JP2008218445A - Photoelectric conversion device and solid-state imaging device - Google Patents

Abstract

A photoelectric conversion element capable of sharpening an absorption spectrum and reducing a dark current is provided.
A photoelectric conversion unit including a pair of electrodes (11, 13) and a photoelectric conversion layer (12a) disposed between the pair of electrodes (11, 13) is applied, and a bias voltage is applied between the pair of electrodes (11, 13). A photoelectric conversion element A for extracting a photocurrent, wherein the photoelectric conversion layer 12a absorbs light in a specific wavelength range and generates a charge corresponding to the light, for example, tin phthalocyanine Mixing with a matrix material (for example, TMM-1) that is transparent to light in a wavelength range wider than the specific wavelength range including the specific wavelength range and has a property of transporting charges generated in the photoelectric conversion material Consists of layers.
[Selection] Figure 1

Description

  The present invention has a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes, and applies a bias voltage between the pair of electrodes to extract a signal. About.

  In a single-plate color solid-state imaging device typified by a CCD type or CMOS type image sensor, three or four types of color filters are arranged in a mosaic pattern on an array of light receiving units that perform photoelectric conversion. Accordingly, color signals corresponding to the color filters are output from the respective light receiving units, and a color image is generated by performing signal processing on these color signals.

  However, in a color solid-state imaging device in which color filters are arranged in a mosaic shape, about 2/3 of incident light is absorbed by the color filter in the case of a primary color filter, light use efficiency is poor and sensitivity is low. There's a problem. Further, since only one color signal can be obtained at each light receiving unit, the resolution is poor, and in particular, there is a problem that false colors are conspicuous.

  Therefore, in order to overcome such a problem, a stacked solid-state imaging device having a structure in which three photoelectric conversion layers are stacked on a semiconductor substrate has been researched and developed (for example, Patent Documents 1 and 2 below). . This stacked solid-state imaging device includes, for example, a light receiving unit structure in which photoelectric conversion layers that generate charges (electrons, holes) for B, G, and R light are sequentially stacked from a light incident surface. Each light receiving unit is provided with a charge accumulating unit for accumulating charges generated in the photoelectric conversion layer, and a signal reading circuit capable of reading a signal corresponding to the charges accumulated in the charge accumulating unit. Each photoelectric conversion layer is sandwiched between a pair of electrodes, and one of the pair of electrodes is electrically connected to the charge storage unit, so that the charge generated in the photoelectric conversion layer and moved to the one electrode is stored in the charge storage unit. Has been accumulating.

  In the case of an image pickup device having such a structure, incident light is almost photoelectrically converted and read out, the utilization efficiency of visible light is close to 100%, and color signals of three colors of R, G, and B are obtained in each light receiving unit. Therefore, it is possible to generate a good image with high sensitivity and high resolution (false colors are not noticeable). For the photoelectric conversion layer used in such a stacked solid-state imaging device, it is required as performance to sharpen the absorption spectrum and reduce the dark current.

  In general, when a photoelectric conversion material in a solution state is thinned by vapor deposition or the like, it is known that the absorption spectrum of the photoelectric conversion material after thinning becomes broader than that in a solution state due to molecular association. For this reason, it is difficult to realize the required absorption spectrum only by forming the photoelectric conversion layer used for the stacked solid-state imaging device by forming one kind of photoelectric conversion material.

  Therefore, in order to sharpen the absorption spectrum of the photoelectric conversion layer, the photoelectric conversion layer is a laminated structure of a photoelectric conversion material layer made of one type of photoelectric conversion material and a single type of charge transport layer not having a photoelectric conversion function. A technique to be realized by the above has been proposed (see Patent Document 3).

  In addition, as a technique for forming a photoelectric conversion layer by mixing two types of materials, conventionally, in the production of solar cells, two types of photoelectric conversion materials, a p-type photoelectric conversion material and an n-type photoelectric conversion material, are mixed to produce photoelectric. A bulk hetero method for forming a conversion layer has been reported (Patent Document 4, Non-Patent Document 1).

Special Table 2002-502120 JP 2002-83946 A JP 2006-93691 A JP 2002-76391 A M.Hiramto, H.Fujiwara, M.Yokoyama, Journal of Applied Physics (J.Appl.Phys.) 1992 72, 3781

  The technique disclosed in Patent Document 3 is to form a photoelectric conversion layer by laminating a transparent charge transport layer and a photoelectric conversion material layer. The absorption spectrum of the photoelectric conversion material layer itself is a solution of the photoelectric conversion material. For example, in the case of using a photoelectric conversion material in which the absorption spectrum becomes broad due to the thin film, the imaging device obtains the absorption spectrum of the photoelectric conversion layer. It is difficult to sharpen to the extent that meets the demands.

  Further, the bulk hetero method is effective when it is desired to absorb a wide range of light like a solar cell, and it is difficult to make the absorption spectrum so sharp that it can be applied to an image sensor. If the absorption spectra of the two types of photoelectric conversion materials are completely the same, it is possible to sharpen the absorption spectrum of the photoelectric conversion layer, but this is not possible, so mix the two types of photoelectric conversion materials. Therefore, in most cases, the absorption spectrum becomes broad.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric conversion element capable of sharpening an absorption spectrum and reducing dark current.

  The object of the present invention is achieved by the following configurations (1) to (23).

(1) A photoelectric conversion element having a photoelectric conversion portion including a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes, and applying a bias voltage between the pair of electrodes to extract a signal. In addition, the photoelectric conversion layer mainly absorbs light in a specific wavelength range and generates a charge corresponding to the light, and a range wider than the specific wavelength range including the specific wavelength range A photoelectric conversion element comprising a mixed layer with at least one kind of matrix material that is transparent to light in the wavelength range and has a property of transporting charges generated in the photoelectric conversion material.

(2) The photoelectric conversion element according to (1), wherein the photoelectric conversion material is an organic semiconductor.

(3) The photoelectric conversion element according to (2), wherein the matrix material is an organic semiconductor or an inorganic semiconductor.

(4) The photoelectric conversion element according to any one of (1) to (3), wherein the mixed layer is a layer mixed after vaporizing the photoelectric conversion material and the matrix material in a vacuum. Photoelectric conversion element.

(5) The photoelectric conversion element according to any one of (1) to (4), wherein both of the pair of electrodes are transparent electrodes.

(6) The photoelectric conversion element according to any one of (1) to (5), wherein the photoelectric conversion unit is configured to perform photoelectric conversion from one of the pair of electrodes when a voltage is applied between the pair of electrodes. A photoelectric conversion element comprising a first charge blocking layer for suppressing charge injection into a layer between the one electrode and the photoelectric conversion layer.

(7) The photoelectric conversion element according to (6), wherein the photoelectric conversion unit injects charges from the other of the pair of electrodes into the photoelectric conversion layer when a voltage is applied between the pair of electrodes. A photoelectric conversion element comprising a second charge blocking layer to be suppressed between the other electrode and the photoelectric conversion layer.

(8) The photoelectric conversion element according to any one of (1) to (7), wherein a value obtained by dividing an externally applied voltage between the pair of electrodes by a distance between the pair of electrodes is 1. The photoelectric conversion element which is 0.0 * 10 < ⁵ > V / cm-1.0 * 10 < ⁷ > V / cm.

(9) The photoelectric conversion element according to any one of (1) to (8), wherein the photoelectric conversion material is an organic semiconductor having a maximum peak of an absorption spectrum in a near infrared region.

(10) The photoelectric conversion element according to (9), wherein the photoelectric conversion material is transparent to light in a visible range.

(11) The photoelectric conversion element according to (10), wherein the photoelectric conversion material is SnPc.

(12) The photoelectric conversion element according to any one of (1) to (8), wherein at least one of the photoelectric conversion units is formed on the upper side, the semiconductor substrate is formed in the semiconductor substrate, An electric charge accumulating unit for accumulating electric charges generated in the photoelectric conversion layer of the photoelectric conversion unit, an electrode for extracting the electric charge from the pair of electrodes of the photoelectric conversion unit, and the electric charge accumulating unit are electrically connected. A photoelectric conversion element provided with a connection part connected to.

(13) The photoelectric conversion element according to (12), wherein the semiconductor substrate absorbs light transmitted through the photoelectric conversion layer of the photoelectric conversion unit, and generates a charge corresponding to the light. A photoelectric conversion element including an in-substrate photoelectric conversion unit for accumulation.

(14) The photoelectric conversion element according to (13), wherein the in-substrate photoelectric conversion unit is a plurality of photodiodes that are stacked in the semiconductor substrate and absorb light of different colors.

(15) The photoelectric conversion element according to (13), wherein the in-substrate photoelectric conversion unit absorbs light of different colors arranged in a direction perpendicular to an incident direction of incident light in the semiconductor substrate. A photoelectric conversion element that is a plurality of photodiodes.

(16) The photoelectric conversion element according to (14) or (15), wherein the photoelectric conversion unit stacked above the semiconductor substrate is one, and the plurality of photodiodes are light in a blue wavelength region. A blue photodiode that absorbs light and a red photodiode that absorbs light in the red wavelength range, wherein the photoelectric conversion layer of the photoelectric conversion unit absorbs light in the green wavelength range .

(17) The photoelectric conversion element according to any one of (12) to (15), wherein any one of the at least one photoelectric conversion units has a maximum absorption spectrum in a near infrared region. A photoelectric conversion element that is an organic semiconductor with a peak.

(18) The photoelectric conversion element according to (17), wherein the photoelectric conversion material is transparent to light in a visible range.

(19) The photoelectric conversion element according to (18), wherein the photoelectric conversion material is SnPc.

(20) A solid-state imaging device in which a large number of photoelectric conversion elements according to any one of (12) to (19) are arranged in an array, and is stored in the charge storage section of each of the multiple photoelectric conversion elements. A solid-state imaging device comprising a signal readout unit that reads out a signal corresponding to the charge.

(21) A solid-state imaging device in which a large number of photoelectric conversion devices according to any one of (1) to (11) are arranged in an array, which is formed above the semiconductor substrate and absorbed by the photoelectric conversion layer. A color filter layer that transmits light in a wavelength region different from the wavelength region of the light to be transmitted, and a light that is transmitted through the color filter layer and the photoelectric conversion layer, and is formed in the semiconductor substrate below the photoelectric conversion layer. A solid-state device including a photoelectric conversion element that generates a charge corresponding to the light, and a signal reading unit that reads a signal corresponding to the charge generated in the photoelectric conversion layer and a signal corresponding to the charge generated in the photoelectric conversion element. Image sensor.

(22) The solid-state imaging device according to (21), wherein the color filter layer is formed above the photoelectric conversion layer.

(23) The solid-state imaging device according to (22), wherein the color filter layer includes a plurality of color filters corresponding to each of the plurality of photoelectric conversion elements, and the plurality of color filters have different wavelengths. Solid-state imaging device classified into a plurality of types of color filters that transmit light in the region.

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element which can make an absorption spectrum sharp and can make dark current low can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a photoelectric conversion element according to an embodiment of the present invention.
A photoelectric conversion element A shown in FIG. 1 includes a lower electrode 11, an upper electrode 13 facing the lower electrode 11, a photoelectric conversion layer 12a provided between the lower electrode 11 and the upper electrode 13, a lower electrode 11, At least a photoelectric conversion unit including an electron blocking layer 12b provided between the photoelectric conversion layer 12a and a hole blocking layer 12c provided between the upper electrode 13 and the photoelectric conversion layer 12a is provided. The photoelectric conversion element A applies light from above the upper electrode 13 and applies a bias voltage between the lower electrode 11 and the upper electrode 13 with the light applied, whereby the charge generated in the photoelectric conversion layer 12a is transferred to the lower electrode. 11 or the upper electrode 13, and a signal corresponding to the collected charges can be taken out to the outside.

The upper electrode 13 is a transparent electrode made of a conductive material that is transparent to light in the wavelength range of 400 nm to 2500 nm, and is made of, for example, ITO. In this specification, “transparent to light of a certain wavelength” means that light of that wavelength is transmitted by about 70% or more. A bias voltage is applied to the upper electrode 13 by a wiring (not shown). The polarity of the bias voltage is determined so that electrons move to the upper electrode 13 and holes move to the lower electrode 11 among charges generated in the photoelectric conversion layer 12a. Of course, the bias voltage may be set so that holes move to the upper electrode 13 and electrons move to the lower electrode 11 among the charges generated in the photoelectric conversion layer 12a. The bias voltage is divided by the distance between the lower electrode 11 and the upper electrode 13 so that the value is in the range of 1.0 × 10 ⁵ V / cm to 1.0 × 10 ⁷ V / cm. It is desirable to determine the value.

  The lower electrode 11 may be an electrode made of a conductive material. However, as will be described later, since the incident light may be transmitted therebelow, a transparent electrode may be used in the same manner as the upper electrode 11. desirable. The lower electrode 11 is made of, for example, ITO.

  In order to sharpen the absorption spectrum, the photoelectric conversion layer 12a mainly absorbs light in a specific wavelength region and generates a charge corresponding to the light, and the specific wavelength region includes the specific wavelength region. It is composed of a mixed layer with one kind of matrix material that is transparent to light in a wavelength range wider than the specific wavelength range and has a property of transporting charges generated in the photoelectric conversion material.

  A photoelectric conversion material that absorbs light in a specific wavelength range with a sharp absorption spectrum in a solution state is mixed with a matrix material that has a charge transport property that is transparent to the light in the specific wavelength range. Is referred to as a matrix blend method), the formation of aggregates between molecules of the photoelectric conversion material is suppressed. Further, since the matrix material is transparent to light in a specific wavelength region, the influence on the absorption spectrum of the photoelectric conversion material is small. Therefore, by forming the photoelectric conversion layer 12a by the matrix blend method, an absorption spectrum equivalent to the absorption spectrum of the solution-state photoelectric conversion material can be realized. The reason why the matrix material has the charge transporting property is that it is necessary to move the charges generated in the photoelectric conversion material to the lower electrode 11 and the upper electrode 13.

  In the matrix blend method, for example, the effect can be obtained simply by dispersing the crystal particles of the photoelectric conversion material in a matrix material such as a polymer binder by using a coating method or the like. However, in such a method, the effect is small. . Therefore, the photoelectric conversion material and the matrix material are vaporized in a vacuum so that there is no association between molecules, and then the conditions are determined so that these vaporized materials are mixed immediately before they are adsorbed on the substrate. Thus, a photoelectric conversion layer having a small interaction between molecules of the photoelectric conversion material can be formed, and the above effect can be increased.

  Since the photoelectric conversion element A is applied to an imaging element, as a photoelectric conversion material used for the photoelectric conversion layer 12a, light (B light) in a blue (B) wavelength range (wavelength of about 400 nm to 500 nm) is mainly used. Absorbing B photoelectric conversion material, mainly G photoelectric conversion material that absorbs light (G light) in the wavelength range of green (G) (wavelength of about 500 nm to 600 nm), mainly red (R) wavelength range (wavelength of about 550 nm to 700 nm) R photoelectric conversion material that absorbs light (R light), IR photoelectric conversion material that mainly absorbs light (IR light) in the near infrared (IR) wavelength region (wavelength of about 700 nm to 2500 nm), and the like. Further, these photoelectric conversion materials are preferably organic semiconductors in consideration of photoelectric conversion efficiency and the like.

  As the B photoelectric conversion material, for example, a merocyanine compound or a porphyrin compound can be used. For the G photoelectric conversion material, for example, a quinacridone compound or a merocyanine compound can be used. As the R photoelectric conversion material, for example, a squarylium compound, a croconium compound, a phthalocyanine compound, and a merocyanine compound can be used. For the IR photoelectric conversion material, for example, tin phthalocyanine (SnPc) can be used.

  Note that the matrix material mixed with the photoelectric conversion material by the matrix blend method is not limited to one type, and the same effect can be obtained by using a plurality of types. When the photoelectric conversion material used in the matrix blend method is a p-type semiconductor, the matrix material is preferably an n-type semiconductor. Conversely, when the photoelectric conversion material is an n-type semiconductor, the matrix material is preferably a p-type semiconductor. . In particular, as the matrix material, it is preferable to use a total of three types including a p-type matrix material, an n-type matrix material, and either a p-type matrix material or an n-type matrix material.

  The matrix material may be an organic semiconductor or an inorganic semiconductor that satisfies the above-described conditions. However, the matrix material may be mixed with all of the B photoelectric conversion material, the G photoelectric conversion material, the R photoelectric conversion material, and the IR photoelectric conversion material. Considering that, when a thin film is formed on a substrate with a thickness of 100 nm, the thin film is transparent to light in the wavelength range from about 400 nm to about 2500 nm, and can transport holes and / or electrons. Preferably. Materials satisfying such conditions are listed in Chemical Formulas 1 to 11 below.

  The electron blocking layer 12b suppresses an increase in dark current due to electrons being injected from the lower electrode 11 into the photoelectric conversion layer 12a when a bias voltage is applied between the lower electrode 11 and the upper electrode 13. Is provided to do.

  An electron donating organic material can be used for the electron blocking layer 12b. Specifically, in a low molecular material, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) or 4,4′-bis [N Aromatic diamine compounds such as-(naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Polyphyrin compounds, triazole derivatives, oxa Use of zazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. As the polymer material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be used.

  The thickness of the electron blocking layer 12b is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably 50 nm or more and 100 nm or less. This is because if the thickness is too thin, the dark current suppressing effect is lowered, and if it is too thick, the photoelectric conversion efficiency is lowered.

  The selection range of the material actually used for the electron blocking layer 12b is defined by the material of the adjacent electrode and the material of the adjacent photoelectric conversion layer. The electron affinity (Ea) is 1.3 eV or more larger than the work function (Wf) of the material of the adjacent electrode, and has an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion layer. Things are good.

  When a bias voltage is applied between the lower electrode 11 and the upper electrode 13, the hole blocking layer 12c increases the dark current by injecting holes from the upper electrode 13 into the photoelectric conversion layer 12a. It is provided to suppress this.

  An electron-accepting organic material can be used for the hole blocking layer 12c. As an electron-accepting material, fullerenes such as C60 and C70, carbon nanotubes, derivatives thereof, 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) ) And other oxadiazole derivatives, anthraquinodimethane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8) -Quinolinato) Aluminum complexes, distyrylarylene derivatives, silole compounds and the like can be used.

  The thickness of the hole blocking layer 12c is preferably 10 nm to 200 nm, more preferably 30 nm to 150 nm, and particularly preferably 50 nm to 100 nm. This is because if this thickness is too thin, the dark current suppressing effect is lowered, and if it is too thick, the photoelectric conversion efficiency is lowered.

  The selection range of the material actually used for the hole blocking layer 12c is determined by the material of the adjacent electrode and the material of the adjacent photoelectric conversion layer. The ionization potential (Ip) is 1.3 eV or more larger than the work function (Wf) of the material of the adjacent electrode, and Ea is equal to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion layer. Things are good.

  In the case where the bias voltage is set so that holes out of the charges generated in the photoelectric conversion layer 12a move to the upper electrode 13 and electrons move to the lower electrode 11, the electron blocking layer 12b and the holes What is necessary is just to reverse the position of the blocking layer 12c. Moreover, it is not necessary to provide both the electron blocking layer 12b and the hole blocking layer 12c. If either one is provided, a certain dark current suppressing effect can be obtained.

  Hereinafter, a configuration example of a solid-state imaging element using the photoelectric conversion element A of FIG. 1 will be described.

(First configuration example)
FIG. 2 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion element A shown in FIG. 1, and is a diagram illustrating a first configuration example. In FIG. 2, the same components as those in FIG. The solid-state imaging device 100 includes a large number of one pixel shown in FIG. 2 arranged in an array on the same plane, and can generate one pixel data of image data based on a signal obtained from the one pixel. .

  The solid-state imaging device 100 shown in FIG. 2 has a configuration in which the photoelectric conversion unit shown in FIG. 1 is stacked above the p-type silicon substrate 1 with the insulating layer 7 interposed therebetween with the lower electrode 11 facing the p-type silicon substrate 1 side. It has become. However, in this photoelectric conversion unit, a bias voltage is applied to the lower electrode 11 so that electrons generated in the photoelectric conversion layer 12 a move to the upper electrode 13 and holes move to the lower electrode 11. . The photoelectric conversion material of the photoelectric conversion layer 12a is a G photoelectric conversion material. Further, since the upper electrode 13 is an electrode for extracting electrons, the upper electrode 13 is divided for each pixel. However, the components other than the upper electrode 13 of the photoelectric conversion unit are configured in a single sheet common to all pixels. It has become. The lower electrode 11 is a transparent electrode because it is necessary to transmit light below it.

  When an organic semiconductor is used as the photoelectric conversion material of the photoelectric conversion layer 12a, most of the electrons generated in the photoelectric conversion layer 12a are generated in the vicinity of the upper electrode 13. Therefore, when an electron is taken out by the lower electrode 11, the electron moving distance Becomes longer, and the amount of electrons that can be extracted by recombination or the like decreases. Therefore, in order to prevent electrons from moving for a long distance, in the solid-state imaging device 100, the upper electrode 13 is used as an electrode for collecting electrons. By doing so, it is possible to increase the external quantum efficiency by shortening the moving distance of electrons, and to improve the sensitivity.

  A light shielding film 14 is formed on the upper electrode 13, and a transparent protective film 15 is formed thereon. 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 2 are formed in this order from the shallower side. Has been. 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 for absorbing B light (about 0.2 μm). Therefore, the n region 4 and the p region 3 absorb B 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 R light (about 2 μm). Therefore, the n region 2 and the p-type silicon substrate 1 absorb R 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 upper electrode 13 through a connection portion 9 made of a conductive material such as aluminum, and accumulates electrons collected by the upper electrode 13 through the connection portion 9. The connection portion 9 is electrically insulated by the insulating film 8 except for the upper electrode 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 is photoelectrically converted by the photoelectric conversion layer 12a, and B light and R light are photoelectrically converted by the B photodiode and the R photodiode in the p-type silicon substrate 1 to perform color imaging. it can. In addition, another photoelectric conversion unit is further stacked on the photoelectric conversion unit above the p-type silicon substrate 1, and an n + region for accumulating electrons generated in the photoelectric conversion unit is formed in the silicon substrate 1. By using an IR photoelectric conversion material (for example, SnPc) that is transparent to visible light having a wavelength of 400 nm to 700 nm as the photoelectric conversion material of the photoelectric conversion unit, infrared imaging and color imaging can be performed simultaneously. . Such a solid-state image sensor can be used for an endoscope.

  Note that a signal corresponding to one pixel data of the image data can be obtained by one pixel shown in FIG. 2, so that one pixel can be referred to as one photoelectric conversion element.

(Second configuration example)
In the second configuration example, in the solid-state imaging device illustrated in FIG. 2, two photodiodes are not stacked in the p-type silicon substrate 1, but in two directions perpendicular to the incident direction of incident light. Diodes are arranged so that light of two colors is detected in the p-type silicon substrate 1.

  FIG. 3 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion element having the configuration shown in FIG. 1, and is a diagram showing a second configuration example. 3, the same components as those in FIG. 2 are denoted by the same reference numerals.

  In one pixel of the solid-state imaging device 200 illustrated in FIG. 3, a light shielding film 34 having an opening is formed on the upper electrode 13, and the light receiving region of the photoelectric conversion layer 12 a is limited by the light shielding film 34.

  On the surface of the p-type silicon substrate 1 below the opening of the light shielding film 34, a B photodiode composed of a p region 19 and an n region 18 and an R photodiode composed of a p region 21 and an n region 20 are p-type silicon substrate 1. It is formed side by side on the surface. An arbitrary direction on the surface of the p-type silicon substrate 1 is a direction perpendicular to the incident direction of incident light.

  Above the B photodiode composed of the p region 19 and the n region 18, a color filter 28 that transmits B light is formed through the transparent insulating film 7, and the lower electrode 11 is formed thereon. Above the R photodiode composed of the p region 21 and the n region 20, a color filter 29 that transmits R light through the insulating film 7 is formed, and the lower electrode 11 is formed thereon. The periphery of the color filters 28 and 29 is covered with an insulating film.

  The B photodiode composed of 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 R 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 6 is formed in a portion shielded from light by the light shielding film 34 on the surface of the p-type silicon substrate 1, and the n + region 6 is surrounded by the p region 5.

  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) made of an n channel MOS transistor formed in the p-type silicon substrate 1 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 1, and the electrons accumulated in the n + region 6 5 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 5 and output to the outside of the solid-state imaging device 200. Each MOS circuit is connected to a signal readout pad (not shown) by wiring 35.

  Signal reading may be performed 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 6 are read out to the charge transfer channel formed in the p-type silicon substrate 1, transferred to the amplifier, and the amplifier responds to the electrons. A configuration in which a signal is output may be used.

  With this configuration, the G light is photoelectrically converted by the photoelectric conversion layer 12a, and the B light and the R light are converted by the B photodiode and the R photodiode in the p-type silicon substrate 1 in the same manner as the solid-state imaging device 100 of FIG. Color imaging can be performed by photoelectric conversion. In the p-type silicon substrate 1, B photodiodes, R photodiodes, and G photodiodes that detect G light are arranged on the same plane, and the photoelectric conversion material of the photoelectric conversion unit above the silicon substrate 1 is made visible light. By using a transparent IR photoelectric conversion material (for example, SnPc), infrared imaging and color imaging can be performed simultaneously.

  Note that a signal corresponding to one pixel data of the image data is obtained by one pixel shown in FIG. 3, and thus this one pixel can be referred to as one photoelectric conversion element.

(Third configuration example)
In the third configuration example, a plurality (three in this case) of photoelectric conversion units stacked above the silicon substrate 1 in FIG. 2 are configured.
FIG. 4 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion element having the configuration shown in FIG. 1, and is a diagram showing a third configuration example. In FIG. 4, the same components as those in FIG.
In the solid-state imaging device 300 shown in FIG. 4, a first photoelectric conversion unit is stacked above the silicon substrate 1 with an insulating film 7 interposed therebetween with the lower electrode 11 facing the substrate 1, and an insulating film 60 is interposed therebetween. The second photoelectric conversion part is stacked with the lower electrode 11 facing the substrate 1, and the third photoelectric conversion part is stacked thereon with the insulating film 61 interposed therebetween with the lower electrode 11 facing the substrate 1 side. It has a configuration. A light shielding film 68 is formed on the upper electrode 13 of the third photoelectric conversion unit, and a transparent protective film 67 is formed thereon.

  In the example of FIG. 4, the photoelectric conversion material of the first photoelectric conversion unit is the R photoelectric conversion material, the photoelectric conversion material of the second photoelectric conversion unit is the G photoelectric conversion material, and the photoelectric conversion material of the third photoelectric conversion unit is The photoelectric conversion material is a B photoelectric conversion material. Hereinafter, the first photoelectric conversion unit is referred to as an R photoelectric conversion unit, the second photoelectric conversion unit is referred to as a G photoelectric conversion unit, and the third photoelectric conversion unit is referred to as a B photoelectric conversion unit. The stacking order of the R photoelectric conversion unit, the G photoelectric conversion unit, and the B photoelectric conversion unit is not limited to that illustrated in FIG.

  N + regions 43, 45, and 47 are formed in portions of the silicon substrate 1 that are shielded from light by the light shielding film 68, and each region is surrounded by p regions 42, 44, and 46.

  The n + region 43 is electrically connected to the upper electrode 13 of the R photoelectric conversion portion via a connection portion 54 made of a metal such as aluminum or tungsten, and is collected by the upper electrode 13 via the connection portion 54. Accumulate electrons. The connection portion 54 is electrically insulated by the insulating film 51 except for the upper electrode 13 and the n + region 43.

  The n + region 45 is electrically connected to the upper electrode 13 of the G photoelectric conversion portion via a connection portion 53 made of a metal such as aluminum or tungsten, and is collected by the upper electrode 13 via the connection portion 53. Accumulate electrons. The connection portion 53 is electrically insulated by the insulating film 50 except for the upper electrode 13 and the n + region 45.

  The n + region 47 is electrically connected to the upper electrode 13 of the B photoelectric conversion portion via a connection portion 52 made of a metal such as aluminum or tungsten, and is collected by the upper electrode 13 via the connection portion 52. Accumulate electrons. The connection portion 52 is electrically insulated by an insulating film 49 except for the upper electrode 13 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. Each MOS circuit is connected to a signal readout pad (not shown) by wiring 55. Signal reading may be performed by a CCD and an amplifier instead of a MOS circuit. That is, it is possible to read the electrons accumulated in the n + regions 43, 45 and 47 to the charge transfer channel formed in the silicon substrate 1, transfer them to the amplifier, and output a signal corresponding to the electrons from the amplifier. good.

  According to such a configuration, color imaging can be performed. In addition, another photoelectric conversion part is provided between the B photoelectric conversion part of FIG. 4 and the light shielding film 68, and the photoelectric conversion material of this photoelectric conversion part shall be an IR photoelectric conversion material transparent to visible light. Thus, infrared imaging and color imaging can be performed simultaneously.

  Note that a signal corresponding to one pixel data of the image data can be obtained by one pixel shown in FIG. 4, so that one pixel can be referred to as one photoelectric conversion element.

(Fourth configuration example)
FIG. 5 is a schematic cross-sectional view of a solid-state image sensor using the photoelectric conversion element having the configuration shown in FIG. 1, and is a diagram illustrating a fourth configuration example.

  A p-well layer 102 is formed on the n-type silicon substrate 101. Hereinafter, the n-type silicon substrate 101 and the p-well layer 102 are collectively referred to as a semiconductor substrate. A color filter 113r that mainly transmits R light, a color filter 113g that mainly transmits G light, and a color filter that mainly transmits B light in a row direction on the same plane above the semiconductor substrate and in a column direction perpendicular thereto. A large number of three types of color filters 113b are arranged.

  A known material can be used for the color filter 113r, but such a material transmits part of IR light in addition to R light. A known material can be used for the color filter 113g, but such a material transmits part of IR light in addition to G light. A known material can be used for the color filter 113b, but such a material transmits part of IR light in addition to B light.

  As the arrangement of the color filters 113r, 113g, 113b, a color filter arrangement (Bayer arrangement, vertical stripe, horizontal stripe, etc.) used in a known single-plate solid-state imaging device can be adopted.

  An n-type impurity region (hereinafter referred to as an n region) 103r is formed in the p well layer 102 below the color filter 113r so as to correspond to the color filter 113r, and a pn junction between the n region 103r and the p well layer 102 is formed. Thus, an R photodiode corresponding to the color filter 113r is configured.

  An n region 103g is formed in the p well layer 102 below the color filter 113g so as to correspond to the color filter 113g, and the G region corresponding to the color filter 113g is formed by a pn junction between the n region 103g and the p well layer 102. A photodiode is configured.

  An n region 103b is formed in the p well layer 102 below the color filter 113b so as to correspond to the color filter 113b, and B corresponding to the color filter 113b is formed by a pn junction between the n region 103b and the p well layer 102. A photodiode is configured.

  A lower electrode 11 divided corresponding to each of the color filters 113r, 113g, 113b is formed above each of the n regions 103r, g, b. The lower electrode 11 is a transparent electrode and is made of, for example, ITO.

  On the lower electrode 11, an electron blocking layer 12b, a photoelectric conversion layer 12a, a hole blocking layer 12c, and an upper electrode 13 are laminated in this order. The material constituting the photoelectric conversion layer 12b is an IR photoelectric conversion material. In the solid-state imaging device of FIG. 6, a bias voltage is applied to the upper electrode 13 so that electrons generated in the photoelectric conversion layer 12 a move to the lower electrode 11 and holes move to the upper electrode 13.

  A photoelectric conversion element corresponding to the color filter 113r is formed by the lower electrode 11 corresponding to the color filter 113r, the upper electrode 13 opposed thereto, and a part of the photoelectric conversion layer 12a sandwiched therebetween. Hereinafter, since this photoelectric conversion element is formed on a semiconductor substrate, it is referred to as an R-substrate photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 113g is formed by the lower electrode 11 corresponding to the color filter 113g, the upper electrode 13 opposed thereto, and a part of the photoelectric conversion layer 12a sandwiched therebetween. Hereinafter, since this photoelectric conversion element is formed on a semiconductor substrate, it is referred to as a G-substrate photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 113b is formed by the lower electrode 11 corresponding to the color filter 113b, the upper electrode 13 opposed thereto, and a part of the photoelectric conversion layer 12a sandwiched therebetween. Hereinafter, since this photoelectric conversion element is formed on a semiconductor substrate, it is referred to as a B-substrate photoelectric conversion element.

  Next to the n region 103r in the p-well layer 102 is a high-concentration n-type impurity region (hereinafter referred to as n + region) 104r for accumulating charges generated in the photoelectric conversion layer 12a of the photoelectric conversion element on the R substrate. Is formed. Note that a light shielding film is preferably provided over the n + region 104r in order to prevent light from entering the n + region 104r.

  Next to the n region 103g in the p well layer 102, an n + region 104g for accumulating charges generated in the photoelectric conversion layer 12a of the photoelectric conversion element on the G substrate is formed. In order to prevent light from entering the n + region 104g, a light shielding film is preferably provided on the n + region 104g.

  Next to the n region 103b in the p well layer 102, an n + region 104b for accumulating charges generated in the photoelectric conversion layer 12a of the photoelectric conversion element on the B substrate is formed. Note that a light shielding film is preferably provided over the n + region 104b in order to prevent light from entering the n + region 104b.

  A contact portion 106r made of a metal such as aluminum is formed on the n + region 104r, and a lower electrode 11 is formed on the contact portion 106r. The n + region 104r and the lower electrode 11 are electrically connected by the contact portion 106r. ing. The contact portion 106r is embedded in the transparent insulating layer 107.

  A contact portion 106g made of a metal such as aluminum is formed on the n + region 104g, and a lower electrode 11 is formed on the contact portion 106g. The n + region 104g and the lower electrode 11 are electrically connected by the contact portion 106g. ing. The contact portion 106g is embedded in the insulating layer 107.

  A contact portion 106b made of a metal such as aluminum is formed on the n + region 104b, and a lower electrode 11 is formed on the contact portion 106b. The n + region 104b and the lower electrode 11 are electrically connected by the contact portion 106b. ing. The contact portion 106 b is embedded in the insulating layer 107.

  The regions other than the n regions 103r, 103g, and 103b and the n + regions 104r, 104g, and 104b formed in the p well layer 102 correspond to the charges generated by the R photodiode and accumulated in the n region 103r. A signal reading unit 105r for reading a signal and a signal corresponding to the charge accumulated in the n + region 104r, and a signal corresponding to the charge generated in the G photodiode and accumulated in the n region 103g and accumulated in the n + region 104g A signal reading unit 105g for reading a signal corresponding to the generated charge, a signal corresponding to the charge generated in the B photodiode and accumulated in the n region 103b, and a signal corresponding to the charge accumulated in the n + region 104b And a signal reading unit 105b for reading out each of the signals. Each of the signal readout units 105r, 105g, and 105b can adopt a known configuration using a CCD or a MOS circuit. In order to prevent light from entering the signal reading units 105r, 105g, and 105b, it is preferable to provide a light shielding film on the signal reading units 105r, 105g, and 105b.

  A protective layer 112 is formed on the upper electrode 11, and color filters 113r, 113g, and 113b are formed on the protective layer 112. An n region 103r corresponding to each of the color filters 113r, 113g, and 113b is formed on each of the color filters 113r, 113g, and 113b. , 103g and 103b are formed with microlenses 114 for condensing light.

  In the solid-state imaging device 400 having the above-described configuration, IR light out of light transmitted through the color filter 113r out of incident light is absorbed by the photoelectric conversion layer 12a, and charges corresponding to the IR light are generated here. Similarly, IR light out of the light transmitted through the color filter 113g in the incident light is absorbed by the photoelectric conversion layer 12a, and charges corresponding to the IR light are generated here. Similarly, IR light out of the light transmitted through the color filter 113b in the incident light is absorbed by the photoelectric conversion layer 12a, and charges corresponding to the IR light are generated here.

  When a predetermined bias voltage is applied to the lower electrode 11 and the upper electrode 13, charges generated in the photoelectric conversion layer 12a constituting the photoelectric conversion element on the R substrate move to the n + region 104r and are accumulated therein. Then, a signal corresponding to the charge accumulated in the n + region 104r is read by the signal reading unit 105r and output to the outside of the solid-state imaging device 400. Similarly, charges generated in the photoelectric conversion layer 12a constituting the photoelectric conversion element on the G substrate move to the n + region 104g and are accumulated therein. A signal corresponding to the charge accumulated in the n + region 104g is read out by the signal reading unit 105g and output to the outside of the solid-state imaging device 400. Similarly, the charge generated in the photoelectric conversion layer 12a constituting the photoelectric conversion element on the B substrate moves to the n + region 104b and is accumulated therein. Then, a signal corresponding to the electric charge accumulated in the n + region 104b is read by the signal reading unit 105b and output to the outside of the solid-state imaging device 400.

  The R light that has passed through the color filter 113r and has passed through the photoelectric conversion layer 12a is incident on the R photodiode, and charges corresponding to the amount of incident light are accumulated in the n region 103r. Similarly, the G light transmitted through the color filter 113g and transmitted through the photoelectric conversion layer 12a enters the G photodiode, and charges corresponding to the amount of incident light are accumulated in the n region 103g. Similarly, the B light transmitted through the color filter 113b and transmitted through the photoelectric conversion layer 12a enters the B photodiode, and charges corresponding to the amount of incident light are accumulated in the n region 103b. The charges accumulated in the n regions 103r, 103g, and 103b are read out by the signal reading units 105r, 105g, and 105b and output to the outside of the solid-state imaging device 400.

  Since the arrangement of signals read from the n regions 103r, 103g, and 103b is the same as the arrangement of signals output from the Bayer arrangement single-plate color solid-state imaging device, signal processing used in the single-plate color solid-state imaging device By performing the above, it is possible to generate color image data in which one pixel data has data of three color components of R, G, and B. Further, infrared image data in which one pixel data has infrared color component data can be generated by signals read out and output from the n + regions 104r, 104g, and 104b.

  As described above, the solid-state imaging device 400 is configured to detect the R component signal corresponding to the charge generated in the R photodiode, the G component signal corresponding to the charge generated in the G photodiode, and the charge generated in the B photodiode. The corresponding B component signal, the IR component signal corresponding to the charge generated in the R substrate photoelectric conversion element, the IR component signal corresponding to the charge generated in the G substrate photoelectric conversion element, and the B substrate photoelectric An IR component signal corresponding to the charge generated in the conversion element can be output to the outside. For this reason, if the solid-state imaging device 400 is used, two types of image data of color image data and infrared image data can be obtained by one imaging. Therefore, this solid-state imaging device 400 can be used as an imaging device of an endoscope apparatus that requires an appearance image of a part to be inspected of a human body and an internal image of the part, for example.

  Examples of the present invention will be described below.

(Example 1)
A 25 mm square glass substrate with an ITO electrode was ultrasonically cleaned with acetone, semicoclean, and isopropyl alcohol (IPA) for 15 minutes. Finally, after IPA boiling cleaning, UV / O ₃ cleaning was performed. The substrate was moved to the organic vapor deposition chamber, and the pressure in the chamber was reduced to 1 × 10 ⁻⁴ Pa or less. Then, while rotating the substrate holder, 2-TNATA (tris (-(2-naphthyl) -phenyl-amino) triphenylamine) was deposited on the substrate as an electron blocking layer by a resistance heating method at a deposition rate of 0.5 to 1 kg / sec. Was deposited to a thickness of 1000 mm. Next, tin phthalocyanine purified by sublimation twice or more (manufactured by Aldrich Japan Co., Ltd.) and TMM-1 which has been subjected to sublimation purification are each kept at a deposition rate of 0.5 to 1 kg / sec by a resistance heating method so that the total becomes 700 kg. The photoelectric conversion layer was formed by vapor deposition. At this time, the ratio of the deposition rate of tin phthalocyanine and TMM-1 was 1: 1. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. Next, this substrate was transported to the sputtering chamber while maintaining a vacuum. Thereafter, ITO was deposited on the hole blocking layer so as to have a thickness of 50 mm while maintaining the interior at 1 × 10 ⁻⁴ Pa or less. The area of the photoelectric conversion region formed by the lower electrode and the upper electrode was 2 mm × 2 mm. Without exposing this board | substrate to air | atmosphere, it conveyed to the glove box which kept the water | moisture content and oxygen each 1 ppm or less, and sealed with the glass which put the moisture absorption agent using UV curable resin.

Using the device manufactured in this manner, the constant energy quantum efficiency measurement device (manufactured by Keithley 6430 for the source meter), the upper electrode is set to 5.0 × 10 ⁵ V / with the upper electrode as a positive bias with respect to the lower electrode. The IPCE was calculated by measuring the dark current value flowing when no light was irradiated and the photocurrent value flowing when the light was irradiated when an external electric field of cm was applied. The area of the photoelectric conversion region was irradiated with light from the upper electrode side in a region of 1.5 mmφ out of 2 mm × 2 mm. The amount of light irradiated was 50 μW / cm ² . About the absorption spectrum, it measured using the Hitachi spectrophotometer U-3310 about the photoelectric converting layer vapor-deposited on quartz.

(Example 2)
Substrate cleaning was performed under the same conditions as in Example 1, the substrate was moved to an organic vapor deposition chamber, and the chamber was depressurized to 1 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, 2-TNATA was deposited as an electron blocking layer on the substrate by a resistance heating method so as to have a thickness of 1000 mm at a deposition rate of 0.5 to 1 mm / sec. Next, quinacridone purified by sublimation twice or more (manufactured by DOJINDO) and TMM-2 subjected to sublimation purification were vapor-deposited by a resistance heating method so that the total deposition rate would be 0.5 to 1 mm / sec. Thus, a photoelectric conversion layer was formed. At this time, the ratio of the deposition rate of quinacridone and TMM-2 was 1: 1. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. An ITO film was formed thereon under the same conditions as in Example 1, and after further sealing, the same measurement as in Example 1 was performed. The absorption spectrum was similarly measured.

(Example 3)
Substrate cleaning was performed under the same conditions as in Example 1, the substrate was moved to an organic vapor deposition chamber, and the chamber was depressurized to 1 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, 2-TNATA was deposited as an electron blocking layer on the substrate by a resistance heating method so as to have a thickness of 1000 mm at a deposition rate of 0.5 to 1 mm / sec. Next, squarylium purified by sublimation twice or more and TMM-3 subjected to sublimation purification were vapor-deposited by a resistance heating method so that the total deposition rate would be 0.5 to 1 cm / sec. Formed. At this time, the ratio of the deposition rates of squarylium and TMM-3 was 1: 1. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. An ITO film was formed thereon under the same conditions as in Example 1, and after further sealing, the same measurement as in Example 1 was performed. The absorption spectrum was similarly measured.

(Comparative Example 1)
Substrate cleaning was performed under the same conditions as in Example 1, the substrate was moved to an organic vapor deposition chamber, and the chamber was depressurized to 1 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, 2-TNATA was deposited as an electron blocking layer on the substrate by a resistance heating method so as to have a thickness of 1000 mm at a deposition rate of 0.5 to 1 mm / sec. Next, tin phthalocyanine purified by sublimation twice or more (Aldrich Japan) is vapor-deposited by a resistance heating method so that the film thickness is 350 な が ら while maintaining the vapor deposition rate of 0.5 to 1 Å / sec to form a photoelectric conversion layer. did. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. An ITO film was formed thereon under the same conditions as in Example 1, and after further sealing, the same measurement as in Example 1 was performed. The absorption spectrum was similarly measured.

(Comparative Example 2)
The substrate was cleaned under the same conditions as in Example 1, the substrate was moved to the organic vapor deposition chamber, and the chamber was depressurized to 1 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, 2-TNATA was deposited as an electron blocking layer on the substrate by a resistance heating method so as to have a thickness of 1000 mm at a deposition rate of 0.5 to 1 mm / sec. Next, quinacridone purified by sublimation twice or more (DOJINDO) was vapor-deposited by a resistance heating method so that the film thickness was 350 Å while maintaining the vapor deposition rate at 0.5 to 1 Å / sec to form a photoelectric conversion layer. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. An ITO film was formed thereon under the same conditions as in Example 1, and after further sealing, the same measurement as in Example 1 was performed. The absorption spectrum was similarly measured.

(Comparative Example 3)
The substrate was cleaned under the same conditions as in Example 1, the substrate was moved to the organic vapor deposition chamber, and the chamber was depressurized to 1 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, 2-TNATA was deposited as an electron blocking layer on the substrate by a resistance heating method so as to have a thickness of 1000 mm at a deposition rate of 0.5 to 1 mm / sec. Next, squarylium purified by sublimation twice or more was vapor-deposited by a resistance heating method so that the film thickness was 350 Å while maintaining the vapor deposition rate at 0.5 to 1 Å / sec to form a photoelectric conversion layer. Subsequently, sublimated and refined Alq was vapor-deposited at a vapor deposition rate of 1 to 2 mm / sec to a thickness of 150 mm to form a hole blocking layer. An ITO film was formed thereon under the same conditions as in Example 1, and after further sealing, the same measurement as in Example 1 was performed. The absorption spectrum was similarly measured.

FIG. 6 is a graph showing absorption spectrum measurement results of the element of Example 1 and the element of Comparative Example 1.
As shown in FIG. 6, the absorption spectrum is greater when the photoelectric conversion layer is formed by mixing tin phthalocyanine and TMM-1 than when the photoelectric conversion layer is formed by vapor deposition of tin phthalocyanine alone. It has been proved that the absorption spectrum can be sharpened by the matrix blend method. The dark current value of Example 1 was 9.1 × 10 ⁻⁹ A / cm ² , the IPCE at a wavelength of 730 nm was 31%, and the dark current value of Comparative Example 1 was 7.2 × 10 ⁻⁷ A / cm ^2. IPCE at a wavelength of 720 nm was 30%. From this result, it was found that the dark current value can be lowered while the IPCE is maintained by adopting the matrix blend method.

FIG. 7 is a graph showing the results of absorption spectrum measurement of the device of Example 2 and the device of Comparative Example 2.
As shown in FIG. 7, the absorption spectrum is sharper when the photoelectric conversion layer is formed by mixing quinacridone and TMM-2 than when the photoelectric conversion layer is formed by vapor deposition of quinacridone alone. It has been proved that the absorption spectrum can be sharpened by the matrix blend method. The dark current value of Example 2 is 1.2 × 10 ⁻⁹ A / cm ² , the IPCE at a wavelength of 540 nm is 27%, and the dark current value of Comparative Example 2 is 3.4 × 10 ⁻⁸ A / cm ^2. IPCE at a wavelength of 560 nm was 27%. From this result, it was found that the dark current value can be lowered while the IPCE is maintained by adopting the matrix blend method.

FIG. 8 shows the results of absorption spectrum measurement of the device of Example 3 and the device of Comparative Example 3.
As shown in FIG. 8, the absorption spectrum is sharper when the photoelectric conversion layer is formed by mixing squarylium and TMM-3 than when the photoelectric conversion layer is formed by depositing only squarylium. It has been proved that the absorption spectrum can be sharpened by the matrix blend method. The dark current value of Example 3 was 2.3 × 10 ⁻⁹ A / cm ² , the IPCE at a wavelength of 660 nm was 37%, and the dark current value of Comparative Example 3 was 1.1 × 10 ⁻⁸ A / cm ^2. IPCE at a wavelength of 680 nm was 36%. From this result, it was found that the dark current value can be lowered while the IPCE is maintained by adopting the matrix blend method.

Sectional schematic diagram which shows schematic structure of the photoelectric conversion element which is embodiment of this invention 1 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion device having the configuration shown in FIG. 1 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion device having the configuration shown in FIG. 1 is a schematic cross-sectional view of one pixel of a solid-state imaging device using the photoelectric conversion device having the configuration shown in FIG. Cross-sectional schematic diagram for three pixels of a solid-state imaging device using the photoelectric conversion device having the configuration shown in FIG. The figure which showed the absorption-spectrum measurement result of the element of Example 1 and the element of the comparative example 1 The figure which showed the absorption-spectrum measurement result of the element of Example 2 and the element of the comparative example 2 The figure which showed the absorption-spectrum measurement result of the element of Example 3, and the element of the comparative example 3.

Explanation of symbols

11 Lower electrode 12a Photoelectric conversion layer 12b Electron blocking layer 12c Hole blocking layer 13 Upper electrode A Photoelectric conversion element

Claims (23)

A photoelectric conversion element having a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion layer disposed between the pair of electrodes, and applying a bias voltage between the pair of electrodes to extract a signal;
The photoelectric conversion layer mainly absorbs light in a specific wavelength range and generates a charge corresponding to the light, and a wider wavelength range than the specific wavelength range including the specific wavelength range A photoelectric conversion element comprising a mixed layer with at least one kind of matrix material that is transparent to the light and has a property of transporting charges generated in the photoelectric conversion material. The photoelectric conversion element according to claim 1,
The photoelectric conversion element whose said photoelectric conversion material is an organic semiconductor. The photoelectric conversion element according to claim 2,
A photoelectric conversion element in which the matrix material is an organic semiconductor or an inorganic semiconductor. The photoelectric conversion element according to any one of claims 1 to 3,
A photoelectric conversion element, wherein the mixed layer is a layer mixed after vaporizing the photoelectric conversion material and the matrix material in a vacuum. It is a photoelectric conversion element of any one of Claims 1-4, Comprising:
A photoelectric conversion element in which the pair of electrodes are both transparent electrodes. It is a photoelectric conversion element of any one of Claims 1-5, Comprising:
The photoelectric conversion unit includes a first charge blocking layer that suppresses charge injection from one of the pair of electrodes to the photoelectric conversion layer when a voltage is applied between the pair of electrodes. A photoelectric conversion element provided between the photoelectric conversion layer. The photoelectric conversion element according to claim 6,
The photoelectric conversion unit includes a second charge blocking layer for suppressing charge injection from the other of the pair of electrodes to the photoelectric conversion layer when a voltage is applied between the pair of electrodes. A photoelectric conversion element provided between the photoelectric conversion layer. It is a photoelectric conversion element of any one of Claims 1-7,
The photoelectric conversion element whose value which divided the voltage applied from the outside between the pair of electrodes by the distance between the pair of electrodes is 1.0 × 10 ⁵ V / cm to 1.0 × 10 ⁷ V / cm. It is a photoelectric conversion element of any one of Claims 1-8, Comprising:
A photoelectric conversion element, wherein the photoelectric conversion material is an organic semiconductor having a maximum absorption spectrum peak in the near infrared region. The photoelectric conversion element according to claim 9,
A photoelectric conversion element in which the photoelectric conversion material is transparent to visible light. The photoelectric conversion element according to claim 10,
The photoelectric conversion element whose said photoelectric conversion material is SnPc. It is a photoelectric conversion element of any one of Claims 1-8, Comprising:
A semiconductor substrate on which at least one photoelectric conversion unit is stacked;
A charge storage unit that is formed in the semiconductor substrate and stores charges generated in the photoelectric conversion layer of the photoelectric conversion unit;
A photoelectric conversion element provided with the connection part which electrically connects the electrode for taking out the said electric charge of the said pair of electrodes of the said photoelectric conversion part, and the said charge storage part. The photoelectric conversion element according to claim 12,
A photoelectric conversion element comprising an in-substrate photoelectric conversion unit that absorbs light transmitted through the photoelectric conversion layer of the photoelectric conversion unit in the semiconductor substrate, 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,
A 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 an incident direction of incident light in the semiconductor substrate. The photoelectric conversion element according to claim 14 or 15,
The photoelectric conversion unit stacked above the semiconductor substrate is one,
The plurality of photodiodes are a blue photodiode that absorbs light in a blue wavelength region and a red photodiode that absorbs light in a red wavelength region,
The photoelectric conversion element in which the photoelectric conversion layer of the photoelectric conversion unit absorbs light in a green wavelength region. It is a photoelectric conversion element of any one of Claims 12-15,
The photoelectric conversion element in which the photoelectric conversion material of any one of the at least one photoelectric conversion unit is an organic semiconductor having a maximum peak of an absorption spectrum in a near infrared region. The photoelectric conversion element according to claim 17,
A photoelectric conversion element in which the photoelectric conversion material is transparent to visible light. The photoelectric conversion element according to claim 18, wherein
The photoelectric conversion element whose said photoelectric conversion material is SnPc. A solid-state imaging device in which a large number of photoelectric conversion devices according to any one of claims 12 to 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 charge accumulation unit 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 1 are arranged in an array,
A color filter layer that is formed above the semiconductor substrate and transmits light in a wavelength range different from the wavelength range of light absorbed by the photoelectric conversion layer;
A photoelectric conversion element that is formed in the semiconductor substrate below the photoelectric conversion layer, absorbs light transmitted through the color filter layer and the photoelectric conversion layer, and generates a charge corresponding to the light;
A solid-state imaging device comprising: a signal reading unit that reads a signal corresponding to the charge generated in the photoelectric conversion layer and a signal corresponding to the charge generated in the photoelectric conversion element. The solid-state imaging device according to claim 21,
A solid-state imaging device in which the color filter layer is formed above the photoelectric conversion layer. The solid-state imaging device according to claim 22,
The color filter layer is composed of a number of color filters corresponding to each of a number of the photoelectric conversion elements,
A solid-state imaging device in which the plurality of color filters are classified into a plurality of types of color filters that transmit light in different wavelength ranges.

Images