCN) and the second carbon-containing compound. Note that the HATCN and C shown in Figures 5A and 5B are not the same. 60 Fullerenes and C 70 The energy levels of the fullerenes were calculated using ultraviolet photoelectron spectroscopy (UPS) and low-energy inverse photoelectron spectroscopy (LEIPES), respectively. The energy levels of NBphen, NDI-35, PC-IC, CzBDF, and IT-102 shown in Figures 5A and 5B were calculated from their optical band gaps.

[0040] The work function adjustment layer 25 can be formed, for example, as a mixed film by mixing the first carbon-containing compound and the second carbon-containing compound. As can be seen from Figure 5B, by forming a mixed film, the electron affinity of the mixed film is shifted to a smaller value compared to a single layer film of the first carbon-containing compound, and a work function adjustment layer 25 having an electron affinity of 4.5 eV to 6.0 eV can be formed. Furthermore, the work function adjustment layer 25 (mixed film) has an electron affinity greater than, for example, the work function of the upper electrode 26. This makes it possible to reduce, for example, the generation of dark current. The mixed film (work function adjustment layer 25) has an amorphous or grain size of 10 nm or less. The arithmetic mean roughness (Ra) of the mixed film (work function adjustment layer 25) is 0.8 nm or less. The adhesion of the entire organic photoelectric conversion section 20 including the work function adjustment layer 25 is 0.05 KN / m or more. This reduces the likelihood of film peeling between the work function adjustment layer 25 and the upper electrode 26, thereby improving the manufacturing yield. Furthermore, by setting the mixing ratio of the first carbon-containing compound and the second carbon-containing compound to 0.1 or more and 10 or less, the afterimage characteristics can be improved.

[0041] The work function adjustment layer 25 may be formed as a laminated film of, for example, a layer containing the first carbon-containing compound and a layer containing the second carbon-containing compound. In that case, considering the adhesion between the work function adjustment layer 25 and the upper electrode 26, it is preferable to laminate the layers in the order of the layer containing the first carbon-containing compound and the layer containing the second carbon-containing compound from the photoelectric conversion layer 24 side. The thickness of the work function adjustment layer 25 is, for example, 0.5 nm or more and 30 nm or less.

[0042] Other organic layers may be provided between the photoelectric conversion layer 24 and the lower electrode 21 (for example, between the charge storage layer 23 and the photoelectric conversion layer 24) and between the photoelectric conversion layer 24 and the upper electrode 26 (for example, between the photoelectric conversion layer 24 and the work function adjustment layer 25). Specifically, for example, the charge storage layer 23, hole blocking layer, photoelectric conversion layer 24, electron blocking layer, and work function adjustment layer 25 may be stacked in order from the lower electrode 21 side. Furthermore, a bottoming layer and a hole transport layer may be provided between the lower electrode 21 and the photoelectric conversion layer 24, and a buffer layer may be provided between the photoelectric conversion layer 24 and the upper electrode 26. When a buffer layer is provided between the photoelectric conversion layer 24 and the upper electrode 26, for example adjacent to the work function adjustment layer 25, it is preferable that the buffer layer has an energy level shallower than the work function of the work function adjustment layer 25. It is also preferable that the buffer layer is formed using an organic material having a glass transition temperature higher than 100°C, for example.

[0043] The upper electrode 26 is composed of a conductive film that is light-transmitting, similar to the lower electrode 21. In an imaging device 1 using an image sensor 10 as a unit pixel P, the upper electrode 26 may be separated for each unit pixel P, or it may be formed as a common electrode for each unit pixel P. The upper electrode 26 has a work function smaller than, for example, the work function of the work function adjustment layer 25. The thickness of the upper electrode 26 is, for example, 10 nm to 200 nm.

[0044] The fixed charge layer 28A may be a film with a positive fixed charge or a film with a negative fixed charge. Examples of materials for the film with a negative fixed charge include hafnium oxide, aluminum oxide, zirconium oxide, tantalum oxide, and titanium oxide. Other materials include lanthanum oxide, praseodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, thulium oxide, ytterbium oxide, lutetium oxide, yttrium oxide, aluminum nitride film, hafnium oxynitride film, or aluminum oxynitride film.

[0045] The fixed charge layer 28A may have a structure in which two or more types of films are stacked. This makes it possible to further enhance its function as a hole storage layer, for example, if the film has a negative fixed charge.

[0046] The material of the dielectric layer 28B is not particularly limited, but it is formed from, for example, a silicon oxide film, TEOS, a silicon nitride film, or a silicon oxynitride film.

[0047] The interlayer insulating layer 29 is composed of a single layer film made of one of the following materials: silicon oxide, silicon nitride, and silicon oxynitride (SiON), or a multilayer film made of two or more of these materials.

[0048] A shield electrode 29X is provided on the interlayer insulating layer 29 together with the lower electrode 21. The shield electrode 29X 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 29X further extends within the pixel unit 1a between adjacent pixels in the row direction (Z-axis direction) and column direction (X-axis direction).

[0049] The insulating layer 22 is for electrically isolating the storage electrode 21B and the charge storage layer 23. The insulating layer 22 is provided, for example, on the interlayer insulating layer 29 so as to cover the lower electrode 21. As described above, the insulating layer 22 has an opening 22H on the read electrode 21A, and the read electrode 21A and the charge storage layer 23 are electrically connected through this opening 22H. The insulating layer 22 can be formed using, for example, the same material as the interlayer insulating layer 29, and is composed of a single layer film made of one of the following: silicon oxide, silicon nitride, and silicon oxynitride (SiON), or a laminated film made of two or more of these. The thickness of the insulating layer 22 is, for example, 20 nm to 500 nm.

[0050] The semiconductor substrate 30 is made of, for example, an n-type silicon (Si) substrate and has a p-well 31 in a predetermined region. The second surface 30B of the p-well 31 is provided with the transfer transistors Tr2 and Tr3, the amplifier transistor AMP, the reset transistor RST, the selection transistor SEL, etc. Peripheral circuit section 130 (see, for example, Figure 22) consisting of logic circuits, etc., is provided around the periphery of the semiconductor substrate 30.

[0051] The reset transistor RST (reset transistor Tr1rst) resets the charge transferred from the organic photoelectric conversion unit 20 to the floating diffusion FD1, and is composed of, for example, a MOS transistor. Specifically, the reset transistor Tr1rst 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.

[0052] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the organic photoelectric conversion unit 20 into a voltage, and is composed of, for example, a MOS transistor. Specifically, the amplifier transistor AMP 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 21A 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.

[0053] 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.

[0054] The inorganic photoelectric conversion units 32B and 32R each have a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R utilize the fact that different wavelengths of light are absorbed in the silicon substrate depending on the depth of incidence of the light, enabling the spectral separation of light in the longitudinal direction. The inorganic photoelectric conversion unit 32B selectively detects blue light, for example, and accumulates a signal charge corresponding to blue light, and is installed at a depth at which blue light can be efficiently photoelectrically converted. The inorganic photoelectric conversion unit 32R selectively detects red light, for example, and accumulates a signal charge corresponding to red light, and is installed at a depth at which red light can be efficiently photoelectrically converted. Note that blue (B) corresponds to a wavelength range of, for example, 450 nm to 495 nm, and red (R) corresponds to a wavelength range of, for example, 620 nm to 750 nm. The inorganic photoelectric conversion units 32B and 32R only need to be able to detect light in some or all of the wavelength ranges within their respective wavelength ranges.

[0055] The inorganic photoelectric conversion unit 32B is composed of, for example, a p+ region that serves as a hole storage layer and an n region that serves as an electron storage layer. The inorganic photoelectric conversion unit 32R has, 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 inorganic photoelectric conversion unit 32B is connected to a vertical transfer transistor Tr2. The p+ region of the inorganic photoelectric conversion unit 32B is bent along the transfer transistor Tr2 and connected to the p+ region of the inorganic photoelectric conversion unit 32R.

[0056] The transfer transistor Tr2 (transfer transistor TR2trs) is for transferring the signal charge corresponding to blue (in this case, electrons), which is generated and accumulated in the inorganic photoelectric conversion unit 32B, to the floating diffusion FD2. Since the inorganic photoelectric conversion unit 32B is formed deep from the second surface 30B of the semiconductor substrate 30, it is preferable that the transfer transistor TR2trs of the inorganic photoelectric conversion unit 32B is configured as a vertical transistor. The transfer transistor TR2trs is also connected to the transfer gate line TG2. Furthermore, a floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2trs. The charge accumulated in the inorganic photoelectric conversion unit 32B is read out to the floating diffusion FD2 via a transfer channel formed along the gate Gtrs2.

[0057] The transfer transistor Tr3 (transfer transistor TR3trs) transfers the signal charge (in this case, electrons) corresponding to the red color, which is generated and accumulated in the inorganic photoelectric conversion unit 32R, to the floating diffusion FD3, and is composed of, for example, a MOS transistor. The transfer transistor TR3trs is also connected to the transfer gate line TG3. Furthermore, the floating diffusion FD3 is provided in the region 38C near the gate Gtrs3 of the transfer transistor TR3trs. The charge accumulated in the inorganic photoelectric conversion unit 32R is read out to the floating diffusion FD3 via a transfer channel formed along the gate Gtrs3.

[0058] On the second surface 30B 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 inorganic photoelectric conversion unit 32B. In addition, a reset transistor TR3rst, an amplifier transistor TR3amp, and a selection transistor TR3sel are provided, which constitute the control unit of the inorganic photoelectric conversion unit 32R.

[0059] 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.

[0060] 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. Furthermore, 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.

[0061] 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.

[0062] 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.

[0063] 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. Furthermore, 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.

[0064] 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.

[0065] 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 111 that constitutes the drive circuit. The signal lines (data output lines) VSL1, VSL2, VSL3 are connected to the horizontal drive circuit 113 that constitutes the drive circuit.

[0066] The lower first contact 45, the lower second contact 46, the upper first contact 39C, and the upper second contact 39D are made of doped silicon materials such as PDAS (Phosphorus Doped Amorphous Silicon), or metallic materials such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), or tantalum (Ta).

[0067] The protective layer 51 is provided above the organic photoelectric conversion unit 20 and is made of a light-transmitting material. Specifically, the protective layer 51 is made of a single layer film made of, for example, silicon oxide, silicon nitride, and silicon oxynitride, or a laminated film made of two or more of these materials. The thickness of this protective layer 51 is, for example, 100 nm to 30,000 nm.

[0068] The light-shielding film 52 is provided within the protective layer 51, for example, to cover the readout electrode 21A. Examples of materials for the light-shielding film 52 include tungsten (W), titanium (Ti), titanium nitride (TiN), or aluminum (Al), and the light-shielding film 52 is configured as, for example, a W / TiN / Ti laminated film or a W single layer film. The thickness of the light-shielding film 52 is, for example, 50 nm to 400 nm.

[0069] On the protective layer 51, an on-chip lens 53 is provided for each unit pixel P in the pixel portion 100A. The on-chip lens 53 focuses the incident light onto the light-receiving surfaces of the organic photoelectric conversion unit 20, the inorganic photoelectric conversion unit 32B, and the inorganic photoelectric conversion unit 32R.

[0070] (1-2. Method for manufacturing an image sensor) The image sensor 10 of this embodiment can be manufactured, for example, as follows.

[0071] Figures 6 to 12 show the manufacturing method of the image sensor 10 in order of steps. First, as shown in Figure 6, a p-well 31 is formed as a well of the first conductivity type in the semiconductor substrate 30, and inorganic photoelectric conversion sections 32B and 32R of the second conductivity type (e.g., n-type) are formed in this p-well 31. A p+ region is formed near the first surface 30A of the semiconductor substrate 30.

[0072] On the second surface 30B of the semiconductor substrate 30, as shown in Figure 6, 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 30B of the semiconductor substrate 30.

[0073] 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 30A of the semiconductor substrate 30, although they are not shown in Figure 6. After ion implantation, an annealing treatment is performed.

[0074] Next, a support substrate (not shown) or another semiconductor substrate is bonded to the second surface 30B (multilayer wiring layer 40 side) of the semiconductor substrate 30, and then it 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 30A of the semiconductor substrate 30. The above steps can be carried out using technologies commonly used in CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

[0075] Next, as shown in Figure 7, the semiconductor substrate 30 is processed from the first surface 30A side, for example, by dry etching, to form an annular opening 34H. As shown in Figure 7, the depth of the opening 34H penetrates from the first surface 30A to the second surface 30B of the semiconductor substrate 30, and also reaches, for example, the connection portion 41A.

[0076] Next, a negative fixed charge layer 28A is formed on the first surface 30A and the side surface of the opening 34H of the semiconductor substrate 30. Two or more types of films may be laminated as the negative fixed charge layer 28A. This makes it possible to further enhance the function as a hole storage layer. After forming the negative fixed charge layer 28A, a dielectric layer 28B is formed. Next, pad portions 39A and 39B are formed at predetermined positions on the dielectric layer 28B, and then an interlayer insulating layer 29 is formed on the dielectric layer 28B and the pad portions 39A and 39B, and the surface of the interlayer insulating layer 29 is planarized using the CMP (Chemical Mechanical Polishing) method.

[0077] Next, as shown in Figure 8, openings 29H1 and 29H2 are formed on the pad portions 39A and 39B, respectively. Then, conductive material such as Al is embedded in these openings 29H1 and 29H2 to form the upper first contact 39C and the upper second contact 39D.

[0078] Next, as shown in Figure 9, a conductive film 21x is deposited on the interlayer insulating layer 29, and then a photoresist PR is formed at a predetermined position on the conductive film 21x. Subsequently, by etching and removing the photoresist PR, the readout electrode 21A and the storage electrode 21B shown in Figure 10 are patterned.

[0079] Next, as shown in Figure 11, an insulating layer 22 is formed on the interlayer insulating layer 29, the read electrode 21A, and the storage electrode 21B, and then an opening 22H is provided on the read electrode 21A.

[0080] Next, as shown in Figure 12, a charge storage layer 23, a photoelectric conversion layer 24, a work function adjustment layer 25, and an upper electrode 26 are formed on the insulating layer 22. When forming the charge storage layer 23 and the work function adjustment layer 25 using organic materials, it is desirable to form the charge storage layer 23, the photoelectric conversion layer 24, and the work function adjustment layer 25 continuously in a vacuum process (a single vacuum process). Furthermore, the method for forming the photoelectric conversion layer 24 is not necessarily limited to vacuum deposition; other methods, such as spin coating or printing, may also be used. Finally, a protective layer 51 including a light-shielding film 52 and an on-chip lens 53 are formed above the organic photoelectric conversion section 20. With these steps, the image sensor 10 shown in Figure 1 is completed.

[0081] In the image sensor 10, when light enters the organic photoelectric conversion unit 20 via the on-chip lens 53, the light passes through the organic photoelectric conversion unit 20 and then the inorganic photoelectric conversion units 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.

[0082] (Acquisition of green signal by organic photoelectric conversion unit 20) Of the light incident on the image sensor 10, green light is first selectively detected (absorbed) by the organic photoelectric conversion unit 20 and converted into photoelectric energy.

[0083] The organic photoelectric conversion unit 20 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 electron-hole pairs generated in the organic photoelectric conversion unit 20 are extracted from the lower electrode 21 side, transferred to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD1. At the same time, the amount of charge generated in the organic photoelectric conversion unit 20 is modulated into a voltage by the amplifier transistor AMP.

[0084] 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.

[0085] Here, the organic photoelectric conversion unit 20 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 via the through-electrode 34, making it possible to easily reset the charge accumulated in the floating diffusion FD1 using the reset transistor RST.

[0086] 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 26. 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.

[0087] Figure 13 shows an example of the operation of the image sensor 10. (A) shows the potential at the storage electrode 21B, (B) shows the potential at the floating diffusion FD1 (readout electrode 21A), and (C) shows the potential at the gate (Gsel) of the reset transistor TR1rst. In the image sensor 10, the readout electrode 21A and the storage electrode 21B are each supplied with a voltage individually.

[0088] In the imaging device 10, during the accumulation period, a potential V1 is applied to the readout electrode 21A from the drive circuit, and a potential V2 is applied to the accumulation electrode 21B. Here, the potentials V1 and V2 are set such that V2 > V1. As a result, the charges (here, electrons) generated by photoelectric conversion are attracted to the accumulation electrode 21B and accumulated in the region of the charge accumulation layer 23 facing the accumulation electrode 21B (accumulation period). Incidentally, the potential in the region of the charge accumulation layer 23 facing the accumulation electrode 21B becomes a more negative value as the time of photoelectric conversion elapses. Note that holes are sent from the upper electrode 26 to the drive circuit.

[0089] In the imaging device 10, 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 line VDD, and the voltage of the floating diffusion FD1 is reset (reset period).

[0090] After the completion of the reset operation, charge readout is performed. Specifically, at timing t2, a potential V3 is applied to the readout electrode 21A from the drive circuit, and a potential V4 is applied to the accumulation electrode 21B. Here, the potentials V3 and V4 are set such that V3 < V4. As a result, the charges (here, electrons) accumulated in the region corresponding to the accumulation electrode 21B are read out from the readout electrode 21A to the floating diffusion FD1. That is, the charges accumulated in the charge accumulation layer 23 are read out to the control unit (transfer period).

[0091] After the completion of the readout operation, again, a potential V1 is applied to the readout electrode 21A from the drive circuit, and a potential V2 is applied to the accumulation electrode 21B. As a result, the charges (here, electrons) generated by photoelectric conversion are attracted to the accumulation electrode 21B and accumulated in the region of the photoelectric conversion layer 24 facing the accumulation electrode 21B (accumulation period).

[0092] (Acquisition of blue and red signals by the inorganic photoelectric conversion units 32B and 32R) Next, of the light transmitted through the organic photoelectric conversion unit 20, the blue light is absorbed in the inorganic photoelectric conversion unit 32B and the red light is absorbed in the inorganic photoelectric conversion unit 32R, respectively, and converted into photoelectric energy. In the inorganic photoelectric conversion unit 32B, electrons corresponding to the incident blue light are accumulated in the n region of the inorganic photoelectric conversion unit 32B, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2. Similarly, in the inorganic photoelectric conversion unit 32R, electrons corresponding to the incident red light are accumulated in the n region of the inorganic photoelectric conversion unit 32R, and the accumulated electrons are transferred to the floating diffusion FD3 by the transfer transistor Tr3.

[0093] (1-3. Action and Effects) In the image sensor 10 of this embodiment, a work function adjustment layer 25 is provided between the photoelectric conversion layer 24 and the upper electrode 26. The work function adjustment layer 25 is formed using a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. This improves the adhesion between the photoelectric conversion layer 24 and the upper electrode 26, and also strengthens the electric field applied to the photoelectric conversion layer 24. This will be explained below.

[0094] Generally, organic materials used in work function adjustment layers often contain cyano or fluorine groups. These organic materials tend to aggregate between molecules, making it difficult to obtain a homogeneous film. Therefore, in image sensors containing layers made of these organic materials, adhesion decreases at the interface of the laminated film made of dissimilar materials, leading to a decrease in manufacturing yield due to film delamination and other issues. Furthermore, it is suspected that this may lead to a deterioration in the breakdown voltage of dark current due to tunnel conduction caused by the concentration of the electric field on the convex parts of the film surface.

[0095] Furthermore, image sensors using work function adjustment layers made of these organic materials tend to have low response speeds after light irradiation, as they fail to achieve sufficient external quantum efficiency (EQE). This is thought to be because, in work function adjustment layers made of the above organic materials, during the process in which holes flowing from at least the adjacent electron blocking layer or photoelectric conversion layer recombine at the interface with the work function adjustment layer, the delay in the rate of the recombination process or carrier trapping at the interface increases the space charge near the interface, resulting in insufficient electric field applied to the photoelectric conversion layer.

[0096] In contrast, in this embodiment, a work function adjustment layer 25 having an electron affinity of 4.5 eV to 6.0 eV is provided by using a first carbon-containing compound having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. This suppresses aggregation of, for example, the first carbon-containing compound within the work function adjustment layer 25, improving the adhesion between the photoelectric conversion layer 24 and the upper electrode 26. Furthermore, compared to the case where the work function adjustment layer is formed using only the first carbon-containing compound, a smaller electron affinity (for example, 4.5 eV to 6.0 eV) is achieved, substantially increasing the electric field applied to the photoelectric conversion layer 24.

[0097] As described above, the image sensor 10 of this embodiment can improve manufacturing yield by improving the adhesion between the photoelectric conversion layer 24 and the upper electrode 26. In addition, the element characteristics can be improved by strengthening the electric field applied to the photoelectric conversion layer 24. Specifically, for example, the generation of dark current can be reduced and the response speed can be improved.

[0098] Next, a second embodiment and four modified examples of the present disclosure will be described. Note that components corresponding to the image sensor 10 in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0099] <2. Second Embodiment> Figure 14 shows a cross-sectional configuration of an image sensor (image sensor 10A) according to a second embodiment of this disclosure. Similar to the first embodiment, the image sensor 10A constitutes one pixel (unit pixel P) in an imaging device (imaging device 1; see Figure 22), such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras.

[0100] The image sensor 10A is a so-called vertical spectral type image sensor, in which, for example, one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32B and 32R are stacked in the vertical direction. The organic photoelectric conversion unit 20 is provided on the first surface (back surface) 30A side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are embedded and formed within the semiconductor substrate 30 and are stacked in the thickness direction of the semiconductor substrate 30. In this embodiment, the image sensor 10A further includes an electron injection promoting layer 27 having a predetermined gap level between the work function adjustment layer 25 and the upper electrode 26 in the organic photoelectric conversion unit 20.

[0101] The electron injection enhancement layer 27 is designed to promote electron injection from the upper electrode 26 and, as described above, is provided between the work function adjustment layer 25 and the upper electrode 26. The electron injection enhancement layer 27 is configured such that the absolute value B of the difference between the ionization potential of the electron injection enhancement layer 27 and the Fermi level of the upper electrode 26 is greater than or equal to the absolute value A of the difference between the electron affinity of the electron injection enhancement layer 27 calculated from the optical band gap and the Fermi level of the upper electrode 26. Alternatively, the electron injection enhancement layer 27 has an in-gap level near the Fermi level of the upper electrode 26 with a density of states of 1 / 10000 or more relative to the density of states of the ionization potential of the electron injection enhancement layer 27. This increases the electron concentration within the work function adjustment layer 25, improving carrier conductivity at the interface between the photoelectric conversion layer 24 and the work function adjustment layer 25.

[0102] As a constituent material for the electron injection enhancement layer 27, for example, the second carbon-containing compound that constitutes the work function adjustment layer 25 can be used. Specifically, examples include [2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline] (NBphen) and naphthalenediimide molecules (e.g., NDI-35). Other constituent materials for the electron injection enhancement layer 27 include, for example, lithium, cesium, rubidium, lithium oxide, cesium carbonate, rubidium oxide, lithium fluoride, and cesium fluoride. The thickness of the electron injection enhancement layer 27 is, for example, 0.5 nm to 10 nm.

[0103] As described above, in the image sensor 10A of this embodiment, an electron injection enhancement layer 27 is provided between the work function adjustment layer 25 and the upper electrode 26 such that the absolute value B of the difference between the ionization potential of the electron injection enhancement layer 27 and the Fermi level of the upper electrode 26 is greater than or equal to the absolute value A of the difference between the electron affinity of the electron injection enhancement layer 27 calculated from the optical band gap and the Fermi level of the upper electrode 26. Furthermore, in the image sensor 10A of this embodiment, an electron injection enhancement layer 27 is provided between the work function adjustment layer 25 and the upper electrode 26 such that an in-gap level has a density of states of 1 / 10000 or more relative to the density of states of the ionization potential of the electron injection enhancement layer 27, near the Fermi level of the upper electrode 26.

[0104] As in the first embodiment described above, in the image sensor 10 that reads out electrons as signal charges from the readout electrode 21A, holes generated in the photoelectric conversion layer 24 recombine with electrons injected from the upper electrode 26 at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25. This recombination allows electrons (signal charges) to be efficiently read out from the readout electrode 21A. The recombination of holes and electrons at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25 depends on the charge density of holes and electrons.

[0105] In contrast, in this embodiment, the electron injection enhancement layer 27 is provided between the work function adjustment layer 25 and the upper electrode 26. As a result, the electron concentration within the work function adjustment layer 25 increases, and the carrier conductivity at the interface between the photoelectric conversion layer 24 and the work function adjustment layer 25 is improved. This further enhances the electric field applied to the photoelectric conversion layer 24. Therefore, in addition to the effects of the first embodiment, it is possible to further improve the device characteristics. Specifically, for example, the response speed can be further improved, and the EQE can be improved.

[0106] <3. Variant> (3-1. Variation 1) Figure 15 schematically shows the cross-sectional configuration of the image sensor 10B according to Modification 1 of the present disclosure. Similar to the image sensor 10 of the first embodiment described above, the image sensor 10B is an image sensor such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. In this modification, the image sensor 10B consists of two organic photoelectric conversion units 20, 80 and one inorganic photoelectric conversion unit 32 stacked in the vertical direction.

[0107] The organic photoelectric conversion units 20 and 80 and the inorganic photoelectric conversion unit 32 selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the organic photoelectric conversion unit 20 acquires a green (G) color signal. For example, the organic photoelectric conversion unit 80 acquires a blue (B) color signal. For example, the inorganic photoelectric conversion unit 32 acquires a red (R) color signal. As a result, the image sensor 10B can acquire multiple types of color signals in a single pixel without using a color filter.

[0108] The organic photoelectric conversion units 20 and 80 have a configuration similar to that of the image sensor 10A in the second embodiment described above. Specifically, the organic photoelectric conversion unit 20, like the image sensor 10A, has a lower electrode 21, an insulating layer 22, a charge storage layer 23, a photoelectric conversion layer 24, a work function adjustment layer 25, an electron injection enhancement layer 27, and an upper electrode 26 stacked in this order. The lower electrode 21 consists of a plurality of electrodes (for example, a readout electrode 21A and a storage electrode 21B). Of the lower electrode 21, the readout electrode 21A is electrically connected to the charge storage layer 23 via an opening 22H provided in the insulating layer 22. The organic photoelectric conversion unit 80, like the organic photoelectric conversion unit 20, has a lower electrode 81, an insulating layer 82, a charge storage layer 83, a photoelectric conversion layer 84, a work function adjustment layer 85, an electron injection enhancement layer 87, and an upper electrode 86 stacked in this order. The lower electrode 81 consists of a plurality of electrodes (for example, a readout electrode 81A and a storage electrode 81B). Of the lower electrode 81, the readout electrode 81A is electrically connected to the charge storage layer 83 via an opening 82H provided in the insulating layer 82. The organic photoelectric conversion units 20 and 80 may have the same configuration as the image sensor 10 in the first embodiment described above, and the electron injection promoting layers 27 and 87 may be omitted.

[0109] The read electrode 81A is connected to a through electrode 91 that penetrates the interlayer insulating layer 89 and the organic photoelectric conversion unit 20 and is electrically connected to the read electrode 21A of the organic photoelectric conversion unit 20. 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 84. 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.

[0110] (3-2. Variation 2) Figure 16A schematically shows the cross-sectional configuration of the image sensor 10C according to Modification 2 of the present disclosure. Figure 16B schematically shows an example of the planar configuration of the image sensor 10C shown in Figure 16A, and Figure 16A shows the cross-section along line II shown in Figure 16B. The image sensor 10C is a stacked image sensor in which, for example, an inorganic photoelectric conversion unit 32 and an organic photoelectric conversion unit 60 are stacked. In the pixel section 100A of an imaging device (for example, imaging device 1) equipped with this image sensor 10C, as shown in Figure 16B, for example, a pixel unit 1a consisting of four pixels arranged in a 2x2 grid is repeated as a repeating unit, and is repeatedly arranged in an array consisting of row and column directions.

[0111] In this modified image sensor 10C, above the organic 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 organic 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.

[0112] The organic 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 the lower electrode 61, insulating layer (interlayer insulating layer 69), charge storage layer 63, photoelectric conversion layer 64, work function adjustment layer 65, and upper electrode 66 are stacked in this order. The lower electrode 61, interlayer insulating layer 69, charge storage layer 63, photoelectric conversion layer 64, work function adjustment layer 65, and upper electrode 66 have the same configuration as the lower electrode 21, insulating layer 22, charge storage layer 23, photoelectric conversion layer 24, work function adjustment layer 25, and upper electrode 26 of the image sensor 10 in the first embodiment described above. The lower electrode 61 has, for example, a readout electrode 61A and a storage electrode 61B that are independent of each other, and the readout electrode 61A is shared by, for example, four pixels.

[0113] The inorganic photoelectric conversion unit 32 detects, for example, infrared light in the range of 750 nm to 1300 nm.

[0114] In the image sensor 10C, 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 organic photoelectric conversion unit 60 of each unit pixel (Pr, Pg, Pb) equipped with the respective color filter, while other light, such as infrared light (IR) in the infrared region (e.g., 750 nm to 1000 nm), is transmitted through the organic photoelectric conversion unit 60. This infrared light (IR) transmitted through the organic photoelectric conversion unit 60 is detected by the inorganic photoelectric conversion unit 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 1 equipped with the image sensor 10C can simultaneously generate both visible light images and infrared light images.

[0115] Furthermore, the imaging device 1 equipped with the image sensor 10C 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.

[0116] (2-3. Variation 3) Figure 17A schematically shows the cross-sectional configuration of the image sensor 10D according to Modification 3 of this disclosure. Figure 17B schematically shows an example of the planar configuration of the image sensor 10D shown in Figure 17A, and Figure 17A shows the cross-section along line II-II shown in Figure 17B. In Modification 2 described above, an example was shown in which the color filter 55 is provided above the organic photoelectric conversion unit 60 (on the light incident side S1), but the color filter 55 may also be provided between the inorganic photoelectric conversion unit 32 and the organic photoelectric conversion unit 60, for example, as shown in Figure 17A.

[0117] In the image sensor 10D, 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 organic photoelectric conversion unit 60 (photoelectric conversion layer 64) is configured to selectively absorb light having a wavelength corresponding to, for example, green light (G). In the inorganic photoelectric conversion unit 32R, light having a wavelength corresponding to red light (R) is selectively absorbed, and in the inorganic photoelectric conversion unit 32B, light having a wavelength corresponding to blue light (B) is selectively absorbed. As a result, the inorganic photoelectric conversion unit 32 (inorganic photoelectric conversion units 32R, 32B) located below the organic photoelectric conversion unit 60 and the color filters 55R, 55B, respectively, can acquire signals corresponding to red light (R), green light (G), or blue light (B). In this modified image sensor 10D, 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.

[0118] In the above modified examples 2 and 3, an organic photoelectric conversion unit 60 was shown as an example in which the lower electrode 61, insulating layer 62, charge storage layer 63, photoelectric conversion layer 64, work function adjustment layer 65, and upper electrode 66 were stacked in this order, but the invention is not limited to this. In each of the organic photoelectric conversion units 60, an electron injection layer may be provided between the work function adjustment layer 65 and the upper electrode 66, similar to the second embodiment described above.

[0119] (2-4. Modification 4) Figure 18 schematically shows the cross-sectional configuration of the image sensor 10E according to Modification 4 of the present disclosure. The image sensor 10E of this modification is a modification of the first embodiment described above, and differs from the first embodiment and the like in that the lower electrode 21 consists of one electrode for each unit pixel P.

[0120] Similar to the image sensor 10 described above, the image sensor 10E has one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32B and 32R stacked vertically for each unit pixel P. The organic photoelectric conversion unit 20 is provided on the first surface 30A side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are embedded within the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30.

[0121] The image sensor 10E of this modified example has the same configuration as the image sensor 10 described above, except that the lower electrode 21 of the organic photoelectric conversion unit 20 consists of a single electrode, and an insulating layer 22 and a charge storage layer 23 are not provided between the lower electrode 21 and the photoelectric conversion layer 24.

[0122] Figure 19 schematically shows the cross-sectional configuration of the image sensor 10F according to Modification 4 of this disclosure. Figure 20A schematically shows the cross-sectional configuration of the image sensor 10G according to Modification 4 of this disclosure. Figure 20B schematically shows an example of the planar configuration of the image sensor 10G shown in Figure 20A. Figure 21A schematically shows the cross-sectional configuration of the image sensor 10H according to Modification 4 of this disclosure. Figure 21B schematically shows an example of the planar configuration of the image sensor 10H shown in Figure 21A. The image sensors 10F to 10H are each variations of the above-described variations 1 to 3, and, similar to the image sensor 10E, the lower electrode (e.g., lower electrode 21) consists of one electrode for each unit pixel P, and except that there is no insulating layer (e.g., insulating layer 22) and charge storage layer (e.g., charge storage layer 23) between the lower electrode (e.g., lower electrode 21) and the photoelectric conversion layer (e.g., photoelectric conversion layer 24), they have the same configuration as the corresponding image sensors 10B to 10D of variations 1 to 3.

[0123] As described above, the first embodiment and variations 1 to 3 show examples in which the lower electrodes 21, 61, 81 constituting the organic photoelectric conversion units 20, 60, 80 consist of multiple electrodes (readout electrodes 21A, 61A, 81A and storage electrodes 21B, 61B, 81B), but the invention is not limited to this. The image sensors 10, 10B, 10C, 10D according to the first embodiment and variations 1 to 3 can also be applied when the lower electrodes consist of one electrode for each unit pixel P, and the same effects as the first embodiment and the like can be obtained.

[0124] In this modified example, the organic photoelectric conversion sections 20, 60, and 80 are shown as having the lower electrodes 21, 61, and 81, the photoelectric conversion layers 24, 64, and 84, the work function adjustment layers 25, 65, and 85, and the upper electrodes 26, 66, and 86 stacked in this order, but the invention is not limited to this. In the organic photoelectric conversion sections 20, 60, and 80, electron injection layers may be provided between the work function adjustment layers 25, 65, and 85 and the upper electrodes 26, 66, and 86, respectively, similar to the second embodiment described above.

[0125] <4. Application Examples> (Application Example 1) Figure 22 shows an example of the overall configuration of an imaging device (imaging device 1) equipped with an image sensor (for example, image sensor 10) as shown in Figure 1, etc.

[0126] The imaging device 1 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 1 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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 1. 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.

[0133] The input / output terminal 116 is used for exchanging signals with the outside world.

[0134] (Application Example 2) Furthermore, the imaging device 1 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.

[0135] Figure 23 is a block diagram showing an example of the configuration of electronic device 1000.

[0136] As shown in Figure 23, the electronic device 1000 includes an optical system 1001, an imaging device 1, 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.

[0137] 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 1.

[0138] The imaging device 1 described above is used as the imaging device 1. The imaging device 1 converts the amount of incident light imaged on 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.

[0139] The DSP 1002 performs various signal processing on the signal from the imaging device 1 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.

[0140] (Application Example 3) Figure 24A schematically shows an example of the overall configuration of a photodetection system 2000 equipped with an imaging device 1. Figure 24B 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 1 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.

[0141] 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 24A). 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.

[0142] <5. Application Examples> (Examples of application to endoscopic surgical systems) The technology disclosed herein (the Technology) can be applied to a variety of products. For example, the Technology disclosed herein may be applied to an endoscopic surgical system.

[0143] Figure 25 shows an example of a schematic configuration of an endoscopic surgical system to which the technology described herein (the technology) may be applied.

[0144] Figure 25 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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, the excitation light is 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 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.

[0156] Figure 26 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Figure 25.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] The 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 endoscope 11100 will be equipped with so-called AE (Auto Exposure), AF (Auto Focus), and AWB (Auto White Balance) functions.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] (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).

[0176] Figure 27 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.

[0177] The vehicle control system 12000 comprises multiple electronic control units connected via a communication network 12001. In the example shown in Figure 27, 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 functional configuration of the integrated control unit 12050 is also shown, consisting of a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking system based on information from 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 cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0184] 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.

[0185] 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.

[0186] 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 the vehicle occupants or those outside the vehicle of information. In the example in Figure 27, 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.

[0187] Figure 28 shows an example of the installation position of the imaging unit 12031.

[0188] In Figure 28, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0189] 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.

[0190] Figure 28 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] The above describes an example of a mobile object control system to which the technology described herein may 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 10) 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 images with low noise can be obtained, so that high-precision control using the captured images can be performed in the mobile object control system.

[0196] <6. Examples> Next, embodiments of this disclosure will be described in detail. In the following, image sensors having the cross-sectional configurations shown in Figure 29 (Experiment 1) and Figure 30 (Experiment 2) were fabricated as device samples, and their device characteristics were evaluated.

[0197] [Experiment 1] (Experimental Example 1-1) An ITO film with a thickness of 100 nm was formed on a silicon substrate using a sputtering apparatus. This ITO film was patterned by photolithography and etching to form an ITO electrode (lower electrode 21). Subsequently, the silicon substrate with the ITO electrode was cleaned by UV / ozone treatment, and then the silicon substrate was transferred to a vacuum evaporator. While rotating the substrate holder in a state where the pressure was reduced to 1×10 -5 Pa or less, an organic layer was sequentially laminated on the silicon substrate. First, F6-OPh-26F2 shown in the following formula (1) and fullerene C shown in the following formula (2) were formed at a substrate temperature of 52 °C at film formation rates of 1.0 Å / second and 0.25 Å / second, respectively, so that the thickness of the mixed layer was 10 nm to form a hole blocking layer 24A. Next, F6-OPh-26F2, DPh-BTBT shown in the following formula (3), and fullerene C 60 were formed at a substrate temperature of 52 °C at film formation rates of 0.50 Å / second, 0.50 Å / second, and 0.25 Å / second, respectively, so that the thickness of the mixed layer was 230 nm to form a photoelectric conversion layer 24. Subsequently, CzBDF shown in the following formula (4) was formed at a substrate temperature of 52 °C so that the thickness was 10 nm to form an electron blocking layer 24B. Next, HATCN shown in the following formula (5) and fullerene C 60 were formed at a substrate temperature of 0 °C at film formation rates of 1.4 Å / second and 0.64 Å / second, respectively, so that the thickness of the mixed layer was 10 nm to form a work function adjustment layer 25. Finally, the silicon substrate was transferred to a sputtering apparatus, and an ITO film was formed on the work function adjustment layer 25 with a thickness of 50 nm to form an upper electrode 26. By the above manufacturing method, a sample (Experimental Example 1-1) having a photoelectric conversion region of 1 mm × 1 mm was manufactured. The manufactured device sample was annealed at 150 °C for 210 minutes in a nitrogen (N2) atmosphere.

[0198]

Chemical formula

[0199] (Experimental Example 1-2) In Experimental Example 1-2, the work function adjustment layer 25 was formed from HATCN and fullerene C 60 ​​A device sample (Experimental Example 1-2) was prepared using the same method as in Experimental Example 1-1, except that the film was deposited at a deposition rate of 1.0 Å / sec and 1.0 Å / sec.

[0200] (Experimental Examples 1-3) In Experimental Examples 1-3, the work function adjustment layer 25 was made of HATCN and fullerene C 60 Except for depositing the film at deposition rates of 0.6 Å / sec and 1.4 Å / sec, device samples (Experimental Example 1-3) were prepared using the same method as in Experimental Example 1-1.

[0201] (Experimental Examples 1-4) In Experimental Example 1-4, the work function adjustment layer 25 was made of fullerene C 60 Instead, the fullerene C shown in formula (6) below 70 Except for the use of [specific material], the device sample (Experimental Example 1-4) was prepared using the same method as in Experimental Example 1-3.

[0202] [ka]

[0203] (Experimental Examples 1-5) In Experimental Examples 1-5, the work function adjustment layer 25 was made of HATCN and fullerene C 60 Device samples (Experimental Example 1-5) were prepared using the same method as in Experimental Example 1-3, except that NDI-35, as shown in equation (7) below, was deposited at deposition rates of 0.6 Å / sec, 0.2 Å / sec, and 1.4 Å / sec.

[0204] [ka]

[0205] (Experimental Examples 1-6) In Experimental Example 1-6, the device sample (Experimental Example 1-6) was fabricated using the same method as in Experimental Example 1-1, except that the work function adjustment layer 25 was deposited using only HATCN.

[0206] (Experimental Examples 1-7) In Experimental Example 1-7, the work function adjustment layer 25 was made of fullerene C 60 A device sample (Experimental Example 1-7) was prepared using the same method as in Experimental Example 1-1, except that the NBphen shown in equation (8) below was changed.

[0207] [ka]

[0208] (Experimental Examples 1-8) In Experimental Example 1-8, the device sample (Experimental Example 1-8) was fabricated using the same method as in Experimental Example 1-3, except that the work function adjustment layer 25 was changed from HATCN to the F6-TCNNQ shown in equation (9) below.

[0209] [ka]

[0210] (Experimental Examples 1-9) In Experimental Examples 1-9, the work function adjustment layer 25 was modified to use F6-TCNNQ and fullerene C 60 Except for depositing the film at deposition rates of 0.2 Å / sec and 1.8 Å / sec, device samples (Experimental Example 1-9) were prepared using the same method as in Experimental Example 1-8.

[0211] (Experimental Examples 1-10) In Experimental Example 1-10, the device sample (Experimental Example 1-10) was fabricated using the same method as in Experimental Example 1-8, except that the work function adjustment layer 25 was deposited using only F6-TCNNQ.

[0212] Using the evaluation method described below, the dark current, EQE, and response speed of each device sample in Experimental Examples 1-1 to 1-10, as well as the cohesiveness, adhesion, and yield of the work function adjustment layer 25, were evaluated and summarized in Table 1. Note that the dark current and response time shown in Table 1 were normalized to 1 for the characteristic values ​​of Experimental Example 1-1 for relative comparison.

[0213] (Evaluation of dark current and EQE) The wavelength of light emitted from a green LED light source through a bandpass filter onto the image sensor is 560 nm, and the light intensity is 162 μW / cm². 2 The bias voltage applied between the electrodes of the device sample was controlled using a semiconductor parameter analyzer, and a current-voltage curve was obtained by sweeping the voltage applied to the lower electrode 21 relative to the upper electrode 26. The dark current and bright current values ​​were obtained in the reverse bias applied state (voltage applied at +2.6V), and the EQE was calculated by subtracting the dark current value from the bright current value to convert the value into the number of electrons and dividing by the number of incident photons.

[0214] (Evaluation of response speed) The wavelength of light irradiated onto the device sample from a green LED light source via a bandpass filter 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 was irradiated from the upper electrode 26 side of the device sample. A bias voltage of +2.6V was applied to the lower electrode 21 relative to the upper electrode 26 when pulsed light was irradiated, and the current decay waveform was observed using an oscilloscope. The amount of Coulombs during the current decay process was measured from immediately after irradiation of the light pulse to 110 ms later. This amount of Coulombs was defined as the response time and used as an indicator of response speed.

[0215] (Evaluation of other indicators) For cohesiveness, an atomic force microscope (AFM) was used to determine that films with an arithmetic mean roughness (Ra) of 0.8 nm or less were non-cohesive (A), and films with an arithmetic mean roughness (Ra) greater than 0.8 nm were cohesive (B). For adhesion, the surface-interface cutting method (SAICAS method) was used, and films with a peel strength of 0.05 KN / m or more were classified as A, and those with a peel strength of less than 0.05 KN / m were classified as B. For yield, dark current measurement was used, and a yield of 80% or more was classified as A, and a yield of less than 80% was classified as B. For electron affinity, samples were formed by depositing an ITO film and a single film of each material to be measured on a quartz substrate, and each energy level was determined by UPS and LEIPS.

[0216] [Table 1]

[0217] Table 1 shows that in Experimental Examples 1-1 to 1-5, there was no cohesiveness, high adhesion, excellent yield, and good dark current and response speed. On the other hand, in Experimental Example 1-6, compared to Experimental Examples 1-1 to 1-5, there was cohesiveness, low adhesion, poor yield, and a worsened response speed. This is thought to be because a single layer of HATCN was used for the work function adjustment layer 25 in Experimental Example 1-6. Furthermore, it is thought that the use of a single layer of HATCN as the work function adjustment layer 25 resulted in insufficient carrier conductivity at the interface between the electron blocking layer 24B and the work function adjustment layer 25, leading to insufficient electric field applied to the photoelectric conversion layer 24 and a worsened response speed. In Experimental Example 1-7, the dark current and response speed were worse compared to Experimental Examples 1-1 to 1-5. This is likely because, in Experimental Examples 1-7, a mixed film of HATCN and NBPhen was formed as the work function adjustment layer 25, and the electron affinity of this mixed film was 4.2 eV. As a result, the effect of electron injection from the work function adjustment layer to the photoelectric conversion layer became greater compared to Experimental Examples 1-1 to 1-5.

[0218] In Experimental Examples 1-8 to 1-9, no cohesiveness was observed, adhesion was high, yield was excellent, and dark current and response speed were good. In Experimental Example 1-10, compared to Experimental Examples 1-8 to 1-9, cohesiveness was observed, adhesion was low, yield was poor, and response speed deteriorated. This is thought to be because a single layer of F6-TCNNQ was used for the work function adjustment layer 25 in Experimental Example 1-10. Furthermore, it is thought that the use of a single layer of F6-TCNNQ as the work function adjustment layer 25 resulted in insufficient carrier conductivity at the interface between the electron blocking layer 24B and the work function adjustment layer 25, leading to insufficient electric field applied to the photoelectric conversion layer 24 and thus a deterioration in response speed.

[0219] [Experiment 2] (Experimental Example 2-1) A 100 nm thick ITO film was deposited on a silicon substrate using a sputtering apparatus. This ITO film was patterned by photolithography and etching to form an ITO electrode (lower electrode 21). Subsequently, the silicon substrate with the ITO electrode attached was cleaned with UV / ozone treatment, and then the silicon substrate was transferred to a vacuum deposition machine, resulting in a 1 × 10⁻¹⁶ film. -5 Organic layers were sequentially deposited onto a silicon substrate while rotating the substrate holder under reduced pressure below Pa. First, F6-OPh-26F2 shown in formula (1) and fullerene C shown in formula (2) were added. 60 At a substrate temperature of 52°C, the two materials were deposited at deposition rates of 1.0 Å / sec and 0.25 Å / sec, respectively, to form a hole blocking layer 24A with a mixed layer thickness of 10 nm. Next, F6-OPh-26F2, DPh-BTBT shown in equation (3), and fullerene C were deposited. 60 A photoelectric conversion layer 24 was formed by depositing a mixed layer with a thickness of 230 nm at a substrate temperature of 52°C with deposition rates of 0.50 Å / sec, 0.50 Å / sec, and 0.25 Å / sec, respectively. Next, an electron blocking layer 24B was formed by depositing CzBDF shown in equation (4) at a substrate temperature of 52°C with a thickness of 10 nm. Then, HATCN and fullerene C shown in equation (5) were deposited. 60 At a substrate temperature of 0°C, a work function adjustment layer 25 was formed by depositing a mixed layer with a thickness of 10 nm at deposition rates of 1.4 Å / sec and 0.64 Å / sec, respectively. Next, BBphen shown in equation (8) was deposited at a deposition rate of 0.3 Å / sec to a thickness of 4 nm to form an electron injection enhancement layer 27. Finally, the silicon substrate was transferred to a sputtering apparatus, and an ITO film was deposited on the work function adjustment layer 25 to a thickness of 50 nm to form the upper electrode 26. Using the above fabrication method, a sample (Experimental Example 2-1) having a photoelectric conversion region of 1 mm × 1 mm was prepared. The fabricated device sample was annealed at 150°C for 210 minutes under a nitrogen (N2) atmosphere.

[0220] (Experimental Example 2-2) In Experimental Example 2-2, a device sample (Experimental Example 2-2) was fabricated using the same method as in Experimental Example 2-1, except that the work function adjustment layer 25 was deposited using only HATCN.

[0221] Using the evaluation method described above, the dark current, external quantum efficiency (EQE), and response speed of each device sample in Experimental Examples 2-1 and 2-2 were evaluated and summarized in Table 2. Note that the characteristic values ​​of Experimental Example 1-1 were normalized to 1 for relative comparison.

[0222] [Table 2]

[0223] Experimental Example 2-1 showed higher EQE and superior response speed compared to Experimental Example 1-1. In Experimental Example 2-1, compared to Experimental Example 2-2, the electron concentration of the work function adjustment layer 25 increased by making it a mixed film, improving the carrier conductivity at the interface between the electron blocking layer 24B and the work function adjustment layer 25. As a result, an electric field was more easily applied to the photoelectric conversion layer 24, leading to the high EQE and superior response speed. On the other hand, in Experimental Example 2-2, deterioration in dark current, EQE, and response speed was observed compared to Experimental Example 2-1. This is thought to be because, in Experimental Example 2-2, compared to Experimental Example 2-1, an electron injection promoting layer 27 made of NBphen was provided between the work function adjustment layer 25, which has high cohesiveness and poor flatness, and the upper electrode 26. As a result, NBphen entered the gaps in the domains of the cohesive work function adjustment layer 25, and electrons were directly injected into the photoelectric conversion layer 24. This is thought to have worsened the dark current, and consequently worsened the EQE and response speed. In other words, in Experimental Example 2-1, it was found that the device characteristics were improved by providing an electron injection enhancement layer 27 on top of a highly flat work function adjustment layer 25. On the other hand, in Experimental Example 2-2, which has a work function adjustment layer 25 with high cohesiveness and low flatness, it was found that even with the provision of an electron injection enhancement layer 27, no improvement was obtained compared to Experimental Example 1-6.

[0224] The first and second embodiments, modifications 1 to 4, examples, application examples, and application examples have been described above, but the contents of this disclosure are not limited to the above embodiments, and various modifications are possible. For example, in the first embodiment, the image sensor 10 was configured by stacking an organic photoelectric conversion unit 20 that detects green light and inorganic photoelectric conversion units 32B and 32R that detect blue light and red light, respectively, but the contents of this disclosure are not limited to this structure. That is, the organic photoelectric conversion unit may be configured to detect red light or blue light, or the inorganic photoelectric conversion unit may be configured to detect green light.

[0225] Furthermore, the number and ratio of these organic and inorganic photoelectric conversion units are not limited; two or more organic photoelectric conversion units may be provided, as in Modification 1, or multiple color signals may be obtained using only organic photoelectric conversion units.

[0226] Furthermore, in the above embodiments, an example was shown in which the lower electrode 21 was composed of two electrodes, a read electrode 21A and a storage electrode 21B. However, in addition to this, three or four or more electrodes, such as a transfer electrode or an discharge electrode, may also be provided.

[0227] Furthermore, although the above embodiments show an example in which the lower electrode 21 is formed using multiple electrodes, this technology can also achieve the same effect in an image sensor having a lower electrode consisting of a single electrode.

[0228] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0229] Furthermore, this disclosure may also have the following configuration. According to the technology with the following configuration, a first semiconductor layer is provided between the organic layer, which includes at least a photoelectric conversion layer, and the second electrode, comprising a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV and an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. This improves the adhesion between the organic layer and the second electrode, and also increases the electric field substantially applied to the photoelectric conversion layer, thereby improving manufacturing yield and device characteristics. (1) First electrode and, A second electrode positioned opposite the aforementioned first electrode, An organic layer is provided between the first electrode and the second electrode, and includes at least a photoelectric conversion layer. A first semiconductor layer is provided between the second electrode and the organic layer and comprises a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. An image sensor equipped with this sensor. (2) The image sensor according to (1), wherein the first semiconductor layer is a mixed film obtained by mixing at least the first carbon-containing compound and the second carbon-containing compound. (3) The image sensor according to (2), wherein the mixed film has an electron affinity of 4.5 eV or more and 6.0 eV or less. (4) The image sensor according to (2) or (3), wherein the mixed film has an electron affinity greater than the work function of the second electrode. (5) The image sensor according to any one of (1) to (4) above, wherein the mixing ratio of the first carbon-containing compound and the second carbon-containing compound constituting the first semiconductor layer is 0.1 or more and 10 or less. (6) The imaging device according to any one of (1) to (5), wherein the second carbon-containing compound is a fullerene derivative. (7) The imaging device according to any one of (1) to (6), wherein the crystal grain size of the first semiconductor layer is 10 nm or less. (8) The imaging device according to any one of (1) to (7), wherein the arithmetic mean roughness of the first semiconductor layer is 0.8 nm or less. (9) The imaging device according to any one of (1) to (8), wherein the adhesive force between the first electrode and the second electrode is 0.05 KN / m or more. (10) The imaging device further includes a second semiconductor layer provided between the second electrode and the first semiconductor layer, The imaging device according to any one of (1) to (9), wherein the absolute value B of the difference between the ionization potential of the second semiconductor layer and the Fermi level of the second electrode is not less than the absolute value A of the difference between the electron affinity of the second semiconductor layer calculated from the optical band gap and the Fermi level of the second electrode. (11) The imaging device further includes a second semiconductor layer provided between the second electrode and the first semiconductor layer, The imaging device according to any one of (1) to (9), wherein the second semiconductor layer has an in-gap level with a state density of 1 / 10000 or more with respect to the state density of the ionization potential of the second semiconductor layer in the vicinity of the Fermi level of the second electrode. (12) The imaging device according to any one of (1) to (11), wherein the first electrode is composed of a plurality of electrodes independent of each other. (13) The imaging device according to (12), wherein the first electrode has a charge readout electrode and a charge storage electrode as the plurality of electrodes. (14) The imaging device according to (13), wherein voltages are individually applied to the plurality of electrodes. (15) A third semiconductor layer containing an oxide semiconductor material is placed between the first electrode and the organic layer. An insulating layer is further provided between the first electrode and the third semiconductor layer. The image sensor according to (13) or (14), wherein the charge readout electrode is electrically connected to the third semiconductor layer through an opening provided in the insulating layer. (16) The first electrode is positioned on the side of the organic layer opposite to the light incident surface, as described in any one of (1) to (15). (17) An image sensor according to any one of (1) to (16), wherein an organic photoelectric conversion unit having one or more of the organic layers and one or more inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are laminated together. (18) The inorganic photoelectric conversion unit is embedded and formed in a semiconductor substrate. The organic photoelectric conversion unit is formed on the first surface side of the semiconductor substrate, and is the image sensor according to (17). (19) The aforementioned organic photoelectric conversion unit performs photoelectric conversion of green light, The image sensor according to (18), wherein an inorganic photoelectric conversion unit for performing photoelectric conversion of blue light and an inorganic photoelectric conversion unit for performing photoelectric conversion of red light are stacked inside the semiconductor substrate. (20) It comprises multiple pixels, each of which is provided with one or more image sensors, The aforementioned imaging sensor is First electrode and, A second electrode positioned opposite the aforementioned first electrode, An organic layer is provided between the first electrode and the second electrode, and includes at least a photoelectric conversion layer. A first semiconductor layer is provided between the second electrode and the organic layer and comprises a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. An imaging device having

[0230] This application claims priority based on Japanese Patent Application No. 2021-123630, filed with the Japan Patent Office on 28 July 2021, and all contents of that application are incorporated herein by reference.

[0231] 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, An organic layer is provided between the first electrode and the second electrode, and includes at least a photoelectric conversion layer. A first semiconductor layer is provided between the second electrode and the organic layer and comprises a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. An image sensor equipped with this sensor.

2. The image sensor according to claim 1, wherein the first semiconductor layer is a mixed film obtained by mixing at least the first carbon-containing compound and the second carbon-containing compound.

3. The image sensor according to claim 2, wherein the mixed film has an electron affinity of 4.5 eV or more and 6.0 eV or less.

4. The image sensor according to claim 2, wherein the mixed film has an electron affinity greater than the work function of the second electrode.

5. The image sensor according to claim 1, wherein the mixing ratio of the first carbon-containing compound and the second carbon-containing compound constituting the first semiconductor layer is 0.1 or more and 10 or less.

6. The image sensor according to claim 1, wherein the second carbon-containing compound is a fullerene derivative.

7. The image sensor according to claim 1, wherein the crystal grain size of the first semiconductor layer is 10 nm or less.

8. The image sensor according to claim 1, wherein the arithmetic mean roughness of the first semiconductor layer is 0.8 nm or less.

9. The image sensor according to claim 1, wherein the adhesion force between the first electrode and the second electrode is 0.05 kN / m or more.

10. The second semiconductor layer is further provided between the second electrode and the first semiconductor layer, The image sensor according to claim 1, wherein the absolute value B of the difference between the ionization potential of the second semiconductor layer and the Fermi level of the second electrode is greater than or equal to the absolute value A of the difference between the electron affinity of the second semiconductor layer calculated from the optical band gap and the Fermi level of the second electrode.

11. The second semiconductor layer is further provided between the second electrode and the first semiconductor layer, The image sensor according to claim 1, wherein the second semiconductor layer has an in-gap level near the Fermi level of the second electrode, with a density of states of 1 / 10000 or more relative to the density of states of the ionization potential of the second semiconductor layer.

12. The image sensor according to claim 1, wherein the first electrode comprises a plurality of electrodes that are independent of each other.

13. The image sensor according to claim 12, wherein the first electrode has a plurality of electrodes, including a charge readout electrode and a charge storage electrode.

14. The image sensor according to claim 13, wherein a voltage is applied to each of the plurality of electrodes individually.

15. A third semiconductor layer containing an oxide semiconductor material is placed between the first electrode and the organic layer. An insulating layer is further provided between the first electrode and the third semiconductor layer. The image sensor according to claim 13, wherein the charge readout electrode is electrically connected to the third semiconductor layer through an opening provided in the insulating layer.

16. The image sensor according to claim 1, wherein the first electrode is arranged on the side of the organic layer opposite to the light incident surface.

17. The image sensor according to claim 1, wherein an organic photoelectric conversion unit having one or more of the organic layers and one or more inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are laminated together.

18. The inorganic photoelectric conversion unit is embedded and formed in a semiconductor substrate. The image sensor according to claim 17, wherein the organic photoelectric conversion unit is formed on the first surface side of the semiconductor substrate.

19. The aforementioned organic photoelectric conversion unit performs photoelectric conversion of green light, The image sensor according to claim 18, wherein an inorganic photoelectric conversion unit for performing photoelectric conversion of blue light and an inorganic photoelectric conversion unit for performing photoelectric conversion of red light are stacked inside the semiconductor substrate.

20. It comprises multiple pixels, each of which is provided with one or more image sensors, The aforementioned imaging sensor is First electrode and A second electrode positioned opposite the first electrode, An organic layer is provided between the first electrode and the second electrode, and includes at least a photoelectric conversion layer. A first semiconductor layer is provided between the second electrode and the organic layer and comprises a first carbon-containing compound having an electron affinity of 4.5 eV to 6.0 eV, and having an electron affinity greater than 4.8 eV or greater than the work function of the second electrode, and a second carbon-containing compound having an ionization potential greater than 5.5 eV. An imaging device having

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