solid-state imaging device

Abstract

To provide an infrared cut filter, a filter for a solid-state imaging element, a solid-state imaging element, and a method for manufacturing the filter for the solid-state imaging element in which heat resistance and resistance to a stripping liquid can be improved.SOLUTION: A solid-state imaging element 10 includes an infrared cut filter 13 and a photoelectric conversion element 11, the infrared cut filter 13 including polymethine, cations located one by one on both terminals of the polymethine and having two heterocyclic rings including nitrogen, a cyanine pigment including tris (pentafluoroethyl) trifluoro-phosphoric acid, and a copolymer. The copolymer is represented by the following formula (1) and includes a first repeating unit derived from an acryl monomer including a circular ester group and a second repeating unit derived from a monomer including a functional group which reacts with the circular ester group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid-state imaging device. [Background technology]

[0002] Solid-state imaging devices such as CMOS image sensors and CCD image sensors include photoelectric conversion elements that convert light intensity into electrical signals. One example of a solid-state imaging device is capable of detecting light corresponding to multiple colors. The solid-state imaging device includes a color filter and a photoelectric conversion element for each color, and detects light of each color using the photoelectric conversion element for each color (see, for example, Patent Document 1). Another example of a solid-state imaging device includes an organic photoelectric conversion element and an inorganic photoelectric conversion element, and detects light of each color using the photoelectric conversion element without using a color filter (see, for example, Patent Document 2).

[0003] The solid-state imaging device includes an infrared light cut filter on a photoelectric conversion element. The infrared light absorbing dye in the infrared light cut filter absorbs infrared light, thereby cutting off infrared light that can be detected by each photoelectric conversion element. This improves the detection accuracy of visible light in each photoelectric conversion element. The infrared light cut filter contains, for example, a cyanine dye, which is an infrared light absorbing dye (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-060176 [Patent Document 2] Japanese Patent Application Publication No. 2018-060910 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-219114 Summary of the Invention [Problem to be solved by the invention]

[0005] When a solid-state imaging device including an infrared cut filter is mounted on a mounting substrate, the solid-state imaging device is mounted on the mounting substrate by reflow soldering. During this process, the infrared cut filter of the solid-state imaging device is heated to a temperature that melts the solder. Heating the infrared cut filter denatures the cyanine dye, and as a result, the infrared light transmittance of the infrared cut filter after heating may change from the infrared light transmittance of the infrared cut filter before heating.

[0006] On the other hand, dry etching may be used to pattern an infrared cut filter. In this case, a resist pattern is first formed on the infrared cut filter. Next, the infrared cut filter is etched using the resist pattern, and then the resist pattern is peeled off from the infrared cut filter. The stripping solution used to peel off the resist pattern from the infrared cut filter comes into contact with the infrared cut filter, thereby dissolving a portion of the cyanine dye contained in the infrared cut filter to the outside of the infrared cut filter. This reduces the amount of infrared light absorption expected in the infrared cut filter.

[0007] An object of the present invention is to provide a solid-state imaging device that can improve heat resistance and resistance to a stripping solution. [Means for solving the problem]

[0008] A solid-state imaging device for solving the above problems includes: a cyanine dye containing polymethine, a cation having two nitrogen-containing heterocycles, one at each end of the polymethine, and tris(pentafluoroethyl)trifluorophosphate; an infrared light cut filter containing a copolymer represented by the following formula (1) and including a first repeating unit derived from an acrylic monomer containing a cyclic ether group and a second repeating unit derived from a monomer containing a functional group reactive with the cyclic ether group; and a photoelectric conversion element.

[0009] [ka]

[0010] In formula (1), R1 is a hydrogen atom or a methyl group, R2 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms, and R3 is a cyclic ether group containing an oxygen atom and two or more carbon atoms.

[0011] According to the above configuration, a crosslinked structure is formed by crosslinking a cyclic ether group in the first repeating unit with a functional group reactive with a cyclic ether group in the second repeating unit. This prevents the transmittance of the infrared cut filter from changing due to heating and prevents the infrared light-absorbing dye from eluting into the stripping solution used during dry etching. As a result, it is possible to improve the heat resistance and resistance to the stripping solution of the infrared cut filter.

[0012] In the solid-state imaging device, the monomer containing a cyclic ether group may contain at least one of an epoxy group and an oxetanyl group, which is preferable in terms of reactivity between the cyclic ether group and a functional group reactive with the cyclic ether group contained in the second repeating unit.

[0013] In the solid-state imaging device, the monomer including the functional group reactive with the cyclic ether group may be acidic. This configuration makes it possible to prevent a crosslinking reaction from immediately proceeding at room temperature during the polymerization process of the resin.

[0014] In the solid-state imaging device, the functional group reactive with the cyclic ether group may be a phenolic hydroxyl group. According to this configuration, since the phenolic hydroxyl group exhibits weak acidity, a crosslinking reaction with the cyclic ether group is unlikely to occur during the polymerization process of the resin, but is likely to occur during the heating step in forming the coating film. Therefore, the phenolic hydroxyl group is advantageous in terms of coatability.

[0015] In the solid-state imaging device, the copolymer may contain a third repeating unit derived from an acrylic monomer having an aromatic ring, represented by the following formula (2):

[0016] [ka]

[0017] In formula (2), R4 is a hydrogen atom or a methyl group, and R5 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms. R6 is a hydrogen atom or a predetermined substituent. In formula (2), when R6 is a substituent, m is an integer from 1 to 5.

[0018] In the solid-state imaging device, the copolymer may contain a third repeating unit derived from an acrylic monomer having an alicyclic structure represented by the following formula (3).

[0019] [ka]

[0020] In formula (3), R7 is a hydrogen atom or a methyl group, and R8 is a single bond, a linear alkylene group having 1 or more carbon atoms, or a branched alkylene group having 3 or more carbon atoms. In formula (3), R9 is an alicyclic structure having 3 or more carbon atoms.

[0021] According to the above configuration, the aromatic ring group or alicyclic structure of the third repeating unit is located between the cyanine dye and another cyanine dye located nearby, thereby creating a distance between the cyanine dyes that is sufficient to prevent aggregation of the cyanine dyes, thereby suppressing deterioration of the spectral characteristics at wavelengths that are expected to be absorbed by the cyanine dyes.

[0022] In the above solid-state imaging element, the copolymer may contain the first repeating unit in a proportion of 7.5% by weight or more and 17.5% by weight or less, and the ratio of the weight of the second repeating unit to the weight of the first repeating unit may be 1.0 or more and 3.0 or less.

[0023] According to the above configuration, since the copolymer contains the first repeating unit and the second repeating unit in the above range, a decrease in the infrared light absorbance of the infrared cut filter after heat treatment and treatment with a stripping solution is suppressed, thereby improving both the heat resistance and resistance to the stripping solution of the infrared cut filter.

[0024] In the solid-state imaging device, the copolymer may contain the third repeating unit in a proportion of 65% by weight or more. With this configuration, the copolymer containing the third repeating unit in the above range can suppress deterioration of the spectral characteristics of the infrared cut filter at wavelengths where absorption by the cyanine dye is expected. The solid-state imaging device may include a barrier layer that prevents the transmission of an oxidation source that oxidizes the infrared cut filter. The solid-state imaging device may include a visible light filter and an infrared light pass filter. In the solid-state imaging device, the oxygen permeability of the laminated structure located on the incident surface side of the infrared cut filter is 5.0 cc / m 2 It may be less than / day / atm. The solid-state imaging device may include a bandpass filter that transmits only light having a specific wavelength of visible light and near-infrared light. [Effects of the Invention]

[0025] According to the present invention, the heat resistance and resistance to a stripping solution of an infrared cut filter can be improved. [Brief explanation of the drawings]

[0026] [Figure 1]FIG. 1 is an exploded perspective view showing a structure of a solid-state imaging device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] An infrared light cut filter, a filter for a solid-state imaging device, and a solid-state imaging device according to an embodiment will be described with reference to Figure 1. The solid-state imaging device, a method for manufacturing a filter for a solid-state imaging device, and examples will be described below. In this embodiment, infrared light refers to light having a wavelength in the range of 0.7 μm to 1 mm, and near-infrared light refers to infrared light having a wavelength in the range of 700 nm to 1100 nm.

[0028] [Solid-state imaging device] The solid-state imaging device will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the individual layers of a portion of the solid-state imaging device in isolation.

[0029] 1, the solid-state imaging device 10 includes a solid-state imaging device filter 10F and a plurality of photoelectric conversion elements 11. The plurality of photoelectric conversion elements 11 include a red photoelectric conversion element 11R, a green photoelectric conversion element 11G, a blue photoelectric conversion element 11B, and an infrared light photoelectric conversion element 11P. The photoelectric conversion elements 11R, 11G, and 11B for each color measure the intensity of visible light having a specific wavelength associated with that photoelectric conversion element 11R, 11G, and 11B. Each infrared light photoelectric conversion element 11P measures the intensity of infrared light.

[0030] The solid-state imaging device 10 includes a plurality of red photoelectric conversion elements 11R, a plurality of green photoelectric conversion elements 11G, a plurality of blue photoelectric conversion elements 11B, and a plurality of infrared photoelectric conversion elements 11P. For convenience of illustration, Fig. 1 shows a repeating unit of the photoelectric conversion elements 11 in the solid-state imaging device 10.

[0031] The solid-state imaging device filter 10F includes a plurality of visible light filters, an infrared light pass filter 12P, an infrared light cut filter 13, a plurality of visible light microlenses, and an infrared light microlens 15P.

[0032] The visible light color filter is composed of a red filter 12R, a green filter 12G, and a blue filter 12B. The red filter 12R is located on the light incident side of the red photoelectric conversion element 11R. The green filter 12G is located on the light incident side of the green photoelectric conversion element 11G. The blue filter 12B is located on the light incident side of the blue photoelectric conversion element 11B.

[0033] The infrared light pass filter 12P is located on the light incident side of the infrared light photoelectric conversion element 11P. The infrared light pass filter 12P blocks visible light that can be detected by the infrared light photoelectric conversion element 11P from being transmitted to the infrared light photoelectric conversion element 11P. This improves the accuracy of infrared light detection by the infrared light photoelectric conversion element 11P. The infrared light that can be detected by the infrared light photoelectric conversion element 11P is, for example, near-infrared light.

[0034] The infrared light cut filter 13 is located on the light incident side of the color filters 12R, 12G, and 12B. The infrared light cut filter 13 has a through-hole 13H. When viewed from the perspective opposite the plane in which the infrared light cut filter 13 extends, the infrared light pass filter 12P is located within the area defined by the through-hole 13H. On the other hand, when viewed from the perspective opposite the plane in which the infrared light cut filter 13 extends, the infrared light cut filter 13 is located above the red filter 12R, the green filter 12G, and the blue filter 12B.

[0035] The infrared cut filter 13 contains a cyanine dye, which is an infrared light absorbing dye. The cyanine dye has a maximum infrared light absorptance at any wavelength included in the near-infrared light. Therefore, the infrared cut filter 13 can reliably absorb near-infrared light that passes through the infrared cut filter 13. As a result, near-infrared light that can be detected by the photoelectric conversion elements 11 for each color is sufficiently cut by the infrared cut filter 13. The infrared cut filter 13 can have a thickness of, for example, 300 nm or more and 3 μm or less.

[0036] The barrier layer 14 suppresses the transmission of oxidizing sources through the infrared cut filter 13. The oxidizing sources include oxygen and water. The oxygen permeability of the barrier layer 14 is, for example, 5.0 cc / m 2 / day / atm or less. The oxygen permeability is a value in accordance with JIS K7126:2006. The oxygen permeability is 5.0 cc / m 2 Since the infrared cut filter 13 is set to have a relative humidity of 100% or less, the barrier layer 14 prevents the oxidizing source from reaching the infrared cut filter 13, making the infrared cut filter 13 less susceptible to oxidation by the oxidizing source. This makes it possible to improve the light resistance of the infrared cut filter 13.

[0037] The material forming the barrier layer 14 is an inorganic compound. The material forming the barrier layer 14 is preferably a silicon compound. The material forming the barrier layer 14 may be, for example, at least one selected from the group consisting of silicon nitride, silicon oxide, and silicon oxynitride.

[0038] The microlenses are composed of a red microlens 15R, a green microlens 15G, a blue microlens 15B, and an infrared microlens 15P. The red microlens 15R is located on the light incident side relative to the red filter 12R. The green microlens 15G is located on the light incident side relative to the green filter 12G. The blue microlens 15B is located on the light incident side relative to the blue filter 12B. The infrared microlens 15P is located on the light incident side relative to the infrared light pass filter 12P.

[0039] Each of the microlenses 15R, 15G, 15B, and 15P has an incident surface 15S, which is its outer surface. Each of the microlenses 15R, 15G, 15B, and 15P has a refractive index difference between itself and the outside air, which allows light entering the incident surface 15S to be collected toward each of the photoelectric conversion elements 11R, 11G, 11B, and 11P. Each of the microlenses 15R, 15G, 15B, and 15P contains a transparent resin.

[0040] [Infrared cut filter] The infrared cut filter 13 will be described in more detail below. The infrared cut filter 13 includes a cyanine dye and a copolymer. The cyanine dye includes a polymethine, a cation having two nitrogen-containing heterocycles, one at each end of the polymethine, and an anion, tris(pentafluoroethyl)trifluorophosphate (FAP). The copolymer is represented by the following formula (1), and includes a first repeating unit derived from an acrylic monomer containing a cyclic ether group and a second repeating unit derived from a monomer containing a functional group reactive with the cyclic ether.

[0041] [ka]

[0042] In formula (1), R1 is a hydrogen atom or a methyl group, R2 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms, and R3 is a cyclic ether group containing an oxygen atom and two or more carbon atoms.

[0043] The cyanine dye may have a structure shown in formula (4):

[0044] [ka]

[0045] In the above formula (4), X is a methine or polymethine. The hydrogen atoms bonded to the carbon atoms contained in the methine may be substituted with halogen atoms or organic groups. The polymethine may have a cyclic structure containing the carbon atoms forming the polymethine. The cyclic structure may contain three consecutive carbon atoms among the carbon atoms forming the polymethine. When the polymethine has a cyclic structure, the number of carbon atoms in the polymethine may be 5 or more. Each nitrogen atom is contained in a five- or six-membered heterocycle. The heterocycle may be fused.

[0046] The cyanine dye may also have a structure represented by the following formula (5):

[0047] [ka]

[0048] In the above formula (5), n is an integer of 1 or more. n represents the number of repeating units contained in the polymethine chain. R10 and R11 are hydrogen atoms or organic groups. R12 and R13 are hydrogen atoms or organic groups. R12 and R13 are preferably linear or branched alkyl groups having 1 or more carbon atoms. Each nitrogen atom is contained in a five- or six-membered heterocyclic ring. The heterocyclic ring may be condensed.

[0049] In addition, in formula (4), when the polymethine contains a cyclic structure, the cyclic structure may be, for example, a cyclic structure having at least one unsaturated bond such as an ethylenic double bond, and the unsaturated bond may undergo electron resonance as part of the polymethine chain. Such a cyclic structure may be, for example, a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, a cyclohexadiene ring, a cycloheptene ring, a cyclooctene ring, a cyclooctadiene ring, or a benzene ring. Any of these cyclic structures may have a substituent.

[0050] In addition, in formula (5), a compound in which n is 1 is a cyanine, a compound in which n is 2 is a carbocyanine, and a compound in which n is 3 is a dicarbocyanine. In formula (5), a compound in which n is 4 is a tricarbocyanine.

[0051] The organic groups of R10 and R11 may be, for example, alkyl groups, aryl groups, aralkyl groups, and alkenyl groups. The alkyl groups may be, for example, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, isobutyl groups, tert-butyl groups, isopentyl groups, neopentyl groups, hexyl groups, cyclohexyl groups, octyl groups, nonyl groups, and decyl groups. The aryl groups may be, for example, phenyl groups, tolyl groups, xylyl groups, and naphthyl groups. The aralkyl groups may be, for example, benzyl groups, phenylethyl groups, and phenylpropyl groups. The alkenyl groups may be, for example, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, and octenyl groups.

[0052] At least a portion of the hydrogen atoms in each organic group may be substituted with a halogen atom or a cyano group. The halogen atom may be fluorine, bromine, or chlorine. The organic group after substitution may be, for example, a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, or a cyanoethyl group.

[0053] R12 or R13 may be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a hexyl group, a cyclohexyl group, an octyl group, a nonyl group, and a decyl group.

[0054] The heterocycle containing each nitrogen atom may be, for example, pyrrole, imidazole, thiazole, pyridine, and the like. The cation contained in such a cyanine dye may have a structure represented by the following formula (6) or (7), for example.

[0055] [ka]

[0056] [ka]

[0057] The cation contained in the cyanine dye may have, for example, a structure represented by the following formulas (8) to (47). That is, each nitrogen atom contained in the cyanine dye may be contained in a cyclic structure represented by the following formulas:

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[0098] The cyanine dye has a maximum absorbance value of infrared light at any wavelength between 700 nm and 1100 nm, and therefore the infrared cut filter 13 can reliably absorb near-infrared light that passes through the infrared cut filter 13. As a result, the infrared cut filter 13 sufficiently cuts out near-infrared light that can be detected by the photoelectric conversion elements 11 for each color.

[0099] The absorbance Aλ at wavelength λ is calculated by the following formula. Aλ=-log 10 (%T / 100) The transmittance T is expressed as the ratio (TL / IL) of the intensity of transmitted light (TL) to the intensity of incident light (IL) when infrared light passes through an infrared cut filter 13 containing a cyanine dye. In the infrared cut filter 13, the intensity of transmitted light when the intensity of incident light is set to 1 is the transmittance T, and the value obtained by multiplying the transmittance T by 100 is the transmittance percentage %T.

[0100] Tris(pentafluoroethyl)trifluorophosphate ([(C2F5)3PF3] -) has a structure represented by the following formula (48):

[0101] [ka]

[0102] In the manufacturing process of the solid-state imaging device 10, the infrared cut filter 13 is heated to about 200° C. When the above-described cyanine dye is heated to about 200° C., the structure of the cyanine dye changes, which may change the transmittance of the cyanine dye to infrared light.

[0103] In this regard, the FAP has a molecular weight and molecular structure that allows it to be located in the vicinity of the polymethine chain of the cyanine dye, thereby preventing the polymethine chain of the cyanine dye from being cleaved when the cyanine dye is heated, thereby preventing changes in the infrared light transmittance of the cyanine dye due to heating, and as a result, preventing changes in the infrared light transmittance of the infrared cut filter 13.

[0104] As described above, the infrared cut filter 13 contains a copolymer. The copolymer may contain repeating units derived from a monomer containing acrylic acid or methacrylic acid. The monomer containing acrylic acid is an acrylate, and the monomer containing methacrylic acid is a methacrylate.

[0105] The copolymer includes a first repeating unit and a second repeating unit. The first repeating unit is derived from an acrylic monomer having a cyclic ether group. The second repeating unit is preferably derived from a monomer having a functional group reactive with the cyclic ether group.

[0106] As described above, the first repeating unit is derived from an acrylic monomer having a cyclic ether group. In the first repeating unit, R1 is a hydrogen atom or a methyl group, and R2 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms. R2 may be, for example, a methylene group, an ethylene group, a trimethylene group, a propylene group, or a butylene group. R3 is a cyclic ether group containing an oxygen atom and two or more carbon atoms. The cyclic ether group has an ether bond within a ring formed by including multiple carbon atoms.

[0107] The cyclic ether group may be, for example, an epoxy group, an oxetanyl group, a tetrahydrofuranyl group, or a tetrahydropyranyl group. In terms of reactivity with the functional group of the second repeating unit, the cyclic ether group is preferably an epoxy group or an oxetanyl group. That is, the monomer containing a cyclic ether group preferably contains at least one of an epoxy group and an oxetanyl group.

[0108] Examples of the acrylic monomer having a cyclic ether group include glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-oxiranylethyl (meth)acrylate, 2-glycidyloxyethyl (meth)acrylate, 3-glycidyloxypropyl (meth)acrylate, glycidyloxyphenyl (meth)acrylate, oxetanyl (meth)acrylate, 3-methyl-3-oxetanyl (meth)acrylate, 3-ethyl-3-oxetanyl (meth)acrylate, (3-methyl-3-oxetanyl)methyl (meth)acrylate, (3-ethyl-3 3-oxetanyl)methyl (meth)acrylate, 2-(3-methyl-3-oxetanyl)ethyl (meth)acrylate, 2-(3-ethyl-3-oxetanyl)ethyl (meth)acrylate, 2-[(3-methyl-3-oxetanyl)methyloxy]ethyl (meth)acrylate, 2-[(3-ethyl-3-oxetanyl)methyloxy]ethyl (meth)acrylate, 3-[(3-methyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, 3-[(3-ethyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate.

[0109] The second repeating unit is derived from a monomer having a functional group reactive with a cyclic ether group. Examples of functional groups reactive with a cyclic ether group include a hydroxyl group, a phenolic hydroxyl group, an organic acid, an acid anhydride, and an amino group. These functional groups readily react with a cyclic ether group, and when the functional group forms a crosslinked structure with the cyclic ether group, the heat resistance and resistance to a stripping solution of the infrared cut filter are improved. In particular, it is preferable that the functional group be an acidic functional group from the viewpoint of readily reacting with a cyclic ether group. In other words, it is preferable that the monomer containing a functional group reactive with a cyclic ether group be acidic.

[0110] The functional group reactive with the cyclic ether group is preferably a phenolic hydroxyl group among functional groups exhibiting acidity. The phenolic hydroxyl group exhibits weak acidity, so that the crosslinking reaction with the cyclic ether group is unlikely to occur during the polymerization process of the resin, but is likely to occur during the heating step in producing the coating film. Therefore, the phenolic hydroxyl group is advantageous from the viewpoint of coatability.

[0111] Examples of the monomer having a phenolic hydroxyl group include 4-hydroxyphenyl(meth)acrylate, N-(4-hydroxyphenyl)(meth)acrylamide, 3-(tert-butyl)-4-hydroxyphenyl(meth)acrylate, 4-(tert-butyl)-2-hydroxyphenyl(meth)acrylate, N-(4-hydroxyphenyl)maleimide, N-(3-hydroxyphenyl)maleimide, p-hydroxystyrene, and α-methyl-p-hydroxystyrene. A polymer produced using a monomer having a phenolic hydroxyl group contains a phenolic hydroxyl group in the side chain.

[0112] The copolymer may further contain a third repeating unit. The third repeating unit is preferably derived from an acrylic monomer having an aromatic ring or an acrylic monomer having an alicyclic structure. The third repeating unit derived from an acrylic monomer having an aromatic ring is represented by the following formula (2). The third repeating unit derived from an acrylic monomer having an alicyclic structure is represented by the following formula (3).

[0113] [ka]

[0114] In the above formula (2), R4 is a hydrogen atom or a methyl group, and R5 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms. R6 is a hydrogen atom or a predetermined substituent. In formula (2), when R6 is a substituent, m is an integer from 1 to 5.

[0115] [ka]

[0116] In the above formula (3), R7 is a hydrogen atom or a methyl group, and R8 is a single bond, a linear alkylene group having 1 or more carbon atoms, or a branched alkylene group having 3 or more carbon atoms. In formula (3), R9 is an alicyclic structure having 3 or more carbon atoms.

[0117] Examples of the acrylic monomer having an aromatic ring include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, ethoxylated ortho-phenylphenoxy phenol (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, 4-hydroxyphenyl (meth)acrylate, 2-naphthol (meth)acrylate, 4-biphenyl (meth)acrylate, 9-anthrylmethyl (meth)acrylate, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl (meth)acrylate, phenol ethylene oxide (EO)-modified acrylate, nonylphenol EO-modified acrylate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate.

[0118] Examples of acrylic monomers having an alicyclic structure include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-t-cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, norbornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, and tetracyclododecyl (meth)acrylate.

[0119] The copolymer forming the infrared cut filter 13 contains a first repeating unit and a second repeating unit. Therefore, the cyclic ether group in the first repeating unit and the functional group reactive with the cyclic ether group in the second repeating unit form a crosslinked structure during the heating step of filter formation. This prevents the transmittance of the infrared cut filter from changing due to heating and also prevents the cyanine dye from eluting in the stripping solution used during dry etching. As a result, it is possible to improve the heat resistance and resistance to the stripping solution of the infrared cut filter.

[0120] The copolymer forming the infrared cut filter 13 further contains a third repeating unit. The aromatic ring or alicyclic structure of the third repeating unit is located between the cyanine dye and another cyanine dye located nearby, thereby forming a distance between the cyanine dyes that is sufficient to prevent the cyanine dyes from associating with each other. This prevents deterioration of the spectral characteristics at wavelengths that are expected to be absorbed by the cyanine dyes.

[0121] The copolymer preferably contains the first repeating unit in a proportion of 7.5 to 17.5% by weight, and the ratio of the weight of the second repeating unit to the weight of the first repeating unit is preferably 1.0 to 3.0. When the copolymer contains the first repeating unit and the second repeating unit in the above ranges, a decrease in the infrared light absorbance of the infrared cut filter is suppressed after heat treatment and treatment with a stripping solution.

[0122] The copolymer preferably contains the third repeating unit in a proportion of 65% by weight or more. When the copolymer contains the third repeating unit in the above range, aggregation of the cyanine dye in the infrared cut filter is suppressed, and deterioration of the spectral characteristics at wavelengths expected to be absorbed by the cyanine dye is suppressed.

[0123] The copolymer preferably contains a first repeating unit derived from glycidyl methacrylate, a second repeating unit derived from 4-hydroxyphenyl methacrylate, and a third repeating unit derived from phenyl methacrylate. In this case, the copolymer preferably contains the third repeating unit in a proportion of 65% by weight to 70% by weight, and the weight ratio of the second repeating unit to the first repeating unit is preferably 1.0 to 3.0. This allows the phenyl group in the third repeating unit to be positioned between adjacent cyanine dyes, thereby forming a distance between the cyanine dyes sufficient to prevent association of the cyanine dyes. This reduces changes in the spectral characteristics at wavelengths expected to be absorbed by the cyanine dyes. Furthermore, the phenol group in the second repeating unit crosslinks with the epoxy group in the first repeating unit, forming a crosslinked structure. This reduces changes in the transmittance of the infrared cut filter 13 due to heating and prevents the infrared-absorbing dye from leaching into the stripping solution used during dry etching. As a result, it is possible to improve the heat resistance and resistance to the stripping solution of the infrared cut filter 13.

[0124] The copolymer preferably contains the first repeating unit in a proportion of 7.5% by weight to 17.5% by weight, which prevents a decrease in the infrared light absorbance of the infrared cut filter 13 after heat treatment and treatment with a stripping solution.

[0125] Furthermore, the copolymer preferably contains the second repeating unit in a proportion of 15% by weight to 25% by weight, which prevents a decrease in the infrared light absorbance of the infrared cut filter 13 after heat treatment and treatment with a stripping solution.

[0126] The copolymer may contain a monomer other than the acrylic monomers described above. Examples of the monomer other than the acrylic monomers described above include styrene-based monomers, (meth)acrylic monomers, vinyl ester-based monomers, vinyl ether-based monomers, halogen-containing vinyl-based monomers, and diene-based monomers. Examples of the styrene-based monomers include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, p-methoxystyrene, p-hydroxystyrene, p-acetoxystyrene, vinyltoluene, ethylstyrene, phenylstyrene, and benzylstyrene. Examples of the (meth)acrylic monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. Examples of the vinyl ester-based monomers include vinyl acetate. Examples of the vinyl ether-based monomers include vinyl methyl ether. Examples of the halogen-containing vinyl-based monomers include vinyl chloride. The diene monomer may be, for example, butadiene, isobutylene, etc. The copolymer may contain only one type of monomer other than the above-mentioned acrylic monomer, or may contain two or more types.

[0127] The copolymer may also contain a monomer for adjusting the polarity of the copolymer. The monomer for adjusting the polarity adds an acid group or a hydroxyl group to the copolymer. Such a monomer may be, for example, acrylic acid, methacrylic acid, maleic anhydride, maleic acid half ester, 2-hydroxyethyl acrylate, and 4-hydroxyphenyl (meth)acrylate.

[0128] The copolymer may have any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer structure. If the copolymer has a random copolymer structure, the manufacturing process and preparation with the cyanine dye are easy. Therefore, a random copolymer is preferable to other copolymers.

[0129] The polymerization method for obtaining the copolymer may be, for example, radical polymerization, cationic polymerization, anionic polymerization, living radical polymerization, living cationic polymerization, or living anionic polymerization. Radical polymerization is preferably selected as the polymerization method for obtaining the copolymer because it is easy to produce industrially. Radical polymerization may be solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization. Solution polymerization is preferably used for radical polymerization. By using solution polymerization, the molecular weight of the copolymer can be easily controlled. Furthermore, after polymerization of the monomers, the solution containing the copolymer can be used in the form of a solution for producing a filter for a solid-state imaging device.

[0130] In the radical polymerization, the above-mentioned monomer may be diluted with a polymerization solvent, and then a radical polymerization initiator may be added to polymerize the monomer. The polymerization solvent may be, for example, an ester-based solvent, an alcohol ether-based solvent, a ketone-based solvent, an aromatic solvent, an amide-based solvent, or an alcohol-based solvent. Examples of the ester-based solvent include methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl lactate, ethyl lactate, and propylene glycol monomethyl ether acetate. Examples of the alcohol ether-based solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, 3-methoxy-1-butanol, and 3-methoxy-3-methyl-1-butanol. Examples of the ketone-based solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the aromatic solvent include benzene, toluene, and xylene. Examples of the amide-based solvent include formamide and dimethylformamide. The alcohol-based solvent may be, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, s-butanol, t-butanol, diacetone alcohol, or 2-methyl-2-butanol. Among these, ketone-based solvents and ester-based solvents are preferred because they can be used to manufacture filters for solid-state imaging devices. The above-mentioned polymerization solvents may be used alone or in combination of two or more.

[0131] In radical polymerization, the amount of polymerization solvent used is not particularly limited. When the total amount of monomers is set to 100 parts by weight, the amount of polymerization solvent used is preferably 1 part by weight or more and 1,000 parts by weight or less, and more preferably 10 parts by weight or more and 500 parts by weight or less.

[0132] The radical polymerization initiator may be, for example, a peroxide or an azo compound. The peroxide may be, for example, benzoyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, or di-t-butyl peroxide. The azo compound may be, for example, azobisisobutyronitrile, azobisamidinopropane salt, azobiscyanovaleric acid (salt), or 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0133] The amount of radical polymerization initiator used is preferably 0.0001 to 20 parts by weight, more preferably 0.001 to 15 parts by weight, and even more preferably 0.005 to 10 parts by weight, when the total amount of monomers is set to 100 parts by weight. The radical polymerization initiator may be added to the monomers and polymerization solvent before the start of polymerization, or may be added dropwise to the polymerization reaction system. Adding the radical polymerization initiator dropwise to the monomers and polymerization solvent in the polymerization reaction system is preferred because it can suppress heat generation due to polymerization.

[0134] The reaction temperature for radical polymerization is appropriately selected depending on the types of radical polymerization initiator and polymerization solvent, and is preferably 60° C. or higher and 110° C. or lower from the viewpoints of ease of production and reaction controllability.

[0135] The glass transition temperature of the copolymer is preferably 75° C. or higher, and more preferably 100° C. or higher. If the glass transition temperature is 75° C. or higher, it is possible to more reliably suppress changes in the infrared light transmittance of the infrared cut filter 13 when the infrared cut filter 13 is heated.

[0136] The molecular weight of the copolymer is preferably from 30,000 to 150,000, and more preferably from 50,000 to 150,000. When the molecular weight of the copolymer is within this range, it is possible to more reliably suppress changes in the transmittance of infrared light when the infrared cut filter 13 is heated.

[0137] Copolymers with molecular weights exceeding 150,000 are difficult to form into a coating solution together with the cyanine dye due to an increase in viscosity during polymerization. Therefore, when the molecular weight of the copolymer exceeds 150,000, it is difficult to form the infrared cut filter 13. On the other hand, when the molecular weight of the copolymer is 150,000 or less, it is possible to form a coating solution containing the copolymer and the cyanine dye, making it easier to form the infrared cut filter 13. The average molecular weight of the copolymer is the weight-average molecular weight. The weight-average molecular weight of the copolymer can be measured, for example, by gel permeation chromatography. For example, in a radical polymerization reaction, the molecular weight of the copolymer can be controlled by changing the concentrations of the monomer and radical polymerization initiator in the solution.

[0138] The percentage (MM / MS × 100) of the mass of the monomer (MM) to the sum (MS) of the mass of the copolymer and the mass of the monomers constituting the copolymer is preferably 20% or less. Compared to when the residual monomer is more than 20%, when the infrared light cut filter 13 is heated, the infrared light transmittance of the cyanine dye is less likely to change.

[0139] The percentage (MM / MS x 100) of the mass of the monomer (MM) to the sum (MS) of the mass of the copolymer and the mass of the monomers constituting the copolymer is preferably 10% or less, and even more preferably 3% or less. The mass of the copolymer and the mass of the monomer can be quantified based on the analysis results of the copolymer. The copolymer can be analyzed by, for example, gas chromatography-mass spectroscopy (GC-MS), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), etc.

[0140] The method for changing the ratio of the mass of the monomer to the sum of the mass of the copolymer and the mass of the monomer may be, for example, a method for changing the polymerization time or a method for changing the polymerization temperature. Furthermore, the method for changing the ratio of the mass of the monomer to the sum of the mass of the copolymer and the mass of the monomer may be, for example, a method for changing the concentration of the monomer and the radical polymerization initiator at the start of the polymerization reaction. The method for changing the ratio of the mass of the monomer to the sum of the mass of the copolymer and the mass of the monomer may be, for example, a method for changing the purification conditions after the polymerization reaction. Of these, the method for changing the polymerization time is preferred because it allows for highly accurate control of the change in the ratio of the mass of the monomer.

[0141] When the radical polymerization initiator used in polymerizing the copolymer is an organic peroxide having an aromatic ring in the side chain, the infrared cut filter preferably contains less than 0.35 parts by weight of the organic peroxide when the copolymer contained in the infrared cut filter is set to 100 parts by weight. By containing less than 0.35 parts by weight of the organic peroxide in the infrared cut filter, deterioration of the spectral characteristics of the infrared cut filter in the visible light region and the infrared light region is suppressed.

[0142] [Method of manufacturing filters for solid-state imaging devices] The method for manufacturing the filter 10F for solid-state imaging devices includes forming the infrared light cut filter 13 and patterning the infrared light cut filter 13 by dry etching. Forming the infrared light cut filter 13 results in the formation of an infrared light cut filter 13 containing a cyanine dye and a copolymer. The method for manufacturing the filter 10F for solid-state imaging devices will be described in more detail below.

[0143] Each of the color filters 12R, 12G, 12B, and 12P is formed by forming a coating film containing a colored photosensitive resin and patterning the coating film using photolithography. For example, a coating film containing a red photosensitive resin is formed by applying a coating liquid containing the red photosensitive resin and drying the coating film. The red filter 12R is formed by exposing the coating film containing the red photosensitive resin to an area corresponding to the red filter 12R and developing it. The green filter 12G, blue filter 12B, and infrared light pass filter 12P are also formed by the same method as the red filter 12R.

[0144] The pigments contained in the coloring compositions of the red filter 12R, the green filter 12G, and the blue filter 12B may be organic or inorganic pigments, either singly or in combination. The pigments are preferably pigments with high color development and heat resistance, particularly those with high thermal decomposition resistance, and are preferably organic pigments. Examples of organic pigments include phthalocyanine, azo, anthraquinone, quinacridone, dioxazine, anthanthrone, indanthrone, perylene, thioindigo, isoindoline, quinophthalone, and diketopyrrolopyrrole pigments.

[0145] The coloring component contained in the infrared pass filter 12P may be a black pigment or a black dye. The black pigment may be a single pigment having a black color, or a mixture of two or more pigments having a black color. The black dye may be, for example, an azo dye, an anthraquinone dye, an azine dye, a quinoline dye, a perinone dye, a perylene dye, or a methine dye.

[0146] The photosensitive coloring composition of each color further contains a binder resin, a photopolymerization initiator, a polymerizable monomer, an organic solvent, a leveling agent, and the like. To form the infrared cut filter 13, a coating liquid containing the above-described cyanine dye, copolymer, and organic solvent is applied onto each of the color filters 12R, 12G, 12B, and 12P, and the coating is dried. The dried coating is then cured by heating. This completes the formation of the infrared cut filter 13.

[0147] When forming the through-holes 13H provided in the infrared cut filter 13, first, a photoresist layer is formed on the infrared cut filter 13. This photoresist layer is patterned to form a resist pattern. Next, the infrared cut filter 13 is etched by dry etching using this resist pattern as an etching mask. Then, the resist pattern remaining on the infrared cut filter 13 after etching is removed with a stripping liquid to form the through-holes 13H. In this way, the infrared cut filter can be patterned.

[0148] The stripping liquid may be a liquid capable of dissolving the resist pattern. The stripping liquid may be, for example, N-methylpyrrolidone or dimethyl sulfoxide. The infrared cut filter 13 may be brought into contact with the stripping liquid by any method, such as a dipping method, a spraying method, or a spinning method.

[0149] The barrier layer 14 is formed by a vapor phase deposition method such as sputtering, CVD, or ion plating, or a liquid phase deposition method such as coating. The barrier layer 14 made of silicon oxide is formed, for example, by sputtering a substrate on which the infrared cut filter 13 is formed using a silicon oxide target. The barrier layer 14 made of silicon oxide is formed, for example, by CVD using silane and oxygen on the substrate on which the infrared cut filter 13 is formed. The barrier layer 14 made of silicon oxide is formed, for example, by applying a coating liquid containing polysilazane, modifying it, and drying the coating. The layer structure of the barrier layer 14 may be a single layer structure made of a single compound, a laminate structure of layers made of a single compound, or a laminate structure of layers made of different compounds.

[0150] Each of the microlenses 15R, 15G, 15B, and 15P is formed by forming a coating film containing a transparent resin, patterning the coating film using a photolithography method, and reflowing the coating film using a heat treatment. The transparent resin may be, for example, an acrylic resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyester resin, a polyether resin, a polyolefin resin, a polycarbonate resin, a polystyrene resin, or a norbornene resin.

[0151] [Manufacturing example] [Manufacturing Example 1] Production Examples 1-1 to 1-6 will be described with reference to Table 1. In the copolymer produced by Production Example 1 described below, the weight ratio of each repeating unit in the produced copolymer is equal to the weight ratio of each monomer at the time of producing the copolymer.

[0152] [Table 1]

[0153] [Production Example 1-1] 300 parts by weight of propylene glycol monomethyl ether acetate (PGMAc) was prepared as a polymerization solvent, and 15 parts by weight of glycidyl methacrylate, 15 parts by weight of 4-hydroxyphenyl methacrylate, and 70 parts by weight of phenyl methacrylate were prepared as acrylic monomers.

[0154] Additionally, 1.5 parts by weight of benzoyl peroxide (BPO) was prepared as a radical polymerization initiator. These were placed in a reaction vessel equipped with a stirrer and a reflux condenser, and the mixture was stirred and refluxed for 8 hours while heating to 80°C and introducing nitrogen gas into the reaction vessel. This yielded a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate.

[0155] [Production Example 1-2] In Production Example 1-1, 4-hydroxyphenyl methacrylate was changed to N-(4-hydroxyphenyl) methacrylamide, and a polymer solution containing a copolymer formed from glycidyl methacrylate, N-(4-hydroxyphenyl) methacrylamide, and phenyl methacrylate was obtained in the same manner as in Production Example 1-1.

[0156] [Production Example 1-3] In Production Example 1-1, 4-hydroxyphenyl methacrylate was changed to N-(4-hydroxyphenyl)maleimide. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, N-(4-hydroxyphenyl)maleimide, and phenyl methacrylate was obtained in the same manner as in Production Example 1-1.

[0157] [Production Example 1-4] In Production Example 1-1, glycidyl methacrylate was changed to (3-ethyloxetan-3-yl)methyl methacrylate. Otherwise, a polymer solution containing a copolymer formed from (3-ethyloxetan-3-yl)methyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 1-1.

[0158] [Production Example 1-5] A polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and dicyclopentanyl methacrylate was obtained in the same manner as in Production Example 1-1, except that phenyl methacrylate was changed to dicyclopentanyl methacrylate.

[0159] [Production Example 1-6] In Production Example 1-1, 100 parts by weight of phenyl methacrylate was prepared as a monomer. A polymer solution containing a copolymer formed only from phenyl methacrylate was obtained in the same manner as in Production Example 1-1.

[0160] [Manufacturing Example 2] Preparation Examples 2-1 to 2-11 are described below with reference to Table 2. In Preparation Example 2, the first repeating unit is derived from glycidyl methacrylate (GMA), the second repeating unit is derived from 4-hydroxyphenyl methacrylate (HPMA), and the third repeating unit is derived from phenyl methacrylate (PhMA). In addition, in the copolymer prepared by Preparation Example 2, the weight ratio of each repeating unit in the copolymer produced is equal to the weight ratio of each monomer at the time of copolymer production.

[0161] [Table 2]

[0162] [Production Example 2-1] In Production Example 1-1, the amount of glycidyl methacrylate was changed to 20 parts by weight, the amount of 4-hydroxyphenyl methacrylate was changed to 10 parts by weight, and the amount of phenyl methacrylate was changed to 70 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to the weight of glycidyl methacrylate was set to 0.5. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 1-1.

[0163] [Production Example 2-2] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 15 parts by weight, and the amount of 4-hydroxyphenyl was changed to 15 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to the weight of glycidyl methacrylate was set to 1.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0164] [Production Example 2-3] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 10 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 20 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 2.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0165] [Production Example 2-4] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 7.5 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 22.5 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 3.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0166] [Production Example 2-5] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 6 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 24 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 4.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0167] [Production Example 2-6] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 5 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 25 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 5.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0168] [Production Example 2-7] In Production Example 2-1, the amount of glycidyl methacrylate was changed to 17.5 parts by weight, the amount of 4-hydroxyphenyl methacrylate was changed to 17.5 parts by weight, and the amount of phenyl methacrylate was changed to 65 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to the weight of glycidyl methacrylate was set to 1.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-1.

[0169] [Production Example 2-8] In Production Example 2-7, the amount of glycidyl methacrylate was changed to 11.5 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 23.5 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 2.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-7.

[0170] [Manufacturing Example 2-9] In Production Example 2-7, the amount of glycidyl methacrylate was changed to 10 parts by weight, and the amount of 4-hydroxyphenyl methacrylate was changed to 25 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to glycidyl methacrylate was set to 2.5. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-7.

[0171] [Manufacturing Example 2-10] In Production Example 2-7, the amount of glycidyl methacrylate was changed to 20 parts by weight, the amount of 4-hydroxyphenyl methacrylate was changed to 20 parts by weight, and the amount of phenyl methacrylate was changed to 60 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to the weight of glycidyl methacrylate was set to 1.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-7.

[0172] [Manufacturing Example 2-11] In Production Example 2-7, the amount of glycidyl methacrylate was changed to 25 parts by weight, the amount of 4-hydroxyphenyl methacrylate was changed to 25 parts by weight, and the amount of phenyl methacrylate was changed to 50 parts by weight. As a result, the weight ratio of 4-hydroxyphenyl methacrylate to the weight of glycidyl methacrylate was set to 1.0. Otherwise, a polymer solution containing a copolymer formed from glycidyl methacrylate, 4-hydroxyphenyl methacrylate, and phenyl methacrylate was obtained in the same manner as in Production Example 2-7.

[0173] [Test example] [Test Example 1] In Test Example 1, six types of infrared cut filters were obtained by using the copolymers of Production Examples 1-1 to 1-6 in the following manner. The absorbance of each infrared cut filter was calculated before the test, after the peeling solution resistance test, and after the heat resistance test, using the methods described below. When producing the infrared cut filters of each Test Example, the infrared cut filter used in the peeling solution resistance test and the infrared cut filter used in the heat resistance test, both of which are described below, were separately produced.

[0174] A coating solution containing 0.3 g of cyanine dye, 12.0 g of a 25% polymer solution, and 10 g of propylene glycol monomethyl ether acetate was prepared. The cyanine dye used was the dye represented by formula (6) above, and six polymer solutions containing the copolymers obtained in Production Examples 1-1 to 1-6 were used. The coating solution was applied to a transparent substrate, and the coating was dried. The coating was then heated to 230°C for curing, yielding infrared cut filters of Test Examples 1-1 to 1-6 with a thickness of 1.0 μm.

[0175] [Evaluation method] [Spectral characteristics] The transmittance of the infrared cut filter of each test example for light having wavelengths from 350 nm to 1150 nm was measured using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation). The absorbance was calculated from the transmittance measurement results. This resulted in an absorbance spectrum for each infrared cut filter. The absorbance spectrum of the cyanine dye represented by the above formula (6) has a peak at 950 nm. Therefore, each infrared cut filter was evaluated for its absorbance at 950 nm of 0.8 or greater. An infrared cut filter with an absorbance at 950 nm of 0.8 or greater has infrared light absorption capabilities suitable for use in a solid-state imaging device.

[0176] [Resistance to peeling liquid] After measuring the transmittance of the infrared cut filter of each test example, the infrared cut filter of each test example was immersed in a stripping solution for 1 minute. The transmittance of the infrared cut filter of each test example after immersion was measured using the same method as that used for the infrared cut filter of each test example before immersion. The absorbance was then calculated from the transmittance measurement results. This resulted in an absorbance spectrum for the infrared cut filter of each test example after immersion. The infrared cut filter of each test example after immersion was evaluated for its absorbance at 950 nm of 0.7 or greater. Note that, among the infrared cut filters after immersion in the stripping solution, an infrared cut filter with an absorbance at 950 nm of 0.7 or greater has infrared absorption capabilities suitable for use in a solid-state imaging device.

[0177] [Heat resistance] After measuring the transmittance of the infrared cut filter of each test example, the infrared cut filter of each test example was heated at 250°C. The transmittance of the infrared cut filter of each test example after heating was measured using the same method as that used for the infrared cut filter of each test example before heating. The absorbance was then calculated from the transmittance measurement results. An absorbance spectrum was then obtained for the infrared cut filter of each test example after heating. The infrared cut filter of each test example after heating was evaluated to determine whether it had an absorbance of 0.7 or more at 950 nm. Note that, among the infrared cut filters after heating at 250°C, an infrared cut filter with an absorbance of 0.7 or more at 950 nm has infrared light absorption ability suitable for use in a solid-state imaging device.

[0178] [Evaluation results] The absorbance of the infrared cut filters of Test Examples 1-1 to 1-6 was calculated, and the results are shown in Table 3. In each test example, the absorbance before the test of the infrared cut filter prepared for the peeling solution resistance test was found to be the same as the absorbance before the test of the infrared cut filter prepared for the heat resistance test.

[0179] [Table 3]

[0180] As shown in Table 3, it was found that the absorbance before the resistance test in Test Examples 1-1 to 1-6 was 0.96.

[0181] As described above, it was confirmed that the absorbance at 950 nm of each infrared cut filter before the durability test was 0.8 or more for the infrared cut filters of Test Examples 1-1 to 1-6.

[0182] Furthermore, after the peeling solution resistance test, the absorbance of the infrared cut filter of Test Example 1-1, the infrared cut filter of Test Example 1-2, and the infrared cut filter of Test Example 1-3 was found to be 0.85. The absorbance of the infrared cut filter of Test Example 1-4 was found to be 0.77, the absorbance of the infrared cut filter of Test Example 1-5 was found to be 0.74, and the absorbance of the infrared cut filter of Test Example 1-6 was found to be 0.05.

[0183] In this way, it was found that the resistance of the infrared cut filter to stripping solutions can be improved by having the first repeating unit in the copolymer have a cyclic ether group and the second repeating unit have a phenolic hydroxyl group, which is a functional group that reacts with the cyclic ether group.

[0184] Furthermore, as shown in Table 3, after the heat resistance test, the absorbance of the infrared light cut filter of Test Example 1-1 was 0.80, and the absorbance of the infrared light cut filters of Test Examples 1-2 and 1-3 was 0.82. Furthermore, the absorbance of the infrared light cut filter of Test Example 1-4 was 0.77, the absorbance of the infrared light cut filter of Test Example 1-5 was 0.72, and the absorbance of the infrared light cut filter of Test Example 1-6 was 0.30.

[0185] In this way, it was found that the heat resistance of the infrared light cut filter can be improved by having the first repeating unit in the copolymer have a cyclic ether group and the second repeating unit have a phenolic hydroxyl group, which is a functional group that reacts with the cyclic ether group.

[0186] From the above results, it was found that in the copolymer, the first repeating unit has a cyclic ether group and the second repeating unit has a functional group that reacts with the cyclic ether group, thereby achieving both resistance to stripping solutions and heat resistance of the infrared light cut filter.

[0187] [Test Example 2] In Test Example 2, 11 types of infrared cut filters were obtained by using the copolymers of Production Examples 2-1 to 2-11 in the same manner as in Test Example 1. The absorbance of each infrared cut filter was calculated using the method described above before the test, after the peeling solution resistance test, and after the heat resistance test. When producing the infrared cut filters of each Test Example, the infrared cut filter used in the peeling solution resistance test described below and the infrared cut filter used in the heat resistance test were produced separately.

[0188] [Evaluation method] Absorbance spectra were obtained for the infrared cut filters of Test Examples 2-1 to 2-11 using the same method as in Test Example 1. Furthermore, a test of resistance to a peeling solution and a test of heat resistance were performed on the infrared cut filters of Test Examples 2-1 to 2-11 using the same method as in Test Example 1. Then, an absorbance spectrum was obtained for the infrared cut filters after each test using the same method as in Test Example 1.

[0189] [Evaluation results] The absorbance of the infrared cut filters of Test Examples 2-1 to 2-11 was calculated, and the results are shown in Table 4. In each test example, the absorbance before the test of the infrared cut filter prepared for the peeling solution resistance test was found to be the same as the absorbance before the test of the infrared cut filter prepared for the heat resistance test.

[0190] [Table 4]

[0191] As shown in Table 4, the absorbance before the resistance test in Test Examples 2-1 to 2-9 was found to be 0.96. In contrast, the absorbance before the resistance test in Test Example 2-10 was found to be 0.68, and the absorbance before the resistance test in Test Example 2-11 was found to be 0.59.

[0192] As described above, the absorbance at 950 nm of the infrared cut filter before the test was found to be 0.8 or more in Test Examples 2-1 to 2-9. In contrast, the absorbance at 950 nm of the infrared cut filter before the test was found to be less than 0.8 in Test Examples 2-10 and 2-11.

[0193] That is, it was found that when the proportion of the third repeating unit in the copolymer is 65% by weight or more, the infrared cut filter favorably maintains the spectral characteristics before the test.

[0194] Furthermore, after the peeling resistance test, the absorbance of the infrared cut filter of Test Example 2-1 was 0.02, and the absorbance of the infrared cut filter of Test Example 2-2 was 0.85. The absorbance of the infrared cut filter of Test Example 2-3 was 0.82, and the absorbance of the infrared cut filter of Test Example 2-4 was 0.72. The absorbance of the infrared cut filter of Test Example 2-5 was 0.30, and the absorbance of the infrared cut filter of Test Example 2-6 was 0.05.

[0195] The absorbance of the infrared cut filter of Test Example 2-7 was 0.85, the absorbance of the infrared cut filter of Test Example 2-8 was 0.80, and the absorbance of the infrared cut filter of Test Example 2-9 was 0.72. In addition, the absorbance of the infrared cut filter of Test Example 2-10 was 0.64, and the absorbance of the infrared cut filter of Test Example 2-11 was 0.55.

[0196] Thus, the absorbance at 950 nm of the infrared cut filter after the stripping solution test was found to be 0.7 or more in Test Examples 2-2 to 2-4 and Test Examples 2-7 to 2-9. In contrast, the absorbance at 950 nm of the infrared cut filter after the stripping solution test was found to be less than 0.7 in Test Examples 2-1, 2-5, 2-6, 2-10, and 2-11.

[0197] In other words, it was found that the resistance of the infrared light cut filter to stripping solutions is improved when the proportion of the first repeating unit in the copolymer is 7.5% by weight or more and 17.5% by weight or less, and the ratio of the second repeating unit to the weight of the first repeating unit is 1.0 or more and 3.0 or less.

[0198] Furthermore, as shown in Table 4, after the heat resistance test, the absorbance of the infrared light cut filter of Test Example 2-1 and the infrared light cut filter of Test Example 2-2 was 0.80, and the absorbance of the infrared light cut filter of Test Example 2-3 was 0.82. The absorbance of the infrared light cut filter of Test Example 2-4 and the infrared light cut filter of Test Example 2-5 was 0.80, and the absorbance of the infrared light cut filter of Test Example 2-6 was 0.82. The absorbance of the infrared light cut filter of Test Example 2-7 was 0.72, and the absorbance of the infrared light cut filter of Test Example 2-8 and the infrared light cut filter of Test Example 2-9 was 0.80. Furthermore, the absorbance of the infrared light cut filter of Test Example 2-10 was 0.40, and the absorbance of the infrared light cut filter of Test Example 2-11 was 0.21.

[0199] Thus, it was found that the absorbance at 950 nm of the infrared cut filter after the heat resistance test was 0.7 or more in Test Examples 2-1 to 2-9. In contrast, it was found that the absorbance at 950 nm of the infrared cut filter after the heat resistance test was less than 0.7 in Test Examples 2-10 and 2-11. That is, it was found that the heat resistance of the infrared cut filter was maintained when the ratio of the weight of the first repeating unit to the weight of the second repeating unit was in the range of 0.5 to 5.0, and that the heat resistance was improved by having the third repeating unit be 65 wt % or more.

[0200] As described above, according to one embodiment of the infrared light cut filter, the filter for a solid-state imaging device, the solid-state imaging device, and the method for manufacturing a filter for a solid-state imaging device, the following effects can be obtained.

[0201] (1) A crosslinked structure is formed by crosslinking the cyclic ether group of the first repeating unit with a functional group reactive with the cyclic ether group of the second repeating unit. This prevents the transmittance of the infrared cut filter 13 from changing due to heating and also prevents the infrared light-absorbing dye from leaching into the stripping solution used during dry etching. As a result, the heat resistance and resistance to the stripping solution of the infrared cut filter 13 can be improved.

[0202] (2) It is preferable that the monomer containing a cyclic ether group contains at least one of an epoxy group and an oxetanyl group from the viewpoint of the reactivity between the cyclic ether group and a functional group reactive with the cyclic ether group contained in the second repeating unit.

[0203] (3) The acidity of the functional group that reacts with the cyclic ether group makes it possible to prevent the crosslinking reaction from proceeding immediately at room temperature during the resin polymerization process. (4) Because phenolic hydroxyl groups exhibit weak acidity, crosslinking reactions with cyclic ether groups are unlikely to occur during the resin polymerization process, but are likely to occur during the heating process when forming a coating film. Therefore, phenolic hydroxyl groups are advantageous in terms of coatability.

[0204] (5) The aromatic or alicyclic group of the third repeating unit is located between the cyanine dye and another cyanine dye located nearby, thereby creating a distance between the cyanine dyes that is sufficient to prevent the cyanine dyes from associating with each other, thereby suppressing changes in the spectral characteristics at wavelengths where absorption by the cyanine dyes is expected.

[0205] (6) By the copolymer containing the first repeating unit and the second repeating unit in the above-mentioned ranges, the decrease in the absorbance of infrared light in the infrared cut filter 13 after the heat treatment and the stripping solution treatment is suppressed.

[0206] (7) When the copolymer contains the third repeating unit at a ratio of 65% by mass or more, the deterioration of the spectral characteristics of the infrared cut filter 13 at wavelengths where absorption by the cyanine dye is expected is suppressed.

[0207] (8) If the glass transition temperature of the copolymer is 75° C. or higher, it is possible to more reliably suppress changes in the transmittance of infrared light when the infrared cut filter 13 is heated.

[0208] (9) If the average molecular weight of the copolymer is 30,000 or more and 150,000 or less, it is possible to increase the reliability of suppressing changes in the transmittance of infrared light when the infrared cut filter 13 is heated.

[0209] (10) When the residual monomer content is 20% or less, the infrared light transmittance of the cyanine dye is less likely to change when the infrared cut filter is heated, compared to when the residual monomer content is more than 20%.

[0210] (11) The barrier layer 14 prevents the oxidizing source from reaching the infrared cut filter 13, so that the infrared cut filter 13 is less likely to be oxidized by the oxidizing source.

[0211] [Example of change] The above-described embodiment can be modified as follows. [Barrier layer] The barrier layer 14 is not limited to being disposed between the infrared cut filter 13 and the microlenses 15R, 15G, 15B, and 15P, but may be disposed on the outer surface of each of the microlenses 15R, 15G, 15B, and 15P.

[0212] The solid-state imaging device 10 may include an anchor layer between the barrier layer 14 and the layer below the barrier layer 14. In this case, the anchor layer improves adhesion between the barrier layer 14 and the layer below the barrier layer 14. The solid-state imaging device 10 may also include an anchor layer between the barrier layer 14 and the layer above the barrier layer 14. In this case, the anchor layer improves adhesion between the barrier layer and the layer above the barrier layer. The anchor layer may be formed from a material such as a polyfunctional acrylic resin or a silane coupling agent.

[0213] The layer structure of the barrier layer 14 may be a single layer structure made of a single compound, a laminated structure of layers made of a single compound, or a laminated structure of layers made of different compounds.

[0214] The barrier layer 14 may function as a planarizing layer that fills in the step formed by the surface of the infrared cut filter 13 and the surface of the infrared pass filter 12P. The filter 10F for solid-state imaging devices does not have to have the barrier layer 14. Even in this case, it is possible to obtain the effect equivalent to the above-mentioned (1).

[0215] [others] The thickness of each of the color filters 12R, 12G, and 12B may be equal to or different from that of the infrared pass filter 12P. The thickness of each of the color filters 12R, 12G, and 12B may be, for example, 0.5 μm or more and 5 μm or less.

[0216] The color filter may be a three-color filter consisting of a cyan filter, a yellow filter, and a magenta filter. Alternatively, the color filter may be a four-color filter consisting of a cyan filter, a yellow filter, a magenta filter, and a black filter. Alternatively, the color filter may be a four-color filter consisting of a transparent filter, a yellow filter, a red filter, and a black filter.

[0217] The color filters 12R, 12G, and 12B may have the same thickness as the infrared pass filter 12P, or may have different thicknesses. The thickness of each of the color filters 12R, 12G, and 12B may be, for example, 0.5 μm or more and 5 μm or less.

[0218] The material forming the infrared light cut filter 13 may contain additives that perform other functions, such as a light stabilizer, an antioxidant, a heat stabilizer, and an antistatic agent. The solid-state imaging device 10 has an oxygen permeability of 5.0 cc / m2 in the laminated structure located on the side of the incident surface 15S with respect to the infrared cut filter 13. 2 For example, the laminated structure may be a functional layer such as a planarization layer or an adhesion layer, and may have an oxygen permeability of 5.0 cc / m 2 together with each microlens. 2 It may be less than / day / atm.

[0219] The solid-state imaging element 10 may include a bandpass filter on the light incident side of the multiple microlenses. The bandpass filter transmits only light having specific wavelengths of visible light and near-infrared light, and has a similar function to the infrared light cut filter 13. That is, the bandpass filter can cut out unnecessary infrared light that may be detected by the color photoelectric conversion elements 11R, 11G, and 11B. This improves the detection accuracy of visible light by the color photoelectric conversion elements 11R, 11G, and 11B, as well as the detection accuracy of near-infrared light having wavelengths in the 850 nm or 940 nm band that is the target of detection by the infrared photoelectric conversion element 11P. [Explanation of symbols]

[0220] 10...Solid-state image sensor 10F...Solid-state image sensor filter 11...Photoelectric conversion element 12R...Red filter 12G...Green filter 12B...Blue filter 12P...Infrared light pass filter 13...Infrared light blocking filter 13H...Through hole 14...Barrier layer 15B...Blue microlens 15G...Green microlens 15P...Infrared light microlens 15R...Red microlens

Claims

1. a cyanine dye comprising a polymethine, a cation having two nitrogen-containing heterocycles, one at each end of the polymethine, and tris(pentafluoroethyl)trifluorophosphate; an infrared light cut filter comprising: a copolymer represented by the following formula (1), the copolymer comprising a first repeating unit derived from an acrylic monomer containing a cyclic ether group, and a second repeating unit derived from a monomer containing a functional group reactive with the cyclic ether group; a photoelectric conversion element; Solid-state imaging element. 【Chemistry 1】 In formula (1), R1 is a hydrogen atom or a methyl group, R2 is a single bond, a linear alkylene group having one or more carbon atoms, or a branched alkylene group having three or more carbon atoms, and R3 is a cyclic ether group containing an oxygen atom and two or more carbon atoms.

2. The monomer containing a cyclic ether group contains at least one of an epoxy group and an oxetanyl group. The solid-state imaging device according to claim 1 .

3. The monomer containing a functional group reactive with the cyclic ether group exhibits acidity.

3. The solid-state imaging device according to claim 1.

4. The functional group that reacts with the cyclic ether group is a phenolic hydroxyl group. The solid-state imaging device according to claim 1 .

5. The copolymer contains a third repeating unit derived from an acrylic monomer having an aromatic ring represented by the following formula (2): The solid-state imaging device according to claim 1 . 【Chemistry 2】 In formula (2), R4 is a hydrogen atom or a methyl group, and R5 is a single bond, a linear alkylene group having 1 or more carbon atoms, or a branched alkylene group having 3 or more carbon atoms. R6 is a hydrogen atom or a predetermined substituent. In formula (2), when R6 is a substituent, m is an integer from 1 to 5.

6. The copolymer contains a third repeating unit derived from an acrylic monomer having an alicyclic structure represented by the following formula (3): The solid-state imaging device according to claim 1 . 【Transformation 3】 In formula (3), R7 is a hydrogen atom or a methyl group, R8 is a single bond, a linear alkylene group having 1 or more carbon atoms, or a branched alkylene group having 3 or more carbon atoms, and R9 is an alicyclic structure having 3 or more carbon atoms.

7. The copolymer contains 7.5% by weight or more and 17.5% by weight or less of the first repeating unit, and the ratio of the weight of the second repeating unit to the weight of the first repeating unit is 1.0 or more and 3.0 or less; The solid-state imaging device according to claim 1 .

8. The copolymer contains 65% by weight or more of the third repeating unit.

7. The solid-state imaging device according to claim 5.

9. A visible light filter; an infrared light pass filter; The solid-state imaging device according to claim 1 .

10. The oxygen permeability of the laminated structure located on the incident surface side of the infrared light cut filter is 5.0 cc / m ２ / day / atm or less The solid-state imaging device according to claim 1 .

11. Equipped with a bandpass filter that transmits only light with specific wavelengths of visible light and near-infrared light The solid-state imaging device according to claim 1 .

Images