JP6891415B2 - Solid-state image sensor and solid-state image sensor - Google Patents

Description

The present disclosure relates to a solid-state image sensor provided with a photoelectric conversion layer using an organic semiconductor material, and a solid-state image sensor provided with the solid-state image sensor.

In a solid-state image sensor constructed using an organic semiconductor material, the photoelectric conversion layer is generally formed by laminating or mixing a p-type organic semiconductor and an n-type organic semiconductor. This enables efficient charge generation and charge transport.

Further, for example, in Patent Document 1, a carrier blocking layer (electron blocking layer and a hole blocking layer) and an electric charge are placed between the cathode and the anode and the organic photoelectric conversion film in which the organic photoelectric conversion film is arranged so as to face each other, respectively. An organic photoelectric conversion element having a transport layer (electron transport auxiliary layer and hole transport auxiliary layer) is disclosed. In this organic photoelectric conversion element, the charge extraction efficiency is further improved by providing the charge blocking layer and the charge transport layer.

Japanese Unexamined Patent Publication No. 2014-22525

By the way, the solid-state image sensor is required to have improved electrical characteristics.

It is desirable to provide a solid-state image sensor and a solid-state image sensor capable of improving electrical characteristics.

The solid-state imaging device of the embodiment of the present disclosure includes a lower electrode and an upper electrode arranged to face each other, a photoelectric conversion layer provided between the lower electrode and the upper electrode, and a photoelectric conversion layer and the lower electrode. A lower carrier block layer provided between the photoelectric conversion layer and the upper electrode, and an upper carrier block layer formed of a naphthalenediimide (NDI) -based organic semiconductor material containing a halogen atom in the molecule. , together is provided between the upper electrode and the upper carrier block layer, free of halogen atoms in the molecule, pyridine skeleton in the molecule is formed of a material having a pyrimidine skeleton or a triazine skeleton, the upper electrode and the upper carrier block layer It is provided with an intermediate layer that suppresses modification of the material constituting the above.

The solid-state image sensor according to the embodiment of the present disclosure includes one or a plurality of solid-state image sensors according to the embodiment of the present disclosure for each of a plurality of pixels.

In the solid-state image sensor of one embodiment and the solid-state image sensor of one embodiment of the present disclosure, a halogen atom is not contained between the upper electrode and the upper carrier block layer, and a pyridine skeleton, a pyrimidine skeleton, or a triazine skeleton is provided in the molecule. An intermediate layer formed by the material to be provided is provided. This makes it possible to suppress denaturation of the materials constituting the upper electrode and the upper carrier block layer during film formation.

According to the solid-state image sensor of one embodiment and the solid-state image sensor of one embodiment of the present disclosure, there is no halogen atom between the upper electrode and the upper carrier block layer, and the pyridine skeleton, pyrimidine skeleton or triazine is contained in the molecule. Since the intermediate layer using the material having a skeleton is provided, the modification of the material constituting the upper electrode and the upper carrier block layer at the time of film formation is suppressed. Therefore, it is possible to improve the electrical characteristics.

The effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a schematic diagram which shows the cross-sectional structure of an organic photoelectric conversion part. It is sectional drawing which shows an example of the schematic structure of the solid-state image pickup device which concerns on embodiment of this disclosure. It is a figure which shows the energy level of the organic photoelectric conversion part shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the solid-state image sensor shown in FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process following FIG. It is sectional drawing which shows the process following FIG. It is a functional block diagram of the solid-state image pickup apparatus using the solid-state image sensor shown in FIG. 2 as a pixel. It is a block diagram which shows the schematic structure of the electronic device which used the solid-state image sensor shown in FIG.

Hereinafter, one embodiment in the present disclosure will be described in detail with reference to the drawings. The order of explanation is as follows.
1. 1. Embodiment (example in which an intermediate layer is provided between the upper electrode and the carrier block layer)
1-1. Configuration of solid-state image sensor 1-2. Manufacturing method of solid-state image sensor 1-3. Action / effect 2. Application example

<1. Embodiment>
FIG. 1 schematically shows a cross-sectional configuration of an organic photoelectric conversion unit 20 included in the solid-state image sensor (solid-state image sensor 10) according to the embodiment of the present disclosure. FIG. 2 shows a cross-sectional configuration of the solid-state image sensor 10 provided with the organic photoelectric conversion unit 20 shown in FIG. The solid-state image sensor 10 constitutes one pixel (unit pixel P) in a solid-state image sensor (solid-state image sensor 1; see FIG. 8) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. It is something to do.

(1-1. Configuration of solid-state image sensor)
The solid-state image sensor 10 is, for example, a so-called vertical spectroscopic type in which one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32B and 32R are vertically laminated. The organic photoelectric conversion unit 20 is provided on the first surface (back surface) 30A side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are embedded and formed in the semiconductor substrate 30, and are laminated in the thickness direction of the semiconductor substrate 30. The organic photoelectric conversion unit 20 has a photoelectric conversion layer 23 formed by using a p-type semiconductor and an n-type semiconductor between the lower electrode 21 and the upper electrode 25 arranged so as to face each other. The organic photoelectric conversion unit 20 further has a carrier block layer 22A between the lower electrode 21 and the photoelectric conversion layer 23, and a carrier block layer 22B between the photoelectric conversion layer 23 and the upper electrode 25. In the present embodiment, an intermediate layer 24 is further provided between the carrier block layer 22B and the upper electrode 25.

The organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the organic photoelectric conversion unit 20 acquires a green (G) color signal. The inorganic photoelectric conversion units 32B and 32R acquire blue (B) and red (R) color signals, respectively, depending on the difference in absorption coefficient. As a result, the solid-state image sensor 10 can acquire a plurality of types of color signals in one pixel without using a color filter.

In this embodiment, a case where electrons are read out as signal charges (a case where the n-type semiconductor region is used as a photoelectric conversion layer) among pairs of electrons and holes generated by photoelectric conversion will be described. Further, in the figure, "+ (plus)" attached to "p" and "n" indicates that the concentration of p-type or n-type impurities is high, and "++" indicates that the concentration of p-type or n-type impurities is high. It means that it is even higher than "+".

On the second surface (surface) 30B of the semiconductor substrate 30, for example, floating diffusion (floating diffusion layer) FD1, FD2, FD3, vertical transistor (transfer transistor) Tr1, transfer transistor Tr2, and amplifier transistor (modulation element) ) AMP, a reset transistor RST, and a multilayer wiring 40 are provided. The multilayer wiring 40 has, for example, a configuration in which wiring layers 41, 42, and 43 are laminated in an insulating layer 44.

In the drawings, 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.

In the organic photoelectric conversion unit 20, as described above, the lower electrode 21, the carrier block layer 22A, the photoelectric conversion layer 23, the carrier block layer 22B, the intermediate layer 24, and the upper electrode 25 are on the side of the first surface 30A of the semiconductor substrate 30. It has a structure in which the layers are stacked in this order. In the present embodiment, the upper electrode 25 is separated and formed for each solid-state image sensor 10, for example. The lower electrode 21, the carrier block layer 22A, the photoelectric conversion layer 23, the carrier block layer 22B, and the intermediate layer 24 are provided as continuous layers common to the plurality of solid-state image sensors 10. For example, a layer having a fixed charge (fixed charge layer) 26, a dielectric layer 27 having an insulating property, and an interlayer insulating layer 28 are provided between the first surface 30A of the semiconductor substrate 30 and the lower electrode 21. Has been done. A protective layer 29 is provided on the upper electrode 25. Above the protective layer 29, optical members such as a flattening layer and an on-chip lens (none of which are shown) are arranged.

Through electrodes 34 are provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD3 via the through electrode 34. As a result, in the solid-state image sensor 10, the electric charge generated by the organic photoelectric conversion unit 20 on the first surface 30A side of the semiconductor substrate 30 is satisfactorily transferred to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34. , It is possible to improve the characteristics.

Through electrodes 34 are provided, for example, in each of the solid-state image pickup devices 10 for each organic photoelectric conversion unit 20. The through silicon via 34 has a function as a connector between the organic photoelectric conversion unit 20 and the gate Gamp and the floating diffusion FD3 of the amplifier transistor AMP, and also serves as a transmission path for electric charges (electrons in this case) generated in the organic photoelectric conversion unit 20. It is a thing. The lower end of the through electrode 34 is connected to the connection portion 41A in the wiring layer 41 of the multilayer wiring 40 via, for example, the lower first contact 35. The connection portion 41A and the gate Gamp of the amplifier transistor AMP are connected by a lower second contact 45. The connecting portion 41A and the floating diffusion FD3 are connected by a lower third contact 46. The upper end of the through electrode 34 is connected to the upper electrode 25 via, for example, the upper contact 36.

As shown in FIG. 2, it is preferable that the reset gate Grst of the reset transistor RST is arranged next to the floating diffusion FD3. As a result, the electric charge accumulated in the floating diffusion FD3 can be reset by the reset transistor RST.

The through electrode 34 penetrates the semiconductor substrate 30 and is separated from the semiconductor substrate 30 by, for example, a separation groove 50. The through electrode 34 is made of, for example, the same semiconductor as the semiconductor substrate 30, for example, silicon (Si), and the resistance value is reduced by injecting n-type or p-type impurities (for example, p + in FIG. 2). Is preferable. Further, high-concentration impurity regions (for example, p ++ in FIG. 2) are provided at the upper end and the lower end of the through electrode 34, and the connection resistance with the upper contact 36 and the connection resistance with the lower first contact 35 are further reduced. Is preferable. The through electrode 34 may be made of a metal or a conductive material. By using a metal or a conductive material, the resistance value of the through electrode 34 is further reduced, and the connection resistance between the through electrode 34 and the lower first contact 35, the lower second contact 45, and the lower third contact 46 is further reduced. It becomes possible to do. Examples of the metal or conductive material constituting the through electrode 34 include aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), tantalum (Ta) and the like.

As shown in FIG. 2, the outer surface 51, the inner surface 52, and the bottom surface 53 of the separation groove 50 are covered with, for example, an insulating dielectric layer 27. The dielectric layer 27 has, for example, an outer dielectric layer 27A that covers the outer surface 51 of the separation groove 50 and an inner dielectric layer 27B that covers the inner surface 52 of the separation groove 50. It is preferable that a cavity 54 is provided between the outer dielectric layer 27A and the inner dielectric layer 27B. That is, the separation groove 50 is annular or ring-shaped, and the cavity 54 is annular or ring-shaped concentric with the separation groove 50. As a result, the capacitance generated between the through electrode 34 and the semiconductor substrate 30 can be reduced, the conversion efficiency can be improved, and the delay (afterimage) can be suppressed.

Further, it is preferable that the semiconductor substrate 30 on the outer surface 51 of the separation groove 50 is provided with the same conductive type (n type or p type) impurity region (p + in FIG. 2) as the through electrode 34. Further, it is preferable that the fixed charge layer 26 is provided on the outer surface 51, the inner surface 52 and the bottom surface 53 of the separation groove 50, and the first surface 30A of the semiconductor substrate 30. Specifically, for example, a p-type impurity region (p + in FIG. 2) is provided in the semiconductor substrate 30 on the outer surface 51 of the separation groove 50, and a film having a negative fixed charge is provided as the fixed charge layer 26. Is preferable. This makes it possible to reduce the dark current.

In the solid-state image sensor 10 of the present embodiment, the light incident on the organic photoelectric conversion unit 20 from the upper electrode 25 side is absorbed by the electron acceptor or electron donor at the bulk heterojunction interface of the photoelectric conversion layer 23. The excitons generated by this move to the interface between the electron donor and the electron acceptor, and dissociate into electrons and holes. The charges (electrons and holes) generated here are due to diffusion due to the difference in carrier concentration and the internal electric field due to the difference in work function between the anode (here, the lower electrode 21) and the cathode (here, the upper electrode 25). , Each is carried to a different electrode and detected as a photocurrent. Further, by applying an electric potential between the lower electrode 21 and the upper electrode 25, the transport direction of electrons and holes can be controlled.

Hereinafter, the configuration and materials of each part will be described.

The organic photoelectric conversion unit 20 is an organic solid-state image sensor that absorbs green light corresponding to a part or all of a selective wavelength range (for example, 495 nm to 570 nm) to generate electron-hole pairs. is there.

The lower electrode 21 is provided in a region that faces the light receiving surfaces of the inorganic photoelectric conversion units 32B and 32R formed in the semiconductor substrate 30 and covers these light receiving surfaces. The lower electrode 21 is formed by using a light-transmitting conductive material (transparent conductive material), and is made of, for example, ITO (indium tin oxide). However, as the constituent material of the lower electrode 21, in addition to this ITO, a tin oxide (SnO ₂ ) -based material to which a dopant is added or a zinc oxide-based material obtained by adding a dopant to zinc oxide (ZnO) is used. You may use it. Examples of the zinc oxide-based material include aluminum zinc oxide (AZO) to which aluminum (Al) is added as a dopant, gallium zinc oxide (GZO) to which gallium (Ga) is added, and indium zinc oxide to which indium (In) is added. (IZO) can be mentioned. In addition, indium tungsten oxide (IWO), CuI, InSbO ₄ , ZnMgO, CuInO ₂ , MgIN ₂ O ₄ , CdO, ZnSnO _{3, and the} like may be used. In the solid-state image sensor 1 that uses the solid-state image sensor 10 as one pixel, the lower electrode 21 may be separated for each pixel, or may be formed as a common electrode for each pixel.

The carrier block layer 22A suppresses the injection of electric charges (here, electrons) from the lower electrode 21, for example. Examples of the material for forming the carrier block layer 22A include phenanthroline-based compounds, aluminum quinoline-based compounds, oxadiazole-based compounds, and silol-based compounds. The film thickness of the carrier block layer 22A in the stacking direction (hereinafter, simply referred to as thickness) is preferably, for example, 10 nm or more and 100 nm or less.

The photoelectric conversion layer 23 converts light energy into electrical energy. The photoelectric conversion layer 23 is formed by using an organic semiconductor material that functions as a p-type semiconductor or an n-type semiconductor. The photoelectric conversion layer 23 is provided by laminating or mixing the p-type semiconductor and the n-type semiconductor, and the bonding surface (p / n bonding surface) between the p-type semiconductor and the n-type semiconductor is provided in the layer. Is formed, which has a so-called bulk heterostructure. The p-type semiconductor functions relatively as an electron donor (donor), and the n-type semiconductor functions relatively as an electron acceptor (acceptor). The photoelectric conversion layer 23 provides a place where excitons generated when light is absorbed are separated into electrons and holes. Specifically, the interface between the electron donor and the electron acceptor (p / At the n junction surface), excitons separate into electrons and holes.

Examples of the organic semiconductor material constituting the photoelectric conversion layer 23 include quinacridone, boron chlorinated subphthalocyanine, pentacene, benzothioenobenzothiophene, fullerene and derivatives thereof. The photoelectric conversion layer 23 is composed of a combination of two or more of the above organic semiconductor materials. The organic semiconductor material functions as a p-type semiconductor or an n-type semiconductor depending on the combination thereof.

The organic semiconductor material constituting the photoelectric conversion layer 23 is not particularly limited. In addition to the above-mentioned organic semiconductor materials, for example, any one of naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene, and fluoranthene or a derivative thereof is preferably used. Alternatively, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picolin, thiophene, acetylene and diacetylene and derivatives thereof may be used. In addition, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rodacyanine dyes, xanthene dyes, macrocyclic azaanulene dyes, azulene dyes, naphthoquinones, anthracene dyes, Condensed polycyclic aromatics such as anthracene and pyrene and chain compounds condensed with aromatic or heterocyclic compounds, or containing two components such as quinoline, benzothiazole, and benzoxanthene having a squarylium group and a croconite methine group as binding chains. A nitrogen heterocycle or a cyanine-like dye bonded by a squarylium group and a croconite methine group can be preferably used. The metal complex dye is preferably, but is not limited to, a dithiol metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye, or a ruthenium complex dye. The thickness of the photoelectric conversion layer 23 is preferably, for example, 50 nm or more and 500 nm or less.

The carrier block layer 22B suppresses the injection of electric charges (here, holes) from the upper electrode 25, for example. Examples of the material forming the carrier block layer 22B include a material containing a halogen atom in the molecule, for example, an organic semiconductor material such as a naphthalenediimide (NDI) -based material. The thickness of the carrier block layer 22B is preferably, for example, 10 nm or more and 100 nm or less.

The intermediate layer 24 is formed of, for example, a material that does not contain a halogen atom in the molecule. Examples of the material containing no halogen atom in the molecule include a material containing a pyridine skeleton, a pyrimidine skeleton or a triazine skeleton in the molecule. Specific examples thereof include B3PyMPM (bis-4,6- (3,5-di-3-pyridylphenyl) -2-methylpyrimi-dine) and B4PyMPM.

The organic photoelectric conversion unit 20 may be provided with layers other than the carrier block layers 22A and 22B, the photoelectric conversion layer 23 and the intermediate layer 24, for example, a buffer layer and the like.

The upper electrode 25 is formed by using a conductive material (transparent conductive material) having the same light transmittance as the lower electrode 21. Specific examples thereof include ITO (indium tin oxide), tin oxide (SnO ₂ ) -based material to which a dopant is added, and zinc oxide-based material to which a dopant is added. Examples of the zinc oxide-based material include aluminum zinc oxide (AZO) to which aluminum (Al) is added as a dopant, gallium zinc oxide (GZO) to which gallium (Ga) is added, and indium zinc oxide to which indium (In) is added. (IZO) can be mentioned. In addition, indium tungsten oxide (IWO), CuI, InSbO ₄ , ZnMgO, CuInO ₂ , MgIN ₂ O ₄ , CdO, ZnSnO _{3, and the} like may be used. The thickness of the upper electrode 25 is preferably, for example, 10 nm or more and 200 nm or less.

Although a plurality of materials have been mentioned as materials for each layer constituting the organic photoelectric conversion unit 20, the organic photoelectric conversion unit 20 of the present embodiment has, for example, an energy level as shown in FIG. It is preferably selected. Specifically, the work function (WF) of the upper electrode 25 (cathode), the lowest empty orbital (LUMO1) level of the intermediate layer 24, the lowest empty orbital (LUMO2) level of the carrier block layer 22B, and photoelectric conversion. It is preferable that the lowest empty orbital (LUMO3) level of the n-type organic semiconductor material contained in the layer 23 has a magnitude relationship of WF> LUMO1> LUMO2> LUMO3. This makes it possible to improve the efficiency of extracting electric charges (here, electrons) generated in the photoelectric conversion layer 23. Further, at least one of the highest occupied orbital (HOMO1) level of the intermediate layer 24 and the highest occupied orbital (HOMO2) level of the carrier block layer 22B is deeper than the work function (WF) of the upper electrode 25. It is preferably located in the position. This makes it possible to efficiently suppress the injection of electric charges (here, electrons) from the upper electrode 25.

In FIG. 3, the HOMO level of the intermediate layer 24 is shallower than the HOMO level of the carrier block layer 22B, but the level is not limited to this. For example, the HOMO of the intermediate layer 24 may have a deeper level than the HOMO level of the carrier block layer 22B.

The fixed charge layer 26 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, titanium oxide and the like. Materials other than the above include lanthanum oxide, placeodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, hole mium oxide, thulium oxide, ytterbium oxide, and lutetium oxide. , Yttrium oxide, aluminum nitride film, hafnium oxynitride film, aluminum oxynitride film and the like may be used.

The fixed charge layer 26 may have a structure in which two or more types of films are laminated. Thereby, for example, in the case of a film having a negative fixed charge, the function as a hole storage layer can be further enhanced.

The material of the dielectric layer 27 is not particularly limited, but is formed of, for example, a silicon oxide film, TEOS, a silicon nitride film, a silicon acid nitride film, or the like.

The interlayer insulating layer 28 is composed of, for example, a single-layer film made of one of silicon oxide, silicon nitride, silicon oxynitride (SiON), etc., or a laminated film made of two or more of these. ..

The protective layer 29 is made of a light-transmitting material, for example, a single-layer film made of any one of silicon oxide, silicon nitride, silicon oxynitride, etc., or a laminated film made of two or more of them. It is composed of. The thickness of the protective layer 29 is, for example, 100 nm to 30,000 nm.

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. The second surface 30B of the p-well 31 is provided with the above-mentioned vertical transistor Tr1, transfer transistor Tr2, amplifier transistor AMP, reset transistor RST, and the like. Further, a peripheral circuit (not shown) including a logic circuit or the like is provided in the peripheral portion of the semiconductor substrate 30.

The inorganic photoelectric conversion units 32B and 32R each have a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R make it possible to disperse light in the vertical direction by utilizing the fact that the wavelength of light absorbed by the silicon substrate differs depending on the incident depth of light. The inorganic photoelectric conversion unit 32B selectively detects blue light and accumulates a signal charge corresponding to blue light, and is installed at a depth at which blue light can be efficiently photoelectrically converted. The inorganic photoelectric conversion unit 32R selectively detects red light and accumulates a signal charge corresponding to red, and is installed at a depth at which red light can be efficiently photoelectrically converted. Blue (B) is a color corresponding to, for example, a wavelength range of 450 nm to 495 nm, and red (R) is a color corresponding to a wavelength range of, for example, 620 nm to 750 nm. It suffices that the inorganic photoelectric conversion units 32B and 32R can detect light in a part or all of each wavelength range, respectively.

The inorganic photoelectric conversion unit 32B includes, for example, a p + region serving as a hole storage layer and an n region serving as an electron storage layer. The inorganic photoelectric conversion unit 32R has, for example, a p + region serving as a hole storage layer and an n region serving as an electron storage layer (having a pn-p laminated structure). The n region of the inorganic photoelectric conversion unit 32B is connected to the vertical transistor Tr1. The p + region of the inorganic photoelectric conversion unit 32B is bent along the vertical transistor Tr1 and is connected to the p + region of the inorganic photoelectric conversion unit 32R.

The vertical transistor Tr1 is a transfer transistor that transfers the signal charge (electrons in the present embodiment) corresponding to blue generated and accumulated in the inorganic photoelectric conversion unit 32B to the floating diffusion FD1. Since the inorganic photoelectric conversion unit 32B is formed at a position deep from the second surface 30B of the semiconductor substrate 30, it is preferable that the transfer transistor of the inorganic photoelectric conversion unit 32B is composed of the vertical transistor Tr1.

The transfer transistor Tr2 transfers the signal charge (electrons in the present embodiment) corresponding to red color generated and accumulated in the inorganic photoelectric conversion unit 32R to the floating diffusion FD2, and is composed of, for example, a MOS transistor. ing.

The amplifier transistor AMP is a modulation element that modulates the amount of electric charge generated by the organic photoelectric conversion unit 20 into a voltage, and is composed of, for example, a MOS transistor.

The reset transistor RST resets the electric charge transferred from the organic photoelectric conversion unit 20 to the floating diffusion FD3, and is composed of, for example, a MOS transistor.

The lower first contact 35, the lower second contact 45, the lower third contact 46 and the upper contact 36 are made of a doped silicon material such as PDAS (Phosphorus Doped Amorphous Silicon), or aluminum (Al) or tungsten (W). ), Titanium (Ti), Cobalt (Co), Hafnium (Hf), Tantal (Ta) and other metal materials.

(1-2. Manufacturing method of solid-state image sensor)
The solid-state image sensor 10 of the present embodiment can be manufactured, for example, as follows.

4 to 7 show the manufacturing method of the solid-state image sensor 10 in the order of processes. First, as shown in FIG. 4, for example, a p-well 31 is formed as a first conductive type well in the semiconductor substrate 30, and a second conductive type (for example, n-type) inorganic material is formed in the p-well 31. The photoelectric conversion units 32B and 32R are formed. A p + region is formed in the vicinity of the first surface 30A of the semiconductor substrate 30.

Further, as also shown in FIG. 4, an impurity region (p + region) penetrating from the first surface 30A to the second surface 30B of the semiconductor substrate 30 is formed in the region where the through electrode 34 and the separation groove 50 are to be formed. Further, a high-concentration impurity region (p ++ region) is formed in the upper end portion and the lower end portion of the through electrode 34 to be formed.

As also shown in FIG. 4, an n + region serving as floating diffusion FD1 to FD3 is formed on the second surface 30B of the semiconductor substrate 30, and then the gate insulating layer 33, the vertical transistor Tr1, the transfer transistor Tr2, and the amplifier are formed. A gate wiring layer 37 including each gate of the transistor AMP and the reset transistor RST is formed. As a result, the vertical transistor Tr1, the transfer transistor Tr2, the amplifier transistor AMP, and the reset transistor RST are formed. Further, on the second surface 30B of the semiconductor substrate 30, the multilayer wiring 40 composed of the wiring layers 41 to 43 including the lower first contact 35, the lower second contact 45, the lower third contact 46, and the connecting portion 41A and the insulating layer 44. To form.

As the substrate of the semiconductor substrate 30, for example, an SOI (Silicon on Insulator) substrate in which a semiconductor substrate 30, an embedded oxide film (not shown), and a holding substrate (not shown) are laminated is used. Although not shown in FIG. 4, the embedded 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 the semiconductor substrate 30 is turned upside down. Subsequently, the semiconductor substrate 30 is separated from the embedded oxide film and the holding substrate of the SOI substrate to expose the first surface 30A of the semiconductor substrate 30. The above steps can be performed by techniques used in ordinary CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

Next, as shown in FIG. 5, the semiconductor substrate 30 is processed from the first surface 30A side by, for example, dry etching to form a ring-shaped or annular separation groove 50. As shown by the arrow D50A in FIG. 5, the depth of the separation groove 50 preferably reaches the gate insulating layer 33 through the semiconductor substrate 30 from the first surface 30A to the second surface 30B. Further, in order to further enhance the insulating effect on the bottom surface 53 of the separation groove 50, the separation groove 50 penetrates the semiconductor substrate 30 and the gate insulating layer 33 and the multilayer wiring 40 as shown by the arrow D50B in FIG. It is preferable to reach the insulating layer 44 of the above. FIG. 5 shows a case where the separation groove 50 penetrates the semiconductor substrate 30 and the gate insulating layer 33.

Subsequently, as shown in FIG. 6, for example, a negative fixed charge layer 26 is formed on the outer surface 51, the inner surface 52, and the bottom surface 53 of the separation groove 50 and the first surface 30A of the semiconductor substrate 30. Two or more types of films may be laminated as the negative fixed charge layer 26. As a result, the function as a hole storage layer can be further enhanced. After forming the negative fixed charge layer 26, the dielectric layer 27 having the outer dielectric layer 27A and the inner dielectric layer 27B is formed. At this time, by appropriately adjusting the film thickness of the dielectric layer 27 and the film forming conditions, a cavity 54 is formed between the outer dielectric layer 27A and the inner dielectric layer 27B in the separation groove 50.

Next, as shown in FIG. 7, the interlayer insulating layer 28 is formed. Subsequently, the lower electrode 21, the carrier block layer 22A, the photoelectric conversion layer 23, the carrier block layer 22B, the intermediate layer 24, the upper electrode 25, and the protective layer 29 are formed on the interlayer insulating layer 28. Further, an upper contact 36 is formed and connected to the upper end of the through electrode 34. Finally, an optical member such as a flattening layer and an on-chip lens (not shown) are arranged. As a result, the solid-state image sensor 10 shown in FIG. 2 is completed.

In the solid-state image sensor 10, when light is incident on the organic photoelectric conversion unit 20 via an on-chip lens (not shown), the light passes through the organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32B and 32R in this order. In the process of passing through the light, it is photoelectrically converted for each of the green, blue, and red colored lights. Hereinafter, the signal acquisition operation of each color will be described.

(Acquisition of green signal by organic photoelectric conversion unit 20)
Of the light incident on the solid-state image sensor 10, green light is first selectively detected (absorbed) by the organic photoelectric conversion unit 20 and photoelectrically converted.

The organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD3 via a through electrode 34. Therefore, the electrons of the electron-hole pairs generated by the organic photoelectric conversion unit 20 are taken out from the upper electrode 25 side and transferred to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34. , Accumulated in the floating diffusion FD3. At the same time, the amplifier transistor AMP modulates the amount of charge generated in the organic photoelectric conversion unit 20 into a voltage.

Further, next to the floating diffusion FD3, a reset gate Grst of the reset transistor RST is arranged. As a result, the electric charge accumulated in the floating diffusion FD3 is reset by the reset transistor RST.

Here, since the organic photoelectric conversion unit 20 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD3 via the through electrode 34, the electric charge accumulated in the floating diffusion FD3 can be easily reset by the reset transistor RST. It becomes possible to do.

On the other hand, when the through electrode 34 and the floating diffusion FD3 are not connected, it becomes difficult to reset the electric charge accumulated in the floating diffusion FD3, and a large voltage is applied to pull it out to the upper electrode 25 side. become. Therefore, the photoelectric conversion layer 23 may be damaged. In addition, a structure that enables resetting in a short time causes an increase in dark noise, which is a trade-off, and this structure is difficult.

(Acquisition of blue signal and red signal by inorganic photoelectric conversion units 32B and 32R)
Subsequently, of the light transmitted through the organic photoelectric conversion unit 20, blue light is absorbed by the inorganic photoelectric conversion unit 32B and red light is absorbed by the inorganic photoelectric conversion unit 32R in this order, and the light is photoelectrically converted. In the inorganic photoelectric conversion unit 32B, electrons corresponding to the incident blue light are accumulated in the n region of the inorganic photoelectric conversion unit 32B, and the accumulated electrons are transferred to the floating diffusion FD1 by the vertical transistor Tr1. Similarly, in the inorganic photoelectric conversion unit 32R, electrons corresponding to the incident red light are accumulated in the n region of the inorganic photoelectric conversion unit 32R, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2.

(1-3. Action / effect)
In a solid-state image sensor using an organic semiconductor material, as described above, the photoelectric conversion layer is formed to include p-type and n-type organic semiconductor materials in order to enable efficient charge generation and charge transport. ing. Whether an organic semiconductor material used in the photoelectric conversion layer functions as a p-type semiconductor or an n-type semiconductor is a relative relationship between the energy level of the organic semiconductor material and the energy level of the material used together. Depends on.

In organic semiconductors, the level difference between HOMO and LUMO corresponds to the band gap (Eg), the energy difference between HOMO and vacuum level is the ionization potential (I), and the energy difference between LUMO and vacuum level is electron affinity (e.g.). It is called χ). For example, when one of the two types of organic semiconductor materials contained in the photoelectric conversion layer has a higher electron affinity than the other organic semiconductor material, the one organic semiconductor material is the other organic semiconductor. It has higher electron attracting properties than materials. Therefore, one organic semiconductor material functions as an n-type semiconductor, and the other organic semiconductor material functions as a p-type semiconductor. As a method for imparting n-type properties to an organic semiconductor material, for example, there is a method of introducing a halogen atom having a large electronegativity into the molecular structure. For example, the above-mentioned boron chlorinated subphthalocyanine functions as an n-type semiconductor when used together with quinacridone.

Further, as described above, an organic photoelectric conversion element in which an electron blocking layer and a hole blocking layer are provided between the photoelectric conversion layer and the pair of electrodes in order to further improve the charge extraction efficiency has been reported. There is. In an organic photoelectric conversion element having such a configuration, the hole blocking layer is more than an organic semiconductor material that functions as an n-type semiconductor in the photoelectric conversion layer in order to facilitate the extraction of charges (electrons) generated in the photoelectric conversion layer. It is desirable to form using a material having a deep LUMO value (high electron affinity). Therefore, in general, an organic semiconductor material containing a halogen atom in the molecule is also used as the material of the hole blocking layer.

However, when an electrode is formed on a layer containing an organic semiconductor material containing a halogen atom in the molecule (for example, an organic layer such as a hole blocking layer), the electrode is included in the organic semiconductor material at the interface between the electrode and the organic layer. There is a risk that the halogen atom and the electrode material will react and be denatured from each other. In a photoelectric conversion element having an electrode and an organic film in which each material is modified, there arises a problem that electrical characteristics such as deterioration of dark current are deteriorated.

On the other hand, in the present embodiment, a halogen atom is contained between the upper electrode 25 and a layer (for example, the carrier block layer 22B) formed by using an organic semiconductor material containing a halogen atom in the molecule. An intermediate layer 24 made of no material was provided. This makes it possible to suppress the modification of the conductive material constituting the upper electrode 25 and the organic semiconductor material constituting the carrier block layer 22B when the upper electrode 25 is formed.

As described above, in the present embodiment, since the intermediate layer 24 using a material containing no halogen atom is provided between the upper electrode 25 and the carrier block layer 22B, the upper electrode 25 and the upper electrode 25 at the time of forming the upper electrode 25 Degeneration of the material constituting the carrier block layer 22B is suppressed. Therefore, it is possible to provide the solid-state image sensor 10 having excellent electrical characteristics.

<2. Application example>
(Application example 1)
FIG. 8 shows the overall configuration of the solid-state image sensor (solid-state image sensor 1) using the solid-state image sensor 10 described in the above embodiment for each pixel. The solid-state image sensor 1 is a CMOS image sensor, has a pixel unit 1a as an imaging area on the semiconductor substrate 30, and has, for example, a row scanning unit 131 and a horizontal selection unit 133 in a peripheral region of the pixel unit 1a. , A peripheral circuit unit 130 including a row scanning unit 134 and a system control unit 132.

The pixel unit 1a has, for example, a plurality of unit pixels P (corresponding to the solid-state image sensor 10) arranged two-dimensionally 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 a pixel. One end of the pixel drive line Lread is connected to the output end corresponding to each line of the line scanning unit 131.

The row scanning unit 131 is a pixel driving unit that is composed of a shift register, an address decoder, and the like, and drives each pixel P of the pixel unit 1a, for example, in row units. The signal output from each pixel P of the pixel row selected and 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 composed of an amplifier, a horizontal selection switch, and the like provided for each vertical signal line Lsig.

The column scanning unit 134 is composed of a shift register, an address decoder, and the like, and drives each horizontal selection switch of the horizontal selection unit 133 in order while scanning. By the selective scanning by the column scanning unit 134, the signals of each pixel transmitted through each of the vertical signal lines Lsig are 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 may be arranged on the external control IC. It may be. Further, those 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 solid-state image sensor 1. The system control unit 132 further has 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. Controls the drive of peripheral circuits.

(Application example 2)
The above-mentioned solid-state image sensor 1 can be applied to all types of electronic devices having an image pickup function, such as a camera system such as a digital still camera or a video camera, and a mobile phone having an image pickup function. FIG. 9 shows a schematic configuration of the electronic device 2 (camera) as an example. The electronic device 2 is, for example, a video camera capable of capturing a still image or a moving image, and includes a solid-state image sensor 1, an optical system (optical lens) 310, a shutter device 311 and a solid-state image sensor 1 and a shutter device 311. It has a drive unit 313 for driving and a signal processing unit 312.

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

Although the embodiments and application examples have been described above, the contents of the present disclosure are not limited to the above-described embodiments and the like, and various modifications can be made. For example, in the above embodiment, the organic photoelectric conversion unit 20 that detects green light and the inorganic photoelectric conversion units 32B and 32R that detect blue light and red light are laminated as a solid-state image sensor. , The content of this disclosure is not limited to such a structure. That is, the organic photoelectric conversion unit may detect red light or blue light, or the inorganic photoelectric conversion unit may detect green light.

Further, the number and ratio of these organic photoelectric conversion units and inorganic photoelectric conversion units are not limited, and two or more organic photoelectric conversion units may be provided, or a plurality of colors may be provided only by the organic photoelectric conversion unit. A signal may be obtained. Further, the structure is not limited to the structure in which the organic photoelectric conversion unit and the inorganic photoelectric conversion unit are laminated in the vertical direction, and may be arranged in parallel along the substrate surface.

Furthermore, in the above embodiment, the configuration of the back-illuminated solid-state image sensor is illustrated, but the contents of the present disclosure can also be applied to the front-illuminated solid-state image sensor. Further, the solid-state image sensor (solid-state image sensor) of the present disclosure does not have to include all the constituent elements described in the above-described embodiment, and may conversely include other layers.

It should be noted that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

The present disclosure may have the following configuration.
(1)
With the lower and upper electrodes placed facing each other,
A photoelectric conversion layer provided between the lower electrode and the upper electrode,
An upper carrier block layer and a lower carrier block layer provided between the photoelectric conversion layer and the lower electrode and the upper electrode, respectively,
A solid-state image sensor provided between the upper electrode and the upper carrier block layer and provided with an intermediate layer formed of a material containing no halogen atom in the molecule.
(2)
The solid-state imaging device according to (1) above, wherein the upper carrier block layer is formed of an organic semiconductor material containing a halogen atom in the molecule.
(3)
The solid-state image sensor according to (1) or (2) above, wherein the material containing no halogen atom in the molecule is a material containing a pyridine skeleton, a pyrimidine skeleton, or a triazine skeleton in the molecule.
(4)
The solid-state imaging device according to any one of (1) to (3) above, wherein the photoelectric conversion layer includes an n-type organic semiconductor and a p-type organic semiconductor.
(5)
The work function (WF) of the upper electrode, the lowest empty orbital (LUMO1) level of the intermediate layer, the lowest empty orbital (LUMO2) level of the upper carrier block layer, and the n contained in the photoelectric conversion layer. The solid-state image sensor according to (4) above, wherein the lowest empty orbital (LUMO3) level of the type organic semiconductor has a magnitude relationship of WF>LUMO1>LUMO2> LUMO3.
(6)
At least one of the highest occupied orbital (HOMO1) level of the intermediate layer and the highest occupied orbital (HOMO2) level of the upper carrier block layer is a level deeper than the work function (WF) of the upper electrode. The solid-state imaging device according to any one of (1) to (5) above.
(7)
The solid-state image sensor according to any one of (2) to (6) above, wherein the organic semiconductor material containing a halogen atom in the molecule is a naphthalene diimide (NDI) -based material.
(8)
The solid-state image sensor according to any one of (1) to (7) above, wherein the upper electrode is made of a transparent conductive material.
(9)
The upper electrode is formed by containing at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tungsten oxide (IWO) (1) to (8). The solid-state image sensor according to any one of.
(10)
(1) The above (1), wherein an organic photoelectric conversion unit having one or a plurality of the photoelectric conversion layers and one or a plurality of inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are laminated. The solid-state imaging device according to any one of (9) to (9).
(11)
The inorganic photoelectric conversion unit is formed by being embedded in a semiconductor substrate.
The solid-state imaging device according to (10), wherein the organic photoelectric conversion unit is formed on the first surface side of the semiconductor substrate.
(12)
The solid-state image sensor according to (11), wherein a multilayer wiring layer is formed on the second surface side of the semiconductor substrate.
(13)
It has a plurality of pixels, each of which is provided with one or more solid-state image sensors.
The solid-state image sensor
With the lower and upper electrodes placed facing each other,
A photoelectric conversion layer provided between the lower electrode and the upper electrode,
An upper carrier block layer and a lower carrier block layer provided between the photoelectric conversion layer and the lower electrode and the upper electrode, respectively,
A solid-state image sensor provided between the upper electrode and the upper carrier block layer and provided with an intermediate layer formed of a halogen atom-free material.

1 ... Solid-state image sensor, 10 ... Solid-state image sensor, 20 ... Organic photoelectric conversion unit, 21 ... Lower electrode, 22A, 22B ... Carrier block layer, 23 ... Photoelectric conversion layer, 24 ... Intermediate layer, 25 ... Upper electrode, 26 ... Fixed charge layer, 27 ... dielectric layer, 28 ... interlayer insulating layer, 29 ... protective layer, 30 ... semiconductor substrate, 31 ... p well, 32B, 32R ... inorganic photoelectric conversion unit, 33 ... gate insulating layer, 34 ... through electrode , 35 ... Lower first contact, 36 ... Upper contact, 37 ... Gate wiring layer, 40 ... Multilayer wiring, 41, 42, 43 ... Wiring layer, 44 ... Insulation layer, 45 ... Lower second contact, 46 ... Lower third Contact, 50 ... Separation groove.

Claims (10)

With the lower and upper electrodes placed facing each other,
A photoelectric conversion layer provided between the lower electrode and the upper electrode,
A lower carrier block layer provided between the photoelectric conversion layer and the lower electrode,
An upper carrier block layer provided between the photoelectric conversion layer and the upper electrode and formed of a naphthalene diimide (NDI) -based organic semiconductor material containing a halogen atom in the molecule.
Together provided between the upper carrier block layer and the upper electrode, free of halogen atoms in the molecule, pyridine skeleton in the molecule is formed of a material having a pyrimidine skeleton or a triazine skeleton, the upper electrode and the upper A solid-state imaging device including an intermediate layer that suppresses denaturation of materials constituting the carrier block layer. The solid-state image sensor according to claim 1, wherein the photoelectric conversion layer includes an n-type organic semiconductor and a p-type organic semiconductor. The work function (WF) of the upper electrode, the lowest empty orbital (LUMO1) level of the intermediate layer, the lowest empty orbital (LUMO2) level of the upper carrier block layer, and the n contained in the photoelectric conversion layer. The solid-state image sensor according to claim 2, wherein the lowest empty orbital (LUMO3) level of the type organic semiconductor has a magnitude relationship of WF> LUMO1> LUMO2> LUMO3. At least one of the highest occupied orbital (HOMO1) level of the intermediate layer and the highest occupied orbital (HOMO2) level of the upper carrier block layer is a level deeper than the work function (WF) of the upper electrode. The solid-state imaging device according to claim 1, which is located in. The solid-state imaging device according to claim 1, wherein the upper electrode is made of a transparent conductive material. The solid-state imaging according to claim 1, wherein the upper electrode is formed containing at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tungsten oxide (IWO). element. The first aspect of the present invention is that an organic photoelectric conversion unit having one or a plurality of the photoelectric conversion layers and one or a plurality of inorganic photoelectric conversion units that perform photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are laminated. The solid-state image sensor according to the description. The inorganic photoelectric conversion unit is formed by being embedded in a semiconductor substrate.
The solid-state imaging device according to claim 7, wherein the organic photoelectric conversion unit is formed on the first surface side of the semiconductor substrate. The solid-state image sensor according to claim 8, wherein a multilayer wiring layer is formed on the second surface side of the semiconductor substrate. It has a plurality of pixels, each of which is provided with one or more solid-state image sensors.
The solid-state image sensor
With the lower and upper electrodes placed facing each other,
A photoelectric conversion layer provided between the lower electrode and the upper electrode,
A lower carrier block layer provided between the photoelectric conversion layer and the lower electrode,
An upper carrier block layer provided between the photoelectric conversion layer and the upper electrode and formed of a naphthalene diimide (NDI) -based organic semiconductor material containing a halogen atom in the molecule.
Together provided between the upper carrier block layer and the upper electrode, free of halogen atoms in the molecule, pyridine skeleton in the molecule is formed of a material having a pyrimidine skeleton or a triazine skeleton, the upper electrode and the upper A solid-state imaging device including an intermediate layer that suppresses denaturation of materials constituting the carrier block layer.

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