JP5469918B2 - Method for manufacturing photoelectric conversion element, photoelectric conversion element, and imaging element - Google Patents

Description

  The present invention relates to a method for manufacturing a photoelectric conversion element, a photoelectric conversion element, and an imaging element.

  The photoelectric conversion element is applied to an image pickup element, an optical sensor, a solar cell, and the like, and various technical developments aiming at high sensitivity and high speed response are being performed. As a conventional photoelectric conversion element, a photodiode using a silicon semiconductor or the like is well known. However, in recent years, an organic photoelectric conversion element using an organic material has attracted attention in order to easily increase the area and flexibility of the element.

  In an organic photoelectric conversion element, obtaining a high S / N ratio is one of important issues. In order to increase the S / N ratio of the organic photoelectric conversion element, it is necessary to improve the photoelectric conversion efficiency and reduce the dark current. As a technique for improving the photoelectric conversion efficiency, introduction of a pn junction or a bulk heterostructure in the photoelectric conversion film has been studied. In addition, as a technique for reducing the dark current, introduction of a blocking layer or the like has been studied.

  When introducing a pn junction or a bulk heterostructure, an increase in dark current often becomes a problem. In addition, there is a difference in the degree of improvement in photoelectric conversion efficiency depending on the combination of materials, particularly when adopting a method of introducing a bulk heterostructure, S / N may not increase compared to before introducing the bulk heterostructure, Which material to combine is important.

  In addition, the types of materials used and the film structure are one of the main factors of photoelectric conversion efficiency (exciton dissociation efficiency, charge transportability) and dark current (dark carrier amount, etc.). Although it is hardly mentioned, it becomes a governing factor of signal response speed. In particular, when a photoelectric conversion element is used as a solid-state imaging element, it is important to satisfy all of high photoelectric conversion efficiency, low dark current, and high-speed response speed. Which organic photoelectric conversion material and element structure satisfy such performance? It has not been specifically shown whether it is.

Patent Document 1 discloses an imaging device that includes a photoelectric conversion element in which a photoelectric conversion film composed of a p-type semiconductor and an n-type semiconductor is sandwiched between a pair of electrodes, and the photoelectric conversion film contains fullerene or a fullerene derivative. .
Further, in Patent Document 1, in order to improve photoelectric conversion efficiency, a structure having a bulk heterojunction structure layer including the p-type semiconductor and the n-type semiconductor as an intermediate layer between the p-type semiconductor and the n-type semiconductor. Is also described.

  Moreover, in vacuum deposition, in order to prevent impurities from being mixed into the deposition material, a deposition method using a deposition apparatus having a mechanism for feeding the material into the crucible without exposing the material to the atmosphere is disclosed (Patent Document 2).

JP 2007-123707 A JP 2003-89865 A

  However, with the method described in Patent Document 1, it has been difficult to produce a photoelectric conversion element excellent in sensitivity and high-speed response. In addition, Patent Document 2 requires a vapor deposition apparatus having a special mechanism, and even if the technique described in Patent Document 2 is applied to an organic photoelectric conversion element, an element having a high response speed cannot be obtained.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a photoelectric conversion element that has sufficient sensitivity and exhibits a high-speed response.

As a result of intensive studies by the present inventors, it has been found that when the organic photoelectric conversion film is formed, the response speed can be particularly improved by performing the film formation after sufficiently removing the vicinity of the surface in the highly crystalline organic material. .
That is, the said subject can be solved by the following means.
[1]
A method for producing a photoelectric conversion element comprising a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes,
As at least one kind of raw material for forming the photoelectric conversion layer, an organic material containing crystal particles of fullerene or fullerene derivative having a minimum diameter of 0.3 mm or more is used,
Heating the organic material until a stable deposition rate of the organic material is reached;
Sublimating at least 1/5 of the total volume of the crystal particles without forming the photoelectric conversion layer after reaching the stable vapor deposition rate;
After sublimating at least 1/5 of the total volume of the crystal particles, and then forming the photoelectric conversion layer by a vacuum deposition method;
The manufacturing method of the photoelectric conversion element containing this.
[2]
The crystal particles include at least one of single crystal particles and polycrystalline particles composed of a plurality of crystal domains, and the minimum diameter of the single crystal particles is 0.3 mm or more, or the crystal domain size of the polycrystalline particles is 0. The manufacturing method of the photoelectric conversion element as described in [1] which is 3 mm square or more. [3]
The method for producing a photoelectric conversion element according to [1] or [2], wherein the stable vapor deposition rate is 0.1 Å / s or more.
[4]
The method for producing an organic photoelectric conversion element according to any one of [1] to [3], wherein the organic photoelectric conversion element includes a charge blocking layer .
Although this invention is invention which concerns on said [1]-[ 4 ], below, other matters (for example, following (1)-(8)) are also described below.
(1) A method for producing a photoelectric conversion element comprising a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes,
As at least one kind of raw material for forming the photoelectric conversion layer, an organic material containing crystal particles having a minimum diameter of 0.3 mm or more is used.
Heating the organic material until a predetermined stable deposition rate is reached;
Sublimating at least 1/5 of the total volume of the crystal particles without forming the photoelectric conversion layer after reaching the stable vapor deposition rate;
A step of forming a film of the photoelectric conversion layer after sublimating at least 1/5 of the total volume of the organic material;
The manufacturing method of the photoelectric conversion element containing this.
(2) The crystal particles include at least one of single crystal particles and polycrystal particles composed of a plurality of crystal domains, and the minimum diameter of the single crystal particles is 0.3 mm or more, or the crystal domains of the polycrystal particles The manufacturing method of the photoelectric conversion element as described in said (1) whose size is 0.3 mm square or more.
(3) The method for producing a photoelectric conversion element according to (1) or (2), wherein the organic material is a p-type semiconductor compound or an n-type semiconductor compound.
(4) The method for producing a photoelectric conversion element according to (3), wherein the organic material is an n-type semiconductor compound, and the n-type semiconductor compound is fullerene or a fullerene derivative.
(5) The method for producing a photoelectric conversion element according to any one of (1) to (4), wherein the stable vapor deposition rate is 0.1 Å / s or more.
(6) The manufacturing method of the organic photoelectric conversion element in any one of said (1)-(5) in which the said organic photoelectric conversion element contains a charge blocking layer.
(7) The photoelectric conversion element manufactured by the manufacturing method in any one of said (1)-(6).
(8) An imaging device comprising the photoelectric conversion device according to (7).

  According to the manufacturing method of the present invention, it is possible to manufacture a photoelectric conversion element that has sufficient sensitivity and exhibits a high-speed response. Moreover, according to the photoelectric conversion element manufactured by the manufacturing method of the present invention, an imaging element having sufficient sensitivity and showing a high-speed response can be obtained.

It is a cross-sectional schematic diagram which shows an example of a structural example of a photoelectric conversion element. It is a cross-sectional schematic diagram which shows the other structural example of a photoelectric conversion element. It is a schematic diagram which shows the relationship between the heating time of vapor deposition material, and vapor deposition rate. It is a cross-sectional schematic diagram for 1 pixel of the solid-state image sensor which concerns on 1st Embodiment. It is a cross-sectional schematic diagram of the intermediate | middle layer shown in FIG. It is a cross-sectional schematic diagram for 1 pixel of the solid-state image sensor which concerns on 2nd Embodiment. It is a cross-sectional schematic diagram for 1 pixel of the solid-state image sensor which concerns on 3rd Embodiment. It is a cross-sectional schematic diagram of the solid-state image sensor which concerns on 4th Embodiment. It is a partial surface schematic diagram of the image sensor which concerns on 5th Embodiment. It is a cross-sectional schematic diagram of the XX line of the image sensor shown in FIG. It is a figure which shows the specific structural example of the signal reading part shown in FIG.

[Production Method of Photoelectric Conversion Element]
Hereinafter, the manufacturing method according to the present invention will be described in detail.
The photoelectric conversion element which concerns on the manufacturing method of this invention has a pair of electrodes and the photoelectric converting layer arrange | positioned between a pair of electrodes.
1 and 2 show a configuration example of a photoelectric conversion element that is preferably manufactured in the present embodiment.
A photoelectric conversion element 10 shown in FIG. 1 is formed by laminating a photoelectric conversion layer 12 and an upper electrode 15 in this order on a lower electrode 11 that also serves as a substrate.

A preferred embodiment of the production method of the present invention will be described. In the present embodiment, first, the lower electrode 11 is formed.
The method for forming the lower electrode 11 is not particularly limited, and can be appropriately selected in consideration of appropriateness with the material constituting the lower electrode 11. Specifically, it can be formed by a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method.
When the material of the lower electrode 11 is, for example, ITO, it can be formed by a method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), or a dispersion of indium tin oxide. Furthermore, UV-ozone treatment, plasma treatment, or the like can be performed on a film formed using ITO.

  The conditions for forming a transparent electrode film (transparent electrode film) will be described. The silicon substrate temperature at the time of forming the transparent electrode film is preferably 500 ° C. or lower, more preferably 300 ° C. or lower, further preferably 200 ° C. or lower, and further preferably 150 ° C. or lower. Further, a gas may be introduced during the formation of the transparent electrode film, and basically the gas species is not limited, but Ar, He, oxygen, nitrogen and the like can be used. Further, a mixed gas of these gases may be used. In particular, in the case of an oxide material, oxygen defects are often introduced, so that oxygen is preferably used.

  Further, the preferable range of the surface resistance of the transparent electrode film differs depending on whether it is the first electrode film 11 or the second electrode film 15. When the signal readout part has a CMOS structure, the surface resistance of the transparent conductive film is preferably 10000Ω / □ or less, more preferably 1000Ω / □ or less. If the signal reading unit has a CCD structure, the surface resistance is preferably 1000Ω / □ or less, and more preferably 100Ω / □ or less. When used for the second electrode film 13, it is preferably 1000000 Ω / □ or less, more preferably 100000 Ω / □ or less.

Particularly preferable materials for the transparent electrode film are ITO, IZO, SnO ₂ , ATO (antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO ₂ , FTO (fluorine). Doped tin oxide).
The light transmittance of the transparent electrode film is preferably 60% or more, more preferably 80% or more, more preferably 90% or more, at the absorption peak wavelength of the photoelectric conversion film included in the photoelectric conversion part including the transparent electrode film. More preferably, it is 95% or more.

Next, the photoelectric conversion layer 12 is formed on the lower electrode 11.
As at least one kind of raw material for forming the photoelectric conversion layer 12, an organic material containing crystal particles having a minimum diameter of 0.3 mm or more (hereinafter referred to as “crystalline organic material”) is used.
The crystal particles having a minimum diameter of 0.3 mm or more in the present invention are specifically single crystal particles having a minimum diameter of 0.3 mm or more, or polycrystalline particles having a crystal domain size of 0.3 mm square or more. It is preferable to include, for example, particles that are made of a fine powder (sintered body) such as ceramics or particles that have voids on the surface.

The minimum diameter of the crystal particles is preferably 0.3 mm or more, preferably 0.4 mm or more, and more preferably 0.5 mm or more. The upper limit of the minimum diameter of the crystal particles is not particularly limited, but is about 20 mm, preferably 10 mm, more preferably 5 mm.
The content of the crystal particles having a minimum diameter of 0.3 mm or more in the crystalline organic material is preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass. More preferably, it is contained.
In this specification, the content (% by mass) of crystal particles having a minimum diameter of 0.3 mm or more in the crystalline organic material is applied to a lattice-like sieve having a mesh size of 100 μm to 220 μm □, It is obtained by measuring the mass of the remaining particles.

  An organic material including crystal particles of a large size such that the minimum diameter of the crystal particles is 0.3 mm or more can be produced by sublimating a gas at 1 atm under a temperature gradient in a purification technique of an organic semiconductor. . Specifically, according to the method described in Functional Materials, Vol.28, No.6 p.25-32, June 2008 issue, the method described in Journal of Crystal Growth 187. 1998. 449-454, etc. Can be produced.

Note that the crystal particles produced by such a method include spherical, cubic, columnar, needle-like, and other amorphous particles.
The long axis / short axis ratio of the columnar particles or acicular particles is preferably in the range of 1 to 100, more preferably in the range of 1 to 50, and still more preferably in the range of 1 to 20.

As a compound which comprises a crystalline organic material, it selects from the material for forming the photoelectric converting layer mentioned later. Preferably, it is selected from a p-type organic semiconductor compound and an n-type organic semiconductor compound described later. More preferably, the crystalline organic material is an n-type organic semiconductor compound, and more preferably, the crystalline organic material is fullerene or a fullerene derivative.
In addition, it is preferable that the material for forming the photoelectric converting layer 12 contains organic materials other than a crystalline organic material. The other organic material is preferably selected from the p-type organic semiconductor compounds described below.

The photoelectric conversion layer 12 is formed by vapor deposition. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. In the case of forming a film by vacuum vapor deposition, production conditions such as the degree of vacuum and vapor deposition temperature can be set in accordance with a conventional method.
The vacuum deposition method is basically based on the heating method of the compound such as resistance heating deposition method and electron beam heating deposition method, the shape of the deposition source such as crucible and boat, vacuum degree, deposition temperature, substrate temperature, deposition rate, etc. It is a parameter. In order to enable uniform deposition, it is preferable to perform deposition by rotating the substrate. A higher degree of vacuum is preferable, and vacuum deposition is preferably performed at 10 ⁻⁴ Torr or less, more preferably 10 ⁻⁶ Torr or less, and particularly preferably 10 ⁻⁸ Torr or less. It is preferable that all steps during the vapor deposition are performed in a vacuum, and basically the compound is not directly in contact with oxygen and moisture in the outside air. The above-described conditions for vacuum deposition need to be strictly controlled because they affect the crystallinity, amorphousness, density, density, etc. of the organic film. It is preferable to use PI or PID control of the deposition rate using a film thickness monitor such as a quartz crystal resonator or an interferometer. When two or more kinds of compounds are vapor-deposited simultaneously, a co-evaporation method, a flash vapor deposition method, or the like can be preferably used.

When the photoelectric conversion layer 12 is formed by vapor deposition, the crystalline organic material (and an organic material other than the crystalline organic material as necessary) is heated on the heater until a stable vapor deposition rate is reached. The heating method may be any of resistance heating type, electron beam type, high frequency induction type, laser type and the like.
Then, after reaching the stable vapor deposition rate, heating is continued as it is, and at least 1/5 of the total volume of the crystalline organic material is sublimated without forming the photoelectric conversion layer 12. Then, after sublimating at least 1/5 of the total volume of the crystalline organic material, the photoelectric conversion layer is formed.

In this embodiment, the time for which 1/5 of the total volume of the crystalline organic material is sublimated can be calculated as follows.
First, an amount of the crystalline organic material used for vapor deposition is heated in a vapor deposition apparatus to sublimate all. Here, the relationship between the heating time and the deposition rate when the crystalline organic material is heated in the deposition apparatus is shown in FIG. t ₀ is the time to reach the stable deposition rate, t _A is the time when all the crystalline organic material is sublimated, and V is the stable deposition rate. These, calculates the total deposition amount S _A crystalline organic material. That is, if V is substantially constant, it can be obtained by (t _A −t ₀ ) × V. Now the total deposition amount S _A is assumed to be equal to the total volume of the crystalline organic material, the time t at least 1/5 has been sublimated of the total volume can be calculated by the following equation.
(T−t ₀ ) × V = S _A × 1/5, that is,
t = S _A / 5V + t ₀
That is, at least 1/5 of the total volume of the crystalline organic material is sublimated if the sublimation is continued for at least the time t calculated by the above formula.

In the present invention, as described above, when the photoelectric conversion layer is formed, the response speed can be particularly improved by forming the film after sufficiently removing the vicinity of the surface of the crystal particles in the crystalline organic material.
Usually, when a film is formed by sublimating a compound by vapor deposition, the film is formed immediately after the stable vapor deposition rate, and the film is not formed immediately, but after being sublimated for a certain period of time, the vapor deposition is performed. There is no effect on the device performance.
However, according to the present inventors, it has been found that a significant difference occurs in the response speed of the device by changing the time from the arrival of the stable vapor deposition rate to the start of film formation in the crystalline organic material. It can be inferred that there is a difference in the content of impurities (such as oxygen) in the compound and in the vicinity of the surface in the compound, and it is thought that by eliminating impurities on the compound surface, carrier traps disappear and the response speed is improved.

  The volume to be sublimated without film formation is preferably at least 2/5 of the total volume. In addition, from the viewpoint of production efficiency, the sublimation volume is preferably 3/5 or less.

The stable deposition rate is not particularly limited, but is preferably 0.1 Å / s or more, and more preferably 1 Å / s or more. The upper limit of the vapor deposition rate is not particularly limited, but can be about 50 Å / s, preferably 40 Å / s, more preferably 30 Å / s. By setting the stable vapor deposition rate to 1 安定 / s or more, more efficient film formation can be performed.
In addition, after reaching the stable vapor deposition rate, it is preferable to keep the stable vapor deposition rate as it is, but the vapor deposition rate may be varied within a slight range. Specifically, it may vary as long as it is within a range of 0.1 Å / s to 3 Å / s (preferably, a range of 0.1 Å / s to 1 Å / s).

The thickness of the photoelectric conversion layer 12 can be appropriately set according to the type of material used and the maximum value of the voltage applied to the element. Specifically, the value obtained by dividing the voltage applied from the outside to the electrode by the total thickness of the charge blocking layer and the photoelectric conversion layer is 1.0 × 10 ⁵ V / cm to 1.0 × 10 ⁷ V / cm. It is preferable to set it to be cm.

  Finally, the upper electrode 15 is formed on the photoelectric conversion layer 12. The upper electrode 15 can be formed in the same manner as the lower electrode 11.

The photoelectric conversion element manufactured by this embodiment can have charge blocking. By having the charge blocking layer, dark current can be more reliably suppressed.
FIG. 2 shows a configuration example of a photoelectric conversion element having a charge blocking layer.
The photoelectric conversion element 10a shown in FIG. 2A has a configuration in which a voltage is applied to an electrode so as to move holes to the lower electrode 11, and an electron blocking layer 16A and a photoelectric conversion are formed on the lower electrode 11. The layer 12 and the upper electrode 15 are laminated in this order.
In the photoelectric conversion element 10b shown in FIG. 2B, the electron blocking layer 16A, the photoelectric conversion layer 12, the hole blocking layer 16B, and the upper electrode 15 are laminated on the lower electrode 11 in this order. .
2A and 2B, a voltage is applied so that electrons move to the upper electrode 15 and holes move to the lower electrode 11 (that is, the upper electrode 15 is used for extracting electrons). The photoelectric conversion element according to the present invention is not limited to such a form, and a voltage is applied so that electrons move to the lower electrode 11 and holes move to the upper electrode 15. (In other words, the lower electrode 11 may be an electron extraction electrode). In this case, a hole blocking layer is provided between the lower electrode 11 and the photoelectric conversion layer 12, and an electron blocking layer is provided between the upper electrode 15 and the photoelectric conversion layer 12.

The charge blocking layers (16A, 16B) can be formed by vapor deposition. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. In the case of forming a film by vacuum vapor deposition, production conditions such as the degree of vacuum and vapor deposition temperature can be set in accordance with a conventional method.
Examples of the material for forming the charge blocking layer include materials described later.
The thickness of the charge blocking layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably 50 nm or more and 100 nm or less. When the thickness is 10 nm or more, a suitable dark current suppressing effect is obtained, and when the thickness is 300 nm or less, a suitable photoelectric conversion efficiency is obtained.
Note that a plurality of charge blocking layers may be formed.

Next, the electrode which comprises the photoelectric conversion element which concerns on this invention, and the material used for each layer are demonstrated.
(Electrode forming material)
The upper electrode 15 and the lower electrode 11 are made of a conductive material. As the conductive material, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. As metal materials, Li, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Fr, Ra, Sc, Ti, Y, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P , As, Sb, Bi, Se, Te, Po, Br, I, At, B, C, N, F, O, S, and N may be mentioned, but particularly preferred Are Al, Pt, W, Au, Ag, Ta, Cu, Cr, Mo, Ti, Ni, Pd, and Zn.
Specifically, conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc. Metal, gold, silver, chromium, nickel, etc., and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide, copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Examples thereof include organic conductive materials and laminates of these with ITO. Among these, conductive metal oxides are preferable, and ITO and IZO are particularly preferable from the viewpoint of productivity, high conductivity, transparency, and the like.

(Photoelectric conversion layer forming material)
As a material for forming the photoelectric conversion layer 12, an organic material having a photoelectric conversion function is used.
As the organic material, for example, various organic semiconductor materials such as those used in electrophotographic photosensitive materials can be used.
Among them, from the viewpoints of having high photoelectric conversion performance, excellent color separation at the time of spectroscopy, high durability against long-time light irradiation, easy vacuum deposition, etc., the quinacridone skeleton is Particularly preferred are materials containing and organic materials containing a phthalocyanine skeleton.

  When quinacridone is used as the photoelectric conversion layer 12, the photoelectric conversion layer 12 can absorb light in the green wavelength region and generate a charge corresponding to the light.

  As the photoelectric conversion layer 12, zinc phthalocyanine can be used. In this case, the photoelectric conversion layer 12 can absorb light in the red wavelength region and generate a charge corresponding to the light.

  Moreover, it is preferable that the organic material which comprises the photoelectric converting layer 12 contains at least one of a p-type organic semiconductor and an n-type organic semiconductor. As the p-type organic semiconductor and the n-type organic semiconductor, any of quinacridone derivatives, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives can be particularly preferably used.

  A p-type organic semiconductor (compound) is a donor-type organic semiconductor (compound), which is mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound. For example, triarylamine compounds, benzidine compounds, pyran compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamines Compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), nitrogen-containing heterocyclic compounds The metal complex etc. which have as a ligand can be used. Not limited to this, as described above, any organic compound having an ionization potential smaller than that of the organic compound used as the n-type (acceptor property) compound may be used as the donor organic semiconductor.

Among these, a triarylamine compound, a pyran compound, a phthalocyanine compound, a merocyanine compound, and a condensed aromatic carbocyclic compound are preferable, and a triarylamine compound is more preferable.
As a triarylamine compound, the compound of the following general formula (I) is preferable.
Formula (I):

_{Wherein, R 20 ~R 24, R 30} ~R 34, R 41 ~R 44 independently represents a hydrogen atom or a substituent. R _{20 to} R ₂₄ and R _{30 to} R ₃₄ may be bonded to each other to form a ring. Ar represents an arylene group or heteroarylene group which may have a substituent.

Examples of the substituent represented by R _{20 to} R ₂₄ , R _{30 to} R ₃₄ , R _{41 to} R ₄₄ or the substituent that Ar has include a substituent W described later, preferably a halogen atom (for example, a fluorine atom, chlorine) Atoms, bromine atoms, iodine atoms), alkyl groups having 1 to 30 carbon atoms (preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms) (for example, methyl, ethyl, n-propyl, isopropyl, t-butyl) N-octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl), a cycloalkyl group (preferably a cycloalkyl group having 3 to 30 carbon atoms (for example, cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl), C2-C30 alkenyl group (eg, vinyl, allyl, prenyl, geranyl, oleyl), carbon 2 to 30 alkynyl groups (eg, ethynyl, propargyl, trimethylsilylethynyl groups), aryl groups having 6 to 30 carbon atoms (eg, phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl, ferrocenyl) A heterocyclic group having 2 to 50 carbon atoms (consisting of 5 or 6 members, which may be aromatic or non-aromatic, such as 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl), cyano group, hydroxy Group, nitro group, carboxy group, alkoxy group, aryloxy group, amino group, sulfamoyl group, sulfo group, or a combination thereof.
These groups may further have a substituent.
Of these, a halogen atom, an alkyl group, an aryl group, and an alkoxy group are more preferable, an alkyl group or an aryl group is more preferable, and an unsubstituted alkyl group having 1 to 5 carbon atoms or a phenyl group is more preferable.

R _{20 to} R ₂₄ and R _{30 to} R ₃₄ are preferably a hydrogen atom, an alkyl group, or an aryl group. Among them, it is more preferable that R ₂₀ and R ₃₀ are an alkyl group or an aryl group, and other R _{21 to} R ₂₄ and R _{31 to} R ₃₄ are hydrogen atoms.
R _{41 to} R ₄₄ are preferably a hydrogen atom, an alkyl group, or an aryl group. Among them, it is preferable that R ₄₂ and R ₄₃ are alkyl groups or aryl groups, and R ₄₁ and R ₄₄ are hydrogen atoms.

Ar represents an arylene group or heteroarylene group which may have a substituent. Examples of the arylene group or heteroarylene group include a phenylene group, a naphthylene group, an anthrylene group, a thienylene group, a pyridinylene group, and a furylene group.
Ar is preferably an arylene group which may have a substituent, more preferably a phenylene group or a naphthylene group which may have a substituent, and more preferably an unsubstituted phenylene group. Or it is an unsubstituted naphthylene group.

  Specific examples of the compound represented by the general formula (I) are shown below, but the present invention is not limited thereto.

  An n-type organic semiconductor (compound) is an acceptor organic semiconductor (compound), which is represented by mainly an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound. For example, condensed aromatic carbocyclic compounds (naphthalene, anthracene, fullerene, phenanthrene, tetracene, pyrene, perylene, fluoranthene, or derivatives thereof), 5- to 7-membered heterocyclic compounds containing a nitrogen atom, an oxygen atom, or a sulfur atom (E.g. pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, Benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, oxadiazo , Imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, nitrogen-containing heterocyclic compounds as ligands Etc. Note that the present invention is not limited thereto, and as described above, any organic compound having an electron affinity higher than that of the organic compound used as the donor organic compound may be used as the acceptor organic semiconductor.

As the n-type organic semiconductor, fullerene or fullerene derivatives are preferably used.
The fullerene, fullerene _{C 60,} fullerene _{C 70,} fullerene _{C 76,} fullerene _{C 78,} fullerene _{C 80,} fullerene _{C 82,} fullerene _{C 84,} fullerene _{C 90,} fullerene _{C 96,} fullerene _{C 240,} fullerene _540, mixed fullerene Represents a fullerene nanotube, and a fullerene derivative represents a compound having a substituent added thereto. As the substituent, an alkyl group, an aryl group, or a heterocyclic group is preferable.
Examples of the fullerene derivative include the following compounds, but the present invention is not limited thereto.

  In addition, as for fullerene and fullerene derivatives, there are quarterly chemical reviews No. edited by the Chemical Society of Japan. 43 (1999), JP-A-10-167994, JP-A-11-255508, JP-A-11-255509, JP-A-2002-241323, JP-A-2003-19681, and the like. It can also be used.

As an organic material used for the photoelectric conversion layer, a p-type organic dye or an n-type organic dye can also be used.
Any p-type organic dye or n-type organic dye may be used, but preferably a cyanine dye, a styryl dye, a hemicyanine dye, a merocyanine dye (including zero methine merocyanine (simple merocyanine)), a trinuclear merocyanine Dye, 4-nuclear merocyanine dye, rhodacyanine dye, complex cyanine dye, complex merocyanine dye, allopolar dye, oxonol dye, hemioxonol dye, squalium dye, croconium dye, azamethine dye, coumarin dye, arylidene dye, anthraquinone dye, triphenylmethane Dye, azo dye, azomethine dye, spiro compound, metallocene dye, fluorenone dye, fulgide dye, perylene dye, phenazine dye, phenothiazine dye, quinone dye, indigo Dye, diphenylmethane dye, polyene dye, acridine dye, acridinone dye, diphenylamine dye, quinacridone dye, quinophthalone dye, phenoxazine dye, phthaloperylene dye, porphyrin dye, chlorophyll dye, phthalocyanine dye, metal complex dye, condensed aromatic carbocyclic dye (Naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives).

  The metal complex compound is a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal, and the metal ion in the metal complex is not particularly limited, but preferably Beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, or tin ion, more preferably beryllium ion, aluminum ion, gallium ion, or zinc ion, still more preferably aluminum ion, or zinc ion Ion. As the ligand contained in the metal complex, there are various known ligands. For example, “Photochemistry and Photophysics of Coordination Compounds” published by Springer-Verlag H. Yersin in 1987, “Organometallic Chemistry— Examples of the ligands described in “Basics and Applications—” published by Akio Yamamoto, 1982, etc.

  The photoelectric conversion layer preferably has a bulk heterojunction structure layer including a p-type semiconductor and an n-type semiconductor. When the photoelectric conversion layer has a bulk heterojunction structure, the disadvantage that the carrier diffusion length of the photoelectric conversion layer is short can be compensated, and the photoelectric conversion efficiency of the photoelectric conversion layer can be improved. The bulk heterojunction structure is described in detail in Japanese Patent Application Laid-Open No. 2005-303266.

(Material for forming charge blocking layer)
Examples of the material for forming the charge blocking layer (hole blocking layer, electron blocking layer) include the following. An electron-accepting organic material can be used for the hole blocking layer.
Examples of the electron-accepting material include 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) and other oxadiazole derivatives, anthraquinodimethane derivatives, and diphenylquinone derivatives. , Bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8-quinolinato) aluminum complexes, distyrylarylene derivatives, silole compounds, etc. Can do. Moreover, even if it is not an electron-accepting organic material, it can be used if it is a material which has sufficient electron transport property. Porphyrin compounds, styryl compounds such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4H pyran), and 4H pyran compounds can be used.
Specifically, the following compounds are preferable. In the following specific examples, Ea and Ip represent electron affinity Ea (eV) and ionization potential Ip (eV), respectively.

An electron donating organic material can be used for the electron blocking layer.
Specifically, in a low molecular material, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) or 4,4′-bis [N Aromatic diamine compounds such as-(naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Porphyrin compounds, triazole derivatives, oxazizazo Derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. In the polymer material, a polymer such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, or a derivative thereof can be used. Any compound having a sufficient hole transporting property can be used.
Specifically, the following compounds are preferable. In the following specific examples, Ea and Ip represent electron affinity Ea (eV) and ionization potential Ip (eV), respectively.

[Image sensor]
Next, a configuration example of an image sensor including a photoelectric conversion element will be described. In the configuration examples described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and the description thereof is simplified or omitted.

  Hereinafter, a configuration example of a solid-state imaging element using the photoelectric conversion element according to the present embodiment will be described. In the following description, reference will be made to FIGS.

(First embodiment)
FIG. 4 is a schematic cross-sectional view of one pixel of the solid-state imaging device for explaining the first embodiment. FIG. 5 is a schematic cross-sectional view of the intermediate layer shown in FIG. This solid-state imaging device has a large number of one pixel shown in FIG. 4 arranged in an array on the same plane, and one pixel data of image data can be generated by a signal obtained from the one pixel.

  One pixel of the solid-state imaging device shown in FIG. 4 includes an n-type silicon substrate 1, a transparent insulating film 7 formed on the n-type silicon substrate 1, a first electrode film 11 formed on the insulating film 7, And a photoelectric conversion unit including the intermediate layer 12 formed on the first electrode film 11 and the second electrode film 13 formed on the intermediate layer 12, and an opening is provided on the photoelectric conversion unit. A light shielding film 14 is formed, and the light receiving region of the intermediate layer 12 is limited by the light shielding film 14. A transparent insulating film 15 is formed on the light shielding film 14 and the second electrode film 13. In addition, the photoelectric conversion part formed on the insulating film 7 can employ | adopt the structure of the photoelectric conversion element shown in FIG.

  As shown in FIG. 5, the intermediate layer 12 is formed by laminating an undercoat layer / electron blocking layer 122, a photoelectric conversion layer 123, and a hole blocking / buffer layer 124 in this order on the first electrode film 11. Composed.

  The photoelectric conversion layer 123 generates charges including electrons and holes in response to incident light from above the second electrode film 13, and has a lower electron mobility than the hole mobility, The vicinity of the second electrode film 13 includes a material having characteristics that generate more electrons and holes than the vicinity of the electrode film 11. Since the photoelectric conversion layer 123 can be used in common for all pixels, it may be a single-layer film, and does not need to be separated for each pixel.

  The photoelectric conversion layer included in the intermediate layer 12 includes a p-type semiconductor layer, an n-type semiconductor layer (preferably a mixed / dispersed (bulk heterojunction structure) layer), and includes a p-type semiconductor and an n-type semiconductor. It is preferable that the organic compound whose orientation is controlled is included in at least one of the above, and more preferably, the organic compound whose orientation is controlled is included in both the p-type semiconductor and the n-type semiconductor. As this organic compound, those having π-conjugated electrons are preferably used, and it is more preferable that the π-electron plane is oriented at an angle close to parallel rather than perpendicular to the substrate (electrode substrate). The angle with respect to the substrate is preferably 0 ° or more and 80 ° or less, more preferably 0 ° or more and 60 ° or less, further preferably 0 ° or more and 40 ° or less, and further preferably 0 ° or more and 20 ° or less. Particularly preferably, it is 0 ° or more and 10 ° or less, and most preferably 0 ° (that is, parallel to the substrate). As described above, the organic compound layer whose orientation is controlled may be partially included in the entire intermediate layer 12, but preferably the proportion of the portion whose orientation is controlled with respect to the entire intermediate layer 12 is 10%. This is the case, more preferably 30% or more, further preferably 50% or more, more preferably 70% or more, particularly preferably 90% or more, and most preferably 100%. Such a state compensates for the shortage of the carrier diffusion length of the photoelectric conversion element layer by controlling the orientation of the organic compound contained in the intermediate layer 12, and improves the photoelectric conversion efficiency of the photoelectric conversion film. .

  In the case where the orientation of the organic compound is controlled, it is more preferable that the heterojunction plane (for example, the pn junction plane) is not parallel to the substrate. It is more preferable that the heterojunction plane is oriented not at a parallel to the substrate (electrode substrate) but at an angle close to the vertical. The angle with respect to the substrate is preferably 10 ° or more and 90 ° or less, more preferably 30 ° or more and 90 ° or less, further preferably 50 ° or more and 90 ° or less, and further preferably 70 ° or more and 90 ° or less. Particularly preferably, it is 80 ° or more and 90 ° or less, and most preferably 90 ° (that is, perpendicular to the substrate). The organic compound layer whose heterojunction surface is controlled as described above may be partially included in the entire intermediate layer 12. Preferably, the proportion of the portion whose orientation is controlled with respect to the entire intermediate layer 12 is 10% or more, more preferably 30% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably 90%. % Or more, most preferably 100%. In such a case, the area of the heterojunction surface in the intermediate layer 12 increases, the amount of carriers of electrons, holes, electron-hole pairs, etc. generated at the interface increases, and the photoelectric conversion efficiency can be improved. In the above-described photoelectric conversion layer in which the orientation of both the heterojunction plane and the π-electron plane of the organic compound is controlled, the photoelectric conversion efficiency can be particularly improved. These states are described in detail in Japanese Patent Application Laid-Open No. 2006-086493 (Japanese Patent Application No. 2004-079931). In terms of light absorption, the thickness of the organic dye layer is preferably as large as possible, but considering the ratio that does not contribute to charge separation, the thickness of the organic dye layer is preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, Especially preferably, it is 80 nm or more and 200 nm or less.

  In the photoelectric conversion layer 123 made of an organic material, if light is incident from above the second electrode 13 in the above-described configuration, a large number of electrons and holes generated by light absorption are generated in the vicinity of the second electrode 13, In general, it does not occur so much in the vicinity of the first electrode 11. This is because most of the light near the absorption peak wavelength of the photoelectric conversion layer 123 is absorbed in the vicinity of the second electrode 13, and the light absorption rate decreases as the distance from the vicinity of the second electrode 13 increases. Is attributed. For this reason, unless the electrons or holes generated in the vicinity of the second electrode 13 are efficiently moved to the silicon substrate, the photoelectric conversion efficiency is lowered, resulting in a decrease in sensitivity of the element. Further, since the signal due to the light wavelength strongly absorbed in the vicinity of the second electrode 13 is reduced, as a result, the so-called broadening of the spectral sensitivity is caused.

  Further, in the photoelectric conversion layer 123 made of an organic material, the electron mobility is generally much smaller than the hole mobility. Furthermore, it is known that the electron mobility in the photoelectric conversion layer 123 made of an organic material is easily affected by oxygen, and that the electron mobility is further reduced when the photoelectric conversion layer 123 is exposed to the atmosphere. For this reason, when the electrons are moved to the silicon substrate 1, if the movement distance of the electrons generated in the vicinity of the second electrode 13 in the photoelectric conversion layer 123 is long, a part of the electrons is deactivated during the movement of the electrons. As a result, the sensitivity is lowered and the spectral sensitivity is broadened.

  In order to prevent a decrease in sensitivity and a broadening of spectral sensitivity, it is effective to efficiently move electrons or holes generated in the vicinity of the second electrode 13 to the silicon substrate 1. A problem is how to handle electrons or holes generated in the conversion layer 123.

Since the solid-state imaging device 1000 includes the photoelectric conversion layer 123 having the above-described characteristics, as described above, holes are collected by the first electrode film 11 which is an electrode opposite to the light incident side electrode. By using this, the external quantum efficiency can be increased, and the sensitivity can be improved and the spectral sensitivity can be sharpened. Therefore, in the solid-state imaging device 1000, the first electrode is formed such that electrons generated in the photoelectric conversion layer 123 move to the second electrode film 13 and holes generated in the photoelectric conversion layer 123 move to the first electrode film 11. A voltage is applied to the film 11 and the second electrode film 13.

  One function of the undercoat / electron blocking layer 122 is to relieve unevenness on the first electrode film 11. When the first electrode film 11 has irregularities, or when dust adheres to the first electrode film 11, a low molecular organic material is deposited thereon to form the photoelectric conversion layer 123. It is easy to form a fine crack in the photoelectric conversion layer 123, that is, a portion where the photoelectric conversion layer 123 is formed only thin. At this time, if the second electrode film 13 is further formed thereon, the crack portion is covered by the second electrode film 13 and close to the first electrode film 11, so that a DC short circuit and an increase in leakage current are likely to occur. In particular, when TCO is used as the second electrode film 13, the tendency is remarkable. For this reason, the unevenness | corrugation can be relieve | moderated by providing the undercoat film | membrane and electron blocking layer 122 on the 1st electrode film 11 previously, and these can be suppressed.

  It is important that the undercoat / electron blocking layer 122 is a homogeneous and smooth film. In particular, when obtaining a smooth film, preferred materials include organic polymer materials such as polyaniline, polythiophene, polypyrrole, polycarbazole, PTPDES, and PTPDK, and can also be formed by spin coating.

  The electron blocking layer 122 is provided in order to reduce dark current caused by the injection of electrons from the first electrode film 11, and the electrons from the first electrode film 11 are injected into the photoelectric conversion layer 123. Stop.

  The hole blocking / buffer layer 125 is provided as a hole blocking layer in order to reduce dark current caused by holes injected from the second electrode film 13. In addition to the function of blocking the injection into the photoelectric conversion layer 123, in some cases, the second electrode film 13 is formed to reduce the damage given to the photoelectric conversion layer 123.

  When the second electrode film 13 is formed on the photoelectric conversion layer 123, high-energy particles existing in the apparatus used for forming the second electrode film 13, such as sputtered particles and secondary electrons in the case of sputtering, When Ar particles, oxygen negative ions, or the like collide with the photoelectric conversion layer 123, the photoelectric conversion layer 123 may be altered, and performance degradation such as an increase in leakage current or a decrease in sensitivity may occur. As one method for preventing this, it is preferable to provide the buffer film 125 on the photoelectric conversion layer 123.

  Returning to FIG. 4, in the n-type silicon substrate 1, a p-type semiconductor region (hereinafter abbreviated as p-region) 4, an n-type semiconductor region (hereinafter abbreviated as n-region) 3, and a p-region from the shallower side. 2 are formed in this order. A high-concentration p region (referred to as a p + region) 6 is formed on the surface portion of the p region 4 that is shielded by the light shielding film 14, and the p + region 6 is surrounded by the n region 5.

  The depth of the pn junction surface between the p region 4 and the n region 3 from the surface of the n-type silicon substrate 1 is a depth that absorbs blue light (about 0.2 μm). Therefore, the p region 4 and the n region 3 absorb blue light, generate holes corresponding thereto, and form a photodiode (B photodiode) that accumulates the holes. Holes generated in the B photodiode are accumulated in the p region 4.

  The depth of the pn junction surface between the p region 2 and the n-type silicon substrate 1 from the surface of the n-type silicon substrate 1 is a depth that absorbs red light (about 2 μm). Therefore, the p region 2 and the n-type silicon substrate 1 absorb red light, generate holes corresponding to the red light, and form a photodiode (R photodiode) that accumulates the holes. Holes generated in the R photodiode are accumulated in the p region 2.

  The p + region 6 is electrically connected to the first electrode film 11 via a connection portion 9 formed in an opening opened in the insulating film 7, and is connected to the first electrode film 11 via the connection portion 9. Accumulate the collected holes. The connection portion 9 is electrically insulated by the insulating film 8 except for the first electrode film 11 and the p + region 6.

  The holes accumulated in the p region 2 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) made of a p-channel MOS transistor formed in the n-type silicon substrate 1 and accumulated in the p region 4. The generated holes are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n region 3, and the electrons accumulated in the p + region 6 5 is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in 5 and output to the outside of the solid-state imaging device 1000. These MOS circuits constitute the signal readout section in the claims. Each MOS circuit is connected to a signal readout pad (not shown) by wiring 10. If extraction electrodes are provided in the p region 2 and the p region 4 and a predetermined reset potential is applied, each region is depleted, and the capacitance of each pn junction becomes an infinitely small value. Thereby, the capacity | capacitance produced in a joint surface can be made very small.

  With such a configuration, for example, G light can be photoelectrically converted by the photoelectric conversion layer 123, and B light and R light can be photoelectrically converted by the B photodiode and the R photodiode in the n-type silicon substrate 1. In addition, since G light is first absorbed at the top, color separation between BG and between GR is excellent. This is a great advantage over a solid-state imaging device in which three PDs are stacked in a silicon substrate and all BGR light is separated in the silicon substrate. In the following description, the part (B photodiode and R photodiode) that performs photoelectric conversion made of an inorganic material formed in the n-type silicon substrate 1 of the solid-state imaging device 1000 is also referred to as an inorganic layer.

  In addition, light that has passed through the photoelectric conversion layer 123 is absorbed between the n-type silicon substrate 1 and the first electrode film 11 (for example, between the insulating film 7 and the n-type silicon substrate 1), and according to the light. It is also possible to form an inorganic photoelectric conversion portion made of an inorganic material that generates and accumulates the charges. In this case, a MOS circuit for reading a signal corresponding to the charge accumulated in the charge accumulation region of the inorganic photoelectric conversion unit is provided in the n-type silicon substrate 1, and the wiring 10 is also connected to this MOS circuit. It ’s fine.

The first electrode film 11 plays a role of collecting holes generated and moved in the photoelectric conversion layer 123. The first electrode film 11 is separated for each pixel, whereby image data can be generated. In the configuration shown in FIG. 4, since the n-type silicon substrate 1 also performs photoelectric conversion, the first electrode film 11 preferably has a visible light transmittance of 60% or more, and preferably 90% or more. More preferred. In the case where the photoelectric conversion region does not exist below the first electrode film 11, the first electrode film 11 may be low in transparency. As a material, any of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, and Au can be most preferably used.

The second electrode film 13 has a function of discharging electrons generated and moved in the photoelectric conversion layer 123. The second electrode film 13 can be used in common for all pixels. For this reason, in the solid-state imaging device 1000, the second electrode film 13 is a single-layer film common to all pixels. Since the second electrode film 13 needs to make light incident on the photoelectric conversion layer 123, it is necessary to use a material having high transparency to visible light. The second electrode film 13 preferably has a visible light transmittance of 60% or more, more preferably 90% or more. As a material, any of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, and Au can be most preferably used.

  As the inorganic layer, a pn junction or a pin junction of a compound semiconductor such as crystalline silicon, amorphous silicon, or GaAs is generally used. In this case, since color separation is performed based on the light penetration depth of silicon, the spectral range detected by each stacked light receiving unit is broad. However, color separation is significantly improved by using the photoelectric conversion layer 123 as an upper layer as shown in FIG. 4, that is, by detecting light transmitted through the photoelectric conversion layer 123 in the depth direction of silicon. In particular, as shown in FIG. 4, when G light is detected by the photoelectric conversion layer 123, light transmitted through the photoelectric conversion layer 123 becomes B light and R light. Only light is used and color separation is improved. Even when the photoelectric conversion layer 123 detects B light or R light, color separation is remarkably improved by appropriately selecting the depth of the pn junction surface of silicon.

  The structure of the inorganic layer is preferably npn or pnpn from the light incident side. In particular, by providing a p layer on the surface and increasing the surface potential, holes generated in the vicinity of the surface and dark current can be trapped and dark current can be reduced. preferable.

  FIG. 4 shows a configuration in which one photoelectric conversion unit is stacked above the n-type silicon substrate 1, but a configuration in which a plurality of photoelectric conversion units are stacked above the n-type silicon substrate 1 is also possible. is there. A configuration in which a plurality of photoelectric conversion units are stacked will be described in a later embodiment. In this case, the light detected by the inorganic layer may be one color, and preferable color separation can be achieved. Further, when detecting four colors of light with one pixel of the solid-state imaging device 1000, for example, a configuration in which one color is detected with one photoelectric conversion unit and three colors are detected with an inorganic layer, A structure in which two photoelectric conversion units are stacked to detect two colors and two colors are detected in the inorganic layer, three photoelectric conversion units are stacked to detect three colors, and one color is detected in the inorganic layer Configuration etc. can be considered. Further, the solid-state imaging device 1000 may be configured to detect only one color with one pixel. In this case, the p region 2, the n region 3, and the p region 4 are eliminated in FIG.

  The inorganic layer will be described in more detail. As a preferable configuration of the inorganic layer, a photoconductive type, a pn junction type, a Schottky junction type, a PIN junction type, an MSM (metal-semiconductor-metal) type light receiving element or a phototransistor type light receiving element can be given. In particular, as shown in FIG. 4, a plurality of first conductivity type regions and second conductivity type regions that are opposite to the first conductivity type are stacked in a single semiconductor substrate. It is preferable to use an inorganic layer formed by forming each bonding surface of the first conductivity type region and the second conductivity type region to a depth suitable for mainly photoelectrically converting light in a plurality of different wavelength bands. . As the single semiconductor substrate, single crystal silicon is preferable, and color separation can be performed using absorption wavelength characteristics depending on the depth direction of the silicon substrate.

As the inorganic semiconductor, an InGaN-based, InAlN-based, InAlP-based, or InGaAlP-based inorganic semiconductor can also be used. The nGaN-based inorganic semiconductor is adjusted so as to have a maximum absorption value in the blue wavelength range by appropriately changing the composition of In. That is, the composition is In _x Ga _1-x N (0 ≦ X <1). Such a compound semiconductor is manufactured using a metal organic chemical vapor deposition method (MOCVD method). A nitride semiconductor InAlN system using Al, which is the same group 13 raw material as Ga, can also be used as a short wavelength light receiving section in the same manner as the InGaN system. It is also possible to use InAlP or InGaAlP lattice-matched to the GaAs substrate.

  The inorganic semiconductor may have a buried structure. The embedded structure means a structure in which both ends of the short wavelength light receiving part are covered with a semiconductor different from the short wavelength light receiving part. The semiconductor covering both ends is preferably a semiconductor having a band gap wavelength shorter than or equivalent to the band gap wavelength of the short wavelength light receiving part.

  Further, when a plurality of intermediate layers 12 are stacked, the first electrode film 11 and the second electrode film 13 are each photoelectrically connected from the photoelectric conversion film located closest to the light incident side to the photoelectric conversion film located farthest. It is necessary to transmit light having a wavelength other than the light detected by the conversion layer, and it is preferable to use a material that transmits light of 90%, more preferably 95% or more with respect to visible light.

  The second electrode film 13 is preferably made plasma-free. By creating the second electrode film 13 free of plasma, the influence of plasma on the substrate can be reduced, and the photoelectric conversion characteristics can be improved. Here, plasma free means that no plasma is generated during the formation of the second electrode film 13, or the distance from the plasma generation source to the substrate is 2 cm or more, preferably 10 cm or more, more preferably 20 cm or more, It means a state in which the plasma reaching the substrate is reduced.

  Examples of apparatuses that do not generate plasma during the formation of the second electrode film 13 include an electron beam vapor deposition apparatus (EB vapor deposition apparatus) and a pulse laser vapor deposition apparatus. Regarding EB deposition equipment or pulse laser deposition equipment, “Surveillance of Transparent Conductive Films” supervised by Yutaka Sawada (published by CMC, 1999); ), "Transparent conductive film technology" by the Japan Society for the Promotion of Science (Ohm Co., 1999), and the references attached thereto, etc. can be used. Hereinafter, a method of forming a transparent electrode film using an EB vapor deposition apparatus is referred to as an EB vapor deposition method, and a method of forming a transparent electrode film using a pulse laser vapor deposition apparatus is referred to as a pulse laser vapor deposition method.

  For an apparatus that can realize a state in which the distance from the plasma generation source to the substrate is 2 cm or more and the arrival of plasma to the substrate is reduced (hereinafter referred to as a plasma-free film forming apparatus), for example, an opposed target sputtering Equipment, arc plasma deposition, etc. are considered, and these are supervised by Yutaka Sawada "New development of transparent conductive film" (published by CMC, 1999), and supervised by Yutaka Sawada "New development of transparent conductive film II" (published by CMC) 2002), “Transparent conductive film technology” (Ohm Co., 1999) by the Japan Society for the Promotion of Science, and references and the like attached thereto can be used.

  When a transparent conductive film such as TCO is used as the second electrode film 13, a DC short circuit or an increase in leakage current may occur. One reason for this is thought to be that fine cracks introduced into the photoelectric conversion layer 123 are covered by a dense film such as TCO, and conduction between the first electrode film 11 on the opposite side is increased. For this reason, in the case of an electrode having a poor film quality such as Al, an increase in leakage current hardly occurs. By controlling the film thickness of the second electrode film 13 with respect to the film thickness of the photoelectric conversion layer 123 (that is, the crack depth), an increase in leakage current can be largely suppressed. The thickness of the second electrode film 13 is desirably 1/5 or less, preferably 1/10 or less of the thickness of the photoelectric conversion layer 123.

  Usually, when the conductive film is made thinner than a certain range, the resistance value is rapidly increased. However, in the solid-state imaging device 1000 of the present embodiment, the sheet resistance is preferably 100 to 10,000 Ω / □, and the film can be thinned. The degree of freedom in the thickness range is large. Further, the thinner the transparent conductive thin film is, the less light is absorbed, and the light transmittance is generally increased. The increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion layer 123 and increases the photoelectric conversion ability. In consideration of the suppression of leakage current, the increase in the resistance value of the thin film, and the increase in transmittance due to the thinning, the thickness of the transparent conductive thin film is preferably 5 to 100 nm, more preferably 5 to 20 nm. Something is desirable.

  The material of the transparent electrode film is preferably one that can be formed by a plasma-free film forming apparatus, an EB vapor deposition apparatus, and a pulse laser vapor deposition apparatus. For example, a metal, an alloy, a metal oxide, a metal nitride, a metal boride, an organic conductive compound, a mixture thereof, and the like are preferable. Specific examples include tin oxide, zinc oxide, indium oxide, and indium zinc oxide. (IZO), indium tin oxide (ITO), conductive metal oxides such as indium tungsten oxide (IWO), metal nitrides such as titanium nitride, metals such as gold, platinum, silver, chromium, nickel, aluminum, and these A mixture or laminate of a metal and a conductive metal oxide, an inorganic conductive material such as copper iodide or copper sulfide, an organic conductive material such as polyaniline, polythiophene or polypyrrole, a laminate of these and ITO, Etc. Also, supervised by Yutaka Sawada “New Development of Transparent Conductive Film” (published by CMC, 1999), supervised by Yutaka Sawada “New Development of Transparent Conductive Film II” (published by CMC, 2002), “Transparency by Japan Society for the Promotion of Science” Those described in detail in “Technology of Conductive Film” (Ohm Co., 1999) may be used.

(Second Embodiment)
In the present embodiment, the inorganic layer having the configuration shown in FIG. 4 described in the first embodiment is not stacked with two photodiodes in an n-type silicon substrate, but is perpendicular to the incident direction of incident light. Two photodiodes are arranged in the direction to detect light of two colors in the n-type silicon substrate.

FIG. 6 is a schematic cross-sectional view of one pixel of a solid-state image sensor for explaining a fourth embodiment of the present invention.
One pixel of the solid-state imaging device 2000 shown in FIG. 6 includes an n-type silicon substrate 17, a first electrode film 30 formed above the n-type silicon substrate 17, an intermediate layer 31 formed on the first electrode film 30, And a photoelectric conversion part comprising the second electrode film 32 formed on the intermediate layer 31, and a light shielding film 34 having an opening is formed on the photoelectric conversion part. Therefore, the light receiving area of the intermediate layer 31 is limited. A transparent insulating film 33 is formed on the light shielding film 34.

  The first electrode film 30, the intermediate layer 31, and the second electrode film 32 have the same configuration as the first electrode film 11, the intermediate layer 12, and the second electrode film 13.

  On the surface of the n-type silicon substrate 17 below the opening of the light shielding film 34, a photodiode composed of the n region 19 and the p region 18 and a photodiode composed of the n region 21 and the p region 20 are formed on the surface of the n-type silicon substrate 17. It is formed side by side. An arbitrary direction on the surface of the n-type silicon substrate 17 is a direction perpendicular to the incident direction of incident light.

  Above the photodiode composed of the n region 19 and the p region 18, a color filter 28 that transmits B light through a transparent insulating film 24 is formed, and a first electrode film 30 is formed thereon. A color filter 29 that transmits R light through a transparent insulating film 24 is formed above the photodiode composed of the n region 21 and the p region 20, and a first electrode film 30 is formed thereon. The periphery of the color filters 28 and 29 is covered with a transparent insulating film 25.

  The photodiode composed of the n region 19 and the p region 18 absorbs the B light transmitted through the color filter 28 and generates holes corresponding thereto, and accumulates the generated holes in the p region 18. The photodiode composed of the n region 21 and the p region 20 absorbs the R light transmitted through the color filter 29 and generates holes corresponding thereto, and accumulates the generated holes in the p region 20.

  A p + region 23 is formed on the surface of the p-type silicon substrate 17 that is shielded by the light shielding film 34, and the p + region 23 is surrounded by the n region 22.

  The p + region 23 is electrically connected to the first electrode film 30 via a connection portion 27 formed in an opening opened in the insulating films 24 and 25, and the first electrode film is connected via the connection portion 27. The holes collected at 30 are accumulated. The connecting portion 27 is electrically insulated by the insulating film 26 except for the first electrode film 30 and the p + region 23.

  The holes accumulated in the p region 18 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n-type silicon substrate 17 and accumulated in the p region 20. The generated holes are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n-type silicon substrate 17, and the holes accumulated in the p + region 23 are The signal is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n region 22 and output to the outside of the solid-state imaging device 2000. These MOS circuits constitute the signal readout section in the claims. Each MOS circuit is connected to a signal readout pad (not shown) by wiring 35.

  The signal reading unit may be constituted by a CCD and an amplifier instead of the MOS circuit. That is, the holes accumulated in the p region 18, the p region 20, and the p + region 23 are read out to the CCD formed in the n-type silicon substrate 17, transferred to the amplifier by the CCD, and transferred from the amplifier to the holes. A signal reading unit that outputs a corresponding signal may be used.

  As described above, the signal reading unit includes a CCD and a CMOS structure, but CMOS is preferable from the viewpoint of power consumption, high-speed reading, pixel addition, partial reading, and the like.

  In FIG. 6, the color filters 28 and 29 perform color separation of the R light and the B light. However, the color filters 28 and 29 are not provided, and the depths of the pn junction surfaces of the p region 20 and the n region 21 are as follows. The depths of the pn junction surfaces of the p region 18 and the n region 19 may be adjusted to absorb the R light and the B light with the respective photodiodes. In this case, the light transmitted through the intermediate layer 31 is absorbed between the n-type silicon substrate 17 and the first electrode film 30 (for example, between the insulating film 24 and the n-type silicon substrate 17), and according to the light. It is also possible to form an inorganic photoelectric conversion portion made of an inorganic material that generates and accumulates the charges. In this case, a MOS circuit for reading a signal corresponding to the charge accumulated in the charge accumulation region of the inorganic photoelectric conversion unit is provided in the n-type silicon substrate 17, and the wiring 35 is also connected to this MOS circuit. It ’s fine.

  Alternatively, a single photodiode provided in the n-type silicon substrate 17 may be used, and a plurality of photoelectric conversion units may be stacked above the n-type silicon substrate 17. Further, a plurality of photodiodes provided in the n-type silicon substrate 17 may be provided, and a plurality of photoelectric conversion units may be stacked above the n-type silicon substrate 17. If there is no need to produce a color image, a single photodiode provided in the n-type silicon substrate 17 and only one photoelectric conversion unit may be stacked.

(Third embodiment)
The solid-state imaging device of the present embodiment has a configuration in which a plurality (three in this case) of photoelectric conversion layers are stacked above a silicon substrate without providing the inorganic layer having the configuration shown in FIG. 4 described in the first embodiment. .
FIG. 7 is a schematic cross-sectional view of one pixel of a solid-state imaging device for explaining the third embodiment of the present invention.
7 includes a first electrode film 56, an intermediate layer 57 stacked on the first electrode film 56, and a second electrode film 58 stacked on the intermediate layer 57 above the silicon substrate 41. An R photoelectric conversion unit including the first electrode film 60, an intermediate layer 61 stacked on the first electrode film 60, and a B photoelectric conversion unit including the second electrode film 62 stacked on the intermediate layer 61, The first electrode film 64, the intermediate layer 65 stacked on the first electrode film 64, and the G photoelectric conversion portion including the second electrode film 66 stacked on the intermediate layer 65 are respectively included in the first electrode The film is laminated in this order with the film facing the silicon substrate 41 side.

  A transparent insulating film 48 is formed on the silicon substrate 41, an R photoelectric conversion portion is formed thereon, a transparent insulating film 59 is formed thereon, a B photoelectric conversion portion is formed thereon, and A transparent insulating film 63 is formed thereon, a G photoelectric conversion portion is formed thereon, a light shielding film 68 having an opening is formed thereon, and a transparent insulating film 67 is formed thereon. .

  The first electrode film 64, the intermediate layer 65, and the second electrode film 66 included in the G photoelectric conversion unit have the same configuration as the first electrode film 11, the intermediate layer 12, and the second electrode film 13 illustrated in FIG. .

  The first electrode film 60, the intermediate layer 61, and the second electrode film 62 included in the B photoelectric conversion unit have the same configuration as the first electrode film 11, the intermediate layer 12, and the second electrode film 13 illustrated in FIG. . However, the photoelectric conversion layer included in the intermediate layer 61 uses a material that absorbs blue light and generates electrons and holes according to the blue light.

  The first electrode film 56, the intermediate layer 57, and the second electrode film 58 included in the R photoelectric conversion unit have the same configuration as the first electrode film 11, the intermediate layer 12, and the second electrode film 13 illustrated in FIG. . However, the photoelectric conversion layer included in the intermediate layer 57 uses a material that absorbs red light and generates electrons and holes corresponding thereto.

  The respective electron and hole blocking layers included in the intermediate layers 61 and 57 have signal charges in the relationship between the HOMO and LUMO energy levels of the respective photoelectric conversion films and the HOMO and LUMO levels of the respective blocking layers in contact therewith. It is preferable to select an appropriate material and configuration so that an energy barrier does not occur during the transportation of the material.

  P + regions 43, 45, and 47 are formed in portions of the silicon substrate 41 that are shielded by the light-shielding film 68, and each region is surrounded by n regions 42, 44, and 46.

  The p + region 43 is electrically connected to the first electrode film 56 via a connection portion 54 formed in an opening opened in the insulating film 48, and is connected to the first electrode film 56 via the connection portion 54. Accumulate the collected holes. The connecting portion 54 is electrically insulated by the insulating film 51 except for the first electrode film 56 and the p + region 43.

  The p + region 45 is electrically connected to the first electrode film 60 through a connection portion 53 formed in an opening formed in the insulating film 48, the R photoelectric conversion portion, and the insulating film 59. Then, holes collected by the first electrode film 60 are accumulated. The connection portion 53 is electrically insulated by the insulating film 50 except for the first electrode film 60 and the p + region 45.

  The p + region 47 is electrically connected to the first electrode film 64 through the insulating film 48, the R photoelectric conversion portion, the insulating film 59, the B photoelectric conversion portion, and the connection portion 52 formed in the opening opened in the insulating film 63. And the holes collected by the first electrode film 64 are accumulated through the connection portion 52. The connecting portion 52 is electrically insulated by the insulating film 49 except for the first electrode film 64 and the p + region 47.

  The holes accumulated in the p + region 43 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n region 42 and accumulated in the p + region 45. The holes are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed in the n region 44, and the holes accumulated in the p + region 47 are converted into the n region 46. The signal is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of a p-channel MOS transistor formed therein, and output to the outside of the solid-state imaging device 3000. These MOS circuits constitute the signal readout section in the claims. Each MOS circuit is connected to a signal readout pad (not shown) by wiring 55. The signal reading unit may be constituted by a CCD and an amplifier instead of the MOS circuit. That is, the holes accumulated in the p + regions 43, 45, and 47 are read out to the CCD formed in the silicon substrate 41, transferred to the amplifier by the CCD, and a signal corresponding to the holes is output from the amplifier. A simple signal reading unit may be used.

  Note that light transmitted through the intermediate layers 57, 61, and 65 is received between the silicon substrate 41 and the first electrode film 56 (for example, between the insulating film 48 and the silicon substrate 41), and in response to the light. It is also possible to form an inorganic photoelectric conversion portion made of an inorganic material that generates and accumulates the charges. In this case, a MOS circuit for reading a signal corresponding to the charge accumulated in the charge accumulation region of the inorganic photoelectric conversion unit is provided in the silicon substrate 41, and the wiring 55 may be connected to this MOS circuit. .

  As described above, the configuration in which a plurality of photoelectric conversion layers described above in the first embodiment and the second embodiment are stacked on the silicon substrate can be realized by the configuration as shown in FIG.

  In the above description, the photoelectric conversion layer that absorbs B light can absorb light of at least 400 to 500 nm, and preferably has a peak wavelength absorptance of 50% or more in that wavelength region. Means. The photoelectric conversion layer that absorbs G light means that it can absorb light of at least 500 to 600 nm, and preferably has a peak wavelength absorptance of 50% or more in that wavelength region. The photoelectric conversion layer that absorbs R light means that it can absorb light of at least 600 to 700 nm, and preferably has an absorption factor of a peak wavelength in the wavelength region of 50% or more.

  In the case of the configuration of the first embodiment or the third embodiment, a pattern for detecting colors in the order of BGR, BRG, GBR, GRB, RBG, RGB from the upper layer is conceivable. Preferably, the uppermost layer is G. In the case of the configuration as in the second embodiment, when the upper layer is the R layer, the lower layer is the same BG layer, and when the upper layer is the B layer, the lower layer is the same plane and the upper layer is the G layer. In the case of layers, a combination in which the lower layer is the same plane and the BR layer is possible. Preferably, the upper layer is a G layer and the lower layer is a BR layer on the same plane.

(Fourth embodiment)
FIG. 8 is a schematic cross-sectional view of a solid-state imaging device for explaining a fourth embodiment of the present invention. In FIG. 8, a cross section for two pixels in a pixel portion, which is a portion that accumulates charges by detecting light, a wiring connected to an electrode in the pixel portion, a bonding PAD connected to the wiring, and the like are formed. The cross section with the peripheral circuit part which is a part to be performed is also shown.

  In the n-type silicon substrate 413 of the pixel portion, a p region 421 is formed on the surface portion, an n region 422 is formed on the surface portion of the p region 421, and a p region 423 is formed on the surface portion of the n region 422. N region 424 is formed on the surface of p region 423.

  The p region 421 accumulates red (R) component holes photoelectrically converted by a pn junction with the n-type silicon substrate 413. The potential change in the p region 421 due to the accumulation of R component holes is read out from the MOS transistor 426 formed in the n-type silicon substrate 413 to the signal readout PAD 427 through the metal wiring 419 connected thereto. .

  The p region 423 accumulates blue (B) component holes photoelectrically converted by the pn junction with the n region 422. The potential change in the p region 423 due to the accumulation of the B component holes is read out from the MOS transistor 426 ′ formed in the n region 422 to the signal readout PAD 427 through the metal wiring 419 connected thereto.

  In the n region 424, a hole accumulation region 425 composed of a p region for accumulating green (G) component holes generated in the photoelectric conversion layer 123 stacked above the n-type silicon substrate 413 is formed. The potential change in the hole accumulation region 425 due to the accumulation of the G component holes is caused by the signal reading PAD 427 from the MOS transistor 426 ″ formed in the n region 424 through the metal wiring 419 connected thereto. Is read out. Usually, the signal readout PAD 427 is provided separately for each transistor from which each color component is read out.

  Here, the p region, the n region, the transistor, the metal wiring, and the like are schematically shown. However, the structure of each is not limited to this, and an optimal one is appropriately selected. Since the B light and R light are separated according to the depth of the silicon substrate, it is important to select the depth from the surface of the silicon substrate such as a pn junction and the doping concentration of each impurity. A technique used in a normal CMOS image sensor can be applied to a CMOS circuit serving as a signal readout unit. A circuit configuration that reduces the number of transistors in the pixel portion, such as a low noise readout column amplifier or a CDS circuit, can be applied.

  A transparent insulating film 412 mainly composed of silicon oxide, silicon nitride, or the like is formed on the n-type silicon substrate 413, and a transparent insulating film mainly composed of silicon oxide, silicon nitride, or the like is formed on the insulating film 412. 411 is formed. The thickness of the insulating film 412 is preferably as small as possible, and is 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less, and further preferably 1 μm or less.

  In the insulating films 411 and 412, a plug 415 mainly composed of, for example, tungsten is formed to electrically connect the first electrode film 414 and the p region 425 as the hole accumulation region. The plug 415 is insulated. The film 411 and the insulating film 412 are relay-connected by a pad 416. The pad 416 is preferably made mainly of aluminum. In the insulating film 412, the above-described metal wiring 419, gate electrodes of the transistors 426, 426 ', 426 "and the like are also formed. It is preferable that a barrier layer including a metal wiring is provided. The plug 415 is provided for each pixel.

  A light shielding film 417 is provided in the insulating film 411 in order to prevent noise caused by the generation of electric charges due to the pn junction of the n region 424 and the p region 425. As the light shielding film 417, a film mainly composed of tungsten, aluminum, or the like is usually used. In the insulating film 411, a bonding PAD 420 (PAD for supplying power from the outside) and a signal readout PAD 427 are formed, and a metal wiring for electrically connecting the bonding PAD 420 and a first electrode film 414 described later. (Not shown) is also formed.

  A transparent first electrode film 414 is formed on the plug 415 of each pixel in the insulating film 411. The first electrode film 414 is divided for each pixel, and the light receiving area is determined by this size. The first electrode film 414 is biased through the wiring from the bonding PAD 420. A structure in which holes can be accumulated in the hole accumulation region 425 by applying a negative bias to the first electrode film 414 with respect to a second electrode film 405 described later is preferable.

  The intermediate layer 12 having the same structure as that shown in FIG. 4 is formed on the first electrode film 414, and the second electrode film 405 is formed thereon.

  On the second electrode film 405, a protective film 404 mainly composed of silicon nitride having a function of protecting the intermediate layer 12 is formed. An opening is formed in the protective film 404 at a position that does not overlap with the first electrode film 414 in the pixel portion, and an opening is formed in a part of the bonding PAD 420 in the insulating film 411 and the protective film 404. A wiring 418 made of aluminum or the like for electrically connecting the second electrode film 405 exposed by the two openings and the bonding PAD 420 to apply a potential to the second electrode film 405 is formed inside the opening and the protective film. 404 is formed. As a material of the wiring 418, an alloy containing aluminum such as Al—Si or Al—Cu alloy can be used.

  A protective film 403 mainly composed of silicon nitride or the like for protecting the wiring 418 is formed on the wiring 418. An infrared cut dielectric multilayer film 402 is formed on the protective film 403, and an infrared cut dielectric is formed. An antireflection film 401 is formed on the body multilayer film 402.

  The first electrode film 414 performs the same function as the first electrode film 11 shown in FIG. The second electrode film 405 performs the same function as the second electrode film 13 shown in FIG.

  With the above configuration, it is possible to perform color imaging by detecting light of BGR three colors with one pixel. In the configuration of FIG. 8, R and B are used as common values in two pixels, and only the G value is used separately. However, since the sensitivity of G is important when generating an image, such a configuration is used. Even so, it is possible to generate a good color image.

  The solid-state imaging device described above can be applied to imaging devices such as digital cameras, video cameras, facsimile machines, scanners, and copying machines. It can also be used as an optical sensor such as a bio or chemical sensor.

In addition, the materials mentioned as the insulating film described in the above embodiment are SiOx, SiNx, BSG, PSG, BPSG, Al ₂ O ₃ , MgO, GeO, NiO, CaO, BaO, Fe ₂ O ₃ , Y ₂ O. ₃ , metal oxides such as TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ , and CaF _{2. The} most preferred materials are SiOx, SiNx, BSG, PSG, and BPSG.

  In the first to fourth embodiments, reading of signals from other than the photoelectric conversion layer may use either holes or electrons. That is, as described above, holes are accumulated in the inorganic photoelectric conversion unit provided between the semiconductor substrate and the photoelectric conversion unit stacked on the semiconductor substrate, or in the photodiode formed in the semiconductor substrate. It is good also as a structure which reads the signal according to a hole with a signal read-out part, accumulate | stores an electron with an inorganic photoelectric conversion part or the photodiode formed in a semiconductor substrate, and the signal according to this electron is read with a signal read-out part. It is good also as a structure to read.

  In the first to fourth embodiments, the photoelectric conversion unit provided above the silicon substrate has the configuration shown in FIG. 5, but the photoelectric conversion unit having the configuration shown in FIG. 1 can also be used. is there. According to the configuration shown in FIG. 5, since electrons and holes can be blocked, the dark current suppressing effect is high. When the electrode opposite to the light incident side is an electron extraction electrode, the connecting portion 9 is connected to the second electrode 13 in FIG. 4, and the connecting portion 27 is connected to the second electrode in FIG. 13, in FIG. 7, the connection portion 54 may be connected to the second electrode 58, the connection portion 53 may be connected to the second electrode 62, and the connection portion 52 may be connected to the second electrode 66.

The solid-state imaging device described in the present embodiment has a configuration in which a large number of one pixel shown in FIGS. 4 to 8 is arranged in an array on the same plane, and RGB color signals can be obtained by the one pixel. Therefore, this one pixel can be considered as a photoelectric conversion element that converts RGB light into an electrical signal. For this reason, it can be said that the solid-state imaging device described in the present embodiment has a configuration in which a large number of photoelectric conversion elements as illustrated in FIGS. 4 to 8 are arranged in an array on the same plane.

(Fifth embodiment)
A fifth embodiment in which a solid-state imaging device is realized using the photoelectric conversion device having the configuration shown in FIGS.
FIG. 9 is a partial surface schematic diagram of an image sensor for explaining an embodiment of the present invention. 10 is a schematic cross-sectional view taken along line XX of the image sensor shown in FIG. In FIG. 9, the microlens 14 is not shown.

  A p-well layer 2 is formed on the n-type silicon substrate 1. Hereinafter, the n-type silicon substrate 1 and the p-well layer 2 are collectively referred to as a semiconductor substrate. A color filter 13r that mainly transmits R light, a color filter 13g that mainly transmits G light, and a color filter that mainly transmits B light in a row direction on the same plane above the semiconductor substrate and in a column direction perpendicular thereto. A number of three types of color filters 13b are arranged.

  A known material can be used for the color filter 13r, but such a material transmits R light. A known material can be used for the color filter 13g, but such a material transmits G light. A known material can be used for the color filter 13b, but such a material transmits B light.

  As the arrangement of the color filters 13r, 13g, 13b, a color filter arrangement (Bayer arrangement, vertical stripe, horizontal stripe, etc.) used in a known single-plate solid-state imaging device can be adopted.

  A transparent electrode 11r is formed above the n region 4r, a transparent electrode 11g is formed above the n region 4g, and a transparent electrode 11b is formed above the n region 4b. The transparent electrodes 11r, 11g, and 11b are divided corresponding to the color filters 13r, 13g, and 13b, respectively. The transparent electrodes 11r, 11g, and 11b have the same functions as the lower electrode 11 in FIG.

  On each of the transparent electrodes 11r, 11g, and 11b, a photoelectric conversion film 12 having a single configuration common to each of the color filters 13r, 13g, and 13b is formed.

  On the photoelectric conversion film 12, an upper electrode 13 having a single configuration common to each of the color filters 13r, 13g, and 13b is formed.

  A photoelectric conversion element corresponding to the color filter 13r is formed by the transparent electrode 11r, the upper electrode 13 facing the transparent electrode 11r, and a part of the photoelectric conversion film 12 sandwiched therebetween. Hereinafter, since this photoelectric conversion element is formed on a semiconductor substrate, it is referred to as an R photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 13g is formed by the transparent electrode 11g, the upper electrode 13 facing the transparent electrode 11g, and a part of the photoelectric conversion film 12 sandwiched therebetween. Hereinafter, this photoelectric conversion element is referred to as a G photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 13b is formed by the transparent electrode 11b, the upper electrode 13 facing the transparent electrode 11b, and a part of the photoelectric conversion film 12 sandwiched therebetween. Hereinafter, this photoelectric conversion element is referred to as a B photoelectric conversion element.

A high concentration n-type impurity region (hereinafter referred to as n + region) 4r for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the R substrate is formed in the n region in the p-well layer 2. Yes. In order to prevent light from entering the n + region 4r, it is preferable to provide a light shielding film on the n + region 4r.

  In the n region in the p-well layer 2, an n + region 4g for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the G substrate is formed. In order to prevent light from entering the n + region 4g, it is preferable to provide a light shielding film on the n + region 4g.

  In the n region in the p-well layer 2, an n + region 4b for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the B substrate is formed. In order to prevent light from entering the n + region 4b, it is preferable to provide a light shielding film on the n + region 4b.

  A contact portion 6r made of a metal such as aluminum is formed on the n + region 4r, and a transparent electrode 11r is formed on the contact portion 6r. The n + region 4r and the transparent electrode 11r are electrically connected by the contact portion 6r. ing. The contact portion 6r is embedded in the insulating layer 5 that is transparent to visible light and infrared light.

  A contact portion 6g made of a metal such as aluminum is formed on the n + region 4g, and a transparent electrode 11g is formed on the contact portion 6g. The n + region 4g and the transparent electrode 11g are electrically connected by the contact portion 6g. ing. The contact portion 6g is embedded in the insulating layer 5.

  A contact portion 6b made of a metal such as aluminum is formed on the n + region 4b, and a transparent electrode 11b is formed on the contact portion 6b. The n + region 4b and the transparent electrode 11b are electrically connected by the contact portion 6b. ing. The contact portion 6 b is embedded in the insulating layer 5.

  Signals for reading out signals corresponding to the electric charges generated in the R photoelectric conversion elements and accumulated in the n + regions 4r in the regions other than the n + regions 4r, 4g, 4b formed in the p-well layer 2 A readout unit 5r, a signal readout unit 5g for reading out signals corresponding to the charges generated in the G photoelectric conversion element and accumulated in the n + region 4g, and a signal readout unit 5g generated in the B photoelectric conversion element and accumulated in the n + region 4b. And a signal reading unit 5b for reading out signals corresponding to the charges. Each of the signal reading units 5r, 5g, and 5b can adopt a known configuration using a CCD or a MOS circuit. In order to prevent light from entering the signal readout units 5r, 5g, 5b, it is preferable to provide a light shielding film on the signal readout units 5r, 5g, 5b.

  FIG. 11 is a diagram illustrating a specific configuration example of the signal reading unit 5r illustrated in FIG. In FIG. 11, the same components as those in FIGS. Note that the signal readout units 5r, 5g, and 5b have the same configuration, and thus the description of the signal readout units 5g and 5b is omitted.

  The signal readout unit 5r includes a reset transistor 543 having a drain connected to the n + region 4r, a source connected to the power supply Vn, and a output transistor 542 having a gate connected to the drain of the reset transistor 543 and a source connected to the power supply Vcc. A row selection transistor 541 whose source is connected to the drain of the output transistor 542 and whose drain is connected to the signal output line 545; a reset transistor 546 whose drain is connected to the n region 3r and whose source is connected to the power supply Vn; The output transistor 547 whose gate is connected to the drain of the reset transistor 546, the source is connected to the power supply Vcc, and the row selection transistor 548 whose source is connected to the drain of the output transistor 547 and whose drain is connected to the signal output line 549. And be prepared That.

  By applying a bias voltage between the transparent electrode 11r and the upper electrode 13, a charge is generated according to the light incident on the photoelectric conversion film 12, and the charge moves to the n + region 4r through the transparent electrode 11r. The charge accumulated in the n + region 4r is converted into a signal corresponding to the amount of charge by the output transistor 542. Then, a signal is output to the signal output line 545 by turning on the row selection transistor 541. After the signal is output, the reset transistor 543 resets the charges in the n + region 4r.

  Thus, the signal reading unit 5r can be configured by a known MOS circuit including three transistors.

  Returning to FIG. 10, protective layers 15 and 16 having a two-layer structure for protecting the photoelectric conversion element on the substrate are formed on the photoelectric conversion film 12, and color filters 13 r, 13 g and 13 b are formed on the protective layer 16. Has been.

  The image sensor 100 is manufactured by forming the color filters 13r, 13g, 13b and the like after the photoelectric conversion film 12 is formed. However, the color filters 13r, 13g, 13b include a photolithography process and a baking process. When an organic material is used as the photoelectric conversion film 12, if the photolithography process or the baking process is performed with the photoelectric conversion film 12 exposed, the characteristics of the photoelectric conversion film 12 are deteriorated. In the imaging device 100, protective layers 15 and 16 are provided in order to prevent the deterioration of the characteristics of the photoelectric conversion film 12 due to such a manufacturing process.

The protective layer 15 is preferably an inorganic layer made of an inorganic material formed by the ALCVD method. The ALCVD method is an atomic layer CVD method, can form a dense inorganic layer, and can be an effective protective layer for the photoelectric conversion layer 9. The ALCVD method is also known as the ALE method or ALD method. The inorganic layer formed by the ALCVD method is preferably made of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , MgO, HfO ₂ , Ta ₂ O ₅ , more preferably made of Al ₂ O ₃ , SiO ₂ , Most preferably, it consists of Al ₂ O ₃ .

  The protective layer 16 is formed on the protective layer 15 in order to further improve the protective performance of the photoelectric conversion film 12, and is preferably an organic layer made of an organic polymer. Parylene is preferable as the organic polymer, and parylene C is more preferable. The protective layer 16 may be omitted, and the arrangement of the protective layer 15 and the protective layer 16 may be reversed. The protection effect of the photoelectric conversion film 12 is particularly high in the configuration shown in FIG.

  When a predetermined bias voltage is applied to the transparent electrode 11r and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the R substrate move to the n + region 4r via the transparent electrode 11r and the contact portion 6r. , Accumulated here. Then, a signal corresponding to the electric charge accumulated in the n + region 4r is read by the signal reading unit 5r and output to the outside of the image sensor 100.

  Similarly, when a predetermined bias voltage is applied to the transparent electrode 11g and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the G substrate are transferred to the n + region 4g via the transparent electrode 11g and the contact portion 6g. Go to and accumulate here. Then, a signal corresponding to the electric charge accumulated in the n + region 4g is read out by the signal reading unit 5g and output to the outside of the image sensor 100.

Similarly, when a predetermined bias voltage is applied to the transparent electrode 11b and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the B substrate are transferred to the n + region 4b via the transparent electrode 11b and the contact portion 6b. Go to and accumulate here. Then, a signal corresponding to the electric charge accumulated in the n + region 4b is read by the signal reading unit 5b and output to the outside of the image sensor 100.

As described above, the image sensor 100 generates the R component signal corresponding to the charge generated in the R photoelectric conversion element, the G component signal corresponding to the charge generated in the G photoelectric conversion element, and the B photoelectric conversion element. A B component signal corresponding to the electric charge can be output to the outside. Thereby, a color image can be obtained. With this format, the photoelectric conversion unit becomes thin, so that the resolution is improved and the false color can be reduced. Moreover, since the aperture ratio can be increased regardless of the lower circuit, high sensitivity is possible, and the microlens can be omitted, which is effective in omitting the number of components.
In the present embodiment, the organic photoelectric conversion film has a maximum absorption wavelength in the green light high region and needs to have an absorption region in the entire visible light. However, the organic photoelectric conversion film can be preferably realized by the specified material of the present invention.
As mentioned above, although embodiment of using the photoelectric conversion element of this invention as an image pick-up element was described, since the photoelectric conversion element of this invention shows high photoelectric conversion efficiency, even if it uses it as a solar cell, it shows high performance.
A preferable element configuration for use as a solar cell is the combination of the photoelectric conversion material described in the present invention with the configuration described in the non-patent document (Adv. Mater., 17, 66 (2005)), etc. Can be applied.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is of course not limited to these examples.

[Example 1]
The amorphous ITO (glass) substrate was put into a vapor deposition apparatus (device name: ELORA-500, manufactured by ULVAC Kiko Co., Ltd.), and the pressure was reduced to 1.0 × 10 ⁻⁴ Pa or less. On the substrate, the following organic compound (1) was deposited to a thickness of 20 nm as a charge blocking layer.
Then, the following organic compound (2) and a crystalline fullerene material as a crystalline organic material were placed on the heater at a ratio of 100 nm and 300 nm in terms of a single layer, respectively, and the heater was heated. As the crystalline fullerene material, a material containing 95% by mass or more of crystal particles having a purity of 99% or more and a minimum diameter of 0.3 mm or more was used.
After reaching a stable vapor deposition rate of 1.0 Å / s, the organic compound (2) and the crystalline fullerene material were continuously sublimated for 40 minutes. After sublimation for 40 minutes, the formation of a co-deposited film was started by vacuum heating deposition to form a photoelectric conversion layer. In addition, the substrate temperature at the time of vapor deposition was 25 degreeC. The thickness of the photoelectric conversion layer was 400 nm.
Further, while maintaining a vacuum, amorphous ITO was deposited to a thickness of 10 nm by high-frequency magnetron sputtering to produce a photoelectric conversion element. Glass sealing was performed using a UV curable resin without exposing the device to the atmosphere.

[Example 2]
A device was produced in the same manner as in Example 1 except that the organic compound (2) in the photoelectric conversion layer was changed to the following organic compound (3).

[Example 3]
In Example 2, a device was produced in the same manner except that the sublimation time after the stable vapor deposition rate was obtained during the photoelectric conversion layer formation was 80 minutes.

[Comparative Example 1]
In Example 1, an element was produced in the same manner except that the co-deposition film was formed immediately after the stable vapor deposition rate was obtained when the photoelectric conversion layer was formed.

[Comparative Example 2]
A device was fabricated in the same manner as in Comparative Example 1, except that the organic compound (2) in the photoelectric conversion layer was changed to the organic compound (3).

[Comparative Example 3]
A device was fabricated in the same manner as in Comparative Example 1 except that the crystalline fullerene material in the photoelectric conversion layer was changed to a powdery fullerene material (manufactured by Frontier Carbon Co., Ltd., nanom purple SUH). This powdery fullerene material had an average particle diameter in the range of several μm to several tens of μm.

[Comparative Example 4]
In Comparative Example 3, a device was fabricated in the same manner except that after the stable vapor deposition rate was obtained when the photoelectric conversion layer was formed, sublimation was continued for 40 minutes as it was, and then the co-deposition film was formed.

The time for subliming all fullerenes (C ₆₀ ) used in the above Examples and Comparative Examples at the above stable deposition rate (1.0 Å / s) was 200 minutes. Therefore, in this example, since the film formation is started after 40 minutes or 80 minutes, 1/5 or more of the fullerene total volume is sublimated.

[Evaluation]
Relative response speed with external quantum efficiency (relative value) at the maximum sensitivity wavelength at ²⁰⁰ pA / cm ² dark current and in-film electric field strength of 3.0E + 5 (V / cm) applied. The rise time (relative value) from 0 to 100% signal intensity) was measured. The results are shown in the table below. Note that, when measuring the photoelectric conversion performance of each element, an appropriate voltage was applied.
The relative value in the external quantum efficiency is a relative value when Comparative Example 1 is set to 100, and the rise time is a relative value when Example 2 is set to 100.

As shown in Examples 1 to 3, by using an organic material having high crystallinity and continuing sublimation for a certain period of time without performing film formation after stable vapor deposition, the external quantum efficiency is high, and the signal intensity is 0 to 100%. It can be seen that a photoelectric conversion element with a short rise time is obtained.
On the other hand, as in Comparative Examples 1 and 4, if either one of using an organic material with high crystallinity or continuing sublimation for a certain time without performing film formation after stable vapor deposition is lacking, the effect of the present invention is obtained. It turns out that it cannot be obtained.

11 Lower electrode 12 Photoelectric conversion layer 15 Upper electrode 16A, 16B Charge blocking layer

Claims (4)

A method for producing a photoelectric conversion element comprising a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes,
As at least one kind of raw material for forming the photoelectric conversion layer, an organic material containing crystal particles of fullerene or fullerene derivative having a minimum diameter of 0.3 mm or more is used,
Heating the organic material until a stable deposition rate of the organic material is reached;
Sublimating at least 1/5 of the total volume of the crystal particles without forming the photoelectric conversion layer after reaching the stable vapor deposition rate;
After sublimating at least 1/5 of the total volume of the crystal particles, and then forming the photoelectric conversion layer by a vacuum deposition method;
The manufacturing method of the photoelectric conversion element containing this.   The crystal particles include at least one of single crystal particles and polycrystalline particles composed of a plurality of crystal domains, and the minimum diameter of the single crystal particles is 0.3 mm or more, or the crystal domain size of the polycrystalline particles is 0. The manufacturing method of the photoelectric conversion element of Claim 1 which is more than 3 mm square.   The method for producing a photoelectric conversion element according to claim 1, wherein the stable vapor deposition rate is 0.1 Å / s or more. The manufacturing method of the organic photoelectric conversion element of any one of Claims 1-3 in which the said organic photoelectric conversion element contains a charge blocking layer .

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