JP6231435B2 - Solid-state image sensor - Google Patents

Description

  The present invention relates to a solid-state imaging device that generates a charge in response to received light and converts a visible light image into an electrical signal, and more particularly to a solid-state image that can improve heat resistance without causing bleeding in a captured image. The present invention relates to an image sensor.

  As an image sensor used in digital still cameras, digital video cameras, mobile phone cameras, endoscope cameras, etc., pixels including photodiodes are arranged on a semiconductor substrate such as a silicon chip. Solid-state imaging devices such as a CCD sensor and a CMOS sensor that acquire signal charges corresponding to generated photoelectrons with a CCD-type or CMOS-type readout circuit are widely known. Currently, development of photoelectric conversion elements using organic compounds is underway (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses an organic photoelectric conversion element having a structure in which a plurality of functional layers are stacked, such as a photoelectric conversion layer that absorbs light and generates charges, and an electron blocking layer that suppresses electron injection from an electrode. In order to produce a solid-state imaging device using such an organic photoelectric conversion device, it is necessary to perform formation of a color filter, a wire bonding step, and the like in addition to the formation of an organic compound layer and an electrode. In these steps, since the solid-state imaging device is heated to 200 ° C. or higher, the photoelectric conversion layer used for the imaging device needs to have heat resistance of 200 ° C. or higher. Therefore, Patent Document 2 discloses a method of mixing fullerene or a fullerene derivative in the electron blocking layer as a method for improving the heat resistance of the organic photoelectric conversion element.

JP 2007-88033 A JP 2012-94660 A

  However, when an electron blocking layer mixed with fullerene or a fullerene derivative described in Patent Document 2 comes into contact with an adjacent pixel electrode, there is a problem in that electron injection occurs from the pixel electrode to the electron blocking layer. As a result, charge exchange occurs between adjacent pixel electrodes, and blurring occurs in the captured image.

  An object of the present invention is to provide a solid-state imaging device capable of solving the problems based on the above-described prior art and improving heat resistance without causing blurring in a captured image.

  In order to achieve the above-mentioned object, an insulating layer provided on the surface of the substrate, a plurality of pixel electrodes provided immediately above the insulating layer, and a heat-resistant improving layer provided above the pixel electrode to improve heat resistance And an electron blocking layer that suppresses electron injection from the pixel electrode, a photoelectric conversion layer that is provided above the electron blocking layer and generates charges in response to received light, and photoelectric A heat-resistant improvement layer having a counter electrode provided above the conversion layer and shared by a plurality of pixel electrodes, and a signal readout circuit connected to the pixel electrodes and reading a signal corresponding to the charges collected by the pixel electrodes; Is a layer in which the material constituting the electron blocking layer is mixed with fullerene or a fullerene derivative, and the heat resistance improving layer is discontinuous at least at one position on the gap between the pixel electrodes. There is provided a solid-state imaging device that.

The heat resistance improving layer is a layer in which fullerene or a fullerene derivative and a material constituting an electron blocking layer are mixed, and a groove is preferably formed in an insulating layer between adjacent pixel electrodes.
The depth of the groove and _{T 1,} when the thickness of the heat-resistant improving layer and _{T 2,} it is preferable that _T 2 <T _1. Preferably the difference between the thickness _{T 2} and a depth _{T 1} is not less 5nm or more, and more preferably 10nm or more.
The angle theta ₁ between the surface and a line parallel to the straight line and the substrate connecting the starting point of the groove that is preferably 50 ° or more. The angle of the groove is more preferably from 50 ° to 60 °, and still more preferably from 50 ° to 55 °.
In the electron blocking layer, the angle of the recess formed in the region corresponding to the groove is preferably 30 ° or less, more preferably 20 ° or less, and further preferably 15 ° or less.
A configuration in which an insulator thicker than the pixel electrode is formed between adjacent pixel electrodes may be employed.

The heat resistance improving layer preferably contains fullerene or a fullerene derivative at a ratio of 30% to 70%. The photoelectric conversion layer is preferably made of an organic material.
The photoelectric conversion layer is preferably composed of a bulk hetero layer in which an n-type organic compound and a p-type organic compound are mixed.
The n-type organic compound is preferably fullerene or a fullerene derivative.
The bulk hetero layer preferably contains fullerene in a proportion of 30% to 80%. More preferably, the fullerene content is 50% to 80%, and the fullerene content is particularly preferably 65% to 75%.

  According to the present invention, heat resistance can be improved without degrading dark current, response speed, and conversion efficiency.

It is a typical sectional view showing the solid-state image sensing device of a 1st embodiment of the present invention. (A) is typical sectional drawing which shows the principal part of the solid-state image sensor of the 1st Embodiment of this invention, (b) is the photoelectric conversion element of the solid-state image sensor of the 1st Embodiment of this invention. It is a typical sectional view showing. (A) is a schematic diagram for demonstrating the angle of the groove part of the solid-state image sensor of the 1st Embodiment of this invention, (b) is the electron of the solid-state image sensor of the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the angle of a blocking layer. (A)-(d) is typical sectional drawing which shows the manufacturing method of the solid-state image sensor of the 1st Embodiment of this invention in order of a process. It is typical sectional drawing which shows the principal part of the solid-state image sensor of the 2nd Embodiment of this invention. (A)-(f) is typical sectional drawing which shows the manufacturing method of the solid-state image sensor of the 2nd Embodiment of this invention in order of a process. It is typical sectional drawing which shows the conventional solid-state image sensor. It is a graph which shows the relationship between the angle of the recessed part of an electronic blocking layer, and dark current.

Hereinafter, a solid-state imaging device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic cross-sectional view showing a solid-state imaging device according to the first embodiment of the present invention. FIG. 2A is a schematic cross-sectional view showing the main part of the solid-state imaging device of the first embodiment of the present invention, and FIG. 2B is a photoelectric diagram of the solid-state imaging device of the first embodiment of the present invention. It is typical sectional drawing which shows a conversion element.
In the present invention, “to” indicating a numerical range includes numerical values written on both sides. For example, x is a numerical value A to a numerical value B. The range of x is a range including the numerical value A and the numerical value B, and A ≦ x ≦ B in mathematical symbols.
The solid-state imaging device 10 shown in FIG. 1 can be used for an imaging apparatus such as a digital still camera or a digital video camera. Furthermore, it can also be used by being mounted on an imaging module such as an electronic endoscope and a mobile phone.

A solid-state imaging device 10 shown in FIG. 1 receives incident light L including at least visible light and converts a visible light image into an electrical signal. For example, the solid-state imaging device 10 includes a substrate 12, an insulating layer 14, a pixel electrode 16, a heat resistance improving layer 18, an electron blocking layer 20, a photoelectric conversion layer 22, a counter electrode 24, and a sealing layer 26. , Partition wall 27, color filter 28, light shielding layer 29, and overcoat layer 30.
A reading circuit 40 and a counter electrode voltage supply unit 42 are formed on the substrate 12. Note that the solid-state imaging device 10 is not limited to visible light to be converted into an electric signal, but may be one that converts light in a wavelength band other than visible light into an electric signal.

As the substrate 12, for example, a glass substrate or a semiconductor substrate such as Si is used. An insulating layer 14 made of an insulating material such as silicon nitride or silicon oxide is provided on the surface 12a of the substrate 12. A plurality of pixel electrodes 16 are arranged one-dimensionally or two-dimensionally immediately above the insulating layer 14, that is, on the surface 14 a of the insulating layer 14, with a gap 17 therebetween. A groove portion 15 is formed in a region of the insulating layer 14 corresponding to the gap 17 between the plurality of pixel electrodes 16. At the bottom of the groove portion 15, there is a remaining portion 19 made of the same material as the heat resistance improving layer 18.
A first connection portion 44 that connects the pixel electrode 16 and the readout circuit 40 is formed in the insulating layer 14. Further, a second connection portion 46 that connects the counter electrode 24 and the counter electrode voltage supply unit 42 is formed. The second connection portion 46 is formed at a position not connected to the pixel electrode 16 and the electron blocking layer 20. The first connection portion 44 and the second connection portion 46 are formed of a conductive material such as copper.

  In addition, a wiring layer 48 made of a conductive material for connecting the readout circuit 40 and the counter electrode voltage supply unit 42 to, for example, the outside of the solid-state imaging device 10 is formed inside the insulating layer 14. As described above, the circuit board 11 is formed by forming the pixel electrodes 16 connected to the first connection portions 44 on the surface 14 a of the insulating layer 14 on the substrate 12. The circuit board 11 is also referred to as a CMOS substrate.

Although the heat resistance improving layer 18 is provided on each pixel electrode 16, the heat resistance improving layer 18 is not provided in the gap 17 of the pixel electrode 16, and the heat resistance improving layers 18 are separated from each other and independent. The heat resistance improving layer 18 is not on the same surface on which the plurality of pixel electrodes 16 are provided, in this case, on the surface 14 a of the insulating layer 14. The heat resistance improving layer 18 may be discontinuous in at least one place on the gap 17 between the pixel electrodes 16. In other words, the heat resistance improving layer 18 is not required to be connected at least at one place with the gap 17 between the one pixel electrode 16. This prevents conduction between adjacent pixel electrodes 16.
The heat resistance improving layer 18 improves the heat resistance of the solid-state imaging device 10, and is composed of a mixture of fullerene or a fullerene derivative and a material constituting the electron blocking layer 20. For this reason, charges can move in the heat resistance improving layer 18.

An electron blocking layer 20 is provided so as to cover the heat resistance improving layer 18 and fill the gap 17 of the pixel electrode 16. The electron blocking layer 20 is a layer for suppressing electron injection from the pixel electrode 16 to the photoelectric conversion layer 22.
A photoelectric conversion layer 22 is provided on the electron blocking layer 20. The photoelectric conversion layer 22 receives the incident light L and generates a charge corresponding to the amount of light.

  The heat resistance improving layer 18 is a layer for improving the heat resistance of the solid-state imaging device 10. The heat resistance improving layer 18 is a layer obtained by mixing the material constituting the electron blocking layer 20 and fullerene or a fullerene derivative. The heat resistance improving layer 18 may be a layer in which the ratio of the organic material and fullerene or fullerene derivative is constant, or may be a gradation layer in which the ratio varies depending on the film thickness direction. By providing the heat resistance improving layer 18 between the pixel electrode 16 and the electron blocking layer 20, the heat resistance of the solid state imaging device 10 can be improved without lowering the photoelectric conversion efficiency, dark current characteristics, and light response speed of the solid state imaging device 10. Can be improved. Another functional layer may be provided between the electron blocking layer 20 and the heat resistance improving layer 18.

When C ₆₀ ratio of the fullerene or fullerene derivative refractory improving layer 18 is too large, the hole transport ability of the heat-improving layer 18 is lowered. Further, if the C ₆₀ ratio of the fullerene or fullerene derivative of the mixed film is too small, a sufficient heat resistance improvement effect cannot be obtained. The ratio of fullerene or fullerene derivative in the heat resistance improving layer 18 is preferably 30% to 70%. More preferably, it is 35% to 65%, and further preferably 40% to 60%. By setting the ratio in this region, both heat resistance and charge transportability can be achieved.
The thickness of the heat resistance improving layer 18 is preferably 5 nm or more in order to sufficiently cover the pixel electrode 16, and more preferably 10 nm or more. When the heat resistance improving layer 18 is too thick, there arises a problem that a supply voltage necessary for applying an appropriate electric field strength to the photoelectric conversion layer 22 is increased. For this reason, the thickness of the heat resistance improving layer 18 is preferably 30 nm or less, more preferably 20 nm or less, and further preferably 15 nm or less.

Since the heat resistance improving layer 18 contains fullerene or a fullerene derivative, electrons are injected from the adjacent pixel electrode 16. Therefore, when the heat resistance improving layer 18 is connected between adjacent pixel electrodes 16 as in the solid-state imaging device 100 illustrated in FIG. 7, that is, when the heat resistance improving layer 18 is continuous, the adjacent pixel electrodes 16 are There is a problem that short circuit occurs and charge exchange occurs between the pixel electrodes 16. However, the short circuit between adjacent pixels can be prevented by disconnecting the heat resistance improving layer 18 between adjacent pixel electrodes 16 as in the solid-state imaging device 10 shown in FIG. As a result, charge exchange between adjacent pixel electrodes 16 is prevented, and bleeding does not occur in the captured image.
In the solid-state image sensor 100 shown in FIG. 7, the same components as those in the solid-state image sensor 10 shown in FIG.

  The electron blocking layer 20 is a layer for preventing electrons from being injected from the electrode into the photoelectric conversion layer, and is composed of a single layer or a plurality of layers. The electron blocking layer 20 may be composed of a single organic material film, or may be composed of a mixed film of a plurality of different organic materials.

The electron blocking layer 20 is preferably made of a material having a high electron injection barrier from the adjacent pixel electrode 16 and a high hole transport property. As an electron injection barrier, the electron affinity of the electron blocking layer 20 is preferably 1 eV or less, more preferably 1.3 eV or more, and particularly preferably 1.5 eV or more than the work function of the adjacent pixel electrode 16. .
The electron blocking layer 20 preferably has a thickness of 20 nm or more in order to sufficiently suppress the contact between the pixel electrode 16 and the photoelectric conversion layer 22 and avoid the influence of defects or dust existing on the surface of the pixel electrode 16. More preferably, the thickness is 40 nm or more, and particularly preferably, the thickness is 60 nm or more.
When the electron blocking layer 20 is made too thick, the problem that the supply voltage necessary for applying an appropriate electric field strength to the photoelectric conversion layer becomes high and the carrier transport process in the electron blocking layer 20 is caused by the photoelectric conversion element. A problem occurs that adversely affects performance. The total thickness of the electron blocking layer 20 is preferably 300 nm or less, more preferably 200 nm or less, and still more preferably 100 nm or less.

When the electron blocking layer 20 is composed of a plurality of layers, the total film thickness of the electron blocking layer 20 is preferably 300 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less.
When the thickness of the electron blocking layer is in the above range, it is possible to suppress an increase in supply voltage necessary for applying an appropriate electric field strength to the photoelectric conversion layer. Further, the carrier transport process in the electron blocking layer does not adversely affect the performance of the solid-state imaging device.

The photoelectric conversion layer 22 is a layer that includes a photoelectric conversion material that generates an electric charge according to the amount of incident light L, for example, received light such as visible light. An organic compound can be used as the photoelectric conversion material.
The photoelectric conversion layer 22 is preferably a layer containing a p-type organic compound or an n-type organic compound. The photoelectric conversion layer 22 is more preferably a bulk hetero layer in which a p-type organic compound and an n-type organic compound are mixed. More preferably, it is a bulk hetero layer in which a p-type organic compound and fullerene or a fullerene derivative are mixed. By using a bulk hetero layer as the photoelectric conversion layer 22, it is possible to compensate for the shortcoming of the exciton diffusion length of the organic layer and to improve the photoelectric conversion efficiency. By producing a bulk hetero layer with an optimal mixing ratio, the electron mobility and hole mobility of the photoelectric conversion layer 22 can be increased, and the light response speed of the solid-state imaging device 10 can be sufficiently increased. it can. The ratio of fullerene or fullerene derivative in the bulk hetero layer is preferably 30% to 80%, more preferably 50% to 80%, and particularly preferably 65% to 75% of fullerene. .

The layer containing these organic compounds is formed by, for example, a dry film forming method or a wet film forming 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. Examples of the wet film forming method include a casting method, a spin coating method, a dipping method, and an LB method.
In the case where a polymer compound is used as at least one of the p-type organic compound and the n-type organic compound, the film is preferably formed 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 of the possibility of decomposition, and an oligomer thereof can be preferably used instead. On the other hand, in the present invention, when a low molecule is used, a dry film forming method is preferably used, and a vacuum deposition method is particularly preferably used. In order to enable uniform deposition, it is preferable to perform deposition by rotating the substrate. 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. It is preferable to perform 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.
The electron blocking layer 20 and the photoelectric conversion layer 22 will be described in detail later.

The counter electrode 24 is an electrode facing the pixel electrode 16 and is provided so as to cover the photoelectric conversion layer 22. The counter electrode 24 is provided in common to the plurality of pixel electrodes 16 without being individually separated.
The counter electrode 24 is made of a conductive material that is transparent to the incident light L in order to make light incident on the photoelectric conversion layer 22. The counter electrode 24 is electrically connected to the second connection portion 46 disposed outside the photoelectric conversion layer 22, and is connected to the counter electrode voltage supply portion 42 via the second connection portion 46. Yes.

The counter electrode 24 is preferably a transparent electrode in order to increase the absolute amount of light incident on the photoelectric conversion layer 22 and increase the external quantum efficiency.
Preferred materials for the counter electrode 24 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 counter electrode 24 is preferably 60% or more, more preferably 80% or more, more preferably 90% or more, and more preferably 95% or more in the visible light wavelength.
The counter electrode 24 preferably has a thickness of 5 to 30 nm. By making the counter electrode 24 have a thickness of 5 nm or more, the lower layer can be sufficiently covered, and uniform performance can be obtained. On the other hand, if the thickness of the counter electrode 24 exceeds 30 nm, the counter electrode 24 and the pixel electrode 16 may be locally short-circuited, resulting in an increase in dark current. By making the counter electrode 24 have a film thickness of 30 nm or less, the occurrence of a local short circuit can be suppressed.

Various methods are used for the production of the counter electrode 24 depending on the material. For example, in the case of ITO, a chemical reaction method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a sol-gel method, a dispersion of indium tin oxide is used. A method such as coating is used.
In the present invention, it is preferable to produce the counter electrode 24 without plasma. By producing the counter electrode 24 free of plasma, the influence of plasma on the solid-state imaging device 10 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 counter electrode 24, 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 that reaches is reduced.

  The pixel electrode 16 is an electrode for collecting charges for collecting charges generated in the photoelectric conversion layer 22 between the pixel electrode 16 and the counter electrode 24 facing the pixel electrode 16. The pixel electrode 16 is connected to the readout circuit 40 via the first connection portion 44. The readout circuit 40 is provided on the substrate 12 corresponding to each of the plurality of pixel electrodes 16, and reads out a signal corresponding to the charge collected by the corresponding pixel electrode 16.

  The material of the pixel electrode 16 may be any material as long as it is conductive, and examples thereof include metals, conductive metal oxides, metal nitrides and borides, organic conductive compounds, and mixtures thereof. Specific examples include metals, metal oxides, metal nitrides, metal borides, organic conductive compounds, and mixtures thereof. Specific examples include tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), indium tungsten oxide (IWO), conductive metal oxides such as titanium oxide, and titanium nitride (TiN). Metal nitrides such as gold (Au), platinum (Pt), silver (Ag), chromium (Cr), nickel (Ni), aluminum (Al), etc., and these metals and conductive metal oxides A mixture or laminate of the above, an organic conductive compound such as polyaniline, polythiophene, and polypyrrole, a laminate of these with ITO, and the like. Particularly preferred as the material for the pixel electrode is any one of titanium nitride, molybdenum nitride, tantalum nitride, and tungsten nitride.

The readout circuit 40 is constituted by, for example, a CCD, a CMOS circuit, or a TFT circuit, and is shielded from light by a light shielding layer (not shown) provided in the insulating layer 14. The readout circuit 40 preferably employs a CCD or CMOS circuit for general image sensor applications, and preferably employs a CMOS circuit from the viewpoint of noise and high speed.
Although not shown, for example, a high-concentration n region surrounded by a p region is formed on the substrate 12, and the first connection portion 44 is connected to the n region. A read circuit 40 is provided in the p region. The n region functions as a charge storage unit that stores the charge of the photoelectric conversion layer 22. The signal charge accumulated in the n region is converted into a signal corresponding to the amount of charge by the readout circuit 40 and output to the outside of the solid-state imaging device 10 via the wiring layer 48, for example.

  The counter electrode voltage supply unit 42 applies a predetermined voltage to the counter electrode 24 via the second connection unit 46. When the voltage to be applied to the counter electrode 24 is higher than the power supply voltage of the solid-state imaging device 10, the power supply voltage is boosted by a booster circuit such as a charge pump to supply the predetermined voltage.

The sealing layer 26 is for protecting the photoelectric conversion layer 22 from deterioration factors such as water molecules and oxygen, and the sealing layer 26 covers the counter electrode 24.
The sealing layer 26 protects the photoelectric conversion layer 22 by preventing entry of factors that degrade the organic photoelectric conversion material contained in a solution such as an organic solvent, plasma, or the like in each manufacturing process of the solid-state imaging device 10. Further, after the solid-state imaging device 10 is manufactured, intrusion of factors that degrade organic photoelectric conversion materials such as water molecules and oxygen is prevented, and deterioration of the photoelectric conversion layer 22 is prevented during long-term storage and long-term use. To do. Furthermore, when forming the sealing layer 26, the already formed photoelectric conversion layer 22 is not deteriorated. Further, the incident light L reaches the photoelectric conversion layer 22 through the sealing layer 26. For this reason, the sealing layer 26 is transparent to light having a wavelength detected by the photoelectric conversion layer 22, for example, visible light.

The sealing layer 26 includes at least one layer. In the example illustrated in FIG. 1, the sealing layer 26 is a single layer. The sealing layer 26 is composed of, for example, a silicon oxynitride film (SiON film). The sealing layer 26 is preferably formed by, for example, a vapor deposition method. As the vapor deposition method, for example, a plasma CVD method, a sputtering method, a reactive sputtering method, or an ion plating method can be used. The sealing layer 26 has a total film thickness of 30 to 500 nm, for example.
When the total film thickness of the sealing layer 26 is less than 30 nm, the barrier property may be lowered, or the resistance of the color filter to the developer may be lowered. On the other hand, when the thickness of the sealing layer 26 exceeds 500 nm, it is difficult to suppress color mixing when the pixel size is less than 1 μm.

  The sealing layer 26 is not limited to a single layer structure, and may have a two-layer structure, for example. In this case, the configuration similar to that of the sealing layer 26 described above may be used. In addition, for example, any combination of aluminum oxide (AlOx), silicon oxide (SiOx), and silicon nitride (SiNx) may be used. can do.

  For example, in the solid-state imaging device 10 having a pixel size of less than 2 μm, particularly about 1 μm, if the distance between the color filter 28 and the photoelectric conversion layer 22, that is, the sealing layer 26 is thick, In this case, the influence of the oblique incident component of the incident light L becomes large and color mixing may occur. For this reason, the sealing layer 26 is preferably thin.

  The color filter 28 is formed at a position facing each pixel electrode 16 on the sealing layer 26. The partition wall 27 is provided between the color filters 28 on the sealing layer 26 and is for improving the light transmission efficiency of the color filter 28. The light shielding layer 29 is formed in a region other than the region (effective pixel region) where the color filter 28 and the partition wall 27 are provided on the sealing layer 26, and light is incident on the photoelectric conversion layer 22 formed outside the effective pixel region. This is to prevent this. The color filter 28, the partition wall 27, and the light shielding layer 29 are formed by, for example, a photolithography method.

The overcoat layer 30 is for protecting the color filter 28 from subsequent processes and covers the color filter 28, the partition wall 27, and the light shielding layer 29.
2A and 2B, in the solid-state imaging device 10, the pixel electrode 16, the heat resistance improving layer 18, the electron blocking layer 20, the photoelectric conversion layer 22, the counter electrode 24, and the color filter 28 are arranged upward. One pixel electrode 16 provided is a unit pixel U. A photoelectric conversion element 50 is configured by combining the unit pixel U, the first connection unit 44, and the readout circuit 40.

  For the overcoat layer 30, a polymer material such as an acrylic resin, a polysiloxane resin, a polystyrene resin, or a fluorine resin, or an inorganic material such as silicon oxide or silicon nitride can be used as appropriate. When a photosensitive resin such as polystyrene is used, the overcoat layer 30 can be patterned by a photolithography method, so that it is used as a photoresist when opening the peripheral light shielding layer, sealing layer, insulating layer, etc. on the bonding pad. In addition, it is preferable because the overcoat layer 30 itself can be easily processed as a microlens. On the other hand, it is possible to use the overcoat layer 30 as an antireflection layer, and it is also preferable to form various low refractive index materials used as the partition walls of the color filter 28. In addition, in order to pursue a function as a protective layer and a function as an antireflection layer with respect to a subsequent process, the overcoat layer 30 can be configured to have two or more layers combining the above-described materials.

In the solid-state imaging device 10, as shown in FIG. 2A, it is preferable that T ₂ <T ₁ when the depth of the groove 15 is T ₁ and the thickness of the heat resistance improving layer 18 is T ₂ . As a result, as will be described later, when the heat resistance improving layer 18 is formed, the remaining portion 19 is entirely contained in the groove portion 15, and the remaining portion 19 does not exist in the gap 17 of the pixel electrode 16. That is, there is no heat resistance improving layer 18 having conductivity. Therefore, conduction between adjacent pixel electrodes 16 is prevented, and the effect of the heat resistance improving layer 18 is exhibited without degrading dark current, response speed, and conversion efficiency.
Preferably the difference between the thickness _{T 2} and a depth _{T 1} is not less 5nm or more, and more preferably 10nm or more. The larger the difference between the thickness T ₂ and the depth T ₁ , that is, the greater the step, the thicker the heat resistance improving layer 18 can be, and the heat resistance improving layer 18 can sufficiently cover the pixel electrode 16.

In the solid-state imaging device 10, groove 15 angle theta ₁ of is preferably 50 ° or more. If the angle theta ₁ is not deep groove 15 depth is less than 50 °, there may not be able to break the heat improving layer 18 between adjacent pixel electrodes 16. The angle theta ₁ of the groove 15 and more preferably 50 ° to 60 °, further preferably 55 ° or less than 50 °.
In the solid-state imaging device 10, the electron blocking layer 20 is preferably in the region corresponding to the groove 15, and the angle θ ₂ at the recess 21 is preferably 30 ° or less, more preferably 20 ° or less, and still more preferably 15 ° or less. It is. When the angle θ ₂ at the recess 21 exceeds 30 °, a dense region is formed in the electron blocking layer 20 and the photoelectric conversion layer 22 between the pixel electrodes 16. When the counter electrode 24 formed on the photoelectric conversion layer 22 penetrates into the dense part and an electric field is applied, the electric field is concentrated on a part of the invading counter electrode 24 and dark current may increase. .

The following describes the angle theta ₂ of the angle theta ₁ and the electron-blocking layer 20 of the groove 15.
FIG. 3A is a schematic diagram for explaining the angle of the groove portion of the solid-state imaging device according to the first embodiment of the present invention, and FIG. 3B is a solid-state imaging device according to the first embodiment of the present invention. It is a schematic diagram for demonstrating the angle of this electron blocking layer.
3A and 3B, the same components as those in the solid-state imaging device 10 shown in FIGS. 1 and 2A are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 3 (a), a surface 12a (see FIG. 1) parallel to the plane of the substrate 12 (see FIG. 1) and _{m 1} in the upper surface 15a of the groove 15, the groove 15 the surface of the substrate 12 at the bottom 15b of the and 12a and a line parallel to the _{m 2.} At this time, the starting point of the upper surface 15a of the groove 15 and _{P 1,} the starting point of the bottom surface 15b of the groove 15 and _{P 2.} Then, when a straight line passing through the origin _{P 1} and the starting point _{P 2} and _{m 3,} the angle between the surface 12a and a line parallel _{m 2} and the line _{m 3} of substrate 12 and theta _1. This angle θ ₁ is the angle of the groove 15.
The starting point P ₁ is a boundary between the side surface 15 c of the groove 15 and the surface 14 a of the insulating layer 14 in the cross section of the groove 15. The starting point _{P 2,} which is a boundary between the bottom surface 15b of the side surface 15c and the groove 15 of the groove 15 in the cross section of the groove 15.

Further, as shown in FIG. 3B, in the electron blocking layer 20, a line that passes through the end of the pixel electrode 16 on the groove 15 side and is perpendicular to the surface 12a (see FIG. 1) of the substrate 12 (see FIG. 1). N, and a line passing through the center of the groove 15 and perpendicular to the surface 12a of the substrate 12 is c. In this case, the recess 21 of the electron blocking layer 20, a point of intersection between the line n and P _3, the point of intersection with line c and P _4. A straight line passing through the point _{P 3} and the point _{P 4} and _{m 4.} An angle formed by the parallel line m ₂ and the straight line m ₄ is θ ₂ . This angle θ ₂ is the angle of the electron blocking layer 20.

Next, a method for manufacturing the solid-state imaging device 10 will be described.
4A to 4D are schematic cross-sectional views illustrating the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention in the order of steps.
As shown in FIG. 4A, the first connecting portion 44 and the surface 12a of the substrate 12 on which the readout circuit 40 and the counter electrode voltage supply portion 42 (not shown in FIG. 4A) are formed. A structure in which an insulating layer 14 provided with a second connection portion 46 (not shown in FIG. 4A) and a wiring layer 48 (not shown in FIG. 4A) is prepared.

A TiN conductive layer 60 is formed on the surface 14a of the insulating layer 14 by sputtering, for example.
Next, as shown in FIG. 4B, the conductive layer 60 and a part of the insulating layer 14 are removed by etching to form the groove 15. Thereby, the pixel electrode 16 is formed from the conductive layer 60.
Note that the conductive layer 60 and the insulating layer 14 are not limited to be removed by one etching, and the insulating layer 14 may be removed by etching after the conductive layer 60 is removed by etching.
Next, as shown in FIG. 4C, the fullerene or the fullerene derivative and the material constituting the electron blocking layer 20 are mixed by a vacuum co-evaporation method using a mask (not shown), for example. A heat resistance improving layer 18 is formed on the pixel electrode 16.

  Next, as shown in FIG. 4D, an electron blocking layer 20 is formed on the heat resistance improving layer 18 by, for example, vacuum deposition so as to fill the gaps 17 of the pixel electrodes 16. In this case, the electron blocking layer 20 has a recess 21 formed in a region corresponding to the groove 15.

Thereafter, although not shown, the photoelectric conversion layer 22 is formed on the electron blocking layer 20 by, for example, a vacuum co-evaporation method, and the counter electrode 24 is sequentially formed of ITO by, for example, a high-frequency magnetron sputtering method.
For example, a laminated film of an aluminum oxide film and a silicon nitride film is formed as the sealing layer 26 so as to cover the counter electrode 24. The aluminum oxide film is formed by, for example, atomic layer deposition, and the silicon nitride film is formed by, for example, magnetron sputtering.

Next, the partition wall 27, the color filter 28, and the light shielding layer 29 are formed on the surface 26a of the sealing layer 26 by using, for example, a photolithography method. As the partition wall 27, the color filter 28, and the light shielding layer 29, known materials used for organic solid-state imaging devices are used. The step of forming the partition wall 27, the color filter 28, and the light shielding layer 29 may be performed in a predetermined vacuum or non-vacuum.
Next, the overcoat layer 30 is formed using, for example, a coating method so as to cover the partition wall 27, the color filter 28, and the light shielding layer 29. Thereby, the solid-state image sensor 10 shown in FIG. 1 can be formed. As the overcoat layer 30, a known layer used for an organic solid-state imaging device is used. The overcoat layer 30 may be formed in a predetermined vacuum or non-vacuum.

Next, a second embodiment of the present invention will be described.
FIG. 5 is a schematic cross-sectional view showing the main part of the solid-state imaging device according to the second embodiment of the present invention.
In the present embodiment, the same components as those of the solid-state imaging device 10 shown in FIGS. 1 and 2A are denoted by the same reference numerals, and detailed description thereof is omitted.
In the solid-state imaging device 10a shown in FIG. 5, the illustration is simplified, the configuration above the photoelectric conversion layer 22, the counter electrode voltage supply unit 42 (see FIG. 1), and the second connection unit 46 (see FIG. 1). The wiring layer 48 (see FIG. 1) is not shown.

  The solid-state imaging device 10a shown in FIG. 5 shows only the main part, but the gap 17 between the adjacent pixel electrodes 16 in the insulating layer 14 as compared with the solid-state imaging device 10 shown in FIGS. The groove 15 is not formed in the region corresponding to the above, and instead the insulator 70 is provided in the gap 17 of the pixel electrode 16 and the remaining portion 72 is on the insulator 70. The configuration of is the same as the configuration of the solid-state imaging device 10 shown in FIGS. 1 and 2A, and thus detailed description thereof is omitted.

The insulator 70 is provided so as to protrude from the surface 18 a of the heat resistance improving layer 18. It is assumed that _{T 3} the height of the insulator 70. Thereby, the heat resistance improving layer 18 on the adjacent pixel electrodes 16 is electrically insulated, and conduction between the adjacent pixel electrodes 16 is prevented.
The insulator 70 can have the same composition as the insulating layer 14, and can be composed of, for example, silicon nitride, silicon oxide, or the like. The remaining portion 72 has the same composition as the heat resistance improving layer 18 and is formed in the process of forming the heat resistance improving layer 18.
In the solid-state imaging device 10a of the present embodiment, the dark current, the response speed, and the conversion efficiency are deteriorated by providing the insulator 70 in the gap 17 between the adjacent pixel electrodes 16 to prevent conduction between the heat resistance improving layers 18. The effect of the heat resistance improving layer 18 can be exhibited. The solid-state image sensor 10a of this embodiment can obtain the same effects as the solid-state image sensor 10 of the first embodiment.

Next, a method for manufacturing the solid-state imaging device 10a of the present embodiment will be described.
6A to 6F are schematic cross-sectional views illustrating a method for manufacturing a solid-state imaging device according to the second embodiment of the present invention in the order of steps.
In addition, in the manufacturing method of the solid-state image sensor 10a of this embodiment, the detailed description is the same about the process same as the manufacturing method of the solid-state image sensor 10 of 1st Embodiment shown to Fig.4 (a)-(d). Omitted. Since the process shown in FIG. 6A is the same as the process shown in FIG. 4A, description thereof will be omitted, and description will be given from FIG. 6B.

The conductive layer 60 shown in FIG. 6A is patterned into a pixel electrode pattern by, for example, wet etching or dry etching to form the pixel electrode 16 as shown in FIG. 6B.
Next, as illustrated in FIG. 6C, an insulating film 74 is formed so as to cover the pixel electrodes 16 and fill the gaps 17 between the pixel electrodes 16. The insulating film 74 is made of, for example, silicon nitride or silicon oxide, using a CVD method or a sputtering method. The height T ₃ of the insulating film 74 from the surface 14 a of the insulating layer 14 is higher than the total thickness of the pixel electrode 16 and the heat resistance improving layer 18.

Next, the insulating film 74 is removed by, for example, wet etching or dry etching, leaving the gap 17 portion of the pixel electrode 16. Thus, as shown in FIG. 6 (d), the insulator 70 of the height _{T 3} in the gap 17 of the pixel electrode 16 is formed.
Next, as shown in FIG. 6E, a heat resistant improvement layer is formed by, for example, vacuum co-evaporation using a mixture of fullerene or a fullerene derivative and a material constituting the electron blocking layer 20 on the pixel electrode 16. 18 is formed. In this case, the insulator 70 is higher than the heat resistance improving layer 18 and protrudes from the surface 18 a of the heat resistance improving layer 18. Furthermore, the heat resistance improving layer 18 is also formed on the insulator 70, and this is referred to as a remaining portion 72.

Next, as illustrated in FIG. 6F, the electron blocking layer 20 is formed on the heat resistance improving layer 18 by, for example, a vacuum deposition method.
Thereafter, as described above, the photoelectric conversion layer 22 (see FIG. 5) is formed on the electron blocking layer 20. Other configurations are produced in the same manner as in the first embodiment. Thereby, the solid-state image sensor 10a can be obtained.

Hereinafter, materials and the like constituting the electron blocking layer 20 and the photoelectric conversion layer 22 will be described in detail. First, the photoelectric conversion layer 22 will be described.
Although it does not specifically limit as a material of the photoelectric converting layer 22, By forming with the layer of the bulk hetero structure which mixed the p-type organic compound and the n-type organic compound, the performance of a solid-state image sensor is favorable. Can be.

  The p-type organic compound is a donor-type organic compound, and is mainly an organic compound represented by a hole-transporting organic compound and has 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 compound, benzidine compound, pyrazoline compound, styrylamine compound, hydrazone compound, triphenylmethane compound, carbazole compound, polysilane compound, thiophene compound, phthalocyanine compound, cyanine compound, merocyanine compound, oxonol compound, polyamine compound, indole Compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), nitrogen-containing heterocyclic compounds The metal complex etc. which it has as can be used. Not limited to this, as described above, any organic compound having a lower ionization potential than the organic compound used as the n-type (acceptor) compound may be used as the donor organic compound.

  An n-type organic compound is an acceptor organic compound, and is an organic compound that is mainly represented by an electron transporting organic compound and has a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound. For example, condensed aromatic carbocyclic compounds (naphthalene 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, oxa Azole, imidazopyridine, pyrrolidine, pyrrolopyridine, thiadiazolopyridine, etc.), a polyarylene compound, a fluorene compound, a cyclopentadiene compound, a silyl compound, a metal complex or the like having a nitrogen-containing heterocyclic compound as a ligand. Note that the present invention is not limited to this, 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 compound.

  Any organic dye may be used for the photoelectric conversion layer 22, but a p-type organic dye or an n-type organic dye is preferably used. Any organic dye may be used, but preferably a cyanine dye, styryl dye, hemicyanine dye, merocyanine dye (including zero methine merocyanine (simple merocyanine)), trinuclear merocyanine dye, tetranuclear merocyanine dye, Rhodocyanine dye, complex cyanine dye, complex merocyanine dye, allopolar dye, oxonol dye, hemioxonol dye, squalium dye, croconium dye, azamethine dye, coumarin dye, arylidene dye, anthraquinone dye, triphenylmethane dye, azo dye, azomethine dye , Spiro compounds, metallocene dyes, fluorenone dyes, fulgide dyes, perylene dyes, perinone dyes, phenazine dyes, phenothiazine dyes, quinone dyes, diphenylmeta Dye, polyene dye, acridine dye, acridinone dye, diphenylamine dye, quinacridone dye, quinophthalone dye, phenoxazine dye, phthaloperylene dye, diketopyrrolopyrrole dye, dioxane dye, porphyrin dye, chlorophyll dye, phthalocyanine dye, metal complex dye, condensation And aromatic carbocyclic dyes (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives).

When a solid-state image sensor is a color image sensor, cyanine dye, styryl dye, hemicyanine dye, merocyanine dye, trinuclear merocyanine dye, tetranuclear merocyanine dye, rhodacyanine dye, complex cyanine dye having a high degree of freedom in adjusting the absorption wavelength, In some cases, methine dyes such as complex merocyanine dyes, allopolar dyes, oxonol dyes, hemioxonol dyes, squalium dyes, croconium dyes, azamethine dyes, and the like give preferable wavelength suitability.
The p-type organic compound is preferably a compound represented by the following general formula (1).

In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ , and L ₃ each independently represent an unsubstituted methine group or a substituted methine group. D ₁ represents an atomic group. n represents an integer of 0 or more.
Z ₁ is a ring containing at least two carbon atoms, and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. As a condensed ring containing at least one of a 5-membered ring, a 6-membered ring, and a 5-membered ring and a 6-membered ring, those usually used as an acidic nucleus in a merocyanine dye are preferable. Specific examples thereof include the following: Things.

(A) 1,3-dicarbonyl nucleus: For example, 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6 -Dione etc.
(B) pyrazolinone nucleus: for example, 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, 1- (2-benzothiazoyl) -3-methyl- 2-pyrazolin-5-one and the like.
(C) Isoxazolinone nucleus: For example, 3-phenyl-2-isoxazolin-5-one, 3-methyl-2-isoxazolin-5-one and the like.
(D) Oxindole nucleus: For example, 1-alkyl-2,3-dihydro-2-oxindole and the like.
(E) 2,4,6-triketohexahydropyrimidine nucleus: for example, barbituric acid or 2-thiobarbituric acid and derivatives thereof. Examples of the derivatives include 1-alkyl compounds such as 1-methyl and 1-ethyl, 1,3-dialkyl compounds such as 1,3-dimethyl, 1,3-diethyl and 1,3-dibutyl, and 1,3-diphenyl. 1,3-diaryl compounds such as 1,3-di (p-chlorophenyl) and 1,3-di (p-ethoxycarbonylphenyl), and 1-alkyl-1-aryl compounds such as 1-ethyl-3-phenyl 1,3-di (2-pyridyl) 1,3-diheterocyclic substituents and the like.
(F) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and derivatives thereof. Examples of the derivatives include 3-alkyl rhodanine such as 3-methylrhodanine, 3-ethylrhodanine and 3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and 3- (2-pyridyl). And 3-position heterocyclic-substituted rhodanine such as rhodanine.

(G) 2-thio-2,4-oxazolidinedione (2-thio-2,4- (3H, 5H) -oxazoledione) nucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione, etc. .
(H) Tianaphthenone nucleus: For example, 3 (2H) -thianaphthenone-1,1-dioxide and the like.
(I) 2-thio-2,5-thiazolidinedione nucleus: For example, 3-ethyl-2-thio-2,5-thiazolidinedione and the like.
(J) 2,4-thiazolidinedione nucleus: For example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione and the like.
(K) Thiazolin-4-one nucleus: For example, 4-thiazolinone, 2-ethyl-4-thiazolinone and the like.
(L) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, etc.
(M) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidine Zeon etc.
(N) Imidazolin-5-one nucleus: For example, 2-propylmercapto-2-imidazolin-5-one and the like.
(O) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione and the like.
(P) Benzothiophen-3-one nucleus: for example, benzothiophen-3-one, oxobenzothiophen-3-one, dioxobenzothiophen-3-one and the like.
(Q) Indanone nucleus: For example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone, and the like.

The ring formed by Z ₁ is preferably a 1,3-dicarbonyl nucleus, a pyrazolinone nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body, for example, a barbituric acid nucleus, a 2-thiobarbiti nucleus, Tool acid nucleus), 2-thio-2,4-thiazolidinedione nucleus, 2-thio-2,4-oxazolidinedione nucleus, 2-thio-2,5-thiazolidinedione nucleus, 2,4-thiazolidinedione nucleus, 2 , 4-imidazolidinedione nucleus, 2-thio-2,4-imidazolidinedione nucleus, 2-imidazolin-5-one nucleus, 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus And more preferably a 1,3-dicarbonyl nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body, for example, a barbituric acid nucleus, 2-thio Barbituric acid nucleus), 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus, more preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydro Pyrimidine nucleus (including thioketone body, for example, barbituric acid nucleus, 2-thiobarbituric acid nucleus), particularly preferably 1,3-indandione nucleus, barbituric acid nucleus, 2-thiobarbituric acid nucleus and their Is a derivative.

L ₁ , L ₂ , and L ₃ each independently represent an unsubstituted methine group or a substituted methine group. The substituted methine groups may be bonded to each other to form a ring (eg, a 6-membered ring such as a benzene ring). Although the substituent of the substituted methine group includes the substituent W, it is preferable that all of L ₁ , L ₂ and L ₃ are unsubstituted methine groups.
L _{1 to} L ₃ may be linked to each other to form a ring, and preferred examples of the ring formed include a cyclohexene ring, a cyclopentene ring, a benzene ring, and a thiophene ring.

  n represents an integer of 0 or more, preferably 0 or more and 3 or less, and more preferably 0. When n is increased, the absorption wavelength region can be made longer, or the thermal decomposition temperature is lowered. N = 0 is preferable in that it has appropriate absorption in the visible region and suppresses thermal decomposition during vapor deposition.

D ₁ represents an atomic group. The above-mentioned D ₁ is preferably ^a group containing —NR ^a (R ^b ), and more preferably represents an arylene group substituted with —NR ^a (R ^b ). R ^a and R ^b each independently represent a hydrogen atom or a substituent.

The arylene group represented by D ₁ is preferably an arylene group having 6 to 30 carbon atoms, and more preferably an arylene group having 6 to 18 carbon atoms. The arylene group may have a substituent W described later, and is preferably an arylene group having 6 to 18 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms. Examples include a phenylene group, a naphthyl group, an anthracenylene group, a pyrenylene group, a phenanthrenylene group, a methylphenylene group, and a dimethylphenylene group, and a phenylene group or a naphthyl group is preferable.

Examples of the substituent represented by R ^a and R ^b include the substituent W described later, preferably an aliphatic hydrocarbon group (preferably an alkyl group or alkenyl group optionally having a substituent), an aryl group. (Preferably a phenyl group which may have a substituent) or a heterocyclic group.

The aryl groups represented by R ^a and R ^b are each independently preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 18 carbon atoms. The aryl group may have a substituent, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms which may have an aryl group having 6 to 18 carbon atoms. is there. Examples thereof include a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, a methylphenyl group, a dimethylphenyl group, and a biphenyl group, and a phenyl group or a naphthyl group is preferable.

The heterocyclic groups represented by R ^a and R ^b are preferably each independently a heterocyclic group having 3 to 30 carbon atoms, and more preferably a heterocyclic group having 3 to 18 carbon atoms. The heterocyclic group may have a substituent, preferably a C3-18 heterocyclic ring which may have an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms. It is a group. The heterocyclic group represented by R ^a and R ^b is preferably a condensed ring structure, and furan ring, thiophene ring, selenophene ring, silole ring, pyridine ring, pyrazine ring, pyrimidine ring, oxazole ring, thiazole ring, triazole. A condensed ring structure selected from a ring, an oxadiazole ring and a thiadiazole ring (which may be the same) is preferred. A quinoline ring, an isoquinoline ring, a benzothiophene ring, a dibenzothiophene ring, a thienothiophene ring, a bithienobenzene ring A bithienothiophene ring is preferred.

The arylene group and aryl group represented by D ₁ , R ^a and R ^b are preferably a benzene ring or a condensed ring structure, more preferably a condensed ring structure containing a benzene ring, a naphthalene ring, an anthracene ring, pyrene A benzene ring, a naphthalene ring or an anthracene ring, more preferably a benzene ring or a naphthalene ring.

As the substituent W, a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, an aryl group, and a heterocyclic group (May be referred to as a heterocyclic group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyl group, aryl Oxycarbonyl group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercap Group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic ring Azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (-B (OH) ₂ ), phosphato group (-OPO _(OH) 2), a sulfato group (-OSO ₃ H), and other known substituents.

When R ^a and R ^b represent a substituent (preferably an alkyl group or an alkenyl group), the substituent is an aromatic ring (preferably benzene ring) skeleton of an aryl group substituted by —NR ^a (R ^b ). It may combine with a hydrogen atom or a substituent to form a ring (preferably a 6-membered ring).
R ^a and R ^b may be bonded to each other to form a ring (preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring), and R ^a and R ^b are each L A ring (preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring) may be formed by combining with a substituent in (representing any of L ₁ , L ₂ , and L ₃ ).

The compound represented by the general formula (1) is a compound described in JP-A No. 2000-297068, and compounds not described in JP-A No. 2000-297068 also conform to the synthesis method described in the above-mentioned publication. Can be manufactured.
The compound represented by the general formula (1) is preferably a compound represented by the general formula (2).

In General Formula (2), Z ₂ , L ₂₁ , L ₂₂ , L ₂₃ , and n are synonymous with Z ₁ , L ₁ , L ₂ , L ₃ , and n in General Formula (1), and preferred examples thereof Is the same. D ₂₁ represents a substituted or unsubstituted arylene group. D ₂₂ and D ₂₃ each independently represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group.

The arylene group represented by D ₂₁ has the same meaning as the arylene ring group represented by D ₁ , and preferred examples thereof are also the same. The aryl group represented by D ₂₂ and D ₂₃ is independently the same as the heterocyclic group represented by R ^a and R ^b , and preferred examples thereof are also the same.

  Although the preferable specific example of a compound represented by General formula (1) below is shown using General formula (3), this invention is not limited to these.

In the general formula (3), Z ₃ represents any one of A-1 to A-12 in Table 1 below. L ₃₁ represents methylene and n represents 0. D ₃₁ is any one of B-1 to B-9, and D ₃₂ and D ₃₃ each represent any one of C-1 to C-16. Z ₃ is preferably A-2, D ₃₂ and D ₃₃ are preferably selected from C-1, C-2, C-15, and C-16, and D ₃₁ is B-1 or B- 9 is preferred. In Table 1 below, “*” indicates a binding position.

Particularly preferred p-type organic compounds include dyes or materials having no five or more condensed ring structures (materials having 0 to 4, preferably 1 to 3 condensed ring structures). When a pigment-based p-type organic compound generally used in organic thin-film solar cells is used, the dark current at the pn interface tends to increase, and the optical response is caused by trapping at the crystalline grain boundary. Since it tends to be slow, it is difficult to use it for a solid-state imaging device. For this reason, a dye-based p-type organic compound that is difficult to crystallize, or a material that does not have five or more condensed ring structures can be preferably used for a solid-state imaging device.
More preferred specific examples of the compound represented by the general formula (1) are combinations of substituents, linking groups and partial structures shown in the following Table 2 in the general formula (3), but the present invention is limited to these. is not.

In Table 2, A-1 to A-12, B-1 to B-9, and C-1 to C-16 have the same meanings as shown in Table 1 above.
Although the especially preferable specific example of the compound represented by General formula (1) below is shown, this invention is not limited to these.

(Molecular weight)
The compound represented by the general formula (1) preferably has a molecular weight of 300 or more and 1500 or less, more preferably 350 or more and 1200 or less, and more preferably 400 or more and 900 or less, from the viewpoint of film forming suitability. Further preferred. When the molecular weight is too small, the film thickness of the formed photoelectric conversion film decreases due to volatilization. Conversely, when the molecular weight is too large, vapor deposition cannot be performed and a solid-state imaging device cannot be manufactured.

(Melting point)
The compound represented by the general formula (1) has a melting point of preferably 200 ° C. or higher, more preferably 220 ° C. or higher, and further preferably 240 ° C. or higher from the viewpoint of vapor deposition stability. If the melting point is low, it melts before vapor deposition, and in addition to being unable to form a stable film, the decomposition product of the compound increases, so the photoelectric conversion performance deteriorates.

(Absorption spectrum)
The peak wavelength of the absorption spectrum of the compound represented by the general formula (1) is preferably 450 nm or more and 700 nm or less, more preferably 480 nm or more and 700 nm or less, and more preferably 510 nm or more and 680 nm from the viewpoint of broadly absorbing light in the visible region. More preferably, it is as follows.

(Molar extinction coefficient of peak wavelength)
The higher the molar extinction coefficient is, the better the compound represented by the general formula (1) is from the viewpoint of efficiently using light. Absorption spectrum (chloroform solution), in the visible region of the wavelength 400nm to 700 nm, the molar absorption coefficient preferably ²⁰⁰⁰⁰ -1 ^{cm -1} or more, more preferably ^{30000 m} -1 ^{cm -1} or more, ^{40000M -1 cm} -1 or more Is more preferable.

  The photoelectric conversion layer described above preferably further contains an n-type organic compound in addition to the compound represented by the general formula (1). It is more preferable that the compound represented by the general formula (1) is included in the photoelectric conversion layer 22. The n-type organic compound contained in the photoelectric conversion layer will be described.

The n-type organic compound is preferably fullerene or a fullerene derivative. The fullerene, fullerene _{C 60,} fullerene _{C 70,} fullerene _{C 76,} fullerene _{C 78,} fullerene _{C 80,} fullerene _{C 82,} fullerene _{C 84,} fullerene _{C 90,} fullerene _{C 96,} fullerene _{C 240,} fullerene _{C 540,} mixed Fullerene and fullerene nanotube are represented, and a fullerene derivative represents a compound having a substituent added thereto. As the substituent, an alkyl group, an aryl group, or a heterocyclic group is preferable. As a fullerene derivative, the compound as described in Unexamined-Japanese-Patent No. 2007-123707 is preferable.

In addition, as fullerenes and fullerene derivatives, the Chemical Society of Japan, Quarterly Chemical Review No. 43 (1999), JP-A-10-167994, JP-A-11-255508, JP-A-11-255509, JP-A-2002-241323, JP-A-2003-19681, and the like. It can also be used. Of fullerenes and fullerene derivatives, fullerenes are preferable, and fullerene C ₆₀ is particularly preferable.

  The photoelectric conversion layer preferably has a bulk heterostructure formed by mixing the compound represented by the above general formula (1) and fullerene or a fullerene derivative. The bulk heterostructure is a film (bulk heterolayer) in which a p-type organic compound (compound represented by the general formula (1)) and an n-type organic compound are mixed and dispersed in the photoelectric conversion layer. Can be formed by the method. By including a heterojunction structure, the shortcoming of the short exciton diffusion length of the photoelectric conversion layer can be compensated, and the photoelectric conversion efficiency of the photoelectric conversion layer can be improved. The bulk heterojunction structure is described in detail in JP-A-2005-303266, [0013] to [0014].

  The bulk hetero layer preferably contains 30% to 80% of the fullerene or fullerene derivative in a volume ratio, more preferably the bulk hetero layer contains 50% to 80% of the fullerene or fullerene derivative in a volume ratio of 65% to It is particularly preferable to contain 75%.

  The photoelectric conversion layer can be 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. A dry film forming method is preferable, and a vacuum evaporation method is more preferable. When forming a film by a vacuum evaporation method, manufacturing conditions such as the degree of vacuum and the evaporation temperature can be set according to a conventional method.

  The thickness of the photoelectric conversion layer is preferably from 10 nm to 1000 nm, more preferably from 50 nm to 800 nm, and particularly preferably from 100 nm to 500 nm. By setting it to 10 nm or more, a suitable dark current suppressing effect is obtained, and by setting it to 1000 nm or less, suitable photoelectric conversion efficiency is obtained.

Next, the electron blocking layer 20 will be described.
An electron donating organic material can be used for the electron blocking layer 20. Specifically, 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, tetraphenylporphyrin copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Polyphyrin compounds, triazole derivatives, oxa Diazole 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, carbazole derivatives, bifluorenes A derivative or the like can be used, and as the polymer material, a polymer such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, or a derivative thereof can be used. Even if it is not a compound, it can be used as long as it has sufficient hole transportability.

An inorganic material can also be used as the electron blocking layer 20. In general, since an inorganic material has a dielectric constant larger than that of an organic material, when it is used for the electron blocking layer 20, a large voltage is applied to the photoelectric conversion layer, and the photoelectric conversion efficiency can be increased. Materials that can be used as the electron blocking layer 20 include calcium oxide, chromium oxide, chromium oxide copper, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, Examples include indium silver oxide and iridium oxide.
The ionization potential (Ip) of the electron blocking layer 20 is preferably 5.2 eV or more, more preferably 5.3 eV to 5.8 eV, and even more preferably 5.4 eV to 5.7 eV.

  The present invention is basically configured as described above. The solid-state imaging device of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various modifications or changes may be made without departing from the spirit of the present invention. It is.

Hereinafter, the effect of the solid-state imaging device of the present invention will be specifically described.
In this example, solid-state image sensors of Examples 1 to 9 and Comparative Examples 1 to 5 were fabricated, and the effects of the present invention were confirmed. In addition, the solid-state image sensor of Example 1-Example 9 is the structure shown in FIG. 1, and is formed on the substrate, pixel electrode / heat resistance improving layer / electron blocking layer / photoelectric conversion layer / counter electrode / sealing. Layer configuration. The solid-state image sensor of Comparative Example 1 has the same configuration as that of Example 1 except that the solid-state image sensor of Example 1 is different from the solid-state image sensor of Example 1 in that there is no heat resistance improving layer. The solid-state image sensor of Comparative Example 2 has the same configuration as that of Example 1 except that the solid-state image sensor of Example 1 has no grooves and no heat-resistant improving layer. The solid-state imaging devices of Comparative Examples 3 to 5 have the same configuration as that of Example 1 except that the heat resistance improving layer is connected between the pixel electrodes.
In Table 3 below, “continuous” in the column of the form of the heat-resistant improving layer means that the heat-resistant improving layers are connected between adjacent pixel electrodes. “Discontinuous” means that the heat resistance improving layer is not connected between adjacent pixel electrodes.

Example 1
This is an imaging device in which a heat resistance improving layer, an electron blocking layer, a photoelectric conversion layer, a counter electrode, and a sealing layer are stacked on a Si substrate on which a readout circuit, a charge storage unit, a contact unit, and a pixel electrode are formed. A groove having a depth of 20 nm was formed between adjacent pixel electrodes.
The pixel electrode is made of TiN with a thickness of 10 nm on an SiN insulating layer formed on the Si substrate. The trench is formed in the SiN insulating layer between the pixel electrodes.
The heat resistance improving layer is formed by co-evaporating a mixed film of an organic compound represented by compound 1 and C ₆₀ (compound 1: C ₆₀ = 1: 1 (volume ratio)) in a vacuum with a film thickness of 10 nm.
The electron blocking layer is formed by depositing an organic compound represented by Compound 1 with a thickness of 50 nm by vacuum deposition.

The photoelectric conversion layer is formed by mixing a mixed film of an organic compound represented by Compound 2 and C ₆₀ (compound 2: C ₆₀ = 1: 2 (volume ratio)) with a film thickness of 400 nm by co-evaporation in vacuum.
The counter electrode is made of ITO with a film thickness of 10 nm by high frequency magnetron sputtering.
As the sealing layer, a laminated film of an aluminum oxide film and a silicon nitride film was formed. The aluminum oxide film was formed with a film thickness of 100 nm using an atomic layer deposition apparatus. The silicon nitride film was formed with a film thickness of 100 nm by magnetron sputtering.
In Example 1, the heat resistance improving layer does not exist between the pixel electrodes. The groove angle θ ₁ was 55 °, and the electron blocking layer angle θ ₂ was 28 °.
The angle theta ₁ of the groove, the measurement of the angle theta ₂ of the electron blocking layer is cut portion comprising a groove from the solid-state imaging device produced to obtain a SEM image. Based on this SEM image was measured angle theta ₂ shown in angle theta ₁ and 3 shown in FIG. 3 described above (a) (b).

(Example 2)
The second embodiment has the same configuration as that of the first embodiment, and the manufacturing method thereof is the same manufacturing method as that of the solid-state imaging device of the first embodiment. However, in the solid-state imaging device of Example 2, the groove portion angle θ ₁ was 60 °, and the electron blocking layer angle θ ₂ was 30 °.

(Example 3)
The third embodiment has the same configuration as that of the first embodiment, and the manufacturing method thereof is the same manufacturing method as that of the solid-state imaging device of the first embodiment. However, in the solid-state imaging device of Example 3, the angle θ ₁ of the groove was 52 °, and the angle θ ₂ of the electron blocking layer was 25 °.

Example 4
Example 4 is the same as Example 1 except that the thickness of the heat-resistant improving layer is 15 nm, as compared to Example 1. The production method is also the same production method as that of the solid-state imaging device of Example 1, except that the thickness of the heat-resistant improvement layer is 15 nm as compared with Example 1. In the solid-state imaging device of Example 4, the angle θ ₁ of the groove was 55 °, and the angle θ ₂ of the electron blocking layer was 27 °.

(Example 5)
Example 5 is the same as Example 1 except that the thickness of the heat-resistant improving layer is 5 nm, as compared to Example 1. The production method is also the same production method as that of the solid-state imaging device of Example 1, except that the thickness of the heat-resistant improvement layer is 5 nm as compared with Example 1. The solid-state imaging element according to embodiment 5, the angle theta ₁ of the groove is 55 °, the angle theta ₂ of the electron-blocking layer was 29 °.

(Example 6)
Example 6 is the same as Example 1 except that the depth of the groove is 40 nm. The manufacturing method is also the same manufacturing method as that of the solid-state imaging device of Example 1 except that the depth of the groove is 40 nm as compared with Example 1. The solid-state imaging element according to embodiment 6, the angle theta ₁ of the groove is 45 °, the angle theta ₂ of the electron-blocking layer was 45 °.

(Example 7)
Example 7 has the same configuration as Example 1 except that the depth of the groove is 40 nm and the thickness of the electron blocking layer is 70 nm as compared to Example 1. The manufacturing method is also the same manufacturing method as that of the solid-state imaging device of Example 1 except that the depth of the groove is 40 nm and the thickness of the electron blocking layer is 70 nm as compared with Example 1. In the solid-state imaging device of Example 7, the angle θ ₁ of the groove was 45 °, and the angle θ ₂ of the electron blocking layer was 42 °.

(Example 8)
Example 8 is the same as Example 1 except that the depth of the groove is 40 nm and the thickness of the electron blocking layer is 70 nm. The fabrication method is also solid-state imaging device of Example 1 except that the depth of the groove is 40 nm, the thickness of the electron blocking layer is 70 nm, and the electron blocking layer is annealed as compared with Example 1. Is the same manufacturing method. In the solid-state imaging device of Example 8, the angle θ ₁ of the groove was 45 °, and the angle θ ₂ of the electron blocking layer was 10 °. Note that the annealing treatment was performed at a temperature of 190 ° C. for 10 minutes.

Example 9
Example 9 is the same as Example 1 except that the groove depth is 30 nm and the electron blocking layer thickness is 60 nm, as compared to Example 1. The solid-state imaging device of Example 1 is also the same as that of Example 1 except that the groove depth is 30 nm, the electron blocking layer thickness is 60 nm, and the electron blocking layer is annealed. Is the same manufacturing method. In the solid-state imaging device of Example 9, the angle θ ₁ of the groove was 45 °, and the angle θ ₂ of the electron blocking layer was 36 °.

(Comparative Example 1)
Compared to Example 1, Comparative Example 1 has the same configuration as Example 1 except that there is no heat-resistant improving layer. The manufacturing method is also the same as that of the solid-state imaging device of Example 1 except that the heat-resistant improvement layer is not formed as compared with Example 1. In the solid-state imaging device of Comparative Example 1, the groove portion angle θ ₁ was 55 °, and the electron blocking layer angle θ ₂ was 32 °.

(Comparative Example 2)
Compared to Example 1, Comparative Example 2 has the same configuration as Example 1 except that there is no groove and no heat resistance improving layer. The manufacturing method is the same as the manufacturing method of the solid-state imaging device of Example 1 except that the groove portion is not formed and the heat resistance improving layer is not formed as compared with Example 1. In the solid-state imaging device of Comparative Example 2, the angle θ ₂ of the electron blocking layer was 10 °.

(Comparative Example 3)
Comparative Example 3 is the same as Example 1 except that the depth of the groove is 10 nm, the thickness of the heat-resistant improving layer is 20 nm, and the heat-resistant improving layer is connected between the pixel electrodes. It is the composition. The manufacturing method is also the same as that of the solid-state imaging device of Example 1 except that the depth of the groove is 10 nm and the thickness of the heat-resistant improvement layer is 20 nm, as compared with Example 1.
In the solid-state imaging device of Comparative Example 3, the groove portion angle θ ₁ was 55 °, and the electron blocking layer angle θ ₂ was 36 °.

(Comparative Example 4)
Comparative Example 4 has the same configuration as that of Example 1 except that the heat resistance improving layer is connected between the pixel electrodes with respect to Example 1. The manufacturing method is also the same manufacturing method as that of the solid-state imaging device of Example 1, except that the heat resistance improving layer is formed so as to be continuous between the pixel electrodes as compared with Example 1. In the solid-state imaging device of Comparative Example 4, the groove portion angle θ ₁ was 45 °, and the electron blocking layer angle θ ₂ was 26 °.

(Comparative Example 5)
Comparative Example 5 has the same configuration as that of Example 1 except that the thickness of the electron blocking layer is 60 nm and the heat resistance improving layer is connected between the pixel electrodes. The fabrication method is also the same as that of the solid-state imaging device of the first embodiment except that the heat resistance improving layer is formed so as to be continuous between the pixel electrodes and the thickness of the electron blocking layer is 60 nm as compared with the first embodiment. This is a manufacturing method. In the solid-state imaging device of Comparative Example 5, the groove angle θ ₁ was 48 °, and the electron blocking layer angle θ ₂ was 27 °.

Applying an electric field strength of 2.0 × 10 ⁵ V / cm to the counter electrode of each manufactured solid-state imaging device, each solid-state imaging is performed to determine whether or not there is dark current in an environment where light is not irradiated and whether or not image blurring occurs. Table 3 below shows the evaluation results evaluated without the heat treatment after the device was prepared and the evaluation results after the heat treatment.
Image blur is a phenomenon in which an image blurs due to exchange of carriers between adjacent pixels (decrease in resolution). The presence or absence of image blur was evaluated by taking a resolution chart and determining the presence or absence of image blur.
The heat treatment was performed by holding the solid-state imaging device on a hot plate having a temperature of 240 ° C. for 2 minutes. About a part of produced solid-state image sensor, the solid-state image sensor was heat-processed by hold | maintaining on a hot plate with a temperature of 235 degreeC for 2 minutes. In the column of “After heat treatment (235 ° C., 2 minutes)” in Table 3 below, “-” indicates that heat treatment was not performed. In Table 3 below, each “dark current (relative value)” is a numerical value with the initial state of Example 1 being 1.

In each of Examples 1 to 9, there was no blur of the image, and the performance after heat treatment was not deteriorated.
In addition, when the heat resistance improving layer is also thickened, an external voltage necessary for applying the same electric field strength to the photoelectric conversion layer is increased. The thickness of the heat resistance improving layer is preferably 30 nm or less.

On the other hand, in Comparative Example 1 having no heat resistance improving layer, the dark current increased after the heat treatment. Thus, heat resistance is low. In Comparative Example 1 in order angle theta ₂ of the concave portion of the electron blocking layer is more than 30 °, the electron blocking layer on between the pixel electrodes, coarse grain region is formed in the photoelectric conversion layer. When the counter electrode formed on the photoelectric conversion layer penetrates into the dense part and an electric field is applied, the electric field is concentrated on a part of the counter electrode that has entered, and the dark current increases.
In Comparative Example 2, the dark current increased after the heat treatment because there was no groove and no heat-resistant improving layer.
In Comparative Examples 3 to 5, since the heat resistance improving layer is connected between the pixel electrodes, charges are exchanged between adjacent pixel electrodes, and the dark current increases before the heat treatment. In addition, blurring occurred in the taken resolution chart due to the exchange of charges between adjacent pixel electrodes.

When Example 1, Example 4, Example 5, and Comparative Example 1 are compared, the heat resistance improves as the thickness of the heat resistance improving layer increases. However, it is better to minimize the thickness of the heat-resistant improving layer in that the power consumption increases when the film thickness is large. Specifically, sufficient heat resistance can be obtained if the thickness of the heat resistance improving layer is 5 nm.
When Example 1, Example 2, Example 3, Comparative Example 4, and Comparative Example 5 are compared, when the depth of the groove is 20 nm and the thickness of the heat-resistant improving layer is 10 nm, the angle θ ₁ of the groove is 50 ° or more. By doing so, the heat resistance improving layer can be discontinuous. Groove angle theta ₁ heat improving layer is less than 50 ° as in Comparative Examples 4 and 5 are continuous.

Example 6, Example 7, Example 8, Example 9, a comparison of Comparative Example 4, also at an angle theta ₁ is less than 50 ° of the groove, the non-continuous heat improving layer by the depth of the groove it can. In this case, the angle θ ₂ of the concave portion of the electron blocking layer increases, and the dark current increases. In Example 8, the angle θ ₂ of the concave portion is reduced by performing an annealing process. Moreover, in order to reduce the angle θ ₂ of the concave portion of the electron blocking layer, it is necessary to increase the film thickness of the electron blocking layer. However, if the film thickness is too large, it is necessary to apply a high external voltage to give the same electric field strength. Therefore, it is better to minimize the thickness of the electron blocking layer.

Comparing Examples 1 to 9, is shown in FIG. 8, the dark current increases the angle theta ₂ of the concave portion of the electron blocking layer is greater than 30 °. From this, it is preferable that the angle θ ₂ of the concave portion of the electron blocking layer is 30 ° or less.

DESCRIPTION OF SYMBOLS 10, 10a, 100 Solid-state image sensor 12 Board | substrate 14 Insulating layer 15 Groove part 16 Pixel electrode 18 Heat resistance improvement layer 20 Electron blocking layer 22 Photoelectric conversion layer 24 Counter electrode 26 Sealing layer 27 Partition 28 Color filter 29 Light-shielding layer 30 Overcoat layer 40 Read circuit 42 Counter electrode voltage supply unit 44 First connection unit 46 Second connection unit 48 Wiring layer 50 Photoelectric conversion element 70 Insulator

Claims (11)

An insulating layer provided on the surface of the substrate;
A plurality of pixel electrodes provided immediately above the insulating layer;
A heat resistance improving layer for improving heat resistance, provided above the pixel electrode;
An electron blocking layer that is provided above the heat resistance improving layer and suppresses electron injection from the pixel electrode;
A photoelectric conversion layer that is provided above the electron blocking layer and generates a charge in response to received light;
A counter electrode provided above the photoelectric conversion layer and shared by the plurality of pixel electrodes;
A signal readout circuit that is connected to the pixel electrode and reads out a signal corresponding to the charge collected by the pixel electrode;
It said refractory improving layer is a layer material are mixed constituting the fullerene or fullerene derivative electron blocking layer, and the heat-resistant improving layer has a feature that it is severed between adjacent said pixel electrode A solid-state imaging device.   2. The heat resistance improving layer is a layer in which fullerene or a fullerene derivative and a material constituting the electron blocking layer are mixed, and a groove is formed in the insulating layer between the adjacent pixel electrodes. Solid-state image sensor. Wherein the depth of the groove and T _1, wherein when the thickness of the heat-resistant improving layer and T _2, the solid-state imaging device according to claim 2 is T 2 _{<T 1.} 4. The solid-state imaging device according to claim 2, wherein an angle θ ₁ between a straight line connecting the starting points of the groove and a line parallel to the surface of the substrate is 50 ° or more.   5. The solid-state imaging device according to claim 2, wherein the electron blocking layer has an angle of a recess formed in a region corresponding to the groove portion of 30 ° or less.   The solid-state imaging device according to claim 1, wherein an insulator thicker than a thickness of the pixel electrode is formed between the adjacent pixel electrodes.   The solid-state imaging device according to any one of claims 1 to 6, wherein the heat resistance improving layer contains fullerene or a fullerene derivative at a ratio of 30% to 70%.   The solid-state imaging device according to claim 1, wherein the photoelectric conversion layer is made of an organic material.   The solid-state imaging device according to claim 1, wherein the photoelectric conversion layer is configured by a bulk hetero layer in which an n-type organic compound and a p-type organic compound are mixed.   The solid-state imaging device according to claim 9, wherein the n-type organic compound is fullerene or a fullerene derivative.   The solid-state imaging device according to claim 9 or 10, wherein the bulk hetero layer contains fullerene in a proportion of 30% to 80%.