WO2019150971A1

WO2019150971A1 - Photoelectric conversion element and image pickup device

Info

Publication number: WO2019150971A1
Application number: PCT/JP2019/001253
Authority: WO
Inventors: 雅史坂東; 治典塩見
Original assignee: ソニー株式会社
Priority date: 2018-01-31
Filing date: 2019-01-17
Publication date: 2019-08-08

Abstract

One embodiment of this photoelectric conversion element comprises: a first electrode consisting of a plurality of mutually independent electrodes; a second electrode disposed opposing the first electrode; a photoelectric conversion layer that contains semiconductor nanoparticles and that is disposed between the first electrode and the second electrode; and a semiconductor layer that contains an oxide semiconductor material and that is disposed between the first electrode and the photoelectric conversion layer. The photoelectric conversion layer satisfies ε_CQD/ε_S<3 if the dielectric constant of the photoelectric conversion layer is ε_CQD and the dielectric constant of the semiconductor layer is ε_S.

Description

Photoelectric conversion element and imaging device

The present disclosure relates to, for example, a photoelectric conversion element having a photoelectric conversion layer containing semiconductor nanoparticles and an imaging apparatus including the photoelectric conversion element.

In an imaging apparatus such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, the pixel size is being reduced. In an imaging device having a photoelectric conversion unit outside a semiconductor substrate, charges generated by photoelectric conversion are generally accumulated in a floating diffusion layer (floating diffusion; FD) formed in the semiconductor substrate. .

By the way, in an imaging device provided with a photoelectric conversion unit in a semiconductor substrate, the charge generated by the photoelectric conversion is once accumulated in the photoelectric conversion unit in the semiconductor substrate and then transferred to the FD. For this reason, a photoelectric conversion part can be completely depleted. On the other hand, in the photoelectric conversion unit provided outside the semiconductor substrate, the charge generated by the photoelectric conversion unit is directly accumulated in the FD as described above, so that the photoelectric conversion unit is completely depleted. It was difficult, kTC noise became large, random noise worsened, and the picked-up image quality was reduced.

On the other hand, for example, in Patent Document 1, among the first electrode and the second electrode disposed so as to face each other with the photoelectric conversion layer interposed therebetween, the first electrode side disposed on the side opposite to the light incident side is An image sensor is disclosed that is provided with a charge storage electrode that is spaced apart from one electrode and that is opposed to a photoelectric conversion layer with an insulating layer interposed therebetween. In this imaging device, charges generated by photoelectric conversion can be stored in the photoelectric conversion layer, and the charge storage portion can be completely depleted at the start of exposure. Therefore, it is possible to reduce a decrease in image quality.

JP 2017-157816 A JP 2010-177392 A

Incidentally, in recent years, as a photoelectric conversion element having sensitivity to near-infrared light, for example, in Patent Document 2, a photoelectric conversion element using semiconductor nanoparticles in a photoelectric conversion layer has been developed. In a photoelectric conversion element in which a photoelectric conversion layer is formed using semiconductor nanoparticles, improvement in quantum efficiency is required.

It is desirable to provide a photoelectric conversion element and an imaging device that can improve quantum efficiency.

A photoelectric conversion element according to an embodiment of the present disclosure includes a first electrode including a plurality of independent electrodes, a second electrode disposed opposite to the first electrode, semiconductor nanoparticles, a first electrode, The photoelectric conversion layer provided between the two electrodes and an oxide semiconductor material and a semiconductor layer provided between the first electrode and the photoelectric conversion layer are provided. When the relative dielectric constant of the photoelectric conversion layer is ε _CQD and the relative dielectric constant of the semiconductor layer is ε _S , ε _CQD / ε _S <3 is satisfied.

An imaging apparatus according to an embodiment of the present disclosure includes a plurality of pixels each provided with one or a plurality of photoelectric conversion elements, and includes the photoelectric conversion element according to the embodiment described above as a photoelectric conversion element.

In the photoelectric conversion element according to an embodiment of the present disclosure and the imaging device according to an embodiment, a semiconductor including a photoelectric conversion layer including a semiconductor nanoparticle and an oxide semiconductor material between a first electrode and a second electrode arranged to face each other. The dielectric constant of the photoelectric conversion layer is ε _CQD , and the relative dielectric constant of the semiconductor layer is ε _S , so that the relative dielectric constant of the photoelectric conversion layer satisfies ε _CQD / ε _S <3 . This suppresses recombination of charges generated by photoelectric conversion by applying a strong electric field to the photoelectric conversion layer.

According to the photoelectric conversion element of one embodiment of the present disclosure and the imaging apparatus of one embodiment, a semiconductor layer including an oxide semiconductor material and a photoelectric conversion layer including semiconductor nanoparticles between the first electrode and the second electrode. _Are provided in this order, and the relative dielectric constant of the photoelectric conversion layer (ε _CQD ) satisfies ε _CQD / ε _S <3 with respect to the relative dielectric constant (ε _S ) of the semiconductor layer. An electric field is applied. Therefore, charge recombination in the photoelectric conversion layer is suppressed, and quantum efficiency can be improved.

In addition, the effect described here is not necessarily limited, and may be any effect described in the present disclosure.

It is a cross-sectional schematic diagram of an image sensor according to an embodiment of the present disclosure. It is a cross-sectional schematic diagram of the photoelectric conversion element shown in FIG. FIG. 2 is an equivalent circuit diagram of the image sensor shown in FIG. 1. It is a schematic diagram showing arrangement | positioning of the transistor which comprises the lower electrode and control part of the image pick-up element shown in FIG. It is a schematic diagram of the cross-sectional structure of a semiconductor nanoparticle. It is a figure explaining the principle of operation of the photoelectric conversion element shown in FIG. It is a figure explaining the principle of operation of the photoelectric conversion element shown in FIG. It is a figure explaining the principle of operation of the photoelectric conversion element shown in FIG. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the image pick-up element shown in FIG. It is a cross-sectional schematic diagram showing the process following FIG. 7A. It is a cross-sectional schematic diagram showing the process of following FIG. 7B. It is a cross-sectional schematic diagram showing the process of following FIG. 7C. It is a cross-sectional schematic diagram showing the process following FIG. 7D. FIG. 3 is a timing diagram illustrating an operation example of the photoelectric conversion element illustrated in FIG. 1. It is a potential distribution figure between electrodes at the time of light irradiation of the photoelectric conversion element as a comparative example. FIG. 2 is a potential distribution diagram between electrodes when the photoelectric conversion element shown in FIG. 1 is irradiated with light. It is a block diagram showing the structure of the imaging device which used the image pick-up element shown in FIG. 1 as a pixel. It is a functional block diagram showing an example of the electronic device (camera) using the imaging device shown in FIG. It is a block diagram which shows an example of a schematic structure of an in-vivo information acquisition system. It is a figure which shows an example of a schematic structure of an endoscopic surgery system. It is a block diagram which shows an example of a function structure of a camera head and CCU. It is a block diagram which shows an example of a schematic structure of a vehicle control system. It is explanatory drawing which shows an example of the installation position of a vehicle exterior information detection part and an imaging part. It is a characteristic view showing the relationship between the dielectric constant of the photoelectric converting layer with respect to the dielectric constant of the semiconductor layer in Example, and EQE. It is a characteristic view showing the relationship between the ratio (ε _CQD / ε _S ) of the relative permittivity of the photoelectric conversion layer to the relative permittivity of the semiconductor layer in the example and EQE. It is a characteristic view showing the relationship between the volume ratio of the semiconductor nanoparticle in an Example, EQE, and response time.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description is one specific example of the present disclosure, and the present disclosure is not limited to the following aspects. In addition, the present disclosure is not limited to the arrangement, dimensions, dimensional ratio, and the like of each component illustrated in each drawing. The order of explanation is as follows.
1. Embodiment (an example of a photoelectric conversion element in which the relative dielectric constant of the photoelectric conversion layer is controlled)
1-1. Configuration of image sensor 1-2. Manufacturing method of imaging device 1-3. Image sensor control method 1-4. Action / Effect Application example Example

<1. Embodiment>
FIG. 1 schematically illustrates a cross-sectional configuration of an imaging device (imaging device 1) according to an embodiment of the present disclosure. FIG. 2 schematically shows an enlarged cross-sectional configuration of a main part (photoelectric conversion element 10) of the image sensor 1 shown in FIG. FIG. 3 is an equivalent circuit diagram of the image sensor 1 shown in FIG. FIG. 4 schematically shows the arrangement of the transistors constituting the lower electrode 11 and the control unit of the image sensor 1 shown in FIG. The imaging device 1 constitutes one pixel (unit pixel P) in an imaging device (imaging device 100; see FIG. 11) such as a CMOS image sensor.

(1-1. Configuration of image sensor)
The imaging element 1 is, for example, one in which the photoelectric conversion element 10 is provided on the first surface (back surface) 30 A side of the semiconductor substrate 30. The photoelectric conversion element 10 includes a photoelectric conversion layer 14 formed using semiconductor nanoparticles between a lower electrode 11 (first electrode) and an upper electrode 15 (second electrode) arranged to face each other. A semiconductor layer 13 is provided between the lower electrode 11 and the photoelectric conversion layer 14 via an insulating layer 12. The lower electrode 11 includes a readout electrode 11A, a storage electrode 11B, and a transfer electrode 11C disposed between the readout electrode 11A and the storage electrode 11B, for example, as a plurality of independent electrodes. The storage electrode 11B and the transfer electrode 11C are covered with an insulating layer 12, and the readout electrode 11A is electrically connected to the semiconductor layer 13 through an opening 12H provided in the insulating layer 12. The photoelectric conversion element 10 of the present embodiment is configured such that the ratio of the relative dielectric constant of the photoelectric conversion layer 14 to the relative dielectric constant of the semiconductor layer 13 is less than 3.

In the present embodiment, a case will be described in which electrons are read out as signal charges out of electron-hole pairs (electron-hole pairs) generated by photoelectric conversion. In the figure, “+ (plus)” attached to “p” and “n” indicates that the p-type or n-type impurity concentration is high, and “++” indicates that the p-type or n-type impurity concentration is high. It is higher than “+”.

The photoelectric conversion element 10 is a photoelectric conversion element that absorbs light corresponding to a part or all of a selective wavelength range (for example, 700 nm to 2500 nm) and generates electron-hole pairs. As shown in FIG. 2, the photoelectric conversion element 10 includes, for example, a lower electrode 11, an insulating layer 12, a semiconductor layer 13, a photoelectric conversion layer 14, and an upper electrode 15 stacked in this order on the first surface 30 A side of the semiconductor substrate 30. It has the structure which was made. In FIG. 2, the fixed charge layer 16A, the dielectric layer 16B, the interlayer insulating layer 17 and the like are omitted. For example, the lower electrode 11 is separately formed for each unit pixel P, and will be described in detail later. The lower electrode 11 includes a readout electrode 11A, a storage electrode 11B, and a transfer electrode 11C that are separated from each other with an insulating layer 12 therebetween. . In FIG. 1, the semiconductor layer 13, the photoelectric conversion layer 14, and the upper electrode 15 are illustrated as being separately formed for each image sensor 1. May be.

As described above, the lower electrode 11 includes, for example, a readout electrode 11A, a storage electrode 11B, and a transfer electrode 11C that are independent from each other. The lower electrode 11 can be formed using, for example, a light-transmitting conductive material (transparent conductive material). The band gap energy of the transparent conductive material is preferably 2.5 eV or more, for example, and preferably 3.1 eV or more. A metal oxide can be raised as the transparent conductive material. Specifically, indium-zinc oxide, indium-tin oxide (including ITO, Indium Tin Oxide, Sn-doped In ₂ O ₃ , crystalline ITO, and amorphous ITO), indium added to zinc oxide as a dopant Oxide (IZO), Indium-gallium oxide (IGO) with gallium oxide added with indium as a dopant, Indium-gallium-zinc oxide with zinc oxide added with indium and gallium (IGZO, In -GaZnO ₄₎ , indium-tin-zinc oxide (ITZO) in which indium and tin are added to zinc oxide as dopants, IFO (F-doped In ₂ O ₃ ), tin oxide (SnO ₂ ), ATO (Sb-doped SnO ₂ ), FTO (F-doped SnO ₂ ), zinc oxide (doping other elements) ZnO), aluminum-zinc oxide (AZO) in which aluminum is added as a dopant to zinc oxide, gallium-zinc oxide (GZO) in which gallium is added as a dopant to zinc oxide, titanium oxide (TiO ₂ ) Examples thereof include niobium-titanium oxide (TNO) obtained by adding niobium as a dopant to titanium oxide, antimony oxide, spinel oxide, and oxide having a YbFe ₂ O ₄ structure. In addition, the transparent electrode which uses gallium oxide, titanium oxide, niobium oxide, nickel oxide etc. as a base layer can be mentioned. The thickness of the lower electrode 11 in the Y-axis direction (hereinafter simply referred to as thickness) is, for example, 2 × 10 ⁻⁸ m or more and 2 × 10 ⁻⁷ m or less, preferably 3 × 10 ⁻⁸ m or more and 1 ×. 10 ^-7 m or less.

When the lower electrode 11 does not require transparency, the lower electrode 11 is formed of, for example, platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum ( Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co) and molybdenum ( It can be formed as a single layer film or a laminated film using a metal such as Mo) or an alloy thereof. Specifically, it can be formed using Al—Nd (alloy of aluminum and neodymium), ASC (alloy of aluminum, samarium and copper) or the like. The lower electrode 11 is made of a conductive material such as the above metal or an alloy thereof, polysilicon containing impurities, a carbon-based material, an oxide semiconductor material, a carbon nano tube, and graphene. You may make it form. In addition, the lower electrode 11 may be formed using an organic material (conductive polymer) such as poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid [PEDOT / PSS]. The material may be mixed with a binder (polymer) and paste or ink may be cured to form.

The readout electrode 11A is for transferring signal charges generated in the photoelectric conversion layer 14 to the floating diffusion FD1. The read electrode 11A is provided on the second surface (front surface) 30B side of the semiconductor substrate 20 via, for example, the upper first contact 17A, the pad portion 39A, the through electrode 34, the connection portion 41A, and the lower second contact 46. It is connected to the floating diffusion FD1.

The storage electrode 11 B is for storing signal charges (electrons) in the semiconductor layer 13 among the charges generated in the photoelectric conversion layer 14. The storage electrode 11B is preferably larger than the readout electrode 11A, so that a large amount of charge can be stored.

The transfer electrode 11C is for improving the efficiency of transferring the charge accumulated in the storage electrode 11B to the read electrode 11A, and is provided between the read electrode 11A and the storage electrode 11B. The transfer electrode 11C is connected to a pixel drive circuit constituting the drive circuit via, for example, the upper third contact 17C and the pad portion 39C. The readout electrode 11A, the storage electrode 11B, and the transfer electrode 11C can apply a voltage independently.

The insulating layer 12 is for electrically separating the storage electrode 11B and the transfer electrode 11C from the semiconductor layer 13. For example, the insulating layer 12 is provided on the interlayer insulating layer 17 so as to cover the lower electrode 11. The insulating layer 12 is provided with an opening 12H on the readout electrode 11A of the lower electrode 11, and the readout electrode 11A and the semiconductor layer 13 are electrically connected through the opening 12H. . For example, as shown in FIG. 2, the side surface of the opening 12H preferably has an inclination that widens toward the light incident side S1. Thereby, the movement of charges from the semiconductor layer 13 to the readout electrode 11A becomes smoother.

Examples of the material of the insulating layer 12 include inorganic insulating materials such as silicon oxide materials, metal oxide high dielectric insulating materials such as silicon nitride (SiN _x ), and aluminum oxide (Al ₂ O ₃ ). In addition, polymethyl methacrylate (PMMA), polyvinylphenol (PVP), polyvinyl alcohol (PVA), polyimide, polycarbonate (PC), polyethylene terephthalate (PET), polystyrene, N-2 (aminoethyl) 3-aminopropyltrimethoxy Silanol derivatives (silane coupling agents) such as silane (AEAPTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), octadecyltrichlorosilane (OTS), novolac-type phenol resin, fluorine-based resin, octadecanethiol, dodecyl isocyanate, etc. An organic insulating material (organic polymer) exemplified by linear hydrocarbons having a functional group capable of binding to the control electrode at one end can be given, and these can also be used in combination. As the silicon oxide-based material, silicon oxide (SiO _x ), BPSG, PSG, BSG, AsSG, PbSG, silicon oxynitride (SiON), SOG (spin-on-glass), low dielectric constant material (for example, polyaryl ether) Cycloperfluorocarbon polymer and benzocyclobutene, cyclic fluororesin, polytetrafluoroethylene, fluorinated aryl ether, fluorinated polyimide, amorphous carbon, and organic SOG).

The semiconductor layer 13 accumulates signal charges generated in the photoelectric conversion layer 14 and transfers them to the readout electrode 11A. The carrier density of the semiconductor layer 13 is preferably 1 × 10 ¹⁴ cm ⁻³ or more and 1 × 10 ¹⁷ cm ⁻³ or less, for example. The relative dielectric constant (ε _S ) of the semiconductor layer 13 is preferably 5 or more and 25 or less, for example. The semiconductor layer 13 is preferably formed using a material having a higher charge mobility and a larger band gap than the photoelectric conversion layer 14. Thereby, for example, charge transfer can be speeded up and hole injection from the readout electrode to the semiconductor layer 13 can be suppressed.

The semiconductor layer 13 includes, for example, an oxide semiconductor material. Examples of the oxide semiconductor material include IGZO (In—Ga—Zn—O-based oxide semiconductor), ZTO (Zn—Sn—O-based oxide semiconductor; Zn ₂ SnO ₄ ), and IGZTO (In—Ga—Zn—). Examples thereof include Sn—O-based oxide semiconductors: InGaZnSnO), GTO (Ga—Sn—O-based oxide semiconductors; Ga ₂ O ₃ : SnO ₂ ), and IGO (In—Ga—O-based oxide semiconductors). The semiconductor layer 13 preferably uses at least one of the above oxide semiconductor materials, and among them, IGZO is preferably used. The thickness of the semiconductor layer 13 is, for example, 30 nm to 200 nm, preferably 60 nm to 150 nm.

The photoelectric conversion layer 14 converts light energy into electric energy, and provides a field where excitons generated when absorbing light in a wavelength region of 700 nm to 2500 nm are separated into electrons and holes, for example. The thickness of the photoelectric conversion layer 14 which is a thing is 100 nm or more and 1000 nm or less, for example, Preferably it is 300 nm or more and 800 nm or less.

The photoelectric conversion layer 14 includes semiconductor nanoparticles (semiconductor nanoparticles 14X) and has, for example, a configuration in which a plurality of semiconductor nanoparticles 14X are dispersed in a conductive polymer. The semiconductor nanoparticles 14X are generally particles having a particle size of several to several tens of nanometers. For example, as shown in FIG. 5, the core part 14a, a shell layer 14b provided around the core part 14a, and a shell And a ligand portion 14c bonded to the surface of the layer 14b. Note that the shell layer 14b is not essential, and the semiconductor nanoparticles 14X may be composed of a core portion 14a and a ligand portion 14c bonded to the surface of the core portion 14a. Examples of the material constituting the core portion 14a include silicon and selenium that are group IV semiconductors, and CuInGaSe, CuInSe ₂ , CuInS ₂ , CuAlS ₂ , CuAlSe ₂ , CuGaS ₂ , CuGaSe ₂ , CuZnSnSSe, and ZnCuInSe that are chalcopyrite compounds. , AgAlS ₂ , AgAlSe ₂ , AgInS ₂ , AgInSe ₂ , III-V group compounds GaAs, InAs, InP, AlGaAs, InGaP, AlGaInP, II-VI group compounds CdS, CdSe, CdTe, ZnO, ZnS ZnSe, ZnTe, HgTe, and compound semiconductors such as PbO, PbS, PbSe, and PbTe, which are IV-VI group compounds. Examples of the material constituting the shell layer 14b include PbO, PbO ₂ , Pb ₃ O ₄ , ZnS, ZnSe, ZnTe, and the like.

The semiconductor nanoparticle 14X has a large band gap due to the quantum confinement effect when the particle size is smaller than twice the exciton-bohr radius of the material. The semiconductor nanoparticles 14X of the present embodiment preferably have an average particle size of, for example, 3 nm or more and 6 nm or less. Here, the particle size of the semiconductor nanoparticles 14X is the particle size of the core portion 14a or the core portion 14a including the shell layer 14b when the core portion 14a is covered by the shell layer 14b. The magnitude | size of the core part 14a containing the core part 14a and the shell layer 14b can be adjusted with the raw material supply amount at the time of those synthesis | combination, and reaction conditions. The ligand part 14c is composed of, for example, an adsorption group that interacts with the surface of the core part 14a or the shell layer 14b, and an alkyl chain that binds to the adsorption group. The number of carbons in the alkyl chain is, for example, 2 to 50, and the adsorbing group is, for example, amine, phosphone, phosphine, carboxyl, hydroxyl, thiol. In addition, halogen atoms such as chlorine (Cl), bromine (Br), and iodine (I) may be used.

As described above, the photoelectric conversion layer 14 of the present embodiment preferably has a relative dielectric constant (ε _CQD ) that is less than 3 with respect to the relative dielectric constant of the semiconductor layer 13, in other words, the photoelectric conversion layer 14. Preferably has a dielectric constant satisfying ε _CQD / ε _S <3. For example, when the relative dielectric constant of the semiconductor layer 13 is 10, the relative dielectric constant of the photoelectric conversion layer 14 is preferably less than 30. This makes it possible to apply a strong electric field to the photoelectric conversion layer 14 and suppress recombination of electron-hole pairs generated in the photoelectric conversion layer 14 due to photoelectric conversion.

The relative dielectric constant of the photoelectric conversion layer 14 can be controlled, for example, by changing the type of the semiconductor nanoparticles 14X to be used. Moreover, the relative dielectric constant of the photoelectric conversion layer 14 can be controlled by changing the volume ratio of the semiconductor nanoparticles 14 X included in the photoelectric conversion layer 14. As a method for changing the volume ratio of the semiconductor nanoparticles 14X contained in the photoelectric conversion layer 14, the following three methods may be mentioned. First, the first method includes changing the size of the core portion 14a constituting the semiconductor nanoparticle 14X. For example, when the ligand portion 14c having the same length is used, the volume ratio of the core portion 14a in the semiconductor nanoparticle 14X is reduced by reducing the particle size of the core portion 14a, and the photoelectric conversion layer 14 using the same. The relative dielectric constant of decreases. The second method is to change the length of the ligand portion 14c. For example, when the core part 14a having the same particle diameter is used, by increasing the length of the ligand part 14c, the volume ratio of the core part 14a in the semiconductor nanoparticle 14X becomes small, and the photoelectric conversion layer 14 using the same. The relative dielectric constant of decreases. As a third method, a photoelectric conversion layer 14 may be formed by mixing a conductive material having a relative dielectric constant lower than that of the core portion 14a with the core portion 14a. For example, the relative dielectric constant of the photoelectric conversion layer can be lowered by increasing the mixing ratio of the conductive materials.

Note that if the length of the ligand portion 14c is increased, the conductivity between the semiconductor nanoparticles 14X and the conductivity between the semiconductor nanoparticles 14X and the conductive polymer may be reduced. For this reason, for example, the ligand part 14c used in the second method includes, for example, acenes such as anthracene, carrier conductivity such as thiophene compound represented by the following formula (1) and S-adenosine methionine (SAM) It is preferable to use one having The conductive material to be mixed with the core part 14a in the third method uses the following carrier conductive polymer instead of the ligand part 14c, and mixes with the core part 14a covered with the core part 14a or the shell layer 14b. You may make it use. Examples of the carrier conductive polymer include PEDOT: PSS, low molecular thiophene polymer, 3-hexylthiophene (P3HT), phenyl C61 butyric acid methyl ester (PCBM), Poly [2,1,3-benzothiadiazole-4,7- diyl [4,4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b: 3,4-b ′] dithio-phene-2,6-diyl]] (PCPDTBT), poly (2,3 -bis (2-hexyldecyl) quinoxaline-5,8-diyl-alt-N- (2-hexyldecyl) -dithieno [3,2-b: 2 ', 3'-d] pyrrotgle) (PDTPQx-HD), poly [[4,8-bis] (2-ethylhexyl) oxy] benzo [1,2-b: 4-5-b ′] diophen-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl) ) Carbonyl] ethino] [3,4-b] thiophenzyl] (PTB7), poly [(9,9-di (3,3′-N, N′-trimethylammonium) propylfluorene) -alt-co- (9, 9-dioctyl-fluore ne) diiodide salt (PFN) and the like.

The upper electrode 15 is made of a light transmissive conductive material. The upper electrode 15 may be separated for each unit pixel P, or may be formed as a common electrode for each unit pixel P. The thickness of the upper electrode 15 is, for example, 10 nm to 200 nm.

Note that another layer may be provided between the photoelectric conversion layer 14 and the upper electrode 15. For example, when electrons are read out as signal charges as in this embodiment, a work function such as MoO ₃ , WO ₃ , V ₂ O ₅ is large between the photoelectric conversion layer 14 and the upper electrode 15. A layer made of a material may be added. Thereby, an internal electric field generated between the lower electrode 11 and the upper electrode 15 can be strengthened.

In the photoelectric conversion element 10 of the present embodiment, the near infrared light L incident on the photoelectric conversion element 10 from the upper electrode 15 side is absorbed by the photoelectric conversion layer 14. The excitons generated thereby are separated into electrons and holes by exciton separation as shown in FIG. 6A, for example. The charges (electrons and holes) generated here are caused by diffusion due to the carrier concentration difference or an internal electric field due to the work function difference between the anode (here, the upper electrode 15) and the cathode (here, the lower electrode 11). For example, as shown in FIG. 6B, they are conveyed to different electrodes. The transport direction of electrons and holes is controlled by applying a potential between the lower electrode 11 and the upper electrode 15. Here, the electrons are carried as signal charges to the lower electrode 11 side. The electrons carried to the lower electrode 11 side are accumulated in the semiconductor layer 13 on the storage electrode 11B, and then transferred to the readout electrode 11A and detected as a photocurrent, as shown in FIG. 6C.

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

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

Between the first surface 30A of the semiconductor substrate 30 and the lower electrode 11, for example, a layer (fixed charge layer) 16A having a fixed charge, a dielectric layer 16B having an insulating property, and an interlayer insulating layer 17 are provided. It has been. A protective layer 18 is provided on the upper electrode 15. In the protective layer 18, for example, a light shielding film 21 is provided on the readout electrode 11A, for example. The light shielding film 21A does not extend to at least the storage electrode 11B, and may be provided so as to cover at least the region of the readout electrode 11A that is in direct contact with the photoelectric conversion layer 14. For example, it is preferable that the electrode is provided slightly larger than the readout electrode 11A formed in the same layer as the storage electrode 11B. For example, a color filter 22 is provided on the storage electrode 11B, for example. The color filter 22 is, for example, for preventing visible light from entering the photoelectric conversion layer 14 and may be provided so as to cover at least the region of the storage electrode 11B. Although FIG. 1 shows an example in which the light shielding film 21 and the color filter 22 are provided at different positions in the film thickness direction of the protective layer 18, they may be provided at the same position. Above the protective layer 18, optical members such as a planarizing layer (not shown) and an on-chip lens 23 are disposed.

The fixed charge layer 16A may be a film having a positive fixed charge or a film having a negative fixed charge. Examples of the material of the film having a negative fixed charge include hafnium oxide, aluminum oxide, zirconium oxide, tantalum oxide, and titanium oxide. In addition to the above materials, lanthanum oxide, praseodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holeium oxide, thulium oxide, ytterbium oxide, lutetium oxide Alternatively, an yttrium oxide, an aluminum nitride film, a hafnium oxynitride film, an aluminum oxynitride film, or the like may be used.

The fixed charge layer 16A may have a configuration in which two or more kinds of films are stacked. Thereby, for example, in the case of a film having a negative fixed charge, the function as the hole accumulation layer can be further enhanced.

The material of the dielectric layer 16B is not particularly limited. For example, the dielectric layer 16B is formed of a silicon oxide film, TEOS, a silicon nitride film, a silicon oxynitride film, or the like.

The interlayer insulating layer 17 is constituted by, for example, a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride (SiON), or the like, or a laminated film made of two or more of these. .

The protective layer 18 is made of a light-transmitting material, for example, a single layer film made of any of silicon oxide, silicon nitride, silicon oxynitride, or the like, or a laminated film made of two or more of them. It is comprised by. The thickness of the protective layer 18 is, for example, 100 nm to 30000 nm.

A through electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The photoelectric conversion element 10 is connected to the gate Gamp of the amplifier transistor AMP and one source / drain region 36B of the reset transistor RST (reset transistor Tr1rst) that also serves as the floating diffusion FD1 through the through electrode 34. Thereby, in the imaging device 1, the signal charge generated in the photoelectric conversion element 10 on the first surface 30A side of the semiconductor substrate 30 is favorably transferred to the second surface 30B side of the semiconductor substrate 30 through the through electrode 34, It is possible to improve the characteristics.

The lower end of the through electrode 34 is connected to a connection portion 41A in the wiring layer 41, and the connection portion 41A and the gate Gamp of the amplifier transistor AMP are connected via a lower first contact 45. The connection portion 41A and the floating diffusion FD1 (region 36B) are connected via, for example, the lower second contact 46. The upper end of the through electrode 34 is connected to the readout electrode 11A via, for example, the pad portion 39A and the upper first contact 17A.

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

Next to the floating diffusion FD1 (one source / drain region 36B of the reset transistor RST), the reset gate Grst of the reset transistor RST is arranged. Thereby, the charge accumulated in the floating diffusion FD1 can be reset by the reset transistor RST.

The semiconductor substrate 30 is composed of, for example, an n-type silicon (Si) substrate and has a p-well 31 in a predetermined region. On the second surface 30B of the p-well 31, the above-described amplifier transistor AMP, reset transistor RST, selection transistor SEL, and the like are provided. In addition, a peripheral circuit (not shown) including a logic circuit or the like is provided in the peripheral portion of the semiconductor substrate 30.

The reset transistor RST (reset transistor Tr1rst) resets the charge transferred from the photoelectric conversion element 10 to the floating diffusion FD1, and is configured by a MOS transistor, for example. Specifically, the reset transistor Tr1rst includes a reset gate Grst, a channel formation region 36A, and source /

drain regions

36B and 36C. The reset gate Grst is connected to the reset line RST1, and one source / drain region 36B of the reset transistor Tr1rst also serves as the floating diffusion FD1. The other source / drain region 36C constituting the reset transistor Tr1rst is connected to the power supply VDD.

The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the photoelectric conversion element 10 into a voltage, and is configured by, for example, a MOS transistor. Specifically, the amplifier transistor AMP includes a gate Gamp, a channel formation region 35A, and source /

drain regions

35B and 35C. The gate Gamp is connected to the read electrode 11A and one source / drain region 36B (floating diffusion FD1) of the reset transistor Tr1rst through the lower first contact 45, the connecting portion 41A, the lower second contact 46, the through electrode 34, and the like. Has been. Also, one source / drain region 35B shares a region with the other source / drain region 36C constituting the reset transistor Tr1rst and is connected to the power supply VDD.

The selection transistor SEL (selection transistor TR1sel) includes a gate Gsel, a channel formation region 34A, and source /

drain regions

34B and 34C. The gate Gsel is connected to the selection line SEL1. One source / drain region 34B shares a region with the other source / drain region 35C constituting the amplifier transistor AMP, and the other source / drain region 34C is a signal line (data output line) VSL1. It is connected to the.

The reset line RST1 and the selection line SEL1 are each connected to a vertical drive circuit 112 that constitutes a drive circuit. The signal line (data output line) VSL1 is connected to the column signal processing circuit 113 constituting the drive circuit.

The lower first contact 45, the upper first contact 17A, the upper second contact 17B, and the upper third contact 17C are doped silicon materials such as PDAS (PhosphorusphorDoped Amorphous Silicon), or aluminum (Al), tungsten, for example. It is made of a metal material such as (W), titanium (Ti), cobalt (Co), hafnium (Hf), and tantalum (Ta).

(1-2. Method for Manufacturing Image Sensor)
The image sensor 1 of the present embodiment can be manufactured as follows, for example.

7A to 7E show the manufacturing method of the image sensor 1 in the order of steps. First, as shown in FIG. 7A, for example, a p-well 31 is formed as a first conductivity type well in the semiconductor substrate 30. A p + region is formed in the vicinity of the first surface 30 A of the semiconductor substrate 30.

Similarly, as shown in FIG. 7A, after forming an n + region that becomes the floating diffusion FD1, for example, the gate insulating layer 32, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST are formed on the second surface 30B of the semiconductor substrate 30. And a gate wiring layer 47 including these gates. Thereby, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST are formed. Further, the multilayer wiring 40 including the wiring layers 41 to 43 including the lower first contact 45, the lower second contact 46, and the connecting portion 41A and the insulating layer 44 is formed on the second surface 30B of the semiconductor substrate 30.

As the base of the semiconductor substrate 30, for example, an SOI (Silicon On Insulator) substrate in which a semiconductor substrate 30, a buried oxide film (not shown), and a holding substrate (not shown) are stacked is used. Although not shown in FIG. 7A, the buried oxide film and the holding substrate are bonded to the first surface 30A of the semiconductor substrate 30. After ion implantation, annealing is performed.

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

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

Subsequently, for example, a negative fixed charge layer 16A is formed on the first surface 30A of the semiconductor substrate 30 and the side surface of the opening 34H. Two or more types of films may be stacked as the negative fixed charge layer 16A. Thereby, the function as a hole accumulation layer can be further enhanced. After the negative fixed charge layer 16A is formed, the dielectric layer 16B is formed. Next, after the

pad portions

39A, 39B, and 39C are formed at predetermined positions on the dielectric layer 16B, the interlayer insulating layer 17 is formed on the dielectric layer 16B and the

pad portions

39A, 39B, and 39C. Next, after the interlayer insulating layer 17 is formed, the surface of the interlayer insulating layer 17 is planarized by using, for example, a CMP (Chemical-Mechanical-Polishing) method.

Subsequently, as shown in FIG. 7C, openings 18H1, 18H2, and 18H3 are respectively formed in the interlayer insulating layer 17 on the

pad portions

39A, 39B, and 39C, and then, for example, Al or the like is formed in the openings 18H1, 18H2, and 18H3. Then, the upper first contact 18A, the upper second contact 18B, and the upper third contact 18C are formed.

Subsequently, as illustrated in FIG. 7D, after the conductive film 21x is formed on the interlayer insulating layer 17, the conductive film 21x is formed at predetermined positions (for example, on the pad portion 39A, the pad portion 39B, and the pad portion 39C). A photoresist PR is formed. Thereafter, the readout electrode A, the storage electrode 11B, and the transfer electrode 11C shown in FIG. 7E are patterned by etching and removing the photoresist PR.

Next, after forming the insulating layer 12 on the interlayer insulating layer 17, the readout electrode 11A, the storage electrode 11B, and the upper third contact 18C, an opening 12H is provided on the readout electrode 11A. Thereafter, the semiconductor layer 13, the photoelectric conversion layer 14, the upper electrode 15, the protective layer 19, the light shielding film 21, and the color filter 22 are formed on the interlayer insulating layer 17. Finally, an optical member such as a planarizing layer and an on-chip lens 23 are disposed. Thus, the image sensor 1 shown in FIG. 1 is completed.

(1-3. Image Sensor Control Method)
(Signal acquisition by the photoelectric conversion element 10)
In the image sensor 1 of the present embodiment, light in the near infrared region of light incident on the image sensor 1 is selectively detected (absorbed) by the photoelectric conversion element 10 and subjected to photoelectric conversion.

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

Further, a reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD1. Thereby, the electric charge accumulated in the floating diffusion FD1 is reset by the reset transistor RST.

In the present embodiment, since the photoelectric conversion element 10 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 through the through electrode 34, the charge accumulated in the floating diffusion FD1 can be easily obtained by the reset transistor RST. It becomes possible to reset to.

On the other hand, when the through electrode 34 and the floating diffusion FD1 are not connected, it becomes difficult to reset the charges accumulated in the floating diffusion FD1, and a large voltage is applied to pull out the charge to the upper electrode 15 side. become. For this reason, the photoelectric conversion layer 14 may be damaged. In addition, a structure that can be reset in a short time causes an increase in dark noise, which is a trade-off, so that this structure is difficult.

FIG. 8 shows an operation example of the photoelectric conversion element 10. (A) shows the potential at the storage electrode 11B, (B) shows the potential at the floating diffusion FD1 (reading electrode 11A), and (C) shows the potential at the gate (Gsel) of the reset transistor TR1rst. It is. In the photoelectric conversion element 10, voltages are individually applied to the readout electrode 11A, the storage electrode 11B, and the transfer electrode 11C.

In the photoelectric conversion element 10, during the accumulation period, the potential V1 is applied from the drive circuit to the readout electrode 11A, and the potential V2 is applied to the storage electrode 11B. Here, the potentials V1 and V2 satisfy V1> V2. As a result, signal charges (electrons here) generated by the photoelectric conversion are attracted to the storage electrode 11B and stored in the region of the semiconductor layer 13 facing the storage electrode 11B (storage period). Incidentally, the potential of the region of the semiconductor layer 13 facing the storage electrode 11B becomes a more positive value as the photoelectric conversion time elapses. The holes are sent from the upper electrode 15 to the drive circuit.

In the photoelectric conversion element 10, a reset operation is performed in the later 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. Thereby, in the unit pixel P, the reset transistor TR1rst is turned on. As a result, the voltage of the floating diffusion FD1 is set to the power supply voltage VDD, and the voltage of the floating diffusion FD1 is reset (reset period).

After the reset operation is completed, the charge is read out. Specifically, at timing t2, the potential V3 is applied from the drive circuit to the readout electrode 11A, the potential V4 is applied to the storage electrode 11B, and the potential V5 is applied to the transfer electrode 11C. Here, the potentials V3, V4, and V5 satisfy V4> V5> V3. Thereby, the signal charge accumulated in the region corresponding to the storage electrode 11B moves from the storage electrode 11B to the transfer electrode 11C and the readout electrode 11A in this order, and is read from the readout electrode 11A to the floating diffusion FD1. That is, the charge accumulated in the semiconductor layer 13 is read out to the control unit (transfer period).

After the read operation is completed, the potential V1 is again applied from the drive circuit to the read electrode 11A, and the potential V2 is applied to the storage electrode 11B. As a result, the signal charge generated by the photoelectric conversion is attracted to the storage electrode 11B and stored in the region of the semiconductor layer 13 facing the storage electrode 11B (storage period).

(1-4. Action and effect)
As described above, in recent years, a photoelectric conversion element using semiconductor nanoparticles in a photoelectric conversion layer has been developed as a photoelectric conversion element having sensitivity to near infrared light. In the photoelectric conversion element using semiconductor nanoparticles in the photoelectric conversion layer, from the viewpoint of reset noise, a semiconductor layer is provided between the lower electrode and the photoelectric conversion layer, for example, like the photoelectric conversion element 1000 illustrated in FIG. Yes. The semiconductor layer is for accumulating the charge generated in the photoelectric conversion layer on the charge accumulation electrode constituting the lower electrode and transferring the accumulated charge to the charge collection electrode. For example, the mobility of the charge It is formed using an oxide semiconductor material such as high IGZO. However, in a photoelectric conversion element in which a semiconductor layer and a photoelectric conversion layer using semiconductor nanoparticles are stacked, there is a concern about an increase in dark current and a decrease in quantum efficiency.

FIG. 9 shows a potential distribution between electrodes during light irradiation of a general photoelectric conversion element. The horizontal axis in FIG. 9 indicates the distance from the interface between the electrode disposed on the light incident side and the photoelectric conversion layer. Accordingly, the film thickness of 0 nm is an interface with the electrode disposed on the light incident side, the film thickness of 300 nm is the interface with the electrode disposed on the opposite side to the light incident side, and the film thickness of 200 nm is between the photoelectric conversion layer and This corresponds to the interface with the semiconductor layer. In Figure 9 the solid line, for example, a semiconductor layer having a dielectric constant 10 in donor concentration _{^{^{(N D) 10 15 cm -3}}} , between the electrodes of the photoelectric conversion device using a photoelectric conversion layer having a dielectric constant 30 It represents the potential distribution. The broken line in FIG. 9 indicates, for example, between the electrodes of a photoelectric conversion element using a semiconductor layer having a donor density (N _D ) of 10 ¹⁸ cm ⁻³ and a relative dielectric constant of 10 and a photoelectric conversion layer having a relative dielectric constant of 30. It represents the potential distribution. In a general photoelectric conversion element, as shown in FIG. 9, the energy change in the range of 0 nm to 200 nm corresponding to the photoelectric conversion layer is small compared to the energy change in the film thickness of 200 nm to 300 nm corresponding to the semiconductor layer. It can be seen that the internal electric field applied to the photoelectric conversion layer during light irradiation is weak. It can also be seen that the lower the carrier density (donor density) of the semiconductor layer to be joined, the less the internal electric field is applied to the photoelectric conversion layer during light irradiation.

It is known that the quantum efficiency of a photoelectric conversion element is improved by laminating an n-type semiconductor layer and a photoelectric conversion layer. On the other hand, in order to accumulate charges generated by photoelectric conversion in the semiconductor layer, a photoelectric conversion element provided with a plurality of independent electrodes on the side opposite to the light incident side is used for charge accumulation and transfer operations. The semiconductor layer needs to be depleted. When the depleted semiconductor layer and the photoelectric conversion layer are stacked, an internal electric field is hardly applied to the photoelectric conversion layer as shown in FIG. 9 due to the difference in relative dielectric constant. Therefore, the charge transfer depends on diffusion conduction, and the quantum efficiency decreases.

On the other hand, in the photoelectric conversion element (photoelectric conversion element 10) of the present embodiment, the relative dielectric constant (ε _CQD ) of the photoelectric conversion layer 14 is ε with respect to the relative dielectric constant (ε _S ) of the semiconductor layer 13. _CQD / ε _S <3 was satisfied. FIG. 10 shows the potential distribution between the electrodes when the photoelectric conversion element 10 is irradiated with light. The horizontal axis of FIG. 10 shows the distance from the interface between the electrode (upper electrode 15) and the photoelectric conversion layer (photoelectric conversion layer 14) arranged on the light incident side, as in FIG. Therefore, the film thickness of 0 nm is the interface with the upper electrode 15, the film thickness 300 is the interface with the lower electrode 11, and the film thickness of 200 nm corresponds to the interface between the photoelectric conversion layer 14 and the semiconductor layer 13. The solid line in FIG. 10 represents the potential distribution between the electrodes of the photoelectric conversion element using the photoelectric conversion layer of this embodiment. The broken line in FIG. 10 represents the potential distribution between the electrodes of the photoelectric conversion element using the semiconductor layer having the donor density (N _D ) 10 ¹⁵ cm ⁻³ shown in FIG. 9 as a comparative example. In addition, while the relative dielectric constant (ε _r ) of the photoelectric conversion layer in the comparative example is 30, the relative dielectric constant (ε _CQD ) of the photoelectric conversion layer 14 of the photoelectric conversion element 10 of the present embodiment is 15. Yes. The relative dielectric constant (ε _r ) of the semiconductor layer is 10 for both the comparative example and the photoelectric conversion element 10. In the photoelectric conversion element 10 of this Embodiment, as shown in FIG. 10, it turns out that the strong internal electric field is applied to the photoelectric converting layer 14 at the time of light irradiation compared with a comparative example. Therefore, the efficiency of transport of electrons generated in the photoelectric conversion layer 14 to the storage electrode 11B is improved, and recombination of electron-hole pairs in the photoelectric conversion layer 14 can be suppressed.

As described above, in this embodiment, in this embodiment, the relative dielectric constant of the photoelectric conversion layer 14 is reduced with respect to the relative dielectric constant (ε _S ) of the semiconductor layer 13 by reducing the relative dielectric constant of the photoelectric conversion layer 14. Since ε _CQD ) satisfies ε _CQD / ε _S <3, a strong electric field is applied to the photoelectric conversion layer 14. Therefore, charge recombination in the photoelectric conversion layer 14 is suppressed, and quantum efficiency can be improved.

<2. Application example>
(Application example 1)
FIG. 11 illustrates the overall configuration of an imaging apparatus (imaging apparatus 100) that uses the imaging element 1 described in the above embodiment for each pixel. This imaging device 100 is a CMOS image sensor, and has a pixel unit 1a as an imaging area on a semiconductor substrate 30, and, for example, a row scanning unit 131, a horizontal selection unit 133, and the like in a peripheral region of the pixel unit 1a. A peripheral circuit unit 130 including a column scanning unit 134 and a system control unit 132 is provided.

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

The row scanning unit 131 is configured by a shift register, an address decoder, or the like, and is a pixel driving unit that drives each unit pixel P of the pixel unit 1a, for example, in units of rows. A signal output from each unit pixel P of the pixel row that is selectively scanned by the row scanning unit 131 is supplied to the horizontal selection unit 133 through each of the vertical signal lines Lsig. The horizontal selection unit 133 is configured by an amplifier, a horizontal selection switch, and the like provided for each vertical signal line Lsig.

The column scanning unit 134 includes a shift register, an address decoder, and the like, and drives the horizontal selection switches in the horizontal selection unit 133 in order while scanning. By the selective scanning by the column scanning unit 134, the signal of each pixel transmitted through each of the vertical signal lines Lsig is sequentially output to the horizontal signal line 135 and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal line 135. .

The circuit portion including the row scanning unit 131, the horizontal selection unit 133, the column scanning unit 134, and the horizontal signal line 135 may be formed directly on the semiconductor substrate 30 or provided in the external control IC. It may be. In addition, these circuit portions may be formed on another substrate connected by a cable or the like.

The system control unit 132 receives a clock given from the outside of the semiconductor substrate 30, data for instructing an operation mode, and the like, and outputs data such as internal information of the imaging apparatus 100. The system control unit 132 further includes a timing generator that generates various timing signals, and the row scanning unit 131, the horizontal selection unit 133, the column scanning unit 134, and the like based on the various timing signals generated by the timing generator. Peripheral circuit drive control.

(Application example 2)
The imaging device 100 and the like can be applied to all types of electronic devices having an imaging function, such as a camera system such as a digital still camera and a video camera, and a mobile phone having an imaging function. FIG. 12 shows a schematic configuration of an electronic device 200 (camera) as an example. The electronic device 200 is, for example, a video camera capable of shooting a still image or a moving image, and drives the imaging device 100, an optical system (optical lens) 210, a shutter device 211, the imaging device 100, and the shutter device 211. A driving unit 213 and a signal processing unit 212 are included.

The optical system 210 guides image light (incident light) from a subject to the pixel unit 1a of the imaging apparatus 100. The optical system 210 may be composed of a plurality of optical lenses. The shutter device 211 controls a light irradiation period and a light shielding period for the imaging apparatus 100. The drive unit 213 controls the transfer operation of the imaging device 100 and the shutter operation of the shutter device 211. The signal processing unit 212 performs various signal processing on the signal output from the imaging apparatus 100. The video signal Dout after the signal processing is stored in a storage medium such as a memory, or is output to a monitor or the like.

(Application example 3)
<Application example to in-vivo information acquisition system>
Furthermore, the technology (present technology) according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

FIG. 13 is a block diagram illustrating an example of a schematic configuration of a patient in-vivo information acquisition system using a capsule endoscope to which the technique according to the present disclosure (present technique) can be applied.

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

The capsule endoscope 10100 is swallowed by the patient at the time of examination. The capsule endoscope 10100 has an imaging function and a wireless communication function, and moves inside the organ such as the stomach and the intestine by peristaltic motion or the like until it is spontaneously discharged from the patient. Images (hereinafter also referred to as in-vivo images) are sequentially captured at predetermined intervals, and information about the in-vivo images is sequentially wirelessly transmitted to the external control device 10200 outside the body.

The external control device 10200 comprehensively controls the operation of the in-vivo information acquisition system 10001. Further, the external control device 10200 receives information about the in-vivo image transmitted from the capsule endoscope 10100 and, based on the received information about the in-vivo image, displays the in-vivo image on the display device (not shown). The image data for displaying is generated.

In the in-vivo information acquisition system 10001, an in-vivo image obtained by imaging the inside of the patient's body can be obtained at any time in this manner until the capsule endoscope 10100 is swallowed and discharged.

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

The capsule endoscope 10100 includes a capsule-type casing 10101. In the casing 10101, a light source unit 10111, an imaging unit 10112, an image processing unit 10113, a wireless communication unit 10114, a power supply unit 10115, and a power supply unit 10116 and the control unit 10117 are stored.

The light source unit 10111 includes a light source such as an LED (light-emitting diode), and irradiates the imaging field of the imaging unit 10112 with light.

The image capturing unit 10112 includes an image sensor and an optical system including a plurality of lenses provided in front of the image sensor. Reflected light (hereinafter referred to as observation light) of light irradiated on the body tissue to be observed is collected by the optical system and enters the image sensor. In the imaging unit 10112, in the imaging element, the observation light incident thereon is photoelectrically converted, and an image signal corresponding to the observation light is generated. The image signal generated by the imaging unit 10112 is provided to the image processing unit 10113.

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

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

The power feeding unit 10115 includes a power receiving antenna coil, a power regeneration circuit that regenerates power from a current generated in the antenna coil, a booster circuit, and the like. In the power feeding unit 10115, electric power is generated using a so-called non-contact charging principle.

The power supply unit 10116 is composed of a secondary battery, and stores the electric power generated by the power supply unit 10115. In FIG. 13, in order to avoid complication of the drawing, illustration of an arrow or the like indicating a power supply destination from the power supply unit 10116 is omitted, but the power stored in the power supply unit 10116 is stored in the light source unit 10111. The imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the control unit 10117 can be used for driving them.

The control unit 10117 includes a processor such as a CPU, and a control signal transmitted from the external control device 10200 to drive the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the power feeding unit 10115. Control accordingly.

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

Further, the external control device 10200 performs various image processing on the image signal transmitted from the capsule endoscope 10100, and generates image data for displaying the captured in-vivo image on the display device. As the image processing, for example, development processing (demosaic processing), image quality enhancement processing (band enhancement processing, super-resolution processing, NR (Noise reduction) processing and / or camera shake correction processing, etc.), and / or enlargement processing ( Various signal processing such as electronic zoom processing can be performed. The external control device 10200 controls driving of the display device to display an in-vivo image captured based on the generated image data. Alternatively, the external control device 10200 may cause the generated image data to be recorded on a recording device (not shown) or may be printed out on a printing device (not shown).

Heretofore, an example of the in-vivo information acquisition system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to, for example, the imaging unit 10112 among the configurations described above. Thereby, detection accuracy improves.

(Application example 4)
<Application example to endoscopic surgery system>
The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

FIG. 14 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system to which the technology (present technology) according to the present disclosure can be applied.

FIG. 14 illustrates a state in which an operator (doctor) 11131 is performing an operation on a patient 11132 on a patient bed 11133 using an endoscopic operation system 11000. As shown in the figure, an endoscopic surgery system 11000 includes an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment instrument 11112, and a support arm device 11120 that supports the endoscope 11100. And a cart 11200 on which various devices for endoscopic surgery are mounted.

The endoscope 11100 includes a lens barrel 11101 in which a region having a predetermined length from the distal end is inserted into the body cavity of the patient 11132, and a camera head 11102 connected to the proximal end of the lens barrel 11101. In the illustrated example, an endoscope 11100 configured as a so-called rigid mirror having a rigid lens barrel 11101 is illustrated, but the endoscope 11100 may be configured as a so-called flexible mirror having a flexible lens barrel. Good.

An opening into which the objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101. Irradiation is performed toward the observation target in the body cavity of the patient 11132 through the lens. Note that the endoscope 11100 may be a direct endoscope, a perspective mirror, or a side endoscope.

An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from the observation target is condensed on the image sensor by the optical system. Observation light is photoelectrically converted by the imaging element, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image is generated. The image signal is transmitted to a camera control unit (CCU: “Camera Control Unit”) 11201 as RAW data.

The CCU 11201 is configured by a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and the like, and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Further, the CCU 11201 receives an image signal from the camera head 11102 and performs various kinds of image processing for displaying an image based on the image signal, such as development processing (demosaic processing), for example.

The display device 11202 displays an image based on an image signal subjected to image processing by the CCU 11201 under the control of the CCU 11201.

The light source device 11203 includes a light source such as an LED (light emitting diode), and supplies irradiation light to the endoscope 11100 when photographing a surgical site or the like.

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

The treatment instrument control device 11205 controls the drive of the energy treatment instrument 11112 for tissue ablation, incision, blood vessel sealing, or the like. In order to inflate the body cavity of the patient 11132 for the purpose of securing the field of view by the endoscope 11100 and securing the operator's work space, the pneumoperitoneum device 11206 passes gas into the body cavity via the pneumoperitoneum tube 11111. Send in. The recorder 11207 is an apparatus capable of recording various types of information related to surgery. The printer 11208 is a device that can print various types of information related to surgery in various formats such as text, images, or graphs.

In addition, the light source device 11203 that supplies the irradiation light when the surgical site is imaged to the endoscope 11100 can be configured by, for example, a white light source configured by an LED, a laser light source, or a combination thereof. When a white light source is configured by a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high accuracy. Therefore, the light source device 11203 adjusts the white balance of the captured image. It can be carried out. In this case, laser light from each of the RGB laser light sources is irradiated on the observation target in a time-sharing manner, and the drive of the image sensor of the camera head 11102 is controlled in synchronization with the irradiation timing, thereby corresponding to each RGB. It is also possible to take the images that have been taken in time division. According to this method, a color image can be obtained without providing a color filter in the image sensor.

Further, the driving of the light source device 11203 may be controlled so as to change the intensity of the output light every predetermined time. Synchronously with the timing of changing the intensity of the light, the drive of the image sensor of the camera head 11102 is controlled to acquire an image in a time-sharing manner, and the image is synthesized, so that high dynamic without so-called blackout and overexposure A range image can be generated.

Further, the light source device 11203 may be configured to be able to supply light of a predetermined wavelength band corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissue, the surface of the mucous membrane is irradiated by irradiating light in a narrow band compared to irradiation light (ie, white light) during normal observation. A so-called narrow-band light observation (Narrow Band Imaging) is performed in which a predetermined tissue such as a blood vessel is imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed in which an image is obtained by fluorescence generated by irradiating excitation light. In fluorescence observation, the body tissue is irradiated with excitation light to observe fluorescence from the body tissue (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally administered to the body tissue and applied to the body tissue. It is possible to obtain a fluorescence image by irradiating excitation light corresponding to the fluorescence wavelength of the reagent. The light source device 11203 can be configured to be able to supply narrowband light and / or excitation light corresponding to such special light observation.

FIG. 15 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in FIG.

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 by a transmission cable 11400 so that they can communicate with each other.

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

The imaging device constituting the imaging unit 11402 may be one (so-called single plate type) or plural (so-called multi-plate type). In the case where the imaging unit 11402 is configured as a multi-plate type, for example, image signals corresponding to RGB may be generated by each imaging element, and a color image may be obtained by combining them. Alternatively, the imaging unit 11402 may be configured to include a pair of imaging elements for acquiring right-eye and left-eye image signals corresponding to 3D (dimensional) display. By performing the 3D display, the operator 11131 can more accurately grasp the depth of the living tissue in the surgical site. Note that in the case where the imaging unit 11402 is configured as a multi-plate type, a plurality of lens units 11401 can be provided corresponding to each imaging element.

Further, the imaging unit 11402 is not necessarily provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101 immediately after the objective lens.

The driving unit 11403 is configured by an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. Thereby, the magnification and the focus of the image captured by the imaging unit 11402 can be adjusted as appropriate.

The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from 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.

Further, the communication unit 11404 receives a control signal for controlling driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes, for example, information that specifies the frame rate of the captured image, information that specifies the exposure value at the time of imaging, and / or information that specifies the magnification and focus of the captured image. Contains information about the condition.

Note that the imaging conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. Good. In the latter case, a so-called AE (Auto-Exposure) function, AF (Auto-Focus) function, and AWB (Auto-White Balance) function are mounted on the endoscope 11100.

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

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

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

The image processing unit 11412 performs various types of image processing on the image signal that is RAW data transmitted from the camera head 11102.

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

Further, the control unit 11413 causes the display device 11202 to display a picked-up image showing the surgical part or the like based on the image signal subjected to the image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 detects surgical tools such as forceps, specific biological parts, bleeding, mist when using the energy treatment tool 11112, and the like by detecting the shape and color of the edge of the object included in the captured image. Can be recognized. When displaying the captured image on the display device 11202, the control unit 11413 may display various types of surgery support information superimposed on the image of the surgical unit using the recognition result. Surgery support information is displayed in a superimposed manner and presented to the operator 11131, thereby reducing the burden on the operator 11131 and allowing the operator 11131 to proceed with surgery reliably.

The transmission cable 11400 for connecting the camera head 11102 and the CCU 11201 is an electric signal cable corresponding to electric signal communication, an optical fiber corresponding to optical communication, or a composite cable thereof.

Here, in the illustrated example, communication is performed by wire using the transmission cable 11400. However, communication between the camera head 11102 and the CCU 11201 may be performed wirelessly.

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

Note that although an endoscopic surgery system has been described here as an example, the technology according to the present disclosure may be applied to, for example, a microscope surgery system and the like.

(Application example 5)
<Application examples to mobile objects>
The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be any type of movement such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, a construction machine, and an agricultural machine (tractor). You may implement | achieve as an apparatus mounted in a body.

FIG. 16 is a block diagram illustrating a schematic configuration example of a vehicle control system that is an example of a mobile control system to which the technology according to the present disclosure can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example illustrated in FIG. 16, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, a vehicle exterior information detection unit 12030, a vehicle interior information detection unit 12040, and an integrated control unit 12050. Further, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

The drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 includes a driving force generator for generating a driving force of a vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism that adjusts and a braking device that generates a braking force of the vehicle.

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 keyless entry system, a smart key system, a power window device, or a control device for various lamps such as a headlamp, a back lamp, a brake lamp, a blinker, or a fog lamp. In this case, the body control unit 12020 can be input with radio waves transmitted from a portable device that substitutes for a key or signals from various switches. The body system control unit 12020 receives input of these radio waves or signals, and controls a door lock device, a power window device, a lamp, and the like of the vehicle.

The vehicle outside information detection unit 12030 detects information outside the vehicle on which the vehicle control system 12000 is mounted. For example, the imaging unit 12031 is connected to the vehicle exterior information detection unit 12030. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The vehicle outside information detection unit 12030 may perform an object detection process or a distance detection process such as a person, a car, an obstacle, a sign, or a character on a road surface based on the received image.

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

The vehicle interior information detection unit 12040 detects vehicle interior information. For example, a driver state detection unit 12041 that detects a driver's state is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the vehicle interior information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated or it may be determined whether the driver is asleep.

The microcomputer 12051 calculates a control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside / outside the vehicle acquired by the vehicle outside information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit A control command can be output to 12010. For example, the microcomputer 12051 realizes ADAS (Advanced Driver Assistance System) functions including vehicle collision avoidance or impact mitigation, following traveling based on inter-vehicle distance, vehicle speed maintenance traveling, vehicle collision warning, or vehicle lane departure warning. It is possible to perform cooperative control for the purpose.

Further, the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform cooperative control for the purpose of automatic driving that autonomously travels without depending on the operation.

Further, the microcomputer 12051 can output a control command to the body system control unit 12020 based on information outside the vehicle acquired by the vehicle outside information detection unit 12030. For example, the microcomputer 12051 controls the headlamp according to the position of the preceding vehicle or the oncoming vehicle detected by the outside information detection unit 12030, and performs cooperative control for the purpose of anti-glare, such as switching from a high beam to a low beam. It can be carried out.

The sound image output unit 12052 transmits an output signal of at least one of sound and image to an output device capable of visually or audibly notifying information to a vehicle occupant or the outside of the vehicle. In the example of FIG. 16, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are illustrated as output devices. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

FIG. 17 is a diagram illustrating an example of an installation position of the imaging unit 12031.

In FIG. 17, the imaging unit 12031 includes

imaging units

12101, 12102, 12103, 12104, and 12105.

The

imaging units

12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as a front nose, a side mirror, a rear bumper, a back door, and an upper part of a windshield in the vehicle interior of the vehicle 12100. The imaging unit 12101 provided in the front nose and the imaging unit 12105 provided in the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100. The

imaging units

12102 and 12103 provided in the side mirror mainly acquire an image of the side of the vehicle 12100. The imaging unit 12104 provided in the rear bumper or the back door mainly acquires an image behind the vehicle 12100. The imaging unit 12105 provided on the upper part of the windshield in the passenger compartment is mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

FIG. 17 shows an example of the shooting range of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided in the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the

imaging units

12102 and 12103 provided in the side mirrors, respectively, and the imaging range 12114 The imaging range of the imaging part 12104 provided in the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, an overhead image when the vehicle 12100 is viewed from above is obtained.

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

For example, the microcomputer 12051, based on the distance information obtained from the imaging units 12101 to 12104, the distance to each three-dimensional object in the imaging range 12111 to 12114 and the temporal change in this distance (relative speed with respect to the vehicle 12100). In particular, it is possible to extract, as a preceding vehicle, a three-dimensional object that travels at a predetermined speed (for example, 0 km / h or more) in the same direction as the vehicle 12100, particularly the closest three-dimensional object on the traveling path of the vehicle 12100. it can. Further, the microcomputer 12051 can set an inter-vehicle distance to be secured in advance before the preceding vehicle, and can perform automatic brake control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. Thus, cooperative control for the purpose of autonomous driving or the like autonomously traveling without depending on the operation of the driver can be performed.

For example, the microcomputer 12051 converts the three-dimensional object data related to the three-dimensional object to other three-dimensional objects such as a two-wheeled vehicle, a normal vehicle, a large vehicle, a pedestrian, and a utility pole based on the distance information obtained from the imaging units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microcomputer 12051 is connected via the audio speaker 12061 or the display unit 12062. By outputting an alarm to the driver and performing forced deceleration or avoidance steering via the drive system control unit 12010, driving assistance for collision avoidance can be performed.

At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the captured images of the imaging units 12101 to 12104. Such pedestrian recognition is, for example, whether or not the user is a pedestrian by performing a pattern matching process on a sequence of feature points indicating the outline of an object and a procedure for extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras. It is carried out by the procedure for determining. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 has a rectangular contour line for emphasizing the recognized pedestrian. The display unit 12062 is controlled so as to be superimposed and displayed. Moreover, the audio | voice image output part 12052 may control the display part 12062 so that the icon etc. which show a pedestrian may be displayed on a desired position.

<3. Example>
Next, examples of the present disclosure will be described in detail.

The sample for evaluation was produced using the following method, and the external quantum efficiency (EQE) and photoresponsiveness were evaluated.

First, a glass substrate provided with an ITO electrode having a thickness of 50 nm was washed by UV / ozone treatment, and then a 100 nm thick semiconductor layer made of IGZO was formed on the ITO electrode by sputtering. Subsequently, the substrate was subjected to heat treatment at 350 ° C. for 1 hour in the atmosphere to deplete IGZO. Next, PbS nanoparticles in which oleic acid is coordinated on the surface of the nanoparticles are used as semiconductor nanoparticles, and this and P3HT are dispersed in a chloroform solvent and applied onto the semiconductor layer at a rotational speed of 2500 rpm by a spin coating method. A photoelectric conversion layer was formed. The amount of PbS nanoparticles and P3HT added to the chloroform solvent is such that, for example, when the volume ratio of PbS nanoparticles in the photoelectric conversion layer after film formation is 20%, PbS nanoparticles are added to 1 ml of chloroform. Disperse 70 mg, 30 mg of P3HT. The volume ratio can be adjusted in proportion to the amount of nanoparticles and P3HT. Subsequently, a solution of BDT (1,4-benzenedithiol) dispersed in acetonitrile solvent at a concentration of 0.05 mol / L was added dropwise to exchange the ligand of PbS nanoparticles from oleic acid to BDT. This operation reduces the distance between the nanoparticles and improves the carrier conductivity between the nanoparticles. Next, acetonitrile was added dropwise to wash away excess organic substances such as oleic acid, and then heat treatment was performed at 150 ° C. for 10 minutes in an inert gas atmosphere to remove the residual solvent. Subsequently, an MoO ₃ film having a thickness of 10 nm was formed on the photoelectric conversion layer using a vacuum deposition method, and an ITO film having a thickness of 50 nm was further stacked using a sputtering method, thereby forming an upper electrode. Thus, a photoelectric conversion element having a 1 mm × 1 mm photoelectric conversion region was produced.

Using a similar method, a plurality of samples with different mixing ratios of PbS nanoparticles and P3HT were produced. In addition, these photoelectric conversion layers adjusted the film thickness so that the light absorption amount in wavelength 940nm might become equivalent in each sample.

FIG. 18A shows the relationship between the relative dielectric constant and EQE of the photoelectric conversion layer in which the volume ratio of the PbS nanoparticles is changed. In FIG. 18A, EQE is normalized based on the relative dielectric constant (ε _r ) 30 of the photoelectric conversion layer in a general photoelectric conversion element. FIG. 18B shows the relationship between the ratio of the relative permittivity of the photoelectric conversion layer to the relative permittivity of the semiconductor layer (ε _CQD / ε _S ) and EQE. FIG. 19 shows the relationship between the volume ratio of semiconductor nanoparticles (PbS nanoparticles) in the photoelectric conversion layer, EQE, and photoresponse time using these samples.

The relative permittivity of the photoelectric conversion layer is determined by forming a photoelectric conversion layer on a glass substrate provided with an ITO electrode using the same method, and separately preparing an element having an upper electrode made of Al. The effective area of the element, photoelectric conversion It calculated using the capacity | capacitance obtained by the film thickness and impedance analysis of a layer. EQE was evaluated using a semiconductor parameter analyzer. Specifically, the amount of light (wavelength 940 nm) irradiated from the LED light source to the photoelectric conversion element via the bandpass filter is 10 μW / cm ² and the reverse bias voltage applied between the electrodes is 3 V. The external photoelectric conversion efficiency was calculated from the bright current value and the dark current value. The light response time was measured by using a digital oscilloscope to measure how the bright current value observed during light irradiation falls after the light is blocked. Specifically, light having a wavelength of 940 nm was irradiated for 100 ms at a light amount of 50 μW / cm ² , and the reverse bias voltage applied between the electrodes was set to 3V. The time from immediately after the light interruption until the current value attenuates to 10% at the time of light irradiation was defined as the light response time, which was defined as the light response time.

FIG. 18A shows that EQE decreases in proportion to the relative dielectric constant of the photoelectric conversion layer. In the figure, the solid line shows the device simulation result by the drift diffusion model optimized within the range of values that the physical property parameters of the semiconductor layer and the photoelectric conversion layer can take. FIG. 18B shows the quantum efficiencies obtained by combining a semiconductor layer having a relative dielectric constant in the range of 5 to 25 and a photoelectric conversion layer having a relative dielectric constant in the range of 10 to 50 based on these physical property parameters. The results obtained by device simulation and plotted against ε _CQD / ε _S are shown. From this result, it was found that the ratio of the relative dielectric constant of the semiconductor layer to the relative dielectric constant of the photoelectric conversion layer is preferably ε _CQD / ε _S <3. More preferably, ε _CQD / ε _S <2.6. From FIG. 19, it was found that the photoresponse time was shortened with an increase in the volume ratio of the PbS nanoparticles. This can be presumed that the photoresponsiveness of the photoelectric conversion element is determined by the hole transporting property of P3HT, and the photoresponsiveness is improved by reducing the volume ratio of P3HT. On the other hand, a decrease in EQE was confirmed with an increase in the volume ratio of PbS nanoparticles. This can be presumed to be because the relative permittivity of the photoelectric conversion layer increased as the volume ratio of the PbS nanoparticles increased. From the above, it was found that the volume ratio of PbS nanoparticles in the photoelectric conversion layer is preferably 17% or more and 26% or less in order to achieve both photoresponsiveness and EQE.

The embodiments, application examples, and examples have been described above, but the present disclosure is not limited to the above-described embodiments and the like, and various modifications are possible. For example, in the above-described embodiment, the example in which the photoelectric conversion element 10 that photoelectrically converts light having a wavelength in the near-infrared region is used alone in the imaging element 1 is shown. However, for example, visible light or the like other than the near-infrared region You may use in combination with the other photoelectric conversion element which photoelectrically converts the light of this wavelength. Examples of the other photoelectric conversion element include a so-called inorganic photoelectric conversion element embedded in the semiconductor substrate 30 and a so-called organic photoelectric conversion element in which a photoelectric conversion layer is formed using an organic semiconductor material.

In the above-described embodiment and the like, the configuration of the back-illuminated image sensor 1 is described as an example, but the present invention can also be applied to a front-illuminated image sensor. Furthermore, as described above, when used in combination with other photoelectric conversion elements, it may be configured as a so-called vertical spectral imaging element, or photoelectric conversion of light in other wavelength ranges on a semiconductor substrate. Alternatively, the photoelectric conversion elements may be two-dimensionally arrayed (for example, Bayer array). Furthermore, for example, a substrate on which another functional element such as a memory element is provided on the multilayer wiring side may be laminated.

Further, the photoelectric conversion element 10, the imaging element 1, and the imaging apparatus 100 according to the present disclosure do not have to include all the constituent elements described in the above-described embodiments and the like, and conversely, may include other layers. Good.

Furthermore, the technology of the present disclosure can be applied not only to an imaging device but also to, for example, a solar battery.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

The present disclosure may be configured as follows.
(1)
A first electrode comprising a plurality of electrodes independent from each other;
A second electrode disposed opposite to the first electrode;
A photoelectric conversion layer including semiconductor nanoparticles and provided between the first electrode and the second electrode;
Including an oxide semiconductor material, and a semiconductor layer provided between the first electrode and the photoelectric conversion layer,
The photoelectric conversion layer, the dielectric constant of the photoelectric conversion layer epsilon _CQD, the dielectric constant of the semiconductor layer in the case of the _{_{_{ε S, ε CQD / ε S}}} < photoelectric conversion element meets 3.
(2)
The said semiconductor layer is a photoelectric conversion element as described in said (1) which has a carrier density of 1 * 10 < ¹⁷ > cm <^-3> or less.
(3)
The photoelectric conversion layer further contains a conductive polymer,
The photoelectric conversion element according to (1) or (2), wherein the semiconductor nanoparticles are dispersed in the conductive polymer.
(4)
The photoelectric conversion element according to (3), wherein the volume ratio of the semiconductor nanoparticles in the photoelectric conversion layer is 17% or more and 26% or less.
(5)
The semiconductor nanoparticles have a core part and a ligand part bonded to the surface of the core part,
The core portion includes at least one of PbS, PbSe, PbTe, CuInSe ₂ , ZnCuInSe, CuInS ₂ , HgTe, InAs, InSb, Ag ₂ S, CuZnSnSSe, (1) to (1) 4) The photoelectric conversion element according to any one of the above.
(6)
The semiconductor nanoparticles further have a shell layer provided around the core part,
The photoelectric conversion element according to (5), wherein the shell layer includes at least one of PbO, PbO ₂ , Pb ₃ O ₄ , ZnS, ZnSe, and ZnTe.
(7)
In any one of (1) to (6), the semiconductor layer includes at least one of IGZO, ZTO, Zn ₂ SnO ₄ , InGaZnSnO, GTO, Ga ₂ O ₃ : SnO ₂ and IGO. The photoelectric conversion element as described.
(8)
The first electrode is made of titanium (Ti), silver (Ag), aluminum (Al), magnesium (Mg), chromium (Cr), nickel (Ni), tungsten (W), or copper (Cu). Formed,
The photoelectric conversion element according to any one of (1) to (7), wherein the second electrode is formed using indium tin oxide (ITO).
(9)
Having an insulating layer between the first electrode and the semiconductor layer;
The first electrode is disposed opposite to the photoelectric conversion layer with a charge readout electrode electrically connected to the photoelectric conversion layer through an opening provided in the insulating layer, and the insulating layer interposed therebetween. The photoelectric conversion element according to any one of (1) to (8), comprising a charge storage electrode.
(10)
The photoelectric conversion element according to (9), wherein the first electrode includes a charge transfer electrode between the charge readout electrode and the charge storage electrode.
(11)
The photoelectric conversion element according to any one of (1) to (10), wherein a voltage is individually applied to each of the plurality of electrodes constituting the first electrode.
(12)
A semiconductor substrate;
In any one of (1) to (11), the first electrode, the semiconductor layer, the photoelectric conversion layer, and the second electrode are provided in this order on the first surface side of the semiconductor substrate. The photoelectric conversion element as described.
(13)
The photoelectric conversion element according to (12), wherein the semiconductor substrate includes a drive circuit, and each of the plurality of electrodes constituting the first electrode is connected to the drive circuit.
(14)
The photoelectric conversion device according to (12) or (13), wherein a multilayer wiring layer is formed on a second surface side facing the first surface of the semiconductor substrate.
(15)
Comprising a plurality of pixels each provided with one or more photoelectric conversion elements,
The photoelectric conversion element is
A first electrode comprising a plurality of electrodes independent from each other;
A second electrode disposed opposite to the first electrode;
A photoelectric conversion layer including semiconductor nanoparticles and provided between the first electrode and the second electrode;
Including an oxide semiconductor material, and having a semiconductor layer provided between the first electrode and the photoelectric conversion layer,
The photoelectric conversion layer, the dielectric constant of the photoelectric conversion layer epsilon _CQD, when the relative dielectric constant epsilon _S of the semiconductor layer, ε _CQD / ε _S <3 was filled with and the imaging device.

This application claims priority on the basis of Japanese Patent Application No. 2018-015651 filed on January 31, 2018 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims

A first electrode comprising a plurality of electrodes independent from each other;
A second electrode disposed opposite to the first electrode;
A photoelectric conversion layer including semiconductor nanoparticles and provided between the first electrode and the second electrode;
Including an oxide semiconductor material, and a semiconductor layer provided between the first electrode and the photoelectric conversion layer,
The photoelectric conversion layer, the dielectric constant of the photoelectric conversion layer epsilon CQD, the dielectric constant of the semiconductor layer in the case of the ε S, ε CQD / ε S < photoelectric conversion element meets 3.
The photoelectric conversion element according to claim 1, wherein the semiconductor layer has a carrier density of 1 × 10 17 cm −3 or less.
The photoelectric conversion layer further contains a conductive polymer,
The photoelectric conversion element according to claim 1, wherein the semiconductor nanoparticles are dispersed in the conductive polymer.
The photoelectric conversion element according to claim 3, wherein a volume ratio of the semiconductor nanoparticles in the photoelectric conversion layer is 17% or more and 26% or less.
The semiconductor nanoparticles have a core part and a ligand part bonded to the surface of the core part,
The core portion, PbS, PbSe, PbTe, CuInSe 2, ZnCuInSe, CuInS 2, HgTe, InAs, InSb, Ag 2 S, is configured to include at least one of CuZnSnSSe, according to claim 1 Photoelectric conversion element.
The semiconductor nanoparticles further have a shell layer provided around the core part,
The photoelectric conversion element according to claim 5, wherein the shell layer includes at least one of PbO, PbO 2 , Pb 3 O 4 , ZnS, ZnSe, and ZnTe.
2. The photoelectric conversion element according to claim 1, wherein the semiconductor layer includes at least one of IGZO, ZTO, Zn 2 SnO 4 , InGaZnSnO, GTO, Ga 2 O 3 : SnO 2 and IGO.
The first electrode is made of titanium (Ti), silver (Ag), aluminum (Al), magnesium (Mg), chromium (Cr), nickel (Ni), tungsten (W), or copper (Cu). Formed,
The photoelectric conversion element according to claim 1, wherein the second electrode is formed using indium tin oxide (ITO).
Having an insulating layer between the first electrode and the semiconductor layer;
The first electrode is disposed opposite to the photoelectric conversion layer with a charge readout electrode electrically connected to the photoelectric conversion layer through an opening provided in the insulating layer, and the insulating layer interposed therebetween. The photoelectric conversion element according to claim 1, further comprising a charge storage electrode.
The photoelectric conversion element according to claim 9, wherein the first electrode has a charge transfer electrode between the charge readout electrode and the charge storage electrode.
The photoelectric conversion element according to claim 1, wherein a voltage is individually applied to each of the plurality of electrodes constituting the first electrode.
A semiconductor substrate;
2. The photoelectric conversion element according to claim 1, wherein the first electrode, the semiconductor layer, the photoelectric conversion layer, and the second electrode are provided in this order on the first surface side of the semiconductor substrate.
The photoelectric conversion element according to claim 12, wherein the semiconductor substrate has a drive circuit, and the plurality of electrodes constituting the first electrode are respectively connected to the drive circuit.
The photoelectric conversion element according to claim 12, wherein a multilayer wiring layer is formed on a second surface side facing the first surface of the semiconductor substrate.
Comprising a plurality of pixels each provided with one or more photoelectric conversion elements,
The photoelectric conversion element is
A first electrode comprising a plurality of electrodes independent from each other;
A second electrode disposed opposite to the first electrode;
A photoelectric conversion layer including semiconductor nanoparticles and provided between the first electrode and the second electrode;
Including an oxide semiconductor material, and having a semiconductor layer provided between the first electrode and the photoelectric conversion layer,
The photoelectric conversion layer, the dielectric constant of the photoelectric conversion layer epsilon CQD, when the relative dielectric constant epsilon S of the semiconductor layer, ε CQD / ε S <3 was filled with and the imaging device.