JP2007080936A - Photoelectric conversion element and solid state imaging element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element capable of preventing sensitivity deterioration and broadening of spectral sensitivity. <P>SOLUTION: The photoelectric conversion element has a photoelectric converter composed of a first electrode film 11, a second electrode film 13 facing the first electrode film 11, and a photoelectric conversion layer 12 including a photoelectric conversion film disposed between the first electrode film 11 and the second electrode film 13. Light is incident on the photoelectric conversion film from above the second electrode film 13, the photoelectric conversion film produces electrons and holes in response to the incident light from above the second electrode film 13, mobility of the hole is smaller than that of the electron, and the vicinity of the second electrode film 13 produces more electrons and holes than the vicinity of the first electrode film 11 to permit the second electrode film 13 to be used as an electrode to take out electrons. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a photoelectric conversion unit including a first electrode film, a second electrode film facing the first electrode film, and a photoelectric conversion film disposed between the first electrode film and the second electrode film And a solid-state image sensor in which a large number of photoelectric conversion elements are arranged in an array.

  A conventional optical sensor is generally an element formed by forming a photodiode (PD) in a semiconductor substrate such as silicon (Si). As a solid-state image sensor, a PD is two-dimensionally formed in a semiconductor substrate. 2. Description of the Related Art Flat-type solid-state imaging devices that are arranged and read out a signal corresponding to a signal charge generated by photoelectric conversion in each PD by a CCD or CMOS circuit are widely used. As a method for realizing a color solid-state imaging device, a structure in which a color filter that transmits only light of a specific wavelength for color separation is generally arranged on the light incident surface side of the flat-type solid-state imaging device. As a method widely used in digital cameras and the like at present, color filters that respectively transmit blue (B) light, green (G) light, and red (R) light are regularly arranged on the two-dimensionally arranged PDs. A single-plate type solid-state imaging device arranged in is well known.

  However, in the single-plate solid-state imaging device, the color filter transmits only light of a limited wavelength, so that the light that does not pass through the color filter is not used and the light use efficiency is poor. In addition, with the high integration of pixels, the size of the PD becomes about the same as the wavelength of light, and light is less likely to be guided to the PD. In addition, since blue light, green light, and red light are color-reproduced by detecting them with separate PDs that are close to each other, false colors may be generated. In order to avoid this false color An optical low-pass filter is required, and optical loss due to this filter also occurs.

  Conventionally, as a device for solving these drawbacks, three PDs are stacked in a silicon substrate by utilizing the wavelength dependence of the absorption coefficient of silicon, and color separation is performed by the difference in the depth of the pn junction surface of each PD. A color sensor that performs the above has been reported (see Patent Documents 1, 2, and 3). However, this method has a problem that the wavelength dependence of spectral sensitivity in the stacked PD is broad and color separation is insufficient. In particular, blue and green color separation is insufficient.

  In order to solve this problem, a photoelectric conversion unit that detects green light and generates a signal charge corresponding to the detected green light is provided above the silicon substrate, and blue light and red light are emitted by two PDs stacked in the silicon substrate. A sensor for detection has been proposed (see Patent Document 4). The photoelectric conversion part provided above the silicon substrate is laminated on the first electrode film laminated on the silicon substrate, the photoelectric conversion film made of an organic material laminated on the first electrode film, and the photoelectric conversion film. The signal charge generated in the photoelectric conversion film is applied to the first electrode film and the second electrode film by applying a voltage to the first electrode film and the second electrode film. A signal corresponding to the signal charge that has moved and moved to one of the electrode films is read out by a CCD or CMOS circuit provided in the silicon substrate. In this specification, the photoelectric conversion film refers to a film that absorbs light having a specific wavelength incident thereon and generates electrons and holes according to the absorbed light quantity.

US Pat. No. 5,965,875 US Pat. No. 6,632,701 Japanese Patent Laid-Open No. 7-38136 JP 2003-332551 A

  In the photoelectric conversion film made of an organic material, if light enters from above the second electrode film 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 film. In general, it does not occur so much in the vicinity of one electrode film. This is because most of the light in the vicinity of the absorption peak wavelength of this photoelectric conversion film is absorbed in the vicinity of the second electrode film, and the light absorption rate decreases as the distance from the vicinity of the second electrode film increases. is doing. For this reason, unless the electrons or holes generated in the vicinity of the second electrode film are efficiently transferred to the silicon substrate, the photoelectric conversion efficiency is lowered, resulting in a decrease in sensitivity of the element. In addition, since the signal due to the light wavelength strongly absorbed in the vicinity of the second electrode film decreases, as a result, the so-called broadening of the spectral sensitivity is caused.

  Further, in a photoelectric conversion film made of an organic material, the mobility of electrons is generally much smaller than the mobility of holes. Furthermore, it has been found that the mobility of electrons in a photoelectric conversion film made of an organic material is easily affected by oxygen, and that the mobility of electrons further decreases when the photoelectric conversion film is exposed to the atmosphere. For this reason, when moving electrons to the silicon substrate, if the moving distance of electrons generated in the vicinity of the second electrode film in the photoelectric conversion film 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 the above-described sensitivity degradation and spectral sensitivity broadening, it is conceivable to make the photoelectric conversion film thin or use a material with high electron mobility, but it is necessary to obtain a sufficient amount of light absorption. There is a limit to reducing the film thickness of the photoelectric conversion film, and there is a demerit that the material is greatly restricted if the mobility requirement is satisfied. In order to assist the slow mobility of electrons, it is possible to apply an electric field to the photoelectric conversion film. However, when a sufficiently strong electric field is applied, the injectable leakage current from the two electrodes sandwiching the electric field increases. The S / N of the sensor may be reduced. For this reason, a technique for preventing a decrease in sensitivity and broadening of spectral sensitivity without adopting these methods is desired.

  In order to prevent a decrease in sensitivity and broadening of spectral sensitivity, it is effective to efficiently move electrons or holes generated in the vicinity of the second electrode film to the silicon substrate. To realize this, photoelectric conversion The problem is how to handle electrons or holes generated in the film.

  This invention is made | formed in view of the said situation, and it aims at providing the photoelectric conversion element which can prevent a sensitivity fall and the broadening of spectral sensitivity.

  The photoelectric conversion element of the present invention includes a first electrode film, a second electrode film facing the first electrode film, and a photoelectric conversion film disposed between the first electrode film and the second electrode film. A photoelectric conversion element having a photoelectric conversion unit, wherein light is incident on the photoelectric conversion film from above the second electrode film, and the photoelectric conversion film is incident light from above the second electrode film. Therefore, the second electrode film is used as an electrode for taking out the electrons.

  In the photoelectric conversion element of the present invention, the photoelectric conversion film generates more electrons and holes in the vicinity of the second electrode film than in the vicinity of the first electrode film.

  In the photoelectric conversion element of the present invention, the photoelectric conversion film includes an organic material.

  In the photoelectric conversion element of the present invention, the organic material includes at least one of an organic p-type semiconductor and an organic n-type semiconductor.

  In the photoelectric conversion element of the present invention, the organic p-type semiconductor and the organic n-type semiconductor are any of quinacridone derivatives, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives, respectively. Including.

In the photoelectric conversion element of the present invention, the first electrode film is made of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, or Au.

In the photoelectric conversion element of the present invention, the second electrode film is made of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, or Au.

In the photoelectric conversion element of the present invention, the second electrode film is composed of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , or FTO, and the photoelectric conversion unit includes the photoelectric conversion film and the second electrode film. And a film made of a metal having a work function of 4.5 eV or less.

  In the photoelectric conversion element of the present invention, the transmittance of the second electrode film with respect to visible light is 60% or more.

  In the photoelectric conversion element of the present invention, the transmittance of the first electrode film with respect to visible light is 60% or more.

  In the photoelectric conversion element of the present invention, a voltage is applied to the first electrode film and the second electrode film so that the electrons move to the second electrode film and the holes move to the first electrode film. A semiconductor substrate provided below the first electrode film, an electron storage part formed in the semiconductor substrate for storing the electrons moved to the second electrode film, and A connection portion for electrically connecting the electron storage portion and the second electrode film;

  In the photoelectric conversion element of the present invention, the photoelectric conversion unit has a film made of an organic polymer material between the first electrode film and the photoelectric conversion film.

  The photoelectric conversion element of the present invention absorbs light transmitted through the photoelectric conversion film in the semiconductor substrate below the photoelectric conversion film, generates charges according to the light, and accumulates the charges. A part.

  In the photoelectric conversion element of the present invention, the in-substrate photoelectric conversion unit is a plurality of photodiodes that are stacked in the semiconductor substrate and absorb light of different colors.

  In the photoelectric conversion element of the present invention, the in-substrate photoelectric conversion unit is a plurality of photodiodes that absorb light of different colors arranged in a direction perpendicular to the incident direction of the incident light in the semiconductor substrate. is there.

  In the photoelectric conversion element of the present invention, the plurality of photodiodes have a blue photodiode in which a pn junction surface is formed at a position where blue light can be absorbed, and a pn junction surface at a position where red light can be absorbed. The red photodiode is formed, and the photoelectric conversion film absorbs green light.

  In the photoelectric conversion element of the present invention, the plurality of photodiodes are a blue photodiode that absorbs blue light and a red photodiode that absorbs red light, and the photoelectric conversion film absorbs green light. To do.

  In the photoelectric conversion element of the present invention, a plurality of the photoelectric conversion units are stacked above the semiconductor substrate, and the electron storage unit and the connection unit are provided for each of the plurality of photoelectric conversion units.

  The photoelectric conversion element of the present invention absorbs light transmitted through the first electrode film between the semiconductor substrate and the first electrode film in the immediate vicinity of the semiconductor substrate, and charges according to the light. An inorganic photoelectric conversion unit made of an inorganic material that is generated and accumulated is provided.

  The solid-state imaging device of the present invention is a solid-state imaging device in which a large number of the photoelectric conversion elements are arranged in an array, and a signal corresponding to the charge accumulated in the semiconductor substrate of each of the multiple photoelectric conversion elements. A signal reading unit for reading is provided.

  The solid-state imaging device of the present invention is a solid-state imaging device in which a large number of the photoelectric conversion elements are arranged in an array, and a signal corresponding to the charge accumulated in the semiconductor substrate of each of the multiple photoelectric conversion elements, and And a signal readout unit that reads out a signal corresponding to the charge accumulated in the inorganic photoelectric conversion unit.

  In the solid-state imaging device of the present invention, the photoelectric conversion film and the first electrode film included in the photoelectric conversion element are shared by the plurality of photoelectric conversion elements, and the photoelectric conversion element includes the first Two electrode films are separated for each of the large number of photoelectric conversion elements.

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element which can prevent a sensitivity fall and broadening of spectral sensitivity can be provided.

  The present applicant provides a photoelectric conversion including a first electrode film, a second electrode film facing the first electrode film, and a photoelectric conversion film disposed between the first electrode film and the second electrode film. In the photoelectric conversion element having a portion, when light is incident from above the second electrode film, electrons generated in the photoelectric conversion film are moved to the second electrode film, and electrons moved to the second electrode film are The signal is stored in the charge storage unit formed in the semiconductor substrate, and the signal corresponding to the electrons stored in the charge storage unit is read out to the outside by a signal reading unit such as a CCD or CMOS circuit formed in the semiconductor substrate. As a result, the present inventors have found that the photoelectric conversion efficiency is improved, and the sensitivity reduction and broadening of the spectral sensitivity can be prevented. In the following, first, how important it is to adopt such a signal readout method will be described.

FIG. 1 is a diagram illustrating a configuration example of a photoelectric conversion unit including a pair of electrode films and a photoelectric conversion film sandwiched therebetween.
The photoelectric conversion unit shown in FIG. 1 is a transparent first electrode film ITO, In for adjusting the work function of ITO, quinacridone as a photoelectric conversion film made of an organic material, and a second electrode film Aluminum (Al) is laminated in this order. The thickness of In was 5 nm, and the transmittance for visible light (light having a wavelength of 400 to 700 nm) was about 95%. The thickness of quinacridone was 200 nm. The thickness of Al was 100 nm. Quinacridone was deposited on In by vacuum deposition, and Al was deposited on quinacridone by vacuum deposition.

  In the photoelectric conversion part shown in FIG. 1, how light is absorbed at which depth in the quinacridone film when light is incident on the 200 nm thick quinacridone deposited film formed on the ITO from the ITO side. The simulation data shown is shown in FIG. In the spectrum shown in FIG. 2, (b) is the light absorption in the depth direction of 0 to 50 nm in the quinacridone film, and (c) is the light in the depth direction of 50 to 100 nm in the quinacridone film. (D) is the absorption rate of light in the depth direction of 100 to 150 nm in the quinacridone film, (e) is the absorption rate of light in the depth direction of 150 to 200 nm in the quinacridone film, (a) is the sum of (b) to (e).

  As shown in Fig. 2, most of the light per 570 nm absorption peak wavelength of quinacridone is absorbed in the vicinity of ITO, and absorption at a position far from the light incident side such as (d) or (e) is totally absorbed. Is weak and broad. Therefore, it can be seen that a large amount of electric charge generated by light absorption is generated in the vicinity of ITO and relatively small in the vicinity of Al far from ITO.

Next, in the photoelectric conversion unit shown in FIG. 1, the external quantum efficiency (the number of electrons transferred to the ITO / incident light) when the light generated from the ITO side and generated in the quinacridone is collected by the ITO. FIG. 3 shows the results of measurement of the external quantum efficiency (number of electrons transferred to Al / number of photons of incident light) when electrons are collected by Al.
As described above, since the photoelectric conversion film made of an organic material has electron mobility smaller than hole mobility, when collecting electrons with Al positioned opposite to the light incident side, the Al Electrons are trapped or deactivated by the time they arrive, and it becomes difficult to efficiently collect many electrons generated in the vicinity of ITO to a distant Al electrode. Therefore, as shown in FIG. 3, the external quantum efficiency is greatly reduced even with the same bias voltage when electrons are collected with Al on the opposite side compared to the case where electrons are collected with ITO on the light incident side. In addition, it can be seen that the shape of the action spectrum is broadened in the central wavelength region. This result corresponds well with the spectrum shown in FIG. That is, when collecting electrons with ITO, the action spectrum is close to (b) or (c) of FIG. 2, and when collecting electrons with Al, the action spectrum is (e) or (d) of FIG. Close to). It can be seen that the electron collection efficiency largely dominates the shape of the action spectrum, and it is important to shorten the electron transport distance in order to obtain a sharp action spectrum having a large absolute value.

  Note that some organic materials with relatively high electron mobility are known, but there are many disadvantages as a photoelectric conversion film for use in visible spectroscopy, such as a broad absorption spectrum. In addition, the material whose electron mobility is smaller than the hole mobility is not limited to the organic material, but also exists in the inorganic material. Even when such an inorganic material is used as a photoelectric conversion film, the light incident side It is better to collect electrons with ITO.

In addition, it has been also obtained that the mobility of electrons decreases when an organic material is exposed to the atmosphere (especially oxygen).
FIG. 4 shows that the conditions for collecting electrons with Al were set for the photoelectric conversion part (thickness of quinacridone of 100 nm) shown in FIG. 1, and the space between quinacridone and Al was exposed to the atmosphere under these conditions. It shows the change in external quantum efficiency when and when not exposed.
As shown in FIG. 4, when collecting electrons with Al, exposure to the atmosphere for about 10 minutes reduces the central wavelength region and reduces quantum efficiency. That is, it can be seen that the reduction in external quantum efficiency due to the low electron mobility is further increased by the influence of the atmosphere.

  As described above, the first electrode film, the second electrode film facing the first electrode film, and the photoelectric conversion film made of an organic material disposed between the first electrode film and the second electrode film (A photoelectric conversion film made of a material that generates more electrons and holes on the light incident side and whose hole mobility is larger than the electron mobility) may be used. In the conversion element, external quantum efficiency can be improved by collecting electrons in the electrode film on the light incident side. As a result, in such a photoelectric conversion element, it is possible to improve sensitivity and sharpen spectral sensitivity.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a configuration example will be described which can be cited as a sensor having a configuration in which the photoelectric conversion units as described above are stacked above a semiconductor substrate.

(First embodiment)
FIG. 5 is a schematic cross-sectional view of one pixel of the solid-state imaging device for explaining the first embodiment of the present invention. 6 is a schematic cross-sectional view of the photoelectric conversion layer shown in FIG. This solid-state imaging device has a large number of one pixel shown in FIG. 5 arranged in an array on the same plane, and can generate one pixel data of image data by a signal obtained from the one pixel.
One pixel of the solid-state imaging device shown in FIG. 5 includes a p-type silicon substrate 1, a transparent insulating film 7 formed on the p-type silicon substrate 1, a first electrode film 11 formed on the insulating film 7, A photoelectric conversion layer 12 formed on the first electrode film 11, and a photoelectric conversion unit including the second electrode film 13 formed on the photoelectric conversion layer 12. The provided light shielding film 14 is formed, and the light receiving region of the photoelectric conversion 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.

  As shown in FIG. 6, the photoelectric conversion layer 12 includes an undercoat film 121, an electron blocking film 122, a photoelectric conversion film 123, a hole blocking film 124, and a hole blocking function on the first electrode film 11. A buffer film 125 and a work function adjusting film 126 are stacked in this order. The photoelectric conversion layer 12 should just contain the photoelectric conversion film 123 at least among these.

  The photoelectric conversion film 123 generates charges including electrons and holes according to incident light from above the second electrode film 13, and has a mobility of electrons smaller than the mobility of holes, and the first electrode The vicinity of the second electrode film 13 is configured to include a material having characteristics that generate more electrons and holes than the vicinity of the film 11. A typical example of such a material for the photoelectric conversion film is an organic material. In the configuration of FIG. 5, the photoelectric conversion film 123 uses a material that absorbs green light and generates electrons and holes corresponding thereto. Since the photoelectric conversion film 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 organic material constituting the photoelectric conversion film 123 preferably contains at least one of an organic p-type semiconductor and an organic n-type semiconductor. As the organic p-type semiconductor and the organic n-type 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.

  The organic p-type 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, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indoles 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 it has as 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.

  Organic n-type semiconductors (compounds) are acceptor organic semiconductors (compounds), which are mainly represented by electron-transporting organic compounds and refer to organic compounds that easily accept 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 derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), 5- to 7-membered heterocyclic compounds containing nitrogen atoms, oxygen atoms, and sulfur atoms (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, o Metal complexes having ligands such as saziazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and nitrogen-containing heterocyclic compounds. 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.

  Any p-type organic dye or n-type organic dye may be used, but preferably a cyanine dye, styryl dye, hemicyanine dye, merocyanine dye (including zero methine merocyanine (simple merocyanine)), three nucleus 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, triphenyl Methane 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).

Next, the metal complex compound will be described. The metal complex compound is a metal complex having a ligand having at least one nitrogen atom or 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, and still more preferably aluminum ion or zinc 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 ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Or a bidentate or higher ligand, preferably a bidentate ligand such as a pyridine ligand, a bipyridyl ligand, a quinolinol ligand, a hydroxyphenylazole ligand (hydroxyphenyl) Benzimidazole, hydroxyphenylbenzoxazole ligand, hydroxyphenylimidazole ligand)), alkoxy ligand (preferably 1-30 carbon atoms, more preferably 1-20 carbon atoms, particularly preferably carbon 1-10, for example, methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), aryloxy ligands Preferably it has 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl Oxy, 4-biphenyloxy, etc.), heteroaryloxy ligands (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyl. Oxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, etc.), alkylthio ligands (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio, etc.), arylthio ligands (preferably having 6 to 30 carbon atoms, more preferred) Has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, etc.), a heterocyclic substituted thio ligand (preferably 1 to 30 carbon atoms, more preferably 1 to carbon atoms). 20, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio and the like, or siloxy ligand (preferably Has 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group. More preferably a nitrogen-containing heterocyclic ligand, an aryloxy ligand, a heteroaryloxy group, or a siloxy ligand, Preferably, a nitrogen-containing heterocyclic ligand, an aryloxy ligand, or a siloxy ligand is used.

  The photoelectric conversion layer 12 includes a p-type semiconductor layer and an n-type semiconductor layer, at least one of the p-type semiconductor and the n-type semiconductor is an organic semiconductor, and the p-type semiconductor layer is interposed between the semiconductor layers. It is preferable to include a photoelectric conversion film having a bulk heterojunction structure layer including a n-type semiconductor and an n-type semiconductor as an intermediate layer. In such a case, by including a bulk heterojunction structure in the photoelectric conversion layer 12, it is possible to compensate for the shortcoming that the carrier diffusion length of the photoelectric conversion layer 12 is short, and to improve the photoelectric conversion efficiency of the photoelectric conversion film. The bulk heterojunction structure is described in detail in Japanese Patent Application No. 2004-080639.

  The photoelectric conversion layer 12 may contain a photoelectric conversion film having a structure having two or more repeating structures (tandem structures) of a pn junction layer formed of a p-type semiconductor layer and an n-type semiconductor layer. Preferably, more preferably, a thin layer of conductive material is inserted between the repetitive structures. The number of repeating structures (tandem structures) of the pn junction layer may be any number, but is preferably 2 to 50, more preferably 2 to 30, particularly preferably 2 or 10 in order to increase the photoelectric conversion efficiency. It is. The conductive material is preferably silver or gold, and most preferably silver. The tandem structure is described in detail in Japanese Patent Application No. 2004-079930.

  The photoelectric conversion film included in the photoelectric conversion 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 at least one of them includes an organic compound whose orientation is controlled, and more preferably, it includes a (possible) organic compound whose alignment is controlled 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 photoelectric conversion layer 12, but preferably, the ratio of the portion whose orientation is controlled with respect to the entire photoelectric conversion layer 12 is 10% or more, more preferably 30% or more, more preferably 50% or more, further preferably 70% or more, particularly preferably 90% or more, and most preferably 100%. Such a state compensates the shortcoming of the short carrier diffusion length of the photoelectric conversion layer 12 by controlling the orientation of the organic compound contained in the photoelectric conversion layer 12, and improves the photoelectric conversion efficiency of the photoelectric conversion film. is there.

  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 photoelectric conversion layer 12. Preferably, the ratio of the portion whose orientation is controlled with respect to the entire photoelectric conversion layer 12 is 10% or more, more preferably 30% or more, more preferably 50% or more, still more preferably 70% or more, particularly preferably. 90% or more, most preferably 100%. In such a case, the area of the heterojunction surface in the photoelectric conversion 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 film 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 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.

  The photoelectric conversion layer 12 containing these organic compounds is formed by a dry film formation method or a wet film formation method. Specific examples of the dry film forming method include a vacuum vapor deposition method, a sputtering method, an ion plating method, a physical vapor deposition method such as an MBE method, or a CVD method such as plasma polymerization. As the wet film forming method, a casting method, a spin coating method, a dipping method, an LB method, or the like is used.

In the case where a polymer compound is used as at least one of the p-type semiconductor (compound) and the n-type semiconductor (compound), it is preferable to form the film by a wet film forming method that is easy to prepare. When a dry film formation method such as vapor deposition is used, it is difficult to use a polymer because it may be decomposed, and an oligomer thereof can be preferably used instead. On the other hand, when a low molecule is used, a dry film forming method is preferably used, and a vacuum deposition method is particularly preferably used. The vacuum deposition method is basically based on the method of heating compounds such as resistance heating deposition method and electron beam heating deposition method, shape of deposition source such as crucible and boat, degree of vacuum, deposition temperature, base temperature, deposition rate, etc. It is a parameter. In order to make uniform deposition possible, it is preferable to perform deposition by rotating the substrate. The degree of vacuum is preferably higher, and vacuum deposition is performed at 10 ⁻⁴ Torr or less, preferably 10 ⁻⁶ Torr or less, 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.

  Since the solid-state imaging device 100 includes the photoelectric conversion film 123 having the above-described characteristics, as described above, by collecting electrons with the second electrode film 13 that is an electrode on the light incident side, The 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 100, the first electrode is formed such that electrons generated in the photoelectric conversion film 123 move to the second electrode film 13 and holes generated in the photoelectric conversion film 123 move to the first electrode film 11. A voltage is applied to the film 11 and the second electrode film 13.

The undercoat film 121 is for reducing 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 film 123. It is easy to form a fine crack in the photoelectric conversion element 123, that is, a portion where the photoelectric conversion film 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 121 on the 1st electrode film | membrane 11 previously, and these can be suppressed.
Examples of the undercoat film 121 include organic polymer materials such as polyaniline, polythiophene, polypyrrole, polycarbazole, PTPDES, and PTPDEK, and are preferably formed by a spin coating method.

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

  The hole blocking film 124 is provided to reduce dark current caused by holes injected from the second electrode film 13, and holes from the second electrode film 13 are injected into the photoelectric conversion film 123. To stop.

The hole blocking / buffer film 125 has a function of reducing the damage given to the photoelectric conversion film 123 when the second electrode film 13 is formed, in addition to the function of the hole blocking film 124.
When the second electrode film 13 is formed on the photoelectric conversion film 123, high-energy particles existing in an 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, and the like collide with the photoelectric conversion film 123, the photoelectric conversion film 123 may be deteriorated, and performance degradation such as increase in leakage current and decrease in sensitivity may occur. As one method for preventing this, it is preferable to provide the buffer film 125 on the photoelectric conversion film 123.
The material of the hole blocking / buffer film 125 is preferably an organic substance such as copper phthalocyanine, PTCDA, acetylacetonate complex, or BCP, an organic-metal compound, or an inorganic substance such as MgAg or MgO. Further, the hole blocking and buffer film 125 preferably has a high visible light transmittance so as not to prevent light absorption of the photoelectric conversion film 123, and a material that does not absorb in the visible region is selected. It is preferable to use an extremely thin film thickness. The film thickness of the hole blocking / buffer film 125 varies depending on the structure of the photoelectric conversion film 123, the film thickness of the second electrode film 13, and the like, but it is particularly preferable to use a film thickness of 2 to 50 nm.

The work function adjustment film 126 is for adjusting the work function of the second electrode film 13 and suppressing dark current. When the second electrode film 13 is made of a material having a relatively large work function (for example, 4.5 eV or more) (for example, any of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , and FTO), As a material of the function adjusting film 126, a dark current can be effectively suppressed by using a material containing a metal having a work function of 4.5 eV or less (for example, In). The description of the advantages and the like by providing such a work function adjusting film 126 will be described later.

Here, an example of a preferable production of the photoelectric conversion film 123 shown in FIG. 6 in this embodiment will be described.
As the first electrode film 11, ITO having a thickness of 100 nm is formed on a glass substrate by sputtering. On top of that, PEDOT doped with PSS is spin-coated as a polymer undercoat film 121 having conductivity to reduce damage when the second electrode film 13 is formed by sputtering. 40 nm film is formed. On top of that, m-MTDATA is deposited as an electron blocking film 122 to a thickness of 50 nm by vacuum deposition. A quinacridone film having a thickness of 100 nm is formed thereon as a photoelectric conversion film 123 that absorbs green light by a vacuum deposition method, and an Alq ₃ film is deposited as a hole blocking film 124 by a thickness of 50 nm by a vacuum deposition method. As the film 125, BCP is formed to a thickness of 20 nm by vacuum deposition. On top of that, in order to suitably adjust the work function of the second electrode film 13 as an electron collecting electrode, In is deposited to a thickness of 5 nm by vacuum deposition. Further, as the second electrode film 13, ITO is deposited to a thickness of 10 nm by sputtering under plasma-free conditions. From the deposition of the m-MTDATA to the sputtering deposition of ITO as the second electrode film 13 is performed in a consistent vacuum without exposure to the atmosphere. When light is incident from above the second electrode film 13, the spectral sensitivity is broadened due to the low mobility of the electrons by adopting a suitable configuration for collecting electrons by the second electrode film 13 in this way. And reduction in sensitivity, and further performance degradation due to oxygen is reduced. The chemical formulas of the materials used in this preparation example are listed below.

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

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

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

  The n + region 6 is electrically connected to the second electrode film 13 through a connection portion 9 formed in an opening formed in the insulating film 7, the first electrode film 11, and the photoelectric conversion layer 12. The electrons collected by the second electrode film 13 are accumulated via the part 9. The connection portion 9 is electrically insulated by the insulating film 8 except for the second electrode film 13 and the n + region 6.

  The electrons accumulated in the n region 2 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n channel MOS transistor formed in the p-type silicon substrate 1 and accumulated in the n region 4. The electrons are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n-channel MOS transistor formed in the p region 3, and the electrons accumulated in the n + region 6 The signal is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) composed of n-channel MOS transistors formed in the, and output to the outside of the solid-state imaging device 100. 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 n region 2 and the n region 4 and a predetermined reset potential is applied, each region is depleted, and the capacitance of each pn junction becomes an extremely small value. Thereby, the capacity | capacitance produced in a joint surface can be made very small.

  With such a configuration, G light can be photoelectrically converted by the photoelectric conversion film 123, and B light and R light can be photoelectrically converted by the B photodiode and the R photodiode in the p-type silicon substrate. Also, since G light is first absorbed at the top, color separation between B-G and G-R 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 p-type silicon substrate 1 of the solid-state imaging device 100 is also referred to as an inorganic layer.

  The light transmitted through the photoelectric conversion film 123 is absorbed between the p-type silicon substrate 1 and the first electrode film 11 (for example, between the insulating film 7 and the p-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 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 p-type silicon substrate 1, and the wiring 10 is also connected to the MOS circuit. It ’s fine.

The first electrode film 11 has a function of discharging holes generated and moved in the photoelectric conversion film 123. The first electrode film 11 can be used in common for all pixels. For this reason, in the solid-state imaging device 100, the first electrode film 11 is a single-layer film common to all pixels. In the configuration shown in FIG. 5, since the p-type silicon substrate 1 performs photoelectric conversion, the first electrode film 11 preferably has a visible light transmittance of 60% or more, more preferably 90%. preferable. 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 the material, any of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, and Au can be most preferably used. Details of the first electrode film 11 will be described later.

The second electrode film 13 plays a role of collecting electrons generated and moved in the photoelectric conversion film 123. The second electrode film 13 is separated for each pixel, whereby image data can be generated. Since the second electrode film 13 needs to make light incident on the photoelectric conversion film 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, and more preferably 90%. As the material, any of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , FTO, Al, Ag, and Au can be most preferably used. Details of the second electrode film 13 will be described later.

  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 remarkably improved by using the photoelectric conversion layer 12 as an upper layer as shown in FIG. 5, that is, by detecting light transmitted through the photoelectric conversion layer 12 in the depth direction of silicon. In particular, as shown in FIG. 5, when G light is detected by the photoelectric conversion layer 12, light transmitted through the photoelectric conversion layer 12 becomes B light and R light. Therefore, the separation of light in the depth direction in silicon is BR. Only light is used and color separation is improved. Even when the photoelectric conversion layer 12 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. 5 shows a configuration in which one photoelectric conversion unit is stacked above the p-type silicon substrate 1, but a configuration in which a plurality of photoelectric conversion units are stacked above the p-type silicon substrate 1 is also possible. is there. A configuration in which a plurality of photoelectric conversion units are stacked will be described later in a third 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 100, for example, a configuration in which one color is detected with a photoelectric conversion unit and three colors are detected with an inorganic layer, photoelectric conversion Two parts are stacked to detect two colors and two layers are detected by the inorganic layer, three photoelectric converters are stacked to detect three colors, and one layer is detected from the inorganic layer, etc. Can be considered. The solid-state imaging device 100 may be configured to detect only one color with one pixel. In this case, the n region 2, the p region 3, and the n 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. 5, a plurality of first conductivity type regions and second conductivity type regions, which are opposite to the first conductivity type, are alternately 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.

  As the material of the first electrode film 11 and the second electrode film 13, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Metal materials include 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 can be mentioned, but particularly preferred Are Al, Pt, W, Au, Ag, Ta, Cu, Cr, Mo, Ti, Ni, Pd, Zn.

  The first electrode film 11 takes out holes from the hole-transporting photoelectric conversion film or hole-transporting film contained in the photoelectric conversion layer 12 and discharges them, so that the hole-transporting photoelectric conversion film and the hole-transporting film are discharged. It is selected in consideration of adhesion to adjacent films, electron affinity, ionization potential, stability, and the like. The second electrode film 13 takes out electrons from the electron transport photoelectric conversion film or the electron transport film included in the photoelectric conversion layer 12 and collects them, so that the second electrode film 13 is adjacent to the electron transport photoelectric conversion film, the electron transport film, or the like. It is selected in consideration of adhesion to the film, electron affinity, ionization potential, stability, and the like. Specific examples of these include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), or metals such as gold, silver, chromium and nickel, and these metals and conductive metal oxides. Inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene and polypyrrole, silicon compounds and laminates of these with ITO, etc. In particular, ITO and IZO are preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  Various methods are used for producing the electrode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.), a coating of a dispersion of indium tin oxide, etc. A film is formed by this method. In the case of ITO, UV-ozone treatment, plasma treatment, etc. can be performed.

  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 13. 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 as a material 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.

  In addition, when a plurality of photoelectric conversion layers 12 are stacked, the first electrode film 11 and the second electrode film 13 are respectively 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 photoelectric conversion film, 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), “New Development of Transparent Conductive Films II” supervised by Yutaka Sawada (published by CMC, 2002) ), "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 film 123 are covered by a dense film such as TCO, and conduction between the first electrode film 11 on the opposite side is increased. Therefore, in the case of an electrode having a poor film quality such as Al, an increase in leakage current is unlikely to occur. By controlling the film thickness of the second electrode film 13 with respect to the film thickness of the photoelectric conversion film 123 (that is, the depth of cracks), 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 film 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 100 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 film 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), “Transparent by Japan Society for the Promotion of Science” Those described in detail in “Technology of Conductive Film” (Ohm Co., 1999) may be used.

Next, advantages of providing the work function adjusting film 126 will be described.
When the second electrode film 13 is made of a material having high work function such as ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , and FTO and having high transparency, the dark current at the time of bias application to the second electrode film 13 Is as large as about 10 μA / cm ² when a voltage of 1 V is applied.
As one of the causes of the dark current, a current flowing from the second electrode film 13 to the photoelectric conversion layer 12 when a bias is applied can be considered. When a highly transparent electrode such as ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , and FTO is used as the second electrode film 13, its work function is relatively large (4.5 eV or more), It was thought that the barrier at the time of a hole moving to the photoelectric converting layer 12 became low, and the hole injection to the photoelectric converting film 123 would become easy to occur. Actually, when examining the work function of a highly transparent metal oxide based transparent electrode such as ITO, IZO, SnO ₂ , TiO ₂ , and FTO, for example, the work function of the ITO electrode is about 4.8 eV. The work function of the (aluminum) electrode is considerably higher than that of about 4.3 eV, and other metal oxide-based transparent electrodes other than ITO also have the smallest AZO (Al-doped zinc oxide). Except for about 4.5 eV, it is known that its work function is relatively large, about 4.6 to 5.4 (for example, J. Vac. Sci. Technol. A17 (4), Jul. / See Fig. 12 of Aug 1999 p. 1765-1772).

  When the work function of the second electrode film 13 is relatively large (4.8 eV), the barrier when holes move to the photoelectric conversion film 123 when a bias is applied is lowered, and the photoelectric conversion film 123 is transferred from the second electrode film 13. It is considered that hole injection tends to occur, and as a result, dark current increases. In this embodiment, the dark current is suppressed because the hole blocking film 124 is provided. However, if the work function of the second electrode film 13 is large, the dark current is suppressed even if the hole blocking film 124 is present. It becomes difficult.

  Therefore, in the present embodiment, a film having a work function of 4.5 eV or less is provided between the second electrode film 13 and the photoelectric conversion film 123.

  In the following, metals having a work function of 4.5 eV or less are listed together with their characteristics.

  Examples are shown below, but the present invention is not limited thereto.

[Comparative Example 1]
A glass substrate (commercially available) on which an ITO electrode having a thickness of 250 nm (a work function of 4.8 eV obtained by an atmospheric photoelectron spectrometer AC-2 manufactured by Riken Keiki Co., Ltd .; visible light transmittance of about 90%) was laminated On top of this, quinacridone having a thickness of 100 nm (compound 1 below; 5,12-dihydroquino [2,3-b] acridine-7,14-dione) and an Al electrode having a thickness of 100 nm (work function 4.3 eV; visible light transmission) An example is a case where light is incident from the ITO electrode side and electrons are collected on the ITO electrode side in a structure in which the rate 0%) is sequentially laminated by vacuum deposition. As a result of actual device fabrication and measurement with an element area of 2 mm × 2 mm, the dark current was as large as 9.3 μA / cm ² when a voltage of 1 V was applied (ITO electrode was used as a positive bias to collect electrons, and so on). became.
In this case, since the work function of ITO, which is an electron collection electrode, is large, when a bias voltage is applied, hole injection from the ITO electrode to quinacridone occurs easily, and the dark current is considered to increase.

[Example 1]
On the other hand, a device similar to Comparative Example 1 was fabricated except that In having a small work function of 4.3 eV was laminated on the ITO electrode by 2 nm vacuum deposition and In was interposed between the quinacridone and the ITO electrode (2 nm). In visible light transmittance of In is about 98%). As a result, the dark current when a voltage of 1 V was applied was greatly suppressed by 1.8 nA / cm ² and about 4 digits.
This indicates that hole injection from the electron collection electrode is greatly suppressed by reducing the work function of the ITO electrode as the electron collection electrode.
Similarly, when 550 nm light was incident from the ITO electrode side at an irradiation intensity of 50 μW / cm ² under the 1 V bias application condition, the external quantum efficiency (measured charge number relative to the number of incident photons) was 12%. When a bias voltage of 2 V was applied, the dark current was about 100 nA / cm ² and the external quantum efficiency was 19%.

(Second embodiment)
In the present embodiment, the inorganic layer having the configuration shown in FIG. 5 described in the first embodiment is not stacked with two photodiodes in a p-type silicon substrate, but is perpendicular to the incident light incident direction. Two photodiodes are arranged in such a manner that light of two colors is detected in the p-type silicon substrate.

FIG. 7 is a schematic cross-sectional view of one pixel of a solid-state image sensor for explaining the second embodiment of the present invention.
One pixel of the solid-state imaging device 200 shown in FIG. 7 includes a p-type silicon substrate 17, a first electrode film 30 formed above the p-type silicon substrate 17, and a photoelectric conversion layer 31 formed on the first electrode film 30. And a photoelectric conversion part composed of the second electrode film 32 formed on the photoelectric conversion layer 31, and a light shielding film 34 having an opening is formed on the photoelectric conversion part. The light receiving region of the photoelectric conversion layer 31 is limited by the film 34. A transparent insulating film 33 is formed on the light shielding film 34.

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

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

  Above the photodiode composed of the p region 19 and the n region 18, a color filter 28 that transmits B light is formed through a transparent insulating film 24, and a first electrode film 30 is formed thereon. Above the photodiode composed of the p region 21 and the n region 20, a color filter 29 that transmits R light through a transparent insulating film 24 is formed, 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 including the p region 19 and the n region 18 absorbs the B light transmitted through the color filter 28 and generates electrons corresponding thereto, and accumulates the generated electrons in the n region 18. The photodiode composed of the p region 21 and the n region 20 absorbs the R light transmitted through the color filter 29 and generates electrons corresponding thereto, and accumulates the generated electrons in the n region 20.

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

  The n + region 23 is electrically connected to the second electrode film 32 through a connection portion 27 formed in an opening formed in the insulating films 24 and 25, the first electrode film 30, and the photoelectric conversion layer 31. The electrons collected by the second electrode film 32 are accumulated through the connection portion 27. The connecting portion 27 is electrically insulated by the insulating film 26 except for the second electrode film 32 and the n + region 23.

The electrons accumulated in the n region 18 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n channel MOS transistor formed in the p-type silicon substrate 17 and accumulated in the n region 20. The electrons are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n-channel MOS transistor formed in the p-type silicon substrate 17, and the electrons accumulated in the n + region 23 are converted into the p region. The signal is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n-channel MOS transistor formed in 22 and output to the outside of the solid-state imaging device 200. 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 electrons accumulated in the n region 18, the n region 20, and the n + region 23 are read out to a CCD formed in the p-type silicon substrate 17, and transferred to the amplifier by the CCD. A signal reading unit that outputs a signal may be used.

  As described above, the signal reading unit includes a CCD and a CMOS structure, but CMOS is preferable in terms of power consumption, high-speed reading, pixel addition, partial reading, and the like. In addition, in the case of CMOS, signal charges that can be handled are either electrons or holes, but from the viewpoints of high-speed signal readout derived from charge mobility, completeness of process conditions in manufacturing, etc. Since electrons are superior, it is preferable to connect an electrode for collecting electrons to the n + region.

  In FIG. 7, 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 n region 20 and the p region 21 are as follows. The depths of the pn junction surfaces of the n region 18 and the p region 19 may be adjusted to absorb the R light and the B light by the respective photodiodes. In this case, the light transmitted through the photoelectric conversion layer 31 is absorbed between the p-type silicon substrate 17 and the first electrode film 11 (for example, between the insulating film 24 and the p-type silicon substrate 17), It is also possible to form an inorganic photoelectric conversion portion made of an inorganic material that generates and accumulates a corresponding charge. 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 p-type silicon substrate 17, and the wiring 35 is also connected to the MOS circuit. It ’s fine.

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

(Third embodiment)
The solid-state imaging device of this embodiment has a configuration in which a plurality of (here, three) photoelectric conversion layers are stacked above a silicon substrate without providing the inorganic layer having the configuration shown in FIG. 5 described in the first embodiment.
FIG. 8 is a schematic cross-sectional view of one pixel of a solid-state image sensor for explaining the third embodiment of the present invention.
8 includes a first electrode film 56, a photoelectric conversion layer 57 stacked on the first electrode film 56, and a second electrode stacked on the photoelectric conversion layer 57 above the silicon substrate 41. B photoelectric including an R photoelectric conversion portion including a film 58, a first electrode film 60, a photoelectric conversion layer 61 stacked on the first electrode film 60, and a second electrode film 62 stacked on the photoelectric conversion layer 61. The conversion unit, the G photoelectric conversion unit including the first electrode film 64, the photoelectric conversion layer 65 stacked on the first electrode film 64, and the second electrode film 66 stacked on the photoelectric conversion layer 65, respectively. In this state, the first electrode film included in the structure is laminated in this order with the first electrode 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 photoelectric conversion 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 photoelectric conversion layer 12, and the second electrode film 13 illustrated in FIG. It is.

  The first electrode film 60, the photoelectric conversion 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 photoelectric conversion layer 12, and the second electrode film 13 illustrated in FIG. It is. However, the photoelectric conversion film included in the photoelectric conversion film 61 uses a material that absorbs blue light and generates electrons and holes according to the blue light.

  The first electrode film 56, the photoelectric conversion 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 photoelectric conversion layer 12, and the second electrode film 13 illustrated in FIG. It is. However, the photoelectric conversion film included in the photoelectric conversion film 57 uses a material that absorbs red light and generates electrons and holes corresponding thereto.

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

  The n + region 43 is electrically connected to the second electrode film 58 through a connection portion 54 formed in an opening formed in the insulating film 48, the first electrode film 56, and the photoelectric conversion layer 57. The electrons collected by the second electrode film 58 are accumulated via the part 54. The connection portion 54 is electrically insulated by the insulating film 51 except for the second electrode film 58 and the n + region 43.

  The n + region 45 is electrically connected to the second electrode film 62 via the insulating film 48, the R photoelectric conversion portion, the insulating film 59, the first electrode film 60, and the connection portion 53 formed in the opening opened in the photoelectric conversion layer 61. The electrons collected by the second electrode film 62 are accumulated via the connection portion 53. The connection portion 53 is electrically insulated by the insulating film 50 except for the second electrode film 62 and the n + region 45.

  The n + region 47 includes an insulating film 48, an R photoelectric conversion unit, an insulating film 59, a B photoelectric conversion unit, an insulating film 63, a first electrode film 64, and a connection unit 52 formed in an opening opened in the photoelectric conversion layer 65. The second electrode film 66 is electrically connected, and the electrons collected by the second electrode film 66 are accumulated via the connection portion 52. The connection portion 52 is electrically insulated by the insulating film 49 except for the second electrode film 66 and the n + region 47.

  The electrons accumulated in the n + region 43 are converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n-channel MOS transistor formed in the p region 42, and accumulated in the n + region 45. Is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of an n-channel MOS transistor formed in the p region 44, and the electrons accumulated in the n + region 47 are formed in the p region 46. The signal is converted into a signal corresponding to the amount of charge by a MOS circuit (not shown) formed of the n-channel MOS transistor, and output to the outside of the solid-state imaging device 300. 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. In other words, the signals accumulated in the n + regions 43, 45, and 47 are read out to a CCD formed in the silicon substrate 41, transferred to the amplifier by the CCD, and a signal corresponding to the electrons is output from the amplifier. It may be a reading unit.

  The light transmitted through the photoelectric conversion layers 57, 61, 65 is absorbed between the silicon substrate 41 and the first electrode film 56 (for example, between the insulating film 48 and the silicon substrate 41), and the light is absorbed into the light. It is also possible to form an inorganic photoelectric conversion portion made of an inorganic material that generates and accumulates a corresponding charge. 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 are stacked on the silicon substrate described in the first embodiment and the second embodiment can be realized by the configuration shown in FIG.

  In the above description, the photoelectric conversion film 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 film 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 film that absorbs R light means that it can absorb at least light of 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, and 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 (2), a combination in which the lower layer is the same plane and the BR layer is possible. Preferably, the upper layer is the G layer and the lower layer is the same plane as the BR layer as shown in FIG.

  In addition, in 1st embodiment-3rd embodiment, reading of the signal from photoelectric conversion parts other than a photoelectric converting film may use either a hole or an electron. 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.

(Fourth embodiment)
In this embodiment, the second electrode film that is the electrode on the light incident side of the photoelectric conversion unit described above and the n + region formed in the semiconductor substrate that accumulates the electrons collected by the second electrode film are provided. The specific electrical connection will be described with reference to the manufacturing process diagrams of FIGS. 9 to 12 are diagrams showing the manufacturing process of the solid-state imaging device. The right side of each figure is a plan view, and the left side is a plan view of the right side as viewed from the bottom to the top in the figure. FIG.

  First, a transparent insulating film 72 is formed on a Si substrate 71 on which an n + region, a signal readout unit, and the like are formed, an opening is formed in the insulating film 72 above the n + region, and the second electrode film and the n + are formed in the opening. A connection electrode 73 for electrically connecting the regions is formed. Then, a pad 74 is formed on the metal 73 to obtain a state as shown in FIG. Next, a transparent insulating film 75 is formed on the pad 74 and the insulating film 72 (FIG. 9B), and a first electrode film 76 is formed on the insulating film 75 (FIG. 9C). Next, the first electrode film 76 is patterned by photolithography to form an opening at least above the pad 74 of the first electrode film 76 (FIGS. 10D and 10D ′). Next, a photoelectric conversion layer 77 is formed on the insulating film 75 and the first electrode film 76, a second electrode film 78 is formed on the photoelectric conversion layer 77, and a transparent mask serving as a hard mask is formed on the second electrode film 78. An insulating film 79 is formed (FIG. 10E). Note that the first electrode film 76 may be used as a hard mask without using the insulating film 79 as a hard mask. Next, the photoelectric conversion layer 77, the first electrode film 78, and the insulating film 78 are panned, and an opening is formed at least above the pad 74 (FIG. 11 (f)), and transparent insulation is performed so as to fill the opening. A film 80 is formed (FIG. 11G). Next, the insulating film 80 is patterned to form openings 81 and 82 above a part of the first electrode film 78 and above the pad 74 (FIG. 11H) so as to fill the openings 81 and 82. A connection electrode 83 is formed (FIG. 12I), and the connection electrode 83 is patterned to obtain the state of FIG.

  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.

Further, 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 , and the most preferred materials are SiOx, SiNx, BSG, PSG, and BPSG.

The figure which shows the structural example of the photoelectric conversion part containing a pair of electrode film and the photoelectric conversion film pinched | interposed by this The figure which shows the simulation data of the light absorption rate in the quinacridone of the photoelectric conversion part shown in FIG. The figure which shows the measurement result of the external quantum efficiency of the photoelectric conversion part shown in FIG. The figure which shows the measurement result of the external quantum efficiency of the photoelectric conversion part shown in FIG. 1 is a schematic cross-sectional view of one pixel of a solid-state image sensor for explaining a first embodiment of the present invention. Cross-sectional schematic diagram of the photoelectric conversion layer shown in FIG. Sectional schematic diagram for 1 pixel of the solid-state image sensor for demonstrating 2nd embodiment of this invention Sectional schematic diagram for 1 pixel of the solid-state image sensor for demonstrating 3rd embodiment of this invention The figure which shows the manufacturing process of a solid-state image sensor The figure which shows the manufacturing process of a solid-state image sensor The figure which shows the manufacturing process of a solid-state image sensor The figure which shows the manufacturing process of a solid-state image sensor

Explanation of symbols

1 p-type silicon substrate (semiconductor substrate)
2, 4 n-type semiconductor region 6 High-concentration n-type semiconductor region (electron storage part)
3, 5 p-type semiconductor regions 7, 8, 15 Insulating film 9 Connection portion 10 Wiring 11 First electrode film 12 Photoelectric conversion layer 13 Second electrode film 14 Light shielding film

Claims (22)

Photoelectric conversion having a photoelectric conversion part including a first electrode film, a second electrode film facing the first electrode film, and a photoelectric conversion film disposed between the first electrode film and the second electrode film An element,
Light is incident on the photoelectric conversion film from above the second electrode film,
The photoelectric conversion film generates charges including electrons and holes in response to incident light from above the second electrode film,
A photoelectric conversion element using the second electrode film as an electrode for extracting electrons. The photoelectric conversion element according to claim 1,
The photoelectric conversion element in which the photoelectric conversion film generates more electrons and holes in the vicinity of the second electrode film than in the vicinity of the first electrode film. The photoelectric conversion element according to claim 1, wherein
A photoelectric conversion element in which the photoelectric conversion film includes an organic material. The photoelectric conversion element according to claim 3,
A photoelectric conversion element in which the organic material includes at least one of an organic p-type semiconductor and an organic n-type semiconductor. The photoelectric conversion element according to claim 4,
The photoelectric conversion element in which the organic p-type semiconductor and the organic n-type semiconductor each include any of a quinacridone derivative, a naphthalene derivative, an anthracene derivative, a phenanthrene derivative, a tetracene derivative, a pyrene derivative, a perylene derivative, and a fluoranthene derivative. It is a photoelectric conversion element in any one of Claims 1-5, Comprising:
The first electrode _{film, ITO, IZO, ZnO 2,} SnO 2, TiO 2, FTO, Al, Ag, or the photoelectric conversion element is Au. It is a photoelectric conversion element in any one of Claims 1-6, Comprising:
The second electrode _{film, ITO, IZO, ZnO 2,} SnO 2, TiO 2, FTO, Al, Ag, or the photoelectric conversion element is Au. It is a photoelectric conversion element in any one of Claims 1-6, Comprising:
The second electrode film is ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , or FTO;
The photoelectric conversion element in which the photoelectric conversion unit includes a film made of a metal having a work function of 4.5 eV or less between the photoelectric conversion film and the second electrode film. It is a photoelectric conversion element in any one of Claims 1-8, Comprising:
The photoelectric conversion element whose transmittance | permeability with respect to visible light of said 2nd electrode film is 60% or more. It is a photoelectric conversion element in any one of Claims 1-9, Comprising:
The photoelectric conversion element whose transmittance | permeability with respect to visible light of said 1st electrode film is 60% or more. It is a photoelectric conversion element in any one of Claims 1-10,
In the first electrode film and the second electrode film, a voltage is applied so that the electrons move to the second electrode film and the holes move to the first electrode film,
A semiconductor substrate provided below the first electrode film;
An electron storage section for storing the electrons formed in the semiconductor substrate and moved to the second electrode film;
A photoelectric conversion element provided with the connection part which electrically connects the said electron storage part and said 2nd electrode film. The solid-state imaging device according to claim 11,
The photoelectric conversion element in which the photoelectric conversion unit includes a film made of an organic polymer material between the first electrode film and the photoelectric conversion film. The photoelectric conversion element according to claim 11 or 12,
A photoelectric conversion element including an in-substrate photoelectric conversion unit that absorbs light transmitted through the photoelectric conversion film in the semiconductor substrate below the photoelectric conversion film, generates a charge corresponding to the light, and accumulates the charge. The photoelectric conversion element according to claim 13,
The photoelectric conversion element in which the photoelectric conversion part in the substrate is a plurality of photodiodes that absorb light of different colors stacked in the semiconductor substrate. The photoelectric conversion element according to claim 13,
The photoelectric conversion element in which the in-substrate photoelectric conversion unit is a plurality of photodiodes that absorb light of different colors arranged in a direction perpendicular to the incident direction of the incident light in the semiconductor substrate. The photoelectric conversion element according to claim 14,
The plurality of photodiodes are a blue photodiode having a pn junction surface formed at a position capable of absorbing blue light, and a red photodiode having a pn junction surface formed at a position capable of absorbing red light. Yes,
A photoelectric conversion element in which the photoelectric conversion film absorbs green light. The photoelectric conversion element according to claim 15,
The plurality of photodiodes are a blue photodiode that absorbs blue light and a red photodiode that absorbs red light,
A photoelectric conversion element in which the photoelectric conversion film absorbs green light. The photoelectric conversion element according to any one of claims 10 to 17,
A plurality of the photoelectric conversion units are stacked above the semiconductor substrate,
A photoelectric conversion element in which the electron storage unit and the connection unit are provided for each of the plurality of photoelectric conversion units. The photoelectric conversion element according to claim 10, wherein
An inorganic material that absorbs light transmitted through the first electrode film between the semiconductor substrate and the first electrode film in the immediate vicinity of the semiconductor substrate, generates a charge corresponding to the light, and accumulates it A photoelectric conversion element provided with the inorganic photoelectric conversion part which consists of. A solid-state imaging device in which a large number of photoelectric conversion devices according to claim 10 are arranged in an array,
A solid-state imaging device including a signal reading unit that reads a signal corresponding to the electric charge accumulated in the semiconductor substrate of each of the multiple photoelectric conversion elements. A solid-state imaging device in which a large number of photoelectric conversion devices according to claim 19 are arranged in an array,
A solid-state imaging device including a signal reading unit that reads a signal corresponding to the charge accumulated in the semiconductor substrate of each of the multiple photoelectric conversion elements and a signal corresponding to the charge accumulated in the inorganic photoelectric conversion unit . The solid-state imaging device according to claim 20 or 21,
The photoelectric conversion film and the first electrode film included in the photoelectric conversion element are shared by the entire large number of photoelectric conversion elements,
A solid-state imaging device in which the second electrode film included in the photoelectric conversion device is separated for each of the plurality of photoelectric conversion devices.

Images